Search

Blast furnace slag glass–ceramics were prepared by melting using rare-earth-containing blast furnace slag (REBFS) as the main raw material and Fe 2 O 3 and Cr 2 O 3 as composite nucleating agents. By adding different TiO 2 contents, the study comprehensively revealed the effects of high field strength ions on the glass network structure, crystalline properties, elemental distribution and physicochemical properties. Raman spectroscopy and differential scanning calorimetry revealed that TiO 2 acted primarily as a network modifier in the glass network. The appropriate TiO 2 content disrupted the glass network, decreasing the crystallization activation energy (E C) of the glass–ceramic. However, excess TiO 2 repaired the network structure, thereby increasing the E C. The combined effect of the Cr and Ti substantially improved the crystallization characteristics of the glass-ceramics. Cr 2 O 3 induced the formation of spinel, which promoted the crystallization of the main crystalline augite phase. The self-aggregation of the high field strength Ti4+ ion induced the formation of a titanium- and cerium-containing titanite phase, which also contributed to grain refinement. This titanite phase effectively increased the Vickers hardness and acid and alkali resistances of the glass-ceramics to 9.16 GPa and over 98.5 %, respectively. The excellent physicochemical properties render REBFS glass–ceramics as being promising materials for various construction applications. This research provides theoretical support for comprehensively utilizing blast furnace slag and provides theoretical guidance for preparing slag glass–ceramics possessing desirable physicochemical properties. [ABSTRACT FROM AUTHOR]

A comparative study on three types of fireproofing coatings (namely, cementitious, sodium silicate, and epoxy) was made to determine their effectiveness in protecting steel structures. The effects of these coatings on the external protection of steel were structurally, thermally, and mechanically studied. The prepared cementitious coatings endured the heat until 1200 °C for 1 h showing dimensions stability without deformation nor cracking during firing. Both crushing strength (CS) and bulk density measurements decreased from 69 to 18 kg/cm2 and from 1.62 to 1.00 g/cm3 'respectively' with increasing both perlite and vermiculite percentages. Six of the prepared 48 sodium silicate and epoxy coatings succeeded in bearing heat until 900 °C for 3.5 h sustaining the steel substrates' temperature below 60 °C following the Underwriters Laboratory-94 (UL-94) standard. This protective effect was due to the formation of a hard glassy phase on the steel surface isolating it from the heat by the action of the applied constituents. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) thermograms for these succeeded samples revealed that they gave a high residual weight ranging from 63 to 88% when tested from room temperature up to 900 °C. Performing the scanning electron microscopy (SEM) test revealed that physical blending between both the binder and additives (other coating ingredients') has occurred. The results concluded that the used ingredients, which have low prices, compared to the imported ones, and are locally available, are recommended for the fire protection of steel. [ABSTRACT FROM AUTHOR]

This study reports on the successful synthesis of Zn 2 P 2 O 7 glass using the conventional melt-quenching method. The state of the material has been investigated using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC), to verify its amorphous and glassy state with the onset of two distinct crystallization peaks. These peaks were indicative of the transition to α-Zn 2 P 2 O 7 and γ-Zn 2 P 2 O 7 phases during the annealing process, a finding that was supported by Fourier-transform infrared spectroscopy (FTIR) analysis. This marked the inaugural occasion where the stabilization of both Zn 2 P 2 O 7 phases from their respective annealed glassy state was achieved. The crystallization kinetics and associated parameters of Zn 2 P 2 O 7 glass were deeply delved into, with various models including Kissinger, Ozawa, and the Matusita-Sakka approach. The applied models elucidate the mechanisms of growth and nucleation within the glass matrix. This kinetic study provided valuable insights into the crystallization process, revealing that α-Zn 2 P 2 O 7 is both kinetically and thermally more stable than the γ-phase. However, it is less thermodynamically stable compared to the γ-phase. Besides, the study of phase transformations and crystallization kinetics was enhanced by the analysis of the Avrami index. [ABSTRACT FROM AUTHOR]

This research aimed to create a new Li metasilicate-based glass-ceramic for dental use, prioritizing improved chemical durability (CD) and machinability while preserving good glass-forming ability (GFA) and adequate mechanical properties. Characterization also involved examining fracture strength (S f) and fracture toughness (K IC). The experimental approach involved precise microstructural adjustments through designed compositional changes and controlled thermal treatments. Four compositions underwent scrutiny using mechanical tests, microscopy, differential scanning calorimetry, and X-ray diffraction to analyze the impact of lithium metasilicate (LS) and disilicate (LS2) crystals on these properties. Machinability was evaluated by weight loss measurements during controlled grinding experiments. The developed GCs exhibited interconnected acicular LS and LS2 crystals, which resulted in favorable S f ∼300 MPa and K IC ∼1.7 MPa m1/2 (SEVNB). Although the K IC was smaller than that of an experimental LS-LS2 GC (285 MPa and 3 MPa m1/2(double torsion)) used as a reference, the chemical durability (126 μg/cm2 for ML14F GC) improved by nearly 50 % compared to the reference (∼220 μg/cm2). This study introduced three new GCs with LS as the major phase (rather than the traditional LS2), showcasing commendable GFA, chemical durability and machinability, with satisfactory flexural strength and fracture toughness. [ABSTRACT FROM AUTHOR]

Ho3+-Yb3+ co-doped glass ceramics containing LiGd(WO 4) 2 were prepared by melt crystallization method. By using the methods of differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmittance, and scanning electron microscopy (SEM), the optimal heat treatment condition for the samples was identified to be 580 °C/140 min. In these conditions, the transmittance of glass ceramic is about 75 % in the 380–780 nm range. In the upconversion emission spectra, strong green emission (543 nm) and red emission (650 nm) due to 5F 4 /5S 2 , 5F 5 →5I 8 transitions are observed at 980 nm excitation. Additionally, the optimum doping concentrations of Ho3+ and Yb3+ were 0.12 % and 0.4 %. The crystal field changes around dopant ions were analyzed using J-O theory and Eu3+ probe to explain the up-conversion luminescence enhancement of glass ceramics containing LiGd(WO 4) 2. The chrominance coordinates of 0.12 % Ho3+-0.4 % Yb3+ co-doped glass ceramics are located in the green light region, and the color purity is 95.6 %. In summary, Ho3+-Yb3+ co-doped transparent glass ceramics containing LiGd(WO 4) 2 have potential applications in infrared detection and green solid-state lasers. [ABSTRACT FROM AUTHOR]

Metallic substances are favored for storing and transporting spent nuclear fuels (SNFs) due to their thermal stability, mechanical strength, and corrosion resistance. Adding gadolinium (Gd) significantly enhances neutron shielding, improving efficiency with reduced thickness and dimensions. In this study, Al–Gd 2 O 3 metal nanocomposites were synthesized using powder-processed mechanical milling. The crystal structure features of (100-x)Al-x%Gd 2 O 3 samples with varying percentages of Gd 2 O 3 (5 %, 10 %, and 15 % by weight) were analyzed by X-ray diffraction. Microstructural properties were studied using scanning and transmission electron microscopy (SEM and TEM). The synthesized composites' neutron and γ-radiation shielding characteristics were investigated theoretically using the MCNP6.2 transport code. Analysis of the XRD data revealed prominent peak shifts with increased milling time, indicating reduced particle sizes. Differential scanning calorimetry (DSC) indicated Gd 2 O 3 -induced changes in temperature behavior, and the Vickers microhardness tests demonstrated enhanced mechanical strength with increasing gadolinium concentration. Improved neutron radiation shielding was observed with higher Gd 2 O 3 content. Our study highlights the potential of Gd 2 O 3 -enriched metal matrix composites for advanced industrial applications. [ABSTRACT FROM AUTHOR]

Temperature and pressure are two effective methods to tune the structure and luminescence properties of phosphors. In this study, tetragonal K 3 AlF 6 : Cr3+ phosphors were synthesized through the solid-state method. Its structure stability and luminescence property were in situ studied under temperature and pressure using differential scanning calorimetry (DSC), Raman, and photoluminescence spectra. At ambient conditions, one broadband emission presented in the 1.3–1.9 eV range due to the 4T 2 →4A 2 transition. Three phase transitions presented with increasing temperature to 400 °C, but no much change was observed for its luminescence property. In contrast, its structure was stable during compression, and no phase transition was observed up to 26.1 GPa. Furthermore, the crystal field around Cr3+ was enhanced under pressure, leading to its luminescence changing from broad 4T 2 →4A 2 emission to narrow 2E→4A 2 emission above 4.2 GPa. It was suggested that pressure was more effective for K 3 AlF 6 :5%Cr3+ phosphor. This result provides one effective method to modulate the luminescence property of Cr3+. [ABSTRACT FROM AUTHOR]

Developing sophisticated lithium-ion batteries with high energy and power density requires using high-voltage positive electrodes. Due to its three-dimensional lithium-ion diffusion and greater nominal operating voltage, spinel LiNi 0.5 Mn 1.5 O 4 has emerged as one of lithium-ion batteries' most viable cathode materials. Electrolyte breakdown, Mn dissolution, and rapid cathode-electrolyte interface (CEI) degradation in lithium-ion cells are exacerbated by the high operating voltage of LNMO. Consequently, the long-term cycling of LNMO is hampered by such adverse side effects, making the commercialization of such a battery impractical. Here, we document the enhancement in the electrochemical performance of LNMO by surface modification utilizing a combination of Al 2 O 3 coating and Graphene enveloping employing a facile wet synthesis technique. The presence of highly crystalline spherical secondary microspheres consisting of primary nanoparticles of disordered LiNi 0.5 Mn 1.5 O 4 , the surface modification with Al 2 O 3 , and the subsequent graphene wrapping were all confirmed by structural and surface analysis techniques. The fabricated cells containing the enhanced cathode material (LNMO-Al-GO) were cycled at a C/10 rate for 100 cycles in a voltage window of 3.5–4.9 V, providing a specific discharge capacity of 134.7 ± 3.8 mAhg−1. Delivering a capacity retention of 97.7 ± 3.9% compared to the unmodified LNMO sample (84.7 ± 5.3%). Ex-situ XRD, Electrochemical Impedance Spectroscopy (EIS), and Differential Scanning Calorimetry (DSC) investigations reveal that the alumina coating protects the cathode by acting as a hydrogen fluoride (H.F.) scavenger and minimizes unfavorable phase formations at the CEI, inhibiting Mn3+ dissolution and enhancing cyclability. [ABSTRACT FROM AUTHOR]

Solid waste-based lightweight glass ceramics aroused a great deal of attention with the introduction of green building materials. This material demonstrated high performance while alleviating the pressure of waste accumulation. Lightweight glass ceramic was fabricated from phosphorus tailings and coal gangue as raw materials in this work. The effects of phosphorus tailing ratios (50 wt.% - 100 wt.%) and heat-treatment temperatures (1130 °C – 1170 °C) on the pore morphology, properties and toxicity evaluation of lightweight glass ceramics were investigated. Differential Scanning Calorimetry (DSC), and Thermogravimetric mass spectrometry (TG-MS) tests were performed to characterize the sintering behavior of lightweight glass ceramics. The research found that Fe 2 O 3 in the phosphorus tailings and C and FeS 2 within the coal gangue achieve in-situ foaming by creating the gas at elevated temperatures. Results revealed that increasing the proportion of phosphorus tailings facilitated the generation of the molten glassy phase, which favored the formation of bubbles and the expansion of pores. The average pore size of lightweight glass ceramics enlarged from 15.33 μm to 75.02 μm upon increasing the amount of phosphorus tailings from 50 wt.% to 100 wt.%. Increasing the amount of the glassy phase could be achieved by adjusting the heat-treatment temperature. This not only formed a protective film preventing water penetration into the interior of the lightweight glass ceramics but also effectively protected them from corrosion by acidic and alkaline solutions. The water absorption dropped dramatically from 16.44 % to 3.63 % and the corrosion resistance was greater than 98 % when the temperature rose from 1130 °C to 1170 °C. From the toxicity evaluation, the leaching toxicity of Cr, Cu, Pb and Zn in lightweight glass ceramics was 4 orders of magnitude below the limiting value and an extremely low potential ecological risk index (RI = 3.32) was obtained. The optimal preparation parameters were phosphorus tailings addition of 80 wt.% and a heat-treatment temperature of 1160 °C. The corresponding porosity, bulk density, compressive strength, water absorption, acid resistance and alkali resistance were 51.29 %, 1.38 g/cm3, 10.62 MPa, 4.81 %, 98.63 % and 99.96 %. The findings of the research offered a feasible solution for the development of novel green building materials, simultaneously reducing the environmental hazards of solid wastes. [ABSTRACT FROM AUTHOR]

In this research, we produced ochre/yellow pigments of YIn 0.9 Fe 0.1 O 3 , combined with ZnO pigments, through a citrate-assisted sol-gel approach. We investigated the impact of varying ZnO addition methods (incorporated into the sol-gel bath and physically mixed with YIn 0.9 Fe 0.1 O 3 pigments) on their color properties, near-infrared (NIR) reflectance and photocatalytic activity. The effect of the different ZnO addition methods was investigated on pprecursors and final calcined pigments through X-ray diffraction (XRD), Vis-NIR reflectance, Fourier transform infrared spectroscopy (FT-IR) Scanning Electron Microscope (SEM) and thermal analyses such as thermogravimetry (TGA), and differential scanning calorimetry (DSC). The synthesized nanocomposites were evaluated for their photocatalytic characteristics by examining the degradation of 4-Nitrophenol (4-NP) when exposed to UV radiation. The potential environmental applications of the pigments were investigated not only for direct pollutant degradation but also in terms of energetic sustainability. In fact, the developed pigments can be employed as passive cooling materials to mitigate the temperature of buildings, thus dramatically reducing energy consumption. For this reason, the pigments were embedded into a polymeric binder and coated onto roofing aluminum sheets. The obtained coatings were investigated in terms of NIR reflectance and heat adsorption. The photocatalytic ability of the coatings was assessed by the degradation of 4-NP and methylene blue (MB) under xenon arc lamp. The results obtained indicate the feasibility of producing a pale yellow pigment with both NIR reflectance and photocatalytic capabilities. [ABSTRACT FROM AUTHOR]

The reaction pathways and phase transitions during primary magnesium production via silicon reduction of CaO·MgO under vacuum conditions were examined using thermodynamic calculations, X-ray diffraction (XRD), electron probe microanalyzer scanning (EPMA), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analysis. The findings suggest that the actual chemical reaction involves Si interacting with CaO in dolime to form CaSi 2 , which subsequently serves as a reducing agent to reduce MgO, resulting in magnesium vapor. Solid–solid reactions occur in pellets at temperatures below 1028 °C, whereas solid–liquid reactions take place above this temperature. The solid–liquid reaction notably enhances the reaction rate. In addition, the limited hydration reactivity of the slag from the silicothermic process is attributable to the formation of large MgO particles through the solid–liquid reaction. [ABSTRACT FROM AUTHOR]

The effect of Ta 2 O 5 at the rates of 1, 2, 3 and 4 % mol on the CaO–SrO–B 2 O 3 –Al 2 O 3 –Bi 2 O 3 –SiO 2 glass system was examined by the melt-quenching at 1400 °C. Non-isothermal crystallization kinetics of the compounds were calculated using Differential Scanning Calorimetry (DSC). The kinetics study revealed activation energy values of 109.4 kJ/mol for the T1 composition, 302.14 kJ/mol for the T2 composition, 471.5 kJ/mol for the T3 composition, and 344.7 kJ/mol for the T4 composition, as determined by applying the Kissinger method. According to the average of Avrami parameters, two-dimensional crystal growth was observed in T1 glass and surface crystallization was observed in all other glass. The glass forming ability (GFA) of the glasses was investigated with the values obtained as a result of HSM analysis. In the XRD analysis performed after heat treatment at 850 °C, crystal phase development was observed in the glasses. As a result of the crystallization process, it was observed that wollastonite, strontium aluminum silicate, strontium aluminum oxide and bismuth oxide phases were formed in T1, T2 and T3 glasses. [ABSTRACT FROM AUTHOR]

Easy-to-manufacture photosensitive glass ceramics are vital for wide applications due to their superior thermal, mechanical and chemical properties from an industrial point of view, while their commercialization is strongly limited by the complex effect of material compositions and thermal treatments. Here, the effect of SiO 2 /Li 2 O content on structure and physicochemical properties of photosensitive glass-ceramics was systematically investigated. The photosensitive glass-ceramics were prepared using a melting method based on the Li 2 O–Al 2 O 3 –SiO 2 glass system. The effect of each component content on dielectric constant, dielectric loss and etching properties of the basic glass was studied. The relationship between the structure and properties of photosensitive glass-ceramics before and after crystallization were investigated via differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Raman spectroscopy measurements. The results show that when the SiO 2 /Li 2 O ratio is 76.5/9, the chemical stability of the basic glass is the highest, whereas the etching loss rate is the lowest. After UV exposure and heat treatment, acid-soluble Li 2 SiO 3 crystals were formed inside the glass-ceramic matrix. Compared with the unexposed part, the etching ratio of the photosensitive glass-ceramic reaches its maximal value of 16/1. It is worth mentioning that after heat treatment, the dielectric constant and dielectric loss of the unexposed photosensitive glass-ceramic are slightly higher than those of the basic glass, reaching 6.67 and 5.78 × 10−3 (@1 GHz), respectively. Finally, after acid etching, photosensitive glass-ceramic is exposed via mask exposure and heat treatment to obtain holes with a diameter of 50–60 μm, which can be used as a substrate material in many fields such as communication, aerospace, biomedical and so on. [ABSTRACT FROM AUTHOR]

β -relaxation has been a universal behavior in various glasses with bond kinds of covalent and metallic, as well as the metavalent, which is the typical bonding of chalcogenide phase-change materials (PCMs). Recently, the fragile-to-strong (F–S) transition kinetics has been a significant feature in supercooled liquids of PCMs, to alleviate the contradiction between good thermal stability nearby glass transition temperature and fast crystallization speed around melting temperature. By analyzing the results from the measurements of powder mechanical spectroscopy and flash differential scanning calorimetry, in this work, we revealed the link between β -relaxation and F–S crystallization kinetics in GeTe-GeSe chalcogenide glass system. It was found a positive correlation between β -relaxation and F–S transition, which is accompanied by the results of resistance drift, crystallization temperature, as well as the maximum crystal growth rate. However, the GeTe component, which has large β -relaxation behavior but no F–S transition, does not obey the positive correlation because of the large activation energy of α -relaxation. These findings are expected to build a foundation and illustrate the microscopic mechanism between F–S crystallization kinetics and β -relaxation behavior in chalcogenide glasses. [ABSTRACT FROM AUTHOR]

Er3+ doped high density germanate glasses with compositions of 50GeO 2 -10BaO–10Al 2 O 3 -15Lu 2 O 3 -(15-x) La 2 O 3 -xEr 2 O 3 (x = 0, 0.1, 0.5, 1.0, 1.5, and 2.0, in mol%) have been prepared by the melt-quenching method. The optical and physical properties of the samples were characterized by differential scanning calorimetry (DSC), density, transmittance spectra, photoluminescence (PL) spectra, and X-ray excited luminescence (XEL) spectra. The densities were in the range from 5.90 to 6.07 g/cm3. The strong green emissions around 552 nm of Er3+ were observed upon the excitations of 378 nm light and the X-ray, and the lifetimes of 552 nm emission were in the range of 20.88–96.47 μs. The results show that Er3+ doped high density germanate glasses could be used as potential scintillators for X-ray CT. [ABSTRACT FROM AUTHOR]

Though phase-change materials (PCMs) are regarded as constituent part of next-generation phase-change memory and other unfolding optoelectronic applications, the kinetics study of glass transition and crystallization, significant property in switching remains obscure in high-temperature region. Hence, this paper reports the investigation of glass transition and crystallization kinetics of Te (1-x) (GeSe 0.5)Y x (TGSY) chalcogenide glass using differential scanning calorimetry (DSC) at heating rates 5, 10, 15, 20 °C/min. The effect of increasing Y quantity has been described by connecting structural relaxation kinematics during glass transition phenomena and devitrification while crystallization in chalcogenide glasses with their varied physicochemical characteristics. The inclusion of Y causes a discernible rise in the crystallization rate. The system is compatible with a strong glass-forming liquid, according to the Te (1-x) (GeSe 0.5) Y x material fragility index. According to the average values of the kinetic exponent factors, there is heterogeneous nucleation for the investigated composition, which is subsequently followed by a two- or three-dimensional crystal growth phenomenon. Different glass stability criteria have been discussed based on the relationship between the characteristic temperatures. The C ZW and C LX criteria were found to be inappropriate for discussing glass stability (GS) for the studied compositions based on the heating rate and composition dependencies of all criteria. The C YL criteria of Yuan et al. is the finest and it demonstrates the optimal ability for evaluating the GS, according to the data that was extracted from several GS criteria and their relative change parameters. By adding Y, thermal stability parameter and enthalpy emitted during the transition of glass and crystalline phases have been found to have an inverse relationship. All studied properties can conclude the application of studied material in phase-change material devices. [ABSTRACT FROM AUTHOR]

New glass samples were synthesized from the binary system LiF. PbO with different ratiosby the traditional melt-quenching technique. The corresponding glass-ceramics were formed by heat treating the prepared glasses. Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Transmission electron microscope (TEM) were employed to study the structure of the samples; while characterization of the glass and glass-ceramics were studied using photoluminescence (PL) spectral analysis, electrical, UV–Visible absorption, optical band gap and hardness measurements. The ability to form glass was increased with increase PbO content (1LiF:≥5PbO). Tetragonal and orthorhombic PbO, orthorhombic and monoclinic Pb 2 O 3 , α-PbF 2 and traces of both Li 4 PbO 4 , PbO 1.37 were crystallized under specific heat-treatment circumstances as identified by XRD analysis. The crystal size decreased with increasing the PbO content; it reaches ∼15 nm in case of 10 Pb. PL revealed concentration quenching in glass with 10 Pb, a red shift and enhancement of bands intensity were observed with decrease λ ex , increase heat-treatment temperature and increase PbO concentration. The UV–Visible absorption elucidated that the cutoff wavelength (λ) was shifted toward lower wavelength (blue shift) by increasing PbO content and the values of optical band gap energies recorded 2.69, 2.66 and 2.72 eV for LiF·5PbO, LiF·8PbO, and LiF·10PbO, respectively. The electrical properties recorded conductivity ∼1.2 × 10−6 S m−1 and dielectric constant ∼ 46.8. These characteristics suggests that, the prepared materials exhibited semiconducting and photoluminescence behavior nominated it to be utilized in solar cell applications. [ABSTRACT FROM AUTHOR]

This study reports on the properties of glasses and glass-ceramics isolated in a novel ternary system Na 2 O–NiO-(1-x)P 2 O 5 –xV 2 O 5 with varying concentrations of V 2 O 5 (x = 0, 0.2, 0.4, and 0.6 mol%). The materials were prepared by melting the mixture of reagents with stoichiometric proportions. Their amorphous and crystalline nature was confirmed via the XRD analysis. The vitreous feature and thermal parameters of the glasses were explored using differential scanning calorimetry. The density values have shown an increase and a slight decrease in the molar volume with the increase in the V 2 O 5 content. The elemental composition of the glass and glass-ceramics was studied using energy-dispersive X-ray spectroscopy. In addition, the study examined the influence of the composition on the structure of the materials using both IR and Raman spectroscopies. XRD analysis of annealed samples revealed the presence of different crystalline phases depending on the V 2 O 5 content. The EPR results were influenced by the variation of concentration of V 2 O 5 and indicated the presence of V4+ ions in octahedral sites with tetragonal compression. The analysis of the magnetization according to the magnetic field at different temperatures showed a ferromagnetic behavior at low temperatures and a paramagnetic one at higher temperatures for all glasses. Magnetic susceptibility data reveal a Curie-Weiss behavior and the predominance of antiferromagnetic interactions. The dielectric studies were conducted as a function of temperature and frequencies to evaluate the composition effect on the dielectric constant, dielectric loss, and ionic conductivity. Electrical features were also examined using impedance spectroscopy. [ABSTRACT FROM AUTHOR]

This manuscript reports a successful preparation of cold-sintered soft magnetic composites based on amorphous Co 68.18 Fe 4.32 Si 12.5 B 15 at.% fibres coated with BaTiO 3. The coating was achieved through two techniques hydrothermal and thermal evaporation. The amorphous fibres were characterised via X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and in-situ high temperature X-ray diffraction (HT-XRD). A new technique for the preparation of the fibres based soft magnetic composite is proposed consisting in wounding the fibres on a Teflon support and the application of a cold sintering process in an autoclave. The DC magnetic characterization of the composite compacts revealed that the compact based on fibres coated via the thermal evaporation coating technique exhibits superior magnetic properties (B s = 0.4 T, H c = 1.85 A/m, μ rmax = 49500) compared to the compact based on fibres coated via the hydrothermal method (B s = 0.34 T, H c = 2.31 A/m, μ rmax = 39200). The AC magnetic characterisation of the compacts showed that the magnetic relative permeability of both compacts is constant over the entire tested frequency range tested (50 Hz–10 kHz). The value of the magnetic relative permeability of the composite based on fibres coated via the thermal evaporation technique is around 1650 while for the compact based on hydrothermally coated fibres a value of only 850 was obtained. The total losses were also evaluated, the composite based on thermal evaporation-coated fibres exhibiting the lowest losses of 3.11 W/kg at the frequency of 10 kHz and induction of 0.1 T. The loss separation analysis highlighted that the main type of losses, especially at high frequency, depends on the technique used for the coating of the fibres. [ABSTRACT FROM AUTHOR]

A systematic experimental study of the Y 2 O 3 –Al 2 O 3 –SiO 2 (YAS) compositional system has been carried out with a focus on nanoparticle formation in the high SiO 2 region, where nanoscale phase separation occurs. The unique capabilities of the aerodynamic levitation coupled to the laser-heating method have been exploited and compared to conventional melt-quenching. This systematic study has mainly focused on the region where melting temperatures exceed 1700 °C, which is the maximum temperature commonly available for the preparation of glass by conventional melt-quenching. The feasibility and the effect of the two synthesis routes on the preparation of glass samples have been compared. The prepared samples were characterised by X-ray diffraction, differential scanning calorimetry, Raman spectroscopy, and scanning and transmission electron microscopy. It is evident from the results that in the part of the phase diagram with SiO 2 content above 65 mol% and simultaneously Y 2 O 3 content below 17.5 mol%, the phase separation has led to the formation of amorphous SiO 2 nanoparticles. It has been shown that the size and distribution of the nanoparticles can be controlled not only by the chosen technology but also by changing the starting composition. [ABSTRACT FROM AUTHOR]

Bioglasses are synthesized using the melt-quench technique using two different sources (biowastes and conventional chemicals). These glasses are characterized and tested using various experimental techniques such as X-ray diffraction, field emission-scanning electron microscopy, energy dispersive spectroscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and in-vitro testing in simulated body fluid (SBF). The physical parameters, such as the density of glass samples, are 2.7 ± 0.01 g/cm3 and tend to decrease with increased MgO in glass composition. The MgO increases the phase separation tendency in glasses and stabilizes the hydroxyapatite layer (HAp) with an optimized Ca/P ratio of 1.67. MgO retards the degradation of bioglasses in SBF due to its two different roles in silicate and phosphate structural units. The controlled dissolution rates present an exciting prospect for chemical interactions and accelerated osteointegration in bone regeneration, bone grafting, and many dental applications. [ABSTRACT FROM AUTHOR]

This work presents an easy applicable method for estimating thermal conductivity of oxide ceramic samples in a high-temperature SOFC/SOEC system. An experimental investigation establishes a thermal conductivity map for various oxide ceramics in the temperature range of 700 - 900 °C. Material specific properties are determined using laser flash analysis, displacement measurement for density and differential scanning calorimetry for heat capacity. The total thermal conductivity, incorporating conduction and radiation, is assumed based on a linear relationship with temperature gradient. Deviations in measurements are attributed to increasing radiation effects. The method provides a rough estimation of thermal conductivity, with 8YSZ exhibiting good agreement with literature values and 10Sc1CeSZ showing a range of 2.3 (+0.32/-0.48) - 2.8 (+0.96/-1) W/mK. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing has been used as a promising technology in biomedical sciences and engineering. However, there is a lack of ready-to-use feedstock for biomedical applications. In this work, a series of PLA biocomposite filled with calcium sulfate (CaS) particles up to a maximum content of 40 wt% has been prepared by solvent casting method and subsequently processed into filament form through the melt compounding method. The objective of this study was to investigate the processibility of composite filament with maximum ceramic content through fused filament fabrication (FFF) process to improve the mechanical, thermal and biological performance of virgin PLA for biomedical application. The composite filament was extruded at a temperature of 160 °C at a constant speed with an average diameter of 1.70 ± 08 mm, compatible with the 3D printer's feeding system. Morphological, thermal, mechanical, and crystallization analysis using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric (TGA) analysis was performed on the extruded filament to evaluate the effect of ceramic content in the polymeric matrix. The thermal stability was improved upon addition of CaS particles into the PLA matrix. Subsequently, PLA-CaS solid specimen was 3D-printed and characterized for its mechanical, and geometrical accuracy. The maximum compressive strength obtained is 115 MPa for 20% ceramic loading, which then decreases with increased ceramic content. The biocompatibility test using MC3T3E1 cells confirmed zero cytotoxicity and cell grows well on all PLA and composite specimen. The results revealed that the composite biomaterials could be easily printed even at high ceramic loading and maintain their structural integrity and stability during the additive manufacturing process. These composites could be potential candidates for various biomedical applications, such as bone scaffolds and bioresorbable screws for Anterior Cruciate Ligament (ACL) reconstruction. [Display omitted] [ABSTRACT FROM AUTHOR]

The stability and crystallizability of glasses K 2 O-B 2 O 3 -GeO 2 and K 2 O-B 2 O 3 -SiO 2 systems becomes an important consideration when selecting materials for optical purposes and the immobilization of radioactive wastes. To determine the crystallizability of boron-containing glasses, thermal treatments were carried out at 500 and 680 °C and the formed phases were identified. The structural features of the materials before and after treatment were studied by vibration spectroscopy. Glasses with B 2 O 3 /SiO 2 = 2/5 and B 2 O 3 /GeO 2 = 4/3 ratio proved to be the most resistant to heating. It was observed that the ratio of B/Si and B/Ge has a significant effect on crystallizability at any temperature. Heat treatment at 680 °C results in the formation of potassium borates, silicates, and borosilicates in the borosilicate system, while the crystallization of germanates and potassium borates is characteristic of the borogermanate system. Structural differences between the crystallization products of these two systems are shown to be due to the ability of germanium to form highly oriented structural units. With an increase in the B/Ge ratio, the crystallization of borogermanate glasses is shown to lead to a decrease in the proportion of crystalline borates. Conversely, during the crystallization of the borosilicate system, an increase in the B/Si ratio in the initial glass leads to an increase in their content. [ABSTRACT FROM AUTHOR]

Sintering with sintering aids is widely used to achieve a low sintering temperature of lead-based piezoelectric ceramics. In this study, two low-temperature sintering aids, namely Li 2 CO 3 and CuO, were doped into the x BiAlO 3 -(1- x) PZT + 0.2 wt% MnO 2 composition, and the microstructures and electrical properties were investigated for these ceramics prepared via solid-phase reaction method. Differential Scanning Calorimetry (DSC) indicated that the Li 2 CO 3 liquid phase formed at a lower temperature than that of CuO, while co-dopant of Li 2 CO 3 and CuO will result in a competition between Li+ and Cu2+ ions during the low-temperature sintering processes, which negatively impacts piezoelectric properties. The results demonstrated that the piezoelectric properties of ceramics with only Li 2 CO 3 or CuO additives are much better than ceramics with co-doped Li 2 CO 3 and CuO additives. Ceramics with 0.3 wt% Li 2 CO 3 or 0.1 wt% CuO sintering aid were sintered at 1000 °C, resulting in excellent piezoelectric coefficients (d 33) exceeding 300 pC/N and mechanical quality factors (Q m) of 500 were obtained, respectively. This work provides inspiration for low-temperature sintering strategies in other ceramic materials. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate that Li 7 La 3 Zr 0.5 Nb 0.5 Ta 0.5 Hf 0.5 O 12 (LLZNTH) high-entropy Li-garnet has a fine microstructure and improved mechanical properties compared with Ta-doped Li-garnet (Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , LLZT). The formation, sintering, and electrochemical properties are also studied. The results indicate that the LLZNTH sample has a finer particle size than LLZT after calcination and ball mill. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) regarding the solid-state reaction process indicate that the LLZNTH forms at a lower temperature than LLZT. Both samples can be densified to a relative density up to ∼93–94% at a temperature of 1100 °C, however, they show significantly different sintering and grain growth behaviors. The LLZNTH sample takes 16 h to reach the maximum relative density while the LLZT sample only needs 12 h. LLZNTH sample has a lower grain growth parameter due to the sluggish effects of high-entropy compounds so that it maintains fine microstructures (grain size ∼10 μm) than the LLZT sample (grain size over 100 μm). Due to the fine microstructures, the LLZNTH sample shows both higher flexural strength (84.8 ± 6.9 MPa compared with 47.9 ± 10.1 MPa) and hardness (8.5 ± 0.8 GPa compared with 7.7 ± 0.4 GPa) than the LLZT sample. Ionic conductivity characterizations indicate that the LLZNTH sample shows a moderate conductivity of 4.67 × 10-4 S/cm at room temperature and a low activation energy of 0.25eV. [ABSTRACT FROM AUTHOR]

Nowadays, it is critical to find materials and methods that can help reduce the human impact on the environment. Regenerative thermal oxidizers (RTOs) have a wide range of applications owing to their effective energy saving. Among the different RTOs, thermal-storage RTO ceramics have basic heat storage and release capability. The main objective of this work is to study the preparation of thermal-storage RTO ceramics for the treatment of exhaust gas using bauxite tailings and Bayer red mud from Jiaozuo City (Henan Province) with different mass fractions of magnetite as substitutes for the traditional raw materials (quartz and clay). The effect of the magnetite addition on the performance of the thermal-storage RTO ceramics prepared from the bauxite tailings and red mud was investigated. The raw materials were pressed into cylinder shape and then sintered at 950 °C, 1000 °C, 1050 °C, and 1100 °C. The developed materials were analyzed and characterized via X-ray diffraction and scanning electron microscopy, and specific heat capacity tests (differential scanning calorimetry using the sapphire method) were conducted on the thermal-storage RTO ceramics prepared at the optimal sintering temperature (1050 °C). The ceramics exhibit the best overall performance for magnetite content of 25% and sintering temperature of 1050 °C, with compressive strength of 134.96 MPa, volume density of 3.00 g/cm3, and linear shrinkage of 14.68%. The product also has a remarkably low water absorption rate and apparent porosity, water absorption of 0.02%, apparent porosity of 0.06%. Furthermore, the specific heat capacity is sufficiently high to meet the requirements of high-thermal-storage RTO ceramics. This study provides a new, low-cost solution for the preparation of high-thermal-storage RTO ceramics, which is helpful for reducing the exploitation of natural mineral resources. [ABSTRACT FROM AUTHOR]

Materials with excellent infrared radiation properties are important for preparing infrared radiation coatings that are applied in industrial furnaces, to improve the efficiency of heating equipment. To find a new material with better infrared radiation performance, La 3 Ni 2 O 7 , a layered perovskite structural material, was prepared by the sintering method, and its infrared radiation performance was studied in detail. It was found that La 3 Ni 2 O 7 has excellent infrared radiation properties, and the measured emissivity values at the 3–5 μm waveband were above 0.970, which was determined by its narrower forbidden bandwidth. Furthermore, La 3 Ni 2 O 7 -based coatings on clay brick substrates were prepared. The thermal behavior of the coatings, from room temperature to 1400 °C, was studied using thermogravimetry and differential scanning calorimetry (TG-DSC). The results indicated that a series of reactions occurred for the coatings at temperatures higher than 1000 °C. Furthermore, the coatings were heated in a muffle furnace at 1000 °C, 1100 °C, and 1200 °C, for 60 min to study the effect of thermal reactivity on the infrared radiation performance of the coatings. The results showed that at high temperatures, although the thermal reactivity led to a phase change for the coatings, the change had little effect on the emissivity. Above 1100 °C, La 3 Ni 2 O 7 starts to decompose into La 2 NiO 4 and NiO, and above 1200 °C, the La 2 NiO 4 content is above 50%, implying that the decomposition product La 2 NiO 4 plays a key role in maintaining the high emissivity of the coatings. The emissivity of La 2 NiO 4 specifically fabricated was tested and it was found that its emissivity was above 0.970. Furthermore, thermal shock resistance tests of the coatings were conducted. The results showed that the transition layer was formed by the chemical reactions between La 3 Ni 2 O 7 and the oxides in the substrate, which plays a positive role in prolonging the service life of the coating. • The infrared emissivity in 3–5 μm waveband of La 3 Ni 2 O 7 is higher than 0.970. • Reactions occur in La 3 Ni 2 O 7 -based coatings at temperatures higher than 1000 °C. • La 2 NiO 4 generated by thermal reactivity maintains the high emissivity of the coatings. • The transition layer formed by thermal reactivity improves the thermal shock resistance. [ABSTRACT FROM AUTHOR]

High-aspect-ratio ZrB 2 rod crystals were synthesized via a molten-salt-mediated boro/carbothermal reduction using ZrOCl 2 · 8H 2 O/B 4 C/C as the raw material and NaCl as the flux material. This synthesis may improve the poor fracture toughness of monolithic ZrB 2 ceramics. X-ray diffraction and scanning electron microscopy confirmed that the heat-treatment temperature of 1550 °C and the addition of 50 wt% NaCl were the most effective in the preparation of ZrB 2 grains with a high aspect ratio. Thermogravimetric and differential scanning calorimetry was used to study the influence of NaCl addition, which increased the liquid-phase content. Finally, the growth of ZrB 2 grains along the c-axis into rod-like morphology at elevated temperatures was investigated by transmission electron microscopy. This work revealed that the addition of NaCl has a positive effect on the reducing of synthesis temperature and increasing of products particle size. The ZrB 2 rod crystals synthesized have diameters and aspect ratios of approximately 1 μm and 30, respectively. [ABSTRACT FROM AUTHOR]

Natural and biodegradable polymers with pH-responsive properties, such as alginate and chitosan, are widely exploited for drug delivery applications, most notably in the form of biocompatible microspheres. In addition, thermo-responsive poly(N-isopropyl-acrylamide) (PNIPAM) is often added to biomedical delivery systems due to its lower critical solution temperature close to human physiological conditions. In this work, multi-responsive microspheres (MRMs) consisting of a hydrogel matrix made of alginate, chitosan, and PNIPAM were successfully prepared by extrusion dripping and proposed as delivery system for Ozoile (Stable Ozonides) derived from biological olive oil. Ozoile acts as a biological inducer, regulating the main metabolic pathways and stimulating the endogenous defence system. The MRMs containing Ozoile were prepared from alginate/NIPAM emulsions integrating the lipophilic bioactive principle. The MRMs were further optimised with a chitosan coating to improve their stability and control the degradation behaviour of the hydrogel matrix, with subsequent release of Ozoile. Results in terms of chemical composition from Fourier transform infrared (FTIR) spectroscopy, thermo-responsive properties from differential scanning calorimetry (DSC) analysis, swelling and degradation behaviour were used to establish the potential use of the MRMs for the therapeutic release of Ozoile at specific inflammatory sites. [ABSTRACT FROM AUTHOR]

The interaction between activators (ZnO) and co-activators (stearic acid, SA) represents a key step in the vulcanization process, to generate Zn(II) intermediate complexes that enhance the reaction kinetic and promote the shortening of sulfur bridges, leading to highly cross-linked materials. To understand the influence of the structural, morphological and surface properties of ZnO in the reactivity with SA, in this work, pure ZnO nanoparticles (NPs) and ZnO NPs anchored on SiO 2 (ZnO/SiO 2) were prepared through soft chemistry techniques. Tailoring of morphology and surface features was accomplished through a fine control of the synthetic parameters, as demonstrated by the careful characterization of the activators. Then, the interaction of pure ZnO and ZnO/SiO 2 activators with SA in the absence of rubber was investigated by using Differential Scanning Calorimetry (DSC). The occurrence of Zn(II)-SA complexes with different thermal stability and structural properties was assessed by a comprehensive thermogravimetric and spectroscopic survey. The generation and the chemical structure of these specific vulcanization intermediates was related to the peculiar characteristics of the ZnO/SiO 2 systems and, in turn, to their ability in imparting faster kinetics and higher curing efficiency to isoprene rubber nanocomposites, compared to bare ZnO. These results, besides proposing a valid benchmark for achieving further insights on the interaction of stearic acid with activators, pave the way to provide specific protocols for a better design and implementation of ZnO-based materials able to effectively enhance the rubber vulcanization process, with significant economic and environmental advantages. [ABSTRACT FROM AUTHOR]

Glass transition and crystallization kinetics of lithium-modified zinc borate glasses of the system 20ZnO.xLi 2 O.(80-x) B 2 O 3 (x = 10, 20, 30 and 40) have been studied using the non-isothermal method of differential scanning calorimetry (DSC). The 20ZnO·10Li 2 O.70 B 2 O 3 glass composition has the highest thermal stability and the glass-forming tendency among all other glasses. The activation energy associated with crystallization ((210–318) kJ/mol)), glass transition ((464–531) kJ/mol)), Avrami exponent (3) and frequency factor (2.49 × 109–2.32 × 1017) were extracted from the fitting of different theoretical models and the values are in close agreement with each other. The value of the Avrami exponent was found ∼3 thereby indicates the occurrence of volume nucleation with two-dimensional growth in the currently studied glass system. The formation of Pure monoclinic LiZnBO 3 crystalline phase is observed in 20ZnO·30Li 2 O·50B 2 O 3 and 20ZnO·40Li 2 O·40B 2 O 3 glass compositions which is a potential candidate for electric double-layer capacitance fabrication. [ABSTRACT FROM AUTHOR]

In this paper, K 0.5 Na 0.5 NbO 3 (KNN) samples were successfully synthesized via modified Pechini technique with many different chelating agents. Physicochemical studies as differential scanning calorimetry (DSC) measurements, dielectric measurements, impedance spectroscopy and structural analyses confirmed the influence of chelating agent on phase transformation from the ferroelectric orthorhombic to tetragonal and ferroelectric tetragonal to paraelectric cubic phase. The study of the charge transfer mechanism of KNN is carried out based on small polaron hopping theory. In addition, the high dielectric constant associated with a low dielectric loss observed for KNN material obtained using combination of glycine and oxalic acid makes it a possible use in electronic devices. [ABSTRACT FROM AUTHOR]

The present work aims to design and develop shielded metal arc welding electrode coating fluxes. The thermal properties of the electrode coating fluxes are studied. Ternary phase diagrams of C a F 2 − C a O − A l 2 O 3 and S i O 2 − B a O − A l 2 O 3 are used to determine the range of constituents. 27 flux mixture combinations were created using an extreme vertices design approach. The corrected optical basicity is estimated and utilized for the theoretical estimation of sulfide capacity and water vapor solubility. Thermogravimetric analysis, and differential scanning calorimetry analysis was performed to quantify the thermal response of the flux while heating. Thermogravimetry analysis shows variation of weight loss from 8.49% to 12.25% with the variation in flux composition. Calcite and witherite has positive influence on weight loss. Differential scanning calorimetry shows an overall change in enthalpy from −1076.73 to −7786 J/g. Hot disk analysis reveals fluorspar has a positive effect, whereas calcite has a negative effect on thermal conductivity. The effect of individual flux constituents and their interactions on thermal properties is discussed using regression analysis. The artificial neural network is used for predictive modeling, and the accuracy of its predictions is compared to regression analysis. In comparison to the regression, the model's mean square error improved by nearly 37% on average. The reduction in the mean absolute percentage error of the unseen test data suggests that the artificial neural network approach has better modeling capability. [ABSTRACT FROM AUTHOR]

This paper reports a facile electrospinning method to synthesize aluminosilicate fibers by using aluminum chloride hexahydrate as single aluminum precursor, which contains no harmful or hazardous chemicals in the precursor sol. The results of Fourier transform infrared, X-ray diffraction, simultaneous thermogravimetry and differential scanning calorimetry show that the sols are diphasic. The thermal decomposition behavior, crystallization process and microstructure of the fibers are discussed in detail. The main components of aluminosilicate fibers heat-treated at 1200 °C are mullite (Al 6 Si 2 O 13), alumina (α-Al 2 O 3) and amorphous silica, while the alumina phase disappears when the molar ratio of Si to Al is below 1.5. The diameter and microstructure of fibers with different Si/Al molar ratios are obviously different, which is related to the large difference in conductivity of spinning sols. Bulk fibers and fibrous mats with good flexibility can be easily obtained by using alternative collectors. The tensile strength of the fibrous mats can reach 2.63 MPa and 1.52 MPa after heat-treated at 1000 °C and 1200 °C, respectively. The aluminosilicate fibers fabricated in this work has a noticeable potential in high temperature fields and related applications. [ABSTRACT FROM AUTHOR]

The coalescence of nanocrystals generated by thermal treatments is a phenomenon observed in many materials. In the case of hydroxyapatite (HAp) derived from a biological source such as bovine bone, this transition was observed at temperatures around 700 °C. However, whether this is also the case at lower temperatures has not yet been investigated. With this aim, this work examined HAp samples from cattle calcined at 400–720 °C in increments of 20 °C, to determine the temperature effect on HAp nanocrystals due to coalescence. Differential scanning calorimetry showed that the raw (as prepared) bovine hydroxyapatite exhibited four thermal transition events at which the coalescence of HAp nanocrystals occurred. Infrared analysis showed that the full width at half maximum (FWHM) of the phosphate band decreases with increasing calcination temperature. The FWHM of the X-ray diffraction peaks showed minima values just at the coalescence events, while the unit cell volumes exhibited an opposite trend. The crystallite size of the HAp increases with increasing calcination temperature during the coalescence events, and the Rietveld method shows that the unit cell volume follows the same behavior and shows an opposite behavior in terms of the micro-strain. Scanning electron microscopy (SEM) images of samples calcined at temperatures above 520 °C show the first signs of coalescence, as necks are formed by the union of adjacent HAp nanocrystals. N 2 adsorption-desorption measurements have also shown that the average pore diameter is maintained during thermal processes. Finally, transmission electron microscopy (TEM) was used to observe the coalescence of the nanocrystals of the sample burned at 420 and 520 °C. These thermal events could be because the surface vibrational states of at least two adjacent HAp nanocrystals collapse and form new bulk vibrational states. [ABSTRACT FROM AUTHOR]

Selenium-rich chalcogenides have gained popularity as materials for selector devices due to their unique Ovonic Threshold Switching behavior. Bulk Se 86-x Te 14 Sn x glassy alloys (0 ≤ x ≤ 6) were prepared through the traditional melt quenching method. The samples with Sn atomic percentage (x) = 3 to 6 are found to exhibit a rapid and reversible transition between a highly resistive and conductive state affected by an electric field. A remarkable decrement in threshold voltage (V th) from 453 V to 62 V has been observed with increase in the Tin content. Differential scanning calorimetry (DSC) analysis was carried out to understand the variation of Glass transition temperature (T g), Crystallization temperature (T c), and other important glass stability parameters and their compositional dependence. Se 82 Te 14 Sn 4 sample was found to be thermally most stable with Herby's parameter value (H R) of 0.3860 and a maximum number of switching cycles at room temperature. X-Ray diffraction patterns of annealed samples were compared with pristine glass to study the multi-phasic Se–Te–Sn alloy. Further, the threshold voltage (V th) and the number of threshold switching cycles are found to decrease with an increase in temperature till crystallization on-set temperature (T oc). The temperature-dependent conductivity studies showed an abrupt increase in the conductivity of the samples as the temperature crossed the crystallization onset temperature. [Display omitted] • Se 86-x Te 14 Sn x (0 ≤ x ≤ 6) samples synthesized through the melt-quenching method. • Threshold type of switching was observed for all the synthesized glasses. • DSC studies revealed that the Se 82 Te 14 Sn 4 sample is thermally most stable. • The most stable Se 82 Te 14 Sn 4 sample sustained the highest number of switching cycles. • Annealing studies confirmed the formation of multiphasic crystalline material. [ABSTRACT FROM AUTHOR]

Fluoride (F) is important for enhancing illogical activity of bioceramics. To increase fluoride content of derived Hench bioactive glass (BaG), bioactive fluorosilicate glasses (BaG-F x) were synthesized by using melting method and characterized using different physico-chemical analyses. Fluoride-containing BaGs were synthesized at a temperature of 1350°C. Structural and thermal effect of calcium fluoride (CaF 2) insertion into the glass network in the BaG: SiO 2 –CaO–Na 2 O–P 2 O 5 quaternary system was studied. Indeed, the incorporated amounts of fluorine (CaF 2) (from 5% to 20% by mass) induced significant physico-chemical changes. Through the structural study by X-ray diffraction (XRD), the amorphous character of our fluorosilicate glasses is proven. Infrared (IR) spectroscopy proved the incorporation of fluorine into the glass matrix. In the microstructural framework, we revealed the morphological changes of the glass powders as a function of the CaF 2 content. These results were confirmed by Brunauer, Emmett and Teller (BET) measurements. Through Differential Scanning Calorimetry (DSC) thermal analysis we established the impact of fluoride ions on the structural dynamics and thermodynamic properties of these newly developed bioactive glasses. Accordingly, it was possible for the first time to incorporate as much as 20 wt% of CaF 2 in BaG respecting the conditions of bioactivity and biodegradability required by Hench. After detailed analyses of the transformation entropies of BG-F x as a function of the added CaF 2 content, it can be stated that the intermolecular movements within the fluorosilicate network are more limited as a function of the added CaF 2 amount. This slows down the ion exchange phenomena and subsequently the dissociation of the material in vitro , which can be anticipated to occur after implantation in vivo. [ABSTRACT FROM AUTHOR]

A composite material with superconducting properties, consisting of YBa 2 C u3 O 7-x doped with Ag 2 O, was obtained after 233 h of sintering at 960 °C and followed by a special cooling program in oxygen atmosphere. Preferential orientation of YBa 2 Cu 3 O 7-x (YBCO-123) crystallites was evidenced through X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Small increase of c parameter for orthorhombic YBCO-123 crystalline unit cell together with a slight decrease of oxygen content (7-x) versus Ag content, were encountered. The dimensions of YBCO-123 crystallites are dependent on Ag content. Thermogravimetric analysis (TGA) during heating in flowing air atmosphere from room temperature (RT) to 1100 °C, showed that total mass loss is depending on Ag content. The cooling (from 1100 °C to RT, in air atmosphere) endows optimal oxygen accumulation only for 0 and 5 wt% Ag, while final masses for 10 and 20 wt% of Ag content, are more than 10% less. Differential scanning calorimetry (DSC) showed peritectic melting points for YBa 2 Cu 3 O 7-x dependent on Ag percentage. DSC graphics also highlighted the endothermic effects: silver melting; melting and decomposition of Ag 2 O (in 225.81–345.12 °C temperature range) only for 10 and 20 wt%, but completely missing in the case of 5 wt% Ag content. We concluded that some of Cu sites from YBCO-123 superconductor were substituted by Ag ions. Quasi de Almeida-Thouless lines in the range of magnetic field amplitudes from 0.4 to 800 A/m, in the temperature range from 77 K to RT, were also investigated. Two cases are found concerning intergranular critical currents (J ci): depinning mechanism available for 5 wt% Ag content; the decoupling mechanism for 10, and 20 wt% Ag content. [ABSTRACT FROM AUTHOR]

REBa 2 Cu 3 O 7−δ (REBCO, RE = rare earth elements) cryomagnets have considerable potential for magnetic applications due to their high field trapping capacities over 10 T at temperatures below 77 K. The controlled nucleation of REBCO crystals for attaining superior performance decisively relies on the seeding strategy related to seed material and seeding assembly. Recently, buffer-assisted seeding approaches have been developed for reliable growth, in which buffer-crystals are by-products and discarded after splitting off from main crystals as ceramic waste though containing certain expensive matters such as RE, Ag and Pt. Here, for the first time, we succeeded in utilizing YBCO and NdBCO/Ag buffer-crystals as seeds for producing REBCO crystals under maximum processing temperatures of 1015 ℃ and 1053 ℃, respectively. YBCO specimens were characterized by differential scanning calorimetry and secondary ion mass spectrometry. It was verified that the buffer-crystal was 5.5 K higher than the normal-crystal in peritectic temperature (T p). Furthermore, the highly distributed Mg element was identified in the upper middle part of buffer-crystal, which was diffused from the Mg-involved NdBCO seed in previous fabrication. It is the Mg existence that enhanced T p of the buffer-crystal and made it highly thermal stable in seeding YBCO growth. In contrast to expensive commercial film-seeds and multistep home-prepared crystal-seeds, buffer-crystal-seeds distinctively have cost- and time-saving benefits. Most importantly, the current success adds new value of reusability to buffer-assisted seeding approaches towards a sustainable fabrication of REBCO cryomagnets. [ABSTRACT FROM AUTHOR]

MgO–Al 2 O 3 –SiO 2 glass-ceramics have been widely used in military, industrial, and construction applications. The nucleating agent is one of the most important factors in the production of glass-ceramics as it can control the crystallization temperature or the grain size. In this study, we investigated the effect of replacing P 2 O 5 with different amounts of TiO 2 on the crystallization, structure, and mechanical properties of an MgO–Al 2 O 3 –SiO 2 system. The crystallization and microstructure were investigated by differential scanning calorimetry, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mechanical properties were investigated by measuring the Vickers hardness, Young's modulus, and fracture toughness. The results showed that adding TiO 2 favored the precipitation of fine grains and significantly increased the Vickers hardness, Young's modulus, and fracture toughness of the glasses. Introducing an appropriate amount of TiO 2 can make a glass structure more compact, promote crystallization, and improve the mechanical properties of MgO–Al 2 O 3 –SiO 2 glass-ceramics. [ABSTRACT FROM AUTHOR]

Ion-conducting glasses of AgI-based Ge-Ga-S, Ge-Ga-Se and Ge-Ga-Te with different sulphur group elements were prepared by melt quenching technique. The electrical properties and thermodynamic stability were investigated and compared. Glass transition temperatures and crystallisation temperatures of the samples were measured using differential scanning calorimetry. Results showed that Ge-Ga-S-AgI had the best thermodynamic stability and glass-forming ability, highest ionic conductivity (1.33 × 10−7 S/cm) at room temperature and lowest conductivity activation energy of 0.41 eV. Raman spectroscopy analysis showed that the [GeI n S 4-n ] (n = 1,2,3) structural units in the S series glasses provided a good environment for the effective transport of Ag+ and formed an active ion transport channel. By contrast, the structural units in the Se and Te series contributed less to the transport of Ag+. This work systematically explored the effects of three elements in the sulphur main group on the performance of Ag+ conductive glasses. This study provides a reference for the rational formulation of sulphur-based Ag+ conductive glass components with enhanced comprehensive properties. [ABSTRACT FROM AUTHOR]

Due to the unusual crystallization of (nominally) stoichiometric BaSi 2 O 5 (BS2) glass, which shows unexpected and diverse crystal phases, a series of six glasses with different chemicals and melting procedures were prepared in three laboratories and characterized before and after crystallization by differential scanning calorimetry, density measurements, X-ray diffraction, FTIR, and Raman spectroscopy. The aim of this study was to assess whether there is systematic behavior in the crystallization pathways in relation to precursor chemicals, impurities, and hydroxyl content of this glass. Small glass monoliths were treated at the first DSC crystallization peak and quenched to determine which phases formed in the early-stages of crystallization. The glass transition temperatures (T g) divide these six glasses between those with a T g near 690 °C versus those near 700 °C. The DSC peak crystallization temperatures varied even more; from 855 to 917 °C. In these six glasses, our results are best explained by a combination of metastable high-BaSi 2 O 5 and Ba 6 Si 10 O 26. Monotonic trends in crystallization show that the DSC signal from the Ba-rich phases increases as the T g and the crystallization temperatures increase. The BS2 glasses with both the lowest T g and lowest DSC crystallization temperatures show the most barium disilicate crystal. This leads to the conclusion that the metastable monoclinic high-BaSi 2 O 5 is favored in these conditions. The small differences in glass synthesis conditions and chemicals used strongly influence the relative proportions of phases which crystallize and their kinetics. In-situ and ex-situ diffraction measurements confirm the conclusions above. The structural distinctions between the barium silicate crystals and the BS2 supercooled liquid, and the implications for the role of structural polymerization are discussed. We conclude that high-BaSi 2 O 5 or Ba 6 Si 10 O 26 are the predominant phases in the earliest stages of crystallization. This study highlights the extreme sensitivity of BS2 glass crystallization kinetics and pathways to minor differences in composition and synthesis conditions and explains the different conclusions reached by distinct authors that worked on the crystallization of BS2 glasses. [ABSTRACT FROM AUTHOR]

Tm3+/Dy3+ single and co-doped SrO–MgO–B 2 O 3 (SMB) glasses were fabricated via the conventional melt-quenching technique. The thermal stability of the host glass was determined by a differential scanning calorimetry (DSC) curve. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were measured to characterize the structural properties and vibration features of the as-prepared glasses, respectively. The transmittances of the studied glasses can reach about 90% in the range from 300 to 800 nm. It can be confirmed that Tm3+/Dy3+ single and co-doped SMB glasses can all be efficiently excited by near-ultraviolet (NUV) light through absorption and photoluminescence excitation spectra. Moreover, the emission spectra and fluorescence decay curves confirmed the existence of energy transfer between Tm3+ and Dy3+. The Tm3+/Dy3+ co-doped glasses can both realize tunable emission from blue light to cool white and eventually to warm white light under the excitation of 352, 362, and 365 nm. Furthermore, by using the Inokuti-Hirayama (I–H) model, the energy transfer is testified to be carried out in Tm3+-Dy3+ clusters through the dipole-dipole (d-d) interaction mechanism. More importantly, the thermal stability of Tm3+/Dy3+ co-doped SMB glass was demonstrated by temperature-dependent emission spectra. Overall, these results fully indicate that Tm3+/Dy3+ co-doped SMB glasses have great potential to be used in NUV-based white light-emitting diodes with different requirements. [ABSTRACT FROM AUTHOR]

Dy3+-doped YPO 4 glass ceramic (GC) samples were produced by melt-quenching method and followed heat-treatment. Differential scanning calorimetry curve, X-ray diffraction patterns, Fourier transform infrared spectra, transmission electron microscope images were used to analyze the structure of YPO 4 GC. The optimal GC sample is GC565 (sample heat-treatment at 565 °C for 2 h). The fluorescence intensity ratio (FIR) of emissions from 4I 15/2 and 4F 9/2 to 6H 15/2 of Dy3+ in YPO 4 GC565 excited by 350 nm light was used to detect temperature. The efficient energy difference between 4I 15/2 and 4F 9/2 levels is 1296 cm−1 and the maximum relative sensitivity achieves 2.03 %K−1 at 303 K. Our work indicates that Dy3+-doped YPO 4 GC have a prospective application in optical temperature sensing. [ABSTRACT FROM AUTHOR]

The effects of Al 2 O 3 content on the sintering behaviour, microstructure, and physical properties of Al 2 O 3 /vitrified bonds (SiO 2 –Al 2 O 3 –B 2 O 3 –BaO–Na 2 O–Li 2 O–ZnO–MgO) and Al 2 O 3 /vitrified bond cubic boron nitride (CBN) composites were systematically investigated using X-ray diffraction, differential scanning calorimetry, dilatometry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Various amounts of Al 2 O 3 promoted the formation of BaAl 2 Si 2 O 8 and γ-LiAlSi 2 O 6 , increasing the relative crystallinity of the Al 2 O 3 /vitrified composite from 85.0 to 93.2%, resulting in residual compressive stress on BaAl 2 Si 2 O 8 , thereby influencing the thermal behaviour and mechanical properties of the Al 2 O 3 /vitrified composite. The bulk density, porosity, flexural strength, hardness, and thermal conductivity of 57.5 wt% Al 2 O 3 sintered at 950 °C were 3.12 g/cm3, 6.1%, 169 MPa, 90.5 HRC, and 4.17 W/(m·K), respectively. The coefficient of thermal expansion of the bonding material was 3.83 × 10−6 °C−1, which was comparable to that of CBN, and the number of N–Al bonds were increased, which boosted the flexural strength of the Al 2 O 3 /vitrified CBN composite to 81 MPa. The excellent mechanical properties, compact structure, and suitable interfacial bonding state with the CBN grains of the Al 2 O 3 /vitrified composite make it a promising high-performance bonding material for superhard abrasive tools. [ABSTRACT FROM AUTHOR]

In this article, Ni and Ni-BN-TiC layers were constructed using laser cladding technique (LCT). The microstructure, phase structure, microhardness, elastic modulus, thermal stability, and corrosion behaviors of Ni-BN-TiC layers were investigated using scanning electron microscope (SEM), X-ray diffractometer (XRD), nanoindentation, differential scanning calorimetry (DSC), and electrochemical workstation. The results indicated that Ni-BN-TiC layers possessed a fine and compact microstructure. The exothermic peak of the Ni-BN-TiC layer appeared at 461°C, indicating the highest thermal stability. The mechanical properties of Ni-BN-TiC layer improved with the addition of BN and TiC particles, having an average microhardness of 19.6 GPa, and average elastic modulus of 194.2 GPa. In addition, the corrosion current densities of 45 steel, Ni and Ni-BN-TiC layers were 4.808 μA/cm2, 3.917 μA/cm2, and 2.014 μA/cm2, respectively. The corrosion potentials and corrosion current densities results showed the outstanding corrosion resistance of Ni-BN-TiC layers. [ABSTRACT FROM AUTHOR]

In this study, using a solution casting process, thermoplastic polyurethane elastomer (TPU) composites containing different contents of lead zirconate titanate (PZT) ferroelectric particles were produced. The damping treatment of composites at high volume of fillers was investigated. SEM micrographs showed that PZT particles had a proper distribution in the PU matrix. Differential scanning calorimetry (DSC) thermograms indicates that melting enthalpy decreases by raising PZT filler content. The results of the dynamic mechanical thermal analysis (DMTA) proved that the magnitude of loss factor (tan δ) strongly depends on PZT content, and it decreased from 0.51 to 0.27 as PZT content increased. The value of E 0 increases to 0.32 GPa in the composite reinforced with 50 v% of PZT. The role of PZT on the acoustic behavior of TPU was measured using the acoustic absorption coefficient (a). The results showed that as PZT content increased from 0 to 50%, the acoustic absorption coefficient reached 0.25 at 6000 Hz frequency. The composites of PZT/PU with 0–3 connectivity were poled, and the optimal poling conditions that could be applied without sample breakdown were studied. Moreover, we prepared composites containing 70 vol% PZT particles by modifying the particles. Modification of PZT particles caused a decrease in both d 33 and g 33 constants of the PZT/PU composites. [ABSTRACT FROM AUTHOR]

Complex spinel oxides AB 2 O 4 are inorganic materials, which, due to their refractoriness and a whole range of functional properties, are widely in demand in various fields of the power industry and electronics. This paper reports on the results of an experimental study of the thermophysical properties of zinc gallate, which is a promising material for optoelectronics, solid-state lighting and catalytic and biomedical applications. Highly dispersed single-phase ZnGa 2 O 4 powder was synthesised by gel combustion. As a result of high-temperature sintering of pressed powder blanks, ZnGa 2 O 4 ceramics (≈95% of the theoretical) were produced. According to SEM, the material has a dense microstructure consisting of micron-sized spinel grains. The heat capacity of the material produced was investigated by relaxation, adiabatic and differential scanning calorimetry. By combining experimental data in the range of 8.7–1276 K, a single consistent temperature dependence of ZnGa 2 O 4 heat capacity was obtained for the first time. The analysis of the curve obtained showed no signs of phase transitions in the studied temperature range. Based on the results of calorimetric measurements within the range 0 K–1276 K, the temperature dependences of heat capacity, entropy, enthalpy change and Gibbs energy function were calculated. The absolute entropy of ZnGa 2 O 4 spinel at 298.15 K was 120.23 J/(K·mol). The thermal diffusivity of ZnGa 2 O 4 ceramics measured by laser flash method was 2.6 mm2/s at 300 K, decreasing to 0.46 mm2/s at 1174 K. Its thermal conductivity calculated using experimental data on heat capacity and thermal diffusivity at room temperature was 7.6 W/(m·K). The obtained data are of interest in terms of improving materials based on ZnGa 2 O 4 , which are promising for use in light-emitting diodes and new-generation power semiconductor devices. • Ultra-fine ZnGa 2 O 4 powder was synthesised by a PVA-assisted gel combustion method. • High-density ZnGa 2 O 4 ceramics with micrometre-sized grains (>1 μm) were produced. • The temperature dependence of heat capacity was measured from 8.7 K to 1276 K. • Thermal diffusivities and thermal conductivities of the ceramics prepared were studied. [ABSTRACT FROM AUTHOR]

The well-known standard photo-thermo-refractive (PTR) glass has some limitations in holographic applications in the visible region due to light scattering on the large NaF nanocrystals formed during the photo-thermo-induced (PTI) crystallization process. The large size of the NaF nanocrystals can be reduced by forming more nucleation centers (silver nanoparticles). We suppose this can be achieved by introducing more silver into the batch composition of the glass. However, bromine does not permit high silver concentrations due to the spontaneous crystallization and high Mie-scattering. Therefore, we introduce a novel PTR glass by replacing bromine with chlorine. The novel glass enables us to increase the silver concentration and consequently increase the concentration of the formed nanoparticles. The optical properties, differential scanning calorimetry, and X-ray diffraction analyses were performed on the novel glasses. An experimental and theoretical investigation of the PTI crystallization process was carried out by monitoring the evolution of the surface plasmon resonance (SPR) absorption band. It was found that the UV exposure and heat treatment lead to precipitation of the NaF crystalline phase on a chlorine-containing dielectric shell that surrounds the silver nanoparticle. It was also found that using chlorine instead of bromine leads to a blue shift in the SPR absorption peak location. Volume Bragg gratings were successfully recorded in the novel PTR glasses. The maximum value of the refractive index modulation amplitude obtained for the novel glass is comparable with that for the standard PTR glass. [ABSTRACT FROM AUTHOR]