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This paper studies the effect of pyrolysis temperature on the semiconductor‐conductor transition of pristine polymer‐derived ceramic silicon carbide (PDC SiC). A comprehensive study of microstructural evolution and conduction mechanism of PDC SiC pyrolyzed at the temperature range of 1200°C‐1800°C is presented. At relatively lower pyrolysis temperatures (1200°C‐1600°C), the carbon phase goes through a microstructural evolution from amorphous carbon to nanocrystalline carbon. The PDC SiC samples behave as a semiconductor and the electron transport is governed by the band tail hopping (BTH) mechanism in low pyrolysis temperature (1300°C); by a mixed mechanism driven by band tail hopping and tunneling at intermediate temperature (1500°C). At higher pyrolysis temperatures (1700°C‐1800°C), a percolative network of continuous turbostratic carbon is formed up along the grain boundary of the crystallized SiC. The samples demonstrate metal‐like conductive response and their resistivity increases monotonically with the increasing measuring temperature. [ABSTRACT FROM AUTHOR]

In glass compression molding, most current modeling approaches of temperature‐dependent viscoelastic behavior of glass materials are restricted to thermo‐rheologically simple assumption. This research conducts a detailed study and demonstrates that this assumption, however, is not adequate for glass molding simulations over a wide range of molding temperatures. In this paper, we introduce a new method that eliminates the prerequisite of relaxation functions and shift factors for modeling of the thermo‐viscoelastic material behavior. More specifically, the temperature effect is directly incorporated into each parameter of the mechanical model. The mechanical model parameters are derived from creep displacements using uniaxial compression experiments. Validations of the proposed method are conducted for three different glass categories, including borosilicate, aluminosilicate, and chalcogenide glasses. Excellent agreement between the creep experiments and simulation results is found in all glasses over long pressing time up to 900 seconds and a large temperature range that corresponds to the glass viscosity of log (η) = 9.5 – 6.8 Pas. The method eventually promises an enhancement of the glass molding simulation. [ABSTRACT FROM AUTHOR]

In this paper, crystalline V2O3 and amorphous V2O3/C products are synthesized via one‐pot solution combustion synthesis (SCS) method (completed within 2 minutes). The characteristics of combustion products could be tuned by changing the amounts of glucose. The as‐synthesized crystalline V2O3 nanopowder consists of nanoparticles with average size of ~100 nm. Amorphous V2O3/C composite exhibits large porous microsheet structure in which oxygen vacancy‐enabled amorphous V2O3 particles are embedded into N‐doped carbon microsheets. The existence of oxygen vacancies can promote energetics for the transport of electrons and ions and maintain the integrity of sample surface morphology. Moreover, N‐doping can enhance electrical conductivity and promote the diffusion of electrons and lithium ions. Amorphous V2O3/C composite possesses high reversible capacity and superior cycling stability (833 mAh g−1 at 1 A g−1 after 250 cycles, 867 mAh g−1 at 0.1 A g−1 after 100 cycles), indicating its potential as excellent anode material for lithium‐ion battery. The proposed one‐step, time‐ and energy‐efficient SCS method has the potential to prepare other oxygen vacancy‐enabled transition metal oxides for energy storage. [ABSTRACT FROM AUTHOR]

Forty years ago, Garvie and his Australian co‐workers reported that the stress‐induced transformation of metastable tetragonal zirconia grains to the monoclinic symmetry could give rise to a powerful toughening mechanism. Their results even led them to consider zirconia systems as analogues of certain steels. This seminal paper generated extraordinary excitement in the ceramic community and it is still the subject of extensive research. Transformation toughening is widely used in zirconia materials and results in an increase in strength and toughness when compared to nontransformable ceramics, but the implementation into strong, tough, and sufficiently stable materials has not been fully reached. Zirconia ceramics generally fail at low strains with a much larger scatter in the strength values than metals and require statistical approaches to failure. Here we describe in detail the mechanical behavior laws of ceria‐doped zirconia composites exhibiting a high degree of stress‐induced transformation. They present, to some extent, mechanical behavior analogous to a metal, displaying, (a) significant amount of transformation‐induced plasticity without damage, (b) very high flaw tolerance and (c) almost no dispersion in strength data. They potentially open new application avenues in situations where the advantages of ceramics were dampened by their brittle failure behavior. In particular, the consequences of such behavior for dental implants and additive‐manufactured structures are highlighted. [ABSTRACT FROM AUTHOR]

The quasi‐static confined uniaxial compaction of granular alumina and boron carbide was studied, and the effect of triaxial stress on the materials as a function of increasing particle size was observed. The average particle sizes studied for granular alumina were 170 ± 63, 230 ± 55, 330 ± 67, and 450 ± 83 µm. The average particle size studied for granular boron carbide were 170 ± 40, 190 ± 34, 320 ± 59, and 470 ± 90 µm. The material response at hydrostatic pressure as a function of porosity, the bulk modulus as a function of hydrostatic pressure, and the transmission ratio as a function of applied load was evaluated for increasing particle size. For alumina, the increase in particle size resulted in an increase in strength for a fixed porosity, the bulk modulus of this material did not show clear particle size‐dependent trends, and the transmission ratio increased with increase in particle size. Conversely, for granular boron carbide, the hydrostatic pressure‐porosity curve shifted to the right with increasing particle size, the change in bulk modulus increased with increasing particle size, and no clear particle size‐dependent trends were observed when looking at the transmission ratio during the experiment. Post‐experiment scanning electron microscopy revealed that alumina powder fragmented from elongated shapes to block‐like structures, while boron carbide powder appeared more circular before the experiments and fragmented into smaller comminuted pieces. This paper discusses the implication of the work in the context of the limited experimental data in the field and the modeling of granular advanced ceramics behavior. [ABSTRACT FROM AUTHOR]

Inorganic polymer binders (IPBs) are synthesized by the activation of aluminosilicate precursors with an alkaline solution such as sodium hydroxide. This paper studies the relationship between the composition, structure, and solubility of sodium aluminosilicate hydrates (N–A–S–(H)), the primary binding phase in IPBs. It was found that changing the aqueous Si/Al ratio had little effect on N–A–S–(H) Si/Al ratio, but small changes in the aqueous Si/Na ratio led to substantial changes in N–A–S–(H) Si/Al ratio. Early N–A–S–(H) products were found to be X‐ray amorphous, but a rapid transition to the crystalline phase faujasite occurred after several weeks of aging. The transition of the solid amorphous phase to faujasite was accompanied by a rapid drop in aqueous Si(IV) and Al(III) concentrations. Solubility products were determined, temporally, for the N–A–S–(H) before and after the transition to faujasite and represent new contributions to the literature, particularly for the amorphous state. The results presented here provide fundamental insights that are needed for the development of kinetic and thermodynamic models that can establish phase balances and evolutions of IPBs across a range of precursor compositions and synthesis conditions. [ABSTRACT FROM AUTHOR]

Atomistic computer simulations can provide insights into silicate glass‐environment interactions with the recent development of reactive potentials. However, the accuracy of generated glass structures with these potential was usually not fully examined. In this paper, the capability of the reactive force field (ReaxFF) to describe the short and medium range structure features of sodium silicate glasses in molecular dynamics simulations is investigated by comparing a widely used partial charge pairwise potential and available experimental data. Glass structure information such as pair distribution function (PDF), coordination number, Qn species, neutron broadened structure factor, and X‐ray broadened structure factor of the glass structures from ReaxFF simulations were calculated and compared to evaluate the generated glass structure. Advantages and limitations of the potentials and glass forming procedures, as well as areas of further improvement, were discussed. The results show that the recently refined ReaxFF parameters through the proposed procedure enable the simulations of sodium silicate glass structures with minimal defects, which paves the way to investigate water‐glass interaction mechanisms with the reactive enabled potentials. [ABSTRACT FROM AUTHOR]

A growing demand for white light‐emitting diodes (W‐LEDs) gives rise to continuous exploration of functional fluorescence glasses. In this paper, Tm3+/Dy3+ single‐ and co‐doped glasses with composition (in mol%) of 30P2O5–10B2O3–23SrO–37K2O were synthesized using the melt‐quenching method in air. The physical properties, glass structure, luminescence characteristics and energy transfer mechanism of the glasses were systematically studied. As glass network modifiers, Tm3+ and Dy3+ ions can densify the glass structure. Excitation wavelength and doping concentration of Tm3+/Dy3+ ions have a direct impact on the emission intensities of blue and orange light as well as the color coordinate of the as‐prepared glasses. A white light very close to standard white light can be obtained under 354 nm excitation when the content of Tm3+ and Dy3+ is 0.2 mol% and 1.0 mol%, respectively. The results of the emission spectra and decay curves reveal the existence of energy transfer from Tm3+ to Dy3+. The analytic results based on the Inokuti‐Hirayama model indicate that the electrical dipole‐dipole interaction may be the main mechanism of energy transfer. Moreover, Tm3+/Dy3+ co‐activated glass phosphor has good thermal stability and chrominance stability and it is a promising candidate for white LEDs and display device. [ABSTRACT FROM AUTHOR]

Heat transfer at the interfacial contact is a dominant factor in the thermal behavior of glass during nonisothermal glass molding process. Recent research is developing reliable numerical approaches to quantify contact heat transfer coefficients. In most previous studies, however, both theoretical and numerical models of thermal contact conductance in glass molding attempted to investigate this factor by either omitting surface topography or simplifying the nature of contact surfaces. In fact, the determination of the contact heat transfer coefficient demands a detailed characterization of the contact interface including the surface topography and the thermomechanical behavior of the contact pair. This paper introduces a numerical approach to quantify the contact heat transfer by means of a microscale simulation at the glass‐mold interface. The simulation successfully incorporates modeling of the thermomechanical behaviors and the three‐dimensional topographies from actual surface measurements of the contact pair. The presented numerical model enables the derivation of contact heat transfer coefficients from various contact pressures and surface finishes. Numerical predictions of these coefficients are validated by transient contact heat transfer experiments using infrared thermography to verify the model. [ABSTRACT FROM AUTHOR]

Calcium‐silicate‐hydrates (C–S–H) gel, the main binding phase in cementitious materials, has a complex multiscale texture. Despite decades of intensive research, the relation between C–S–H's chemical composition and mesoscale texture remains experimentally limited to probe and theoretically elusive to comprehend. While the nanogranular texture explains a wide range of experimental observations, understanding the fundamental processes that control particles' size and shape are still obscure. This paper strives to establish a link between the chemistry of C–S–H nanolayers at the molecular level and formation of C–S–H globules at the mesoscale via the potential‐of‐mean‐force (PMF) coarse‐graining approach. We propose a new thermomechanical load‐cycling scheme that effectively packs polydisperse coarse‐grained nanolayers and creates representative C–S–H gel structures at various packing densities. We find that the C–S–H nanolayers percolate at ~10% packing fraction, significantly below the percolation of ideal hard contact oblate particles and rather close to that of overlapping ellipsoids. The agglomeration of C–S–H nanolayers leads to the formation of globular clusters with the effective thickness of ~5 nm, in striking agreement with small angle neutron and X‐ray scattering measurements as well as nanoscale imaging observations. The study of pore structure and local packing distribution in the course of densification shows a transition from a connected pore network to isolated nanoporosity. Furthermore, the calculated mechanical properties are in excellent agreement with statistical nanoindentation experiments, positioning nanolayered morphology as a finer description of C–S–H globule models. Such high‐resolution description becomes indispensable when investigating phenomena that involve internal building blocks of globules such as shrinkage and creep. [ABSTRACT FROM AUTHOR]

This paper firstly reports on a series of nanocomposite thin films composed of a ferroelectric Bi3.6Eu0.4Ti3O12 (BET) and Au‐decorated ZnO nanorods (Au‐ZnO), which are prepared by a ultraviolet‐induced hybrid chemical solution method. The effects of Au nanoparticles (NPs) and ZnO nanorods on the significantly red photoluminescence enhancement of Eu3+ ions are investigated. The results indicate that the larger near band edge (NBE) emission of ZnO by the SPR effect of Au NPs can make an energy transfer from ZnO to Eu3+ ions. Simultaneously, the depression of the deep‐level emission of ZnO can improve the monochromaticity in the visible range. Furthermore, the dielectric and ferroelectric properties of the thin films are also enhanced. The findings suggest that the nanocomposite thin films of a ferroelectric BET and Au‐ZnO could be used as a multifunctional material in the ferroelectric optoelectronic devices with bright light emitting. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) persistent luminescent nanoparticles (N‐PLNPs) endow a long‐term in vivo imaging with deep tissue penetration and high signal to noise ratio. However, synthesis route and applicable afterglow center for N‐PLNPs are still limited. Here, we report on a new synthesis by employing chemical precipitation as the central pivot, which is simpler and has controllable and reproducible routes than the existing technique. We also introduce Fe3+ ion as a new member to join the group of afterglow emitters. Although its NIR luminescence is ubiquitous, its NIR afterglow is still almost never reported. In this paper, SrAl12O19: Fe3+ N‐PLNPs display a NIR persistent luminescence from 750 to 1000 nm, which is assigned to 4T1(4G)→6A1(6S) transition of Fe3+. Furthermore, a surface‐amination technique is proposed to improve the stability of SrAl12O19: Fe3+ N‐PLNPs in aqueous solution. After encapsulating the N‐PLNPs with 3‐aminopropyl triethoxysilane (APTES), SrAl12O19: Fe3+ @APTES nanocomposites exhibit a hydrophilic stability beyond 20 days in aqueous solution. The results make them valuable in studying the biological functions of biomolecules and monitoring cellular networks in their native contexts. [ABSTRACT FROM AUTHOR]

Functional ceramics such as piezoelectrics, thermoelectrics, magnetic materials, ionic conductors, and semiconductors are opening new frontiers that underpin numerous aspects of modern life. This widespread usage comes with a responsibility to understand what impact their mass production has on the environment. Life‐cycle assessment (LCA) is a tool employed for the identification of sustainable materials pathways through the consideration of environmental burdens of materials both during fabrication and as a final product. Although the LCA technique has been widely used for the evaluation of environmental impacts in numerous product supply chains, its application for environmental profiling of functional ceramics is now gaining attention. This paper presents a review of current developments in LCA, including existing and emerging applications with emphasis on the development and fabrication of functional materials and devices (FM&D). Selected published works on LCA of functional ceramics are discussed, highlighting the importance of adopting LCA at the design stage and/or at laboratory stage before expensive investments and resources are committed. Drawing from the extant literature, we show that the integration of environmental and sustainability principles into the overall process of FM&D manufacturing, in a way that anticipates foreseeable harmful consequences while identifying opportunities for improvement, can aid the timely communications of key findings to functional materials developers. This guides the orientation of research, development and deployment, and provides insights toward the prioritization of research activities while potentially averting unintended consequences. It is intended that the review presented will encourage the materials science community to engage with LCA to address important materials design, substitution, and optimization needs. [ABSTRACT FROM AUTHOR]

Carbonation curing provides a promising method for both CO2 sequestration and strength improvement of cement‐based materials. To date, there is little knowledge about the influence of carbonation curing on Ca leaching resistance of cement‐based materials due to the occurrence of both physical and chemical transformation. It was the first time that Ca solid‐liquid equilibrium curves were experimentally established for cement pastes with different carbonation degrees in this paper. Experimental results demonstrated that on the one hand, carbonation curing improves the leaching resistance of cement paste by sequestrating Ca in insoluble CaCO3; on the other hand, potential negative effects may occur due to the accelerated decalcification and increased solubility of C–S–H after carbonation curing. Results of 29SR NMR showed that both carbonation curing and Ca leaching can increase the Si chain length and polymerization degree of C–S–H. Additionally, a modified mathematical model was established to simulate the leaching process of carbonation‐cured cement paste and it was also verified by energy‐dispersive spectroscopy (EDS) results. Therefore, the long‐term leaching resistance of cement‐based materials is possibly degraded by the carbonation curing treatment. [ABSTRACT FROM AUTHOR]

The stereolithography‐based additive manufacturing of white‐colored Al2O3 and ZrO2 ceramics has been widely reported, whereas the stereolithography‐based additive manufacturing of gray‐colored SiC ceramic is very difficult and challenged. In this paper, the reasons for the difficulty which SiC ceramic facing during stereolithography were discussed and compared to Al2O3 and ZrO2 ceramics. The effects of particle size, solid loading, stereolithography parameters, and photoinitiator kind and concentration on the curing ability of SiC slurries were further studied in detail. Finally, complex‐shaped SiC ceramic green parts with high accuracy and high quality were successfully fabricated. This study demonstrated that the stereolithography‐based additive manufacturing had a great possibility for preparing gray‐colored SiC ceramics. [ABSTRACT FROM AUTHOR]

In this paper, an efficient and low‐cost method was developed for producing isolated 2D MoN nanosheets via Na2CO3‐assisted nitridation and exfoliation of natural 2H‐MoS2 by NH3 at 700‐800°C. It was found that, in the presence of Na2CO3, the nitridation of MoS2 with NH3 was a topochemical transformation. After heat treatment the mixture of MoS2 and Na2CO3 in NH3 at 700‐800°C, layered MoN with intercalated Na2S was obtained. Na2CO3 can dramatically promote the topochemical nitridation and exfoliation of MoS2 in NH3. At 750°C, the time for complete nitridation of (commercial) MoS2 can be shortened to 2 hours, which is much shorter than 40 hours in the case without the addition of Na2CO3 as reported in the previous literature. After acid‐washing, the intercalated Na2S was removed, and the generated H2S promoted the further separation of the MoN nanosheets. Finally, dispersed high crystalline 2D MoN nanosheets with thickness of a few nanometers were successfully produced. This method may be also applicable for the production of other 2D nitrides or carbides by nitridation or carbonization of various transition metal dichalcogenides (TMDs) with the assistance of sulfur‐fixed agent. [ABSTRACT FROM AUTHOR]

It is unclear how the densification of fused silica influences the damage of its precision optics subjected to machining. This paper presents a quantitative analysis of the indentation fracture of fused silica involving densification with the embedded center of dilation (ECD) model. The Hertzian stress field and the ECD‐induced stress field were superposed to provide the overall stress distribution in the loading stage. A new method was established to accurately determine the strength of the ECD‐induced stress field with densification effects. With the aid of the ECD model, the starting locations, initiation stages and initiation sequence of crack morphologies were predicted by analyzing the stress fields. To quantitatively study the initiation of conical cracks in fused silica, the strain energy release rate was calculated by linear elastic fracture mechanics (LEFM). The predicted minimum threshold load leading to conical cracking was consistent with the measured values. [ABSTRACT FROM AUTHOR]

Non–rare earth Mn4+‐activated strontium aluminate phosphor is considered to be a promising material for plant cultivation field owing to their advantage of inexpensively, environment friendly, nontoxic, and appropriate spectral range. In this paper, a Sr4−xBaxAl13.99O25:0.01Mn4+,1.4H3BO3 strontium aluminate phosphor is synthesized by a convenient high‐temperature solid‐state reaction. The photoluminescence spectra located at red region with a peak at 655 nm in the range of 600 to 750 nm that can be excited under the excitation of ultraviolet (~346 nm) or blue light (~450 nm). The shape emission band at 655 nm is attributed to the transition of 2Eg‐4A2g. Furthermore, the emission intensity of Sr4−xBaxAl13.99O25: 0.01Mn4+,1.4H3BO3 phosphor is conducted in detail with the variety of Ba2+ doping concentration and the intensity can be enhanced to 140.9% than the Sr4Al13.99O25:0.01Mn4+,1.4H3BO3 when the value of Ba2+ concentration equal to 0.1 mol. In addition, the X‐ray diffraction spectra, element mapping, composition modifying, optical properties, FT‐IR spectra, diffuse reflectance spectra, thermal stability, and fluorescence lifetime are systematically investigated. According to the electro‐luminescent spectra of as‐packaged LED, indicating that the Sr3.9Ba0.1Al13.99O25:0.01Mn4+,1.4H3BO3 phosphor will become a great candidate for plant cultivation LEDs due to the emission spectra match well the plant pigment spectrum. [ABSTRACT FROM AUTHOR]

Phase‐pure [NiO]0.5[Al2O3]0.5 spinel nanoparticles (NPs) with limited aggregation were obtained via liquid‐feed flame spray pyrolysis (LF‐FSP) by combusting metalloorganic precursor solutions. Thereafter "chocolate chip‐like" Nix[NiO0.5‐x][Al2O3]0.5 nanoparticles consisting of primary [NiO0.5‐x][Al2O3]0.5 particles with average particle sizes of 40‐60 nm decorated with Ni metal particles (<10 nm in diameter) dispersed on the surface were synthesized by heat treating the spinel NPs at 800°C/7 h in flowing 5% H2:N2 100 mL/min in a fluidized bed reactor. The synthesized materials were characterized using TEM, XRD, FTIR, and TGA/DTA. The Ni depleted areas consist primarily of γ‐Al2O3. The Ni content (800°C) was determined by TGA to be ≈11.3 wt.% based on TGA oxidation behavior. The successful synthesis of such nanocomposites with limited aggregation on a high temperature support provides a facile route to synthesize well‐defined NP catalysts. This work serves as a baseline study for an accompanying paper, wherein thin, flexible, dense films made from these same NPs are used as regenerable catalysts for carbon nanotube syntheses. [ABSTRACT FROM AUTHOR]

Fe:ZnSe nanopowders were synthesized via the co‐precipitation method for fabricating transparent ceramics. FexZn1−xSe (0.00 ≤ x ≤ 0.06) powders that were calcined at 400°C yielded a single‐phased cubic ZnSe, but when the calcination temperature was raised to 500‐600°C, ZnO phase was created. Introduction of pressure could avoid appearance of ZnO. XRD Scherrer analysis revealed a monotonic increase in lattice parameter with increasing Fe2+ content. The average powder particle size increased with calcination temperature from several nanometers at 80°C to hundreds of nanometers at 600°C. Attempts to pressurelessly sinter ZnSe powders resulted in the partial decomposition of ZnSe, thus spark plasma sintering was employed to sinter Fe0.01Zn0.99Se transparent ceramics with pure ZnSe phase composition, which could be well sintered at 950°C for 30 minutes under an applied pressure of 60 MPa. SEM observations of the polished and thermally etched microstructure of the ceramic revealed a dense microstructure with average grain size of approximately 35 μm, and a few micropores were observed at the grain boundaries. The transparent ceramic exhibited good transmittance in the mid‐far infrared range, with the highest transmittance 57% at 12 μm. This paper confirmed the scheme of synthesis of Fe:ZnSe nanopowders by liquid‐phase co‐precipitation method for sintering transparent ceramics. [ABSTRACT FROM AUTHOR]

Calcium carbonate cements have emerged in the last few years as an attractive candidate for biomedical applications. They can be easily prepared by mixing water with two metastable calcium carbonate phases––amorphous calcium carbonate (ACC) and vaterite––which (re)crystallize into calcite during setting reaction. The transformation kinetics (and therefore the final surface cement composition) strongly depends on the initial mixture design and is controlled by the dissolution of ACC, whereas calcite nucleation typically controls their recrystallization in fluid batch experiments. Novel compositions are presented in this paper by incorporating organic molecules as a proxy to test their capability to carry on other biomolecules like proteins or antibiotics. The hardened samples are microporous and show excellent bioactivity rates, although their mechanical properties still remain poor. However, this would not be a handicap for in‐vivo applications such as bone filling, especially in low mechanical stress locations. [ABSTRACT FROM AUTHOR]

An ever increasing demand for white light‐emitting diodes (W‐LEDs) results in the gradual growth of research on functionalized luminescent glasses. In this paper, single‐composition tunable white‐emitting Eu2+‐Tb3+‐Eu3+ tri‐activated glasses were synthesized by melt quenching method without additional reducing atmosphere. The coexistence of Eu2+ and Eu3+ was confirmed by ultraviolet‐visible transmission spectra, photoluminescent spectra, fluorescence decay curves, and X‐ray photoelectron spectroscopy. Tb3+ can act as bridge to connect Eu2+‐Eu3+ luminescent centers by energy transfer. Tone‐tunable white light can be achieved by coupling the emission centered at 412, 541, and 612 nm contributed from Eu2+, Tb3+, and Eu3+, respectively. By adjusting the relative content of Eu2+/Tb3+/Eu3+, ideal chromaticity coordinates of (0.33, 0.33) can be achieved under excitation of ultraviolet light. High thermal stability and tiny chromaticity shift were exhibited in samples. These results suggest that Eu2+‐Tb3+‐Eu3+ tri‐activated glasses have great potential application in ultraviolet‐driven W‐LEDs. [ABSTRACT FROM AUTHOR]

Monolithic luminescent glass‐ceramic is highly desirable for solid‐state lighting as it is stable and robust, while in practical light‐emitting devices only a thin luminescent layer is used for more efficient excitation and light extraction. In this paper, Mn2+‐doped glass and glass‐ceramic with the composition of 60SiO2‐8Na2O–20ZnO–12Ga2O3 were fabricated by the conventional melt‐quenching technique. We observe that the crystallization of α‐Zn2SiO4 nanocrystals takes place on the glass surface with controllable thickness after heat treatment. The glass samples show typical red emission peaking at λ = 620 nm that can be ascribed to the spin‐forbidden 4T1g(G) → 6A1g(S) transition of Mn2+ (d5) located in the octahedral coordination site of the glass host. After surface crystallization this red emission is retained and a new green emission at 528 nm is observed through the control of the crystallization temperature and duration, thus offering tunable emission characteristics promising for the lighting application. This change in the visible emission is interpreted in terms of the change of coordination state of Mn2+ from octahedral in a glass matrix to tetrahedral in the surface precipitated α‐Zn2SiO4 crystals. [ABSTRACT FROM AUTHOR]

In this paper, anatase TiO2 nanoparticles (14 nm) were coated on the surface of piezoelectric PbTiO3 single crystal fibers by a secondary hydrothermal method, thus a p‐n junction was formed at the interface between TiO2 and PbTiO3. The PbTiO3 fibers were exposed to an external force (by ultrasound) to generate a dynamic piezoelectric electric field in the crystal, which incessantly separates the carriers and improves the photocatalytic efficiency of TiO2. When the ultrasonic frequency is 40 kHz, the TiO2/PbTiO3 fibers have the highest photocatalytic degradation efficiency (96%) for methylene orange (MO), which is up to 60% improvement compared to TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

In this paper, how rare‐earth element dopants (samarium and erbium) affect the scale development of sintered ZrB2/SiC (ZBS) samples during ablation testing was investigated. ZBS billets with five different Sm to Er ratios, with a nominal total amount of 3 mol% dopant incorporated, were prepared by sintering in vacuum to 2000°C and subjected to 60 and 300 seconds ablation cycles. Differences in surface temperatures between ZBS samples with different dopant ratios suggests differences in spectral absorptance/emittance between each of the five compositions investigated. ZBS billets co‐doped with Sm and Er form a beneficial c1‐(Sm/Er)0.2Zr0.8O1.9 oxide scale as the majority phase, with some glassy phase observed. The crystalline c1‐(Sm/Er)0.2Zr0.8O1.9 oxide scale is more thermally stable than the m‐ZrO2 oxide scale typically formed in oxidized ZBS systems, resulting in a more adherent oxide scale to the unreacted material. The crystalline oxide scale and the amorphous phase are formed by a convection cell mechanism where the c1‐(Sm/Er)0.2Zr0.8O1.9 crystalline islands precipitate, grow, and coalesce. [ABSTRACT FROM AUTHOR]

The brownmillerite, also known as tetracalcium aluminoferrite (C4AF), represents a solid solution series of Ca2(AlyFe(2–y))O5 (0 ≥ y ≤ 1.33), which is one of the most important components in ordinary Portland cement. The hydration of brownmillerite in the presence of gypsum attracts massive attentions, but the hydration mechanism remains controversial nowadays. In particular, the influence of Al/Fe ratio on brownmillerite hydration with gypsum is obscure and out of favor. This paper studies the hydration characteristics of a binary system containing brownmillerite and gypsum with variables including two Al/Fe ratios and gypsum contents in an attempt to interpret the retarding mechanism of sulfate ions. When the molar ratio of brownmillerite to gypsum is 1.0, the hydration process of Ca2(Al1.3Fe0.7)O5 shows five distinct stages in the conductivity test, while only two stages are observed in the case of Ca2(Al1.0Fe1.0)O5. A decrease of Al/Fe ratio in brownmillerite leads to severe stagnation of the hydration process. When the molar ratio of Ca2(Al1.0Fe1.0)O5 to gypsum is increased to 2.7, the hydration is able to proceed and also displays five stages similar to Ca2(Al1.3Fe0.7)O5. An adsorption layer of sulfate ions on the surface of brownmillerite contributes to the postponement of brownmillerite hydration. In addition, the concentration of aluminum in the solution is the key to break this adsorption layer and dominate the hydration proceeding of brownmillerite. [ABSTRACT FROM AUTHOR]

Modeling the rate‐dependent mechanical behavior of brittle granular materials is of interest to defense applications, civil and mining engineering, geology, and geophysics. In particular, granulated ceramics in armor systems play a significant role in the overall dynamic material response of ceramics, particularly in their penetration resistance. This paper presents a rate‐dependent constitutive model for brittle granular materials based on a recent reformulation of breakage mechanics theory. The rate‐dependency is introduced via the overstress theory of viscoplasticity. The proposed formulation incorporates the effects of relative density and particle grading on strength and porous compaction/dilation, and is capable of tracking their evolution. The model is devised with internal variables linked to underlying dissipative micromechanisms including configurational reorganization, particle breakage and frictional dissipation. A strategy for calibrating model parameters and required experiments are described. The impact of loading rate on shear strength and grading evolution are explored through a sensitivity analysis. The presented model is capable of capturing several key features of the experimentally observed behavior of brittle granular materials including stress‐, rate‐ and density‐dependent stress‐strain and volume change responses, the competition between dilation and breakage‐induced compaction, the evolving particle grading due to particle breakage, and the evolution toward a critical (steady) state under shearing. A possible application of this micromechanics‐inspired modeling framework involves integrating it into rate‐dependent models for ceramics to assist in improving the impact performance of next‐generation ceramics. [ABSTRACT FROM AUTHOR]

In the previous paper "Optical and Judd‐Ofelt spectroscopic study of Er3+‐doped strontium gadolinium gallium garnet single‐crystal" (J Am Ceram Soc. 2019;102:873–878), we have reported optical and Judd‐Ofelt spectroscopic properties of Er3+‐doped strontium gadolinium gallate (SrGdGa3O7) single‐crystal, and the Judd‐Ofelt study was performed on the basis of unpolarized absorption spectrum of the crystal. Present work reports the corrected unpolarized absorption spectrum and Er3+ concentration in the crystal, and hence corrected Judd‐Ofelt spectroscopic properties and cross‐section data. In addition, the polarization effect was considered in the Judd‐Ofelt analysis on the basis of polarization‐resolved absorption spectra. Effective Judd‐Ofelt parameters are presented and discussed in comparison with the results from the unpolarized spectrum, and consistent results have been obtained. This study also considers the effects of some other factors on the Judd‐Ofelt parameters. These include Er3+ concentration and selection of Er3+ absorption bands for the Judd‐Ofelt analysis. [ABSTRACT FROM AUTHOR]

Spinel crystal formation presents a critical issue and glass formulation in nuclear waste glass processing. In this paper, the interfacial structures of the model borosilicate nuclear waste glasses, the international simple glass (ISG), with two types of spinel crystals, namely the MgAl2O4 and NiFe2O4, were studied using classical molecular dynamics simulations with effective partial charge potentials and recently developed composition‐dependent boron‐related parameters. The simulation results revealed the structural features of the borosilicate nuclear waste glasses and their interfaces with the two types of spinel crystals. It was found that there exist notable structural changes of glasses close to the interfacial region, affected by the adjacent crystal structures, terms of preferential segregation and ordering of cations, as well as ctaion coordination numbers. Specifically, the fraction of fourfold coordinated boron (B3) in glass near the interface decreases as compared to the bulk glass. In addition, the amount of fourfold coordinated Al decreases while fivefold Al increases in the glass region close to the glass‐crystal interface, which suggests indication of initial stage of crystal growth as Al adopts higher (sixfold) coordination like in the crystal as compared to majority of fourfold coordination in the glass. These interfacial structure changes obtained from MD simulations provide evidence of the influence of the precipitated crystals on the surrounding melt and glass and the initial stage of crystal growth. [ABSTRACT FROM AUTHOR]

A novel double‐cladding Ho3+/Tm3+ co‐doped Bi2O3–GeO2–Ga2O3–BaF2 glass fiber, which can be applied to a 2.0‐μm infrared laser, was fabricated by a rod‐tube drawing method. The thermal properties of the glass were studied by differential scanning calorimetry. It showed good thermal stability and matching thermal expansion coefficient for fiber drawing when Tx−Tg > 193°C and the maximum difference of the thermal expansion coefficient is 3.55 × 10−6/°C or less. The 2.0‐μm luminescence characteristics were studied using the central wavelength of 808 nm pump light excitation. The results show that when the concentration ratio of Ho3+/Tm3+ reaches 0.5 mol%:1.0 mol%, the maximum fluorescence intensity was obtained in the core glass, the emission cross section reached 10.09 × 10−21 cm2, and the maximum phonon energy was 751 cm−1. In this paper, a continuous laser output with a maximum power of 0.986 W and a wavelength of 2030 nm was obtained using an erbium‐doped fiber laser as a pump source in a 0.5 m long Ho3+/Tm3+ co‐doped glass fiber. In short, the results show that Ho3+/Tm3+ co‐doped 36Bi2O3–30GeO2–15Ga2O3–10BaF2–9Na2O glass fiber has excellent laser properties, and it is an ideal mid‐infrared fiber material for a 2.0‐μm fiber laser with excellent characteristics [ABSTRACT FROM AUTHOR]

Tm3+‐doped mixed sesquioxide transparent ceramics are attractive candidates for the generation of robust ~2.1 μm lasers. In this paper, laser‐quality Tm:(Lu0.8Sc0.2)2O3 mixed sesquioxide ceramics were shaped for the first time by gelcasting of well‐dispersed nanopowders, which were obtained using a modified coprecipitation method. The dispersibility of starting nanopowders was largely improved using alcohol‐water solvent. The rheological properties of slurries were optimized for gelcasting. We also investigated the densification behavior of the gel‐casted green compacts. In contrast to the dry‐pressing route, it was found that gelcasting could yield more homogeneous and transparent ceramics. The optical in‐line transmittance of the ceramic rod 12 mm in length was as high as 80.3% at 2090 nm. Upon pumping the ceramic rod by 796 nm diode laser, a 1.88 W CW laser at 2090 nm was acquired with a slope efficiency of 24.6% (with respect to the input pump power). [ABSTRACT FROM AUTHOR]

The effect of CaO/Al2O3 mass ratio (C/A) and fluorine content on the viscosity and structure of CaO–Al2O3‐based mold fluxes has been researched in this paper. The viscosity results indicated that increasing fluorine only slightly decreases the viscosity of the slag melt, and higher C/A is also observed to decrease the viscosity of molten slag when the C/A changes from 1.3 to 1.7. Structural analysis of the as‐quenched fluxes using the Raman spectroscopy showed that the amounts of Al–O0 and Si–O–Al structural units all decrease with higher fluorine content and C/A, indicating that a depolymerization of the molten structure is occurring. The results of 27Al and 19F magic angle spinning nuclear magnetic resonance showed that fluorine tends to participate in the network structure and coordinate with Al3+ ions to form complex ionic clusters. The results suggested that the role of fluorine in the CaO–Al2O3‐based slag system is different from the traditional slag system in which fluorine only acts as a diluent, thus reducing the effect of fluorine on lowering the viscosity. In addition, the coordination environment of Al3+ ions can be simplified by higher C/A through promoting the generation of [AlO4]− tetrahedral structures. Besides, the free O2− ions provided by excess CaO would break the Al–O0 bonds and further depolymerize the network structure, thereby decrease the viscosity. [ABSTRACT FROM AUTHOR]

The doping of ZnO is efficient to improve the piezoelectric property and thermal stability of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) based ceramics. However, the underlying physics, especially the local domain structures of the ZnO modified PMN–PT ceramics, which is strongly associated with the electric properties, is not clear yet. In this paper, we investigated the local domain structures and their evolution as a function of x in PMN–0.32PT:xZnO ceramics. It was found that, the domain evolution is mainly caused by the growth of grain size induced by the sintering aiding effect of ZnO at x < 0.04, and the domain evolution can be attributed to the phase transition induced by the partial replacement of Mg2+ by Zn2+ in the B‐site of PMN–PT lattice at x > 0.06. Furthermore, we also investigated the domain structure evolution as functions of temperature and local external electric field in PMN–0.32PT:0.06ZnO ceramics, which exhibited superior piezoelectric property relative to other compositions. We found that the irregular nanodomains are more stable at high‐temperature range, and the regular non‐180° domains exhibited more complex rotation behavior under local electric field, which probably leads to the thermal stability and piezoelectric property enhancement in the ZnO‐modified PMN–0.32PT ceramics. [ABSTRACT FROM AUTHOR]

This paper reports on the phase formation of perovskite Pb(In1/2Nb1/2)O3‐Pb(Zn1/3Nb2/3)O3‐PbTiO3 (PIN‐PZN‐PT) powder when doped with 0.04 to 0.83 mol% ZnO. Air calcination of undoped powder mixtures for 4 hours at 800°C resulted in a mixture of Pb2Zn0.29Nb1.71O6.565 pyrochlore, PIN‐PZN‐PT perovskite, and In2O3. ZnO dopant concentrations as low as 0.04 mol% increased the rate of perovskite formation and resulted in near phase pure perovskite powder of 0.5 μm particle size when heated at 800°C in air. In all cases PbTiO3 and Pb(In1/2Nb1/2)O3 formed prior to PIN‐PZN‐PT formation. ZnO doping promotes perovskite phase formation by increasing the reactivity of the intermediate pyrochlore phase by substituting Zn2+ on Nb5+ sites and forming oxygen vacancies when heated in air. Heating in high PO2 resulted in an incomplete reaction and a mixture of perovskite and pyrochlore whereas low PO2 resulted in phase separation into a mixture of rhombohedral perovskite, tetragonal perovskite, and pyrochlore. The PO2 sensitivity clearly shows that oxygen vacancies due to ZnO‐doping are critical for synthesis of phase pure PIN‐PZN‐PT powder. [ABSTRACT FROM AUTHOR]

Theory predicts Cu‐doped ZnO (ZnO:Cu) has p‐conductivity; however, this has only been demonstrated in a small number of experimental and mechanistic studies. In this paper, ZnO:Cu films were grown in situ with varying Cu content, prepared using radiofrequency atomic source–assisted molecular‐beam vapor deposition. The results indicate that ZnO:Cu films with dopant of Cu2+ only had n‐type behavior. As the Cu content increased, Cu+ was the major dopant and the ZnO:Cu films had p‐type behavior. However, excess Cu dopant resulted in the formation of second phases of Cu2O and Cu–Zn. The formation of a Cu–Zn phase increased the content of Zn vacancy, thus increasing hole concentration. Stronger alloy scattering decreased carrier mobility. Therefore, Cu+ dopant and Zn vacancy give ZnO:Cu films p‐conductivity properties. [ABSTRACT FROM AUTHOR]

It is difficult to observe the thermal shock cracking in real time, so the measurement of the crack after thermal shock is considered as an alternative method. This paper proposes a new experimental method which can exhibit the thermal shock cracking in real time by water quenching of translucent ceramic and high-speed imaging. The crack propagation is captured, and the crack growth rate is calculated. The results confirm the previous theoretical predictions of crack propagation under thermal shock. This paper expands the research on understanding the failure mechanisms of ceramic materials in thermal shock. [ABSTRACT FROM AUTHOR]

Fifty years have elapsed from the moment the first light transmitting ceramic-based commercial item--a sodium vapor-based street lamp component--reached the market. This paper intends to be a brief chronicle (albeit not a chronology) of this first half century of translucent and transparent ceramic history. The main ceramic materials now available in a transparent state are presented and their main applications are described. Applications range from aerospace and relativistic optics to medical care, supermarket shopping, and modern warfare. Light transmitting ceramics usable as laser gain-media, armor windows, IR domes, phosphors, scintillators, and electro-optical components have been developed. The principal achievements this research produced are discussed. Processing strategies for full densification have been devised and quantitative relationships were established between different microstructural features such as amount and size distribution of porosity or level of birefringence, and the level of electromagnetic radiation attenuation they cause. Future prospects list ends the paper. [ABSTRACT FROM AUTHOR]

The ethanolaminic salt of citric acid (commercial name Dolapix CE 64) has commonly been used as a dispersant for colloidal based ceramic forming process. In this paper, a surprise was presented that MgAl2O4 spinel slurries consisting of MgAl2O4 spinel nanoparticles and Dolapix CE 64 gelled in air at room temperature spontaneously. The MgAl2O4 spinel slurries with high solid loading (54 vol%) were prepared with Dolapix CE 64 and the green body with up to 57% relative density was obtained. MgAl2O4 transparent ceramics with small grain size (0.92 μm) and high transmittance (81.7% at 600 nm) were fabricated after pre‐sintering at 1500°C and hot‐isostatic sintering at 1550°C. [ABSTRACT FROM AUTHOR]

We measure the sintering behavior of thin and thick films of ceramics made by stacking several layers of tapes. The stack thickness was varied from 0.12 to 0.50 mm. A powder‐pressed dog‐bone sample, ~1 mm thick served as the baseline. While all specimens exhibit flash sintering, the following differences are noted. (a) The onset of flash, which has been shown to occur within a narrow band of volumetric power density for powder‐pressed dog‐bone shaped specimens, moves to a higher value for the thinner specimens. (b) The power transition collapses, again, to within a narrow band when the power density is normalized with respect to the surface area rather than the volume. (c) Sintering of thinner specimens to full density required a higher current‐density limit. These results point to a deeper significance of black body radiation than its use in estimating the specimen temperature in a steady state of flash that is calculated from the energy balance between electrical and radiated energy. The experiments were carried out on 3 mol% yttria stabilized zirconia at constant heating rate [ABSTRACT FROM AUTHOR]

The most important issue in the processing of nanoscale metal powders is whether the metal nanopowder can be fully consolidated into ultra‐fine‐ or nano‐grained powder metallurgy parts by pressureless sintering. This paper focuses on the sintering behavior of bimodal iron (Fe) nanopowder agglomerates by considering their microstructure and densification kinetics. During the sintering, bimodal Fe nanopowder compacts underwent discontinuous shrinkage behavior until they neared full density. Three contributions to the sintering mechanisms, asymmetric sintering, densification enhancement, and grain growth inhibition, are presented in relation to the effect of bimodal nanopowder structure. Smaller nanoparticles in the bimodal nanopowders, which are predominantly present at the boundaries and interstitial spaces of larger nanoparticles, are responsible for the three mechanisms stated above. This result is strongly supported by the apparent activation energy values ranging from 48.2 to 90.6 kJ/mol, which correspond to the energy for grain‐boundary diffusion in Fe. The experimental results of this study show that bimodal nanopowder agglomerates can be used to produce full density nano‐grained powder metallurgical parts by pressureless sintering. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) has become a widespread additive manufacturing technique for material engineering, but its application in lead‐free Ba0.85Ca0.15Zr0.1Ti0.9O3 piezoelectric ceramics from aqueous systems has not been reported so far to our knowledge. The main obstacle is the high extent of hydrolysis reactions undergone by the starting powders when dispersed in water, hindering the attainment of stable water‐based colloidal suspensions. This paper reports on the preparation of stable aqueous inks from a deagglomerated and surface‐treated powder synthesized by solid‐state reaction and on DIW of macroporous lead‐free piezoelectrics. Based on zeta potential and rheological measurements, the optimal amounts of processing additives (dispersant, binder, and coagulating agent) were selected to transform the initial fluid suspension to a viscoelastic paste with sufficient stiffness and stability for the printing process. Dielectric and piezoelectric properties of samples sintered under different temperatures were also investigated. Preparation procedure of lead‐free ink for direct ink writing [ABSTRACT FROM AUTHOR]

Sunfilters based on hydroxyapatite (HAp) and iron‐containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe‐containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared, respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser‐treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near‐infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties. Laser ablation in liquid leads to improved UV absorption. [ABSTRACT FROM AUTHOR]

This paper evaluated mechanical and thermal stability of alkali‐activated materials obtained from metakaolin and alternative silica sources, such as rice husk ash (RHA) and silica fume (SF), and were reinforced with recycled ceramic particles (RP) obtained by grinding bricks. Specimens were produced, and after 7 days of curing, they were exposed to temperatures between 300 and 1200°C to determine the influence that different percentages of RP had on the mechanical behavior and microstructure of the produced composites. The results showed a reduction in the linear contraction by 10.22% with 20 wt% RP and that the reinforcing materials improved the mechanical performance of the geopolymers after exposure to high temperatures; the compressive strengths reached 137.7 (±11.4)  MPa after being exposed to 1200°C for the matrix based on RHA and 180.6 (±19.15) MPa after being reinforced with 20 wt% RP. The improvement was mainly due to densification and the formation of crystalline products such as leucite, kalsilite, and mullite. [ABSTRACT FROM AUTHOR]

MgO‐based binders have been widely studied for decades. Recently, the MgO–SiO2–H2O system was developed as a novel construction material, however, its reaction mechanism remains unclear. This paper investigated the reaction products and kinetics of MgO/silica fume (SF) pastes with MgO calcinated at different temperatures. The results indicate that MgO presented larger grain size after calcination at higher temperature. Mg(OH)2 and magnesium silicate hydrate (M–S–H) gel were formed when using MgO calcined at 850, 950, and 1050°C. However, only M–S–H gel was formed when using MgO calcined at 1450°C. The reaction kinetics of MgO could be described using α = 1 − e−k*t. The reaction rate of MgO increased with decreasing calcination temperature, increasing SF dosage, and the addition of sodium hexametaphosphate. Only M–S–H gel was formed when the reaction rate of MgO was below the demarcation line (about 0.250 × 10−6 s−1), and the corresponding demarcation area was around 14 days. [ABSTRACT FROM AUTHOR]

We study the diffusive interaction between soda‐lime glass substrates and sputtered aluminum‐doped silica thin films at 650°C, the temperature of commercial soda‐lime glass shaping or tempering. A first rapid migration of alkali ions from substrate to thin film has been described in a companion paper (J Am Ceram Soc. 2018;101:1516). Using the same samples as (J Am Ceram Soc. 2018;101:1516), we focus here on later interactions, when the layer is consumed by the substrate resulting from diffusive interactions. Using Secondary Ion Mass Spectroscopy profilometry, we show that the interdiffusion rate increases with the aluminum doping content of the layer. We show that the alkali uptake of silica layers accelerates diffusive exchanges with the substrate, consistently with a decrease of viscosity of the layer. Diffusion profiles of silicon are well reproduced when solving the diffusion equation for a diffusivity having an exponential dependence with silicon concentration. The diffusivity of aluminum is shown to be 10 times slower than the diffusion of silicon. Specific exchanges of the two network formers with network modifiers are deduced from the composition‐space trajectories, providing evidence for multicomponent diffusive couplings between species. [ABSTRACT FROM AUTHOR]

Three‐dimensional ceramic nanofiber‐assembled materials with large specific surface area and excellent thermal insulation properties are attracting increasing interests for their unique structure and promising applications. In this paper, we propose a facile methodology to fabricate three‐dimensional silicon nitride nanofiber‐knitted ceramic foams via in situ reactive synthesis from silicon foams. Silicon particle‐stabilized foams are fabricated for the first time using long‐chain surfactant cetyltrimethyl ammonium bromide as a hydrophobic modifier. First, the fabrication and stability of silicon foams are investigated. Based on the stable silicon foams, silicon nitride‐based nanofiber‐knitted ceramic foams are synthesized via in situ reactive sintering in nitrogen atmosphere. The novel ceramic foam materials consist of three‐dimensional nanofiber‐assembled strut wall and nanofiber‐spheres in the pores. The diameter of obtained silicon nitride nanofibers ranges from 15 to 100 nm. The unique nanofiber‐knitted foams may have potential applications in specific fields, including catalysis, adsorption, separation, and thermal insulation. [ABSTRACT FROM AUTHOR]

The development of efficient red‐emitting persistent phosphor is still an ongoing challenge. In the search of persistent materials in red range, Pr3+ is a good candidate owing to its transitions between 1D2 and 3H4 state at about 612 nm. In this paper, we investigated the red persistent properties of Pr3+‐doped perovskite oxide ABO3, (A: K, Na and B: Nb), which can be elaborated as large single crystal. KNbO3:Pr3+ appears to have weak photoluminescence and no persistent luminescence. However, the cationic substituted compounds K1−xNaxNbO3:Pr3+ (x = 0, 0.4, 0.5, 0.7 0.9, 1) exhibit intense persistent luminescence, which increases steadily with increase in Na content. We correlated persistence behavior with the position of Metal‐to‐Metal Charge Transfer (MMCT) band, which plays crucial role in tuning of the trap depth. The MMCT band position decreases with the addition of Na contents and the thermoluminescence peak shifts toward higher temperature indicating the formation of deeper traps. This is in good agreement with the enhancement of the persistent luminescence suggesting that a proper tailoring of MMCT is needed to design efficient Pr3+‐persistent phosphors with better performance. A detailed analysis on the trap depth, bandgap energy, and persistent luminescence properties is reported tuning the composition in the K1−xNaxNbO3:Pr powder. Tunable traps depths are obtained by Na/K substitution. Electron and hole traps are evidenced by thermal analysis. This gives new insights in the persistent luminescence mechanism in the Pr3+− doped perovskite compounds. [ABSTRACT FROM AUTHOR]

Ba(Zr0.2Ti0.8)O3‐x(Ba0.7Ca0.3)TiO3 (BZT‐xBCT) is a promising lead‐free ferroelectric system. In this paper, we present two sets of free energy coefficients and carry out phenomenological modeling to study the phase transition and electrocaloric effect. The calculated phase diagram is in excellent quantitative agreement with experiments. Furthermore, we propose a new method based on effective internal electric field to simulate polarization in the macroscopic paraelectric state of ferroelectric relaxor. The computed composition and temperature‐dependent entropy and temperature change induced by electrocaloric effect are in good agreement with the measured data available for single crystal. [ABSTRACT FROM AUTHOR]

Molecular dynamics and related atomistic computer simulations are effective ways in studying the structures and structure–property relations of glass materials. However, simulations of boron oxide (B2O3)‐containing oxide glasses pose a challenge due to the lack of reliable empirical potentials. This paper reports development of a set of partial charge pairwise composition‐dependent potentials for boron‐related interactions that enable simulations of multicomponent borosilicate glasses, together with some of the existing parameters. This set of potentials was tested in sodium borate glasses and sodium borosilicate glasses and it is shown capable to describe boron coordination change with glass composition in wide composition ranges. Structure features such as boron N4 value, density, Qn species distribution, fraction of non‐bridging oxygen around boron and silicon, total correlation function, and bond angle distribution function were calculated and compared with available experimental data. Mechanical properties of the simulated glasses calculated with the new potential also show good agreement with experiments. Therefore, this new set of potential can be used to simulate boron oxide‐containing multicomponent glasses including those with wide industrial and technology applications. [ABSTRACT FROM AUTHOR]

Bioactive glass powders synthesized by solgel are usually porous and exhibit high specific surface areas, conferring them poor ability for scaffolds fabrication using colloidal processing approaches. The difficulties associated with colloidal processing of solgel glass have hindered so far the processing of 3‐D scaffolds by robocasting. This research paper investigates the importance of calcination temperature (CT) and balls to powder ratio (BPR) used upon wet milling on the maximum achievable solid loading in aqueous media. The effects of CT, BPR, and solid loading on the flow behavior and viscoelastic properties of the suspensions/pastes were evaluated in this preliminary work. The aim is to disclose the sets of experimental variables that are most promising for the formulation of printable inks, and open the way for the future fabrication of porous scaffolds by robocasting and other 3‐D additive manufacturing techniques. Difficulties associated with colloidal processing of sol‐gel glass have hindered the processing of 3‐D scaffolds by robocasting. Here we disclose the most promising variables for the formulation of printable inks, opening the way for the future fabrication of porous scaffolds by robocasting and other 3D additive manufacturing techniques. [ABSTRACT FROM AUTHOR]