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Co-precipitation method is used to prepare Mn 2 Ba 2 Gd x Fe 12-x O 22 (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) Y-type hexaferrites. X-ray diffraction patterns reviled that prepared samples have single phase. The lattice parameters of 'a' and 'c' increases from 5.87 Å to 5.89 Å and 43.50 Å to 43.68 Å with the incorporation of Gd3+ (Gadolinium), respectively. Samples crystallite sizes were in the 88.8–201 nm range. The spectrum of FTIR explains Fe-O vibrational bands, which signifies the formation of Y-type hexaferrites. The maximum quality factor 'Q' value is obtained at 2 GHz. The maximum Q value at high frequency suggests the potential uses of prepared samples for multilayered chip inductors operating at high frequencies. A reduction in the values of saturation magnetization (M s), coercivity (H c) as well as in remanence (M r) were observed in 32.0–10.2 emu/g, 19.30–5.41 emu/g, and 3084.60–1071.3 Oe range respectively. The decrement in the squareness ratio was also found in the range of 0.594–0.529. The values of squareness ratios greater than 0.5 specify that the prepared materials have a sole magnetic domain. Due to the high coercivity of the prepared materials, these could be used in devices that use high frequencies and perpendicular recording mediums. [ABSTRACT FROM AUTHOR]

Hexagonal ferrites have drawn significant attention due to a broad range of telecommunication and stealth technology applications. β-Type hexagonal ferrites are rarely used in various technological applications. In the current work, Nd3+ substituted polycrystalline β-type hexagonal ferries with composition LiFe 11-x Nd x O 17 (x = 0.0–0.04, ∇ x = 0.01) were prepared using the sol-gel method. All prepared samples were sintered at 1000 °C for 4 h. The influence of Neodymium (Nd3+) on its structural, electrical, and dielectric properties was investigated. Lattice parameters (a, c) and V cell increased with varying Neodymium substitution levels. The crystallite size was measured in the range of 38–42 nm. Fourier Transform IR (Infrared) spectroscopy exposed the presence of two spectral bands at 416 to 449 cm−1 and 449 to 489 cm−1. XPS (x-ray photoelectron spectroscopy) analysis verified the presence of metal ions and their chemical states in all prepared samples. The dielectric constant, loss, tan δ, and σ ac (ac-conductivity) decreased by increasing Nd3+ content. Jonscher's power law explains the conduction mechanism of charge carriers in all fabricated samples. The influence of relaxation time and grain boundaries on the electrical characteristics of prepared nanomaterials was investigated by impedance analysis. SEM (scanning electron microscopy) confirms the successful formation of β-hexaferrite nanomaterials. A minimum reflection loss of −32.08 dB was observed at 1.5 GHz for the x = 0.04 sample. This minimum reflection loss evidenced the novelty of the research and suggested their usefulness in high-frequency microwave applications. All samples investigated in this research work are suitable for high-frequency applications, multilayer chip inductors, and EM interference shielding. [ABSTRACT FROM AUTHOR]

This paper reports an extensive investigation on the structural, dielectric, ferroelectric and pyroelectric properties of 0.7Ba 1-x Sr x TiO 3 – 0.3Bi 0.5 Na 0.5 TiO 3 (x = 0.0, 0.5, 0.6, 0.7) ceramics synthesized via conventional solid-state reaction (SSR) technique. X-ray diffraction data confirms the presence of pure perovskite phase. The variation of lattice parameters with strontium concentration in 0.7Ba 1-x Sr x TiO 3 – 0.3Bi 0.5 Na 0.5 TiO 3 ceramics were evaluated using the Rietveld refinement of the XRD data. The variation of dielectric permittivity with temperature (ε' ∼ T) shows the diffused phase transition and all the parameters related to the relaxor ferroelectrics (relaxation coefficient, activation energy and freezing temperature) were evaluated. The energy storage properties of the as-prepared ceramics were evaluated using the room temperature PE loop. Amongst the as-prepared ceramics, the composition with x = 0.5 possesses the highest energy storage density of 0.46 J/cm3 with an efficiency of 90 %. The temperature dependent P-E loops were used to study the electrocaloric effect (ECE). The ECE calculations were performed using in-direct method based on Maxwell's thermodynamic relations. A maximum adiabatic temperature change of 0.32 K is achieved at 268 K under a small applied electric field of 25 kV/cm for the ceramic with Sr content x = 0.5. Additionally, electrocaloric responsivity ξ max = 0.13 K mm/kV was also found for the studied ceramics. The above results show that the ceramic 0.7Ba 1-x Sr x TiO 3 – 0.3Bi 0.5 Na 0.5 TiO 3 with the composition x = 0.5 is a viable lead-free option for application in solid state refrigeration. [ABSTRACT FROM AUTHOR]

Perovskite oxides have huge potential applications in carbon capture and utilization as oxygen transport membranes (OTM) and solid oxide fuel cell (SOFC) electrodes. SrFeO 3- δ -based perovskite material, as the promising candidate, possesses high mixed ionic-electronic conductivity, but its partial application is impeded by poor stability under CO 2 conditions. In this work, SrFe 0.9 M 0.1 O 3- δ (SFM, M = Fe, Al, Zr, Nb, W) ceramic membranes were synthesized to study the effects of different valence B-site ions doping on the stability and CO 2 adsorption process of perovskite oxides. The phase structure, thermal expansion property, CO 2 tolerance, and CO 2 absorption mechanism on surfaces of SFM were investigated systematically. B-site doping stables the pure cubic structure, improves the high-temperature structural stability, and reduces the thermal expansion coefficient (TEC) by increasing the lattice parameters and metal-oxygen average binging energy (ABE) of SFM. Moreover, density functional theory (DFT) calculations indicate that although B-site ions doping promotes the adsorption of CO 2 on the FeO 2 -terminated, it inhibits CO 2 adsorption on the Sr-O-Sr site after Zr4+, Nb5+, and W6+ doping, causing the reduction of the CO 2 desorption. The results offer new insights for designing perovskite oxides in the carbon neutralization field. • Different valence ions B-site dope SrFeO 3- δ perovskite oxide used in the CCUS. • SrFe 0.9 M 0.1 O 3- δ (SFM, M = Fe, Al, Zr, Nb, W) ceramic membranes are synthesized. • The increase of lattice parameters stabilizes the cubic structure of SFM. • The structure stability at high temperatures is improved by B-site ion doping. • The CO 2 adsorption mechanism on the SFM surfaces is revealed by DFT calculations. [ABSTRACT FROM AUTHOR]

This paper investigated the impact of Co ions doping on the structure, magnetic properties, and magnetocaloric effect for La 0.8 Sr 0.2 Mn 1- x Co x O 3 ceramics (LSMCO) by sol-gel method and first-principles calculations The use of first-principles calculations was provided for subsequent experiments. The sol-gel preparation of LSMCO ceramics and sintered at 950 °C for 10 h. It was shown that the samples' cell volume and lattice constants changed slightly with increasing Co2+ doping but remained a rhombohedral structure (No.167, R-3c space group) by statistics of TEM and XRD. The average particle size for the LSMCO ceramics ranged from 130 nm to 170 nm. LSMCO's chemical composition was verified by EDS and XPS and it was demonstrated that Co2+ was successfully doped. The oxidation state of La was found to be +3, Mn is a mixture of Mn3+ and Mn4+ valence states, and Co is a mixture of Co3+ and Co2+ valence states using XPS. In the vicinity of Tc, all samples presented the second-order magnetic phase transition from ferromagnetic to paramagnetic resorting to normalization and the Banerjee criterion. The Tc dropped from 292 K to 237 K with increasing Co2+ doping. The blocking temperature and the saturation magnetization were suppressed by the Co2+ substitution while the maximum magnetic entropy change of the LSMCO ceramics was observed to reduce as Co2+ increased. When the external magnetic field is 5 T, the La 0.8 Sr 0.2 Mn 0.95 Co 0.05 O 3 ceramics has a Tc of 292 K and a maximum magnetic entropy change value of 3.47 J/(kg K). [ABSTRACT FROM AUTHOR]

This study explores a novel method for fabricating Ca-α-sialon ceramics using a calcium aluminate oxide eutectic additive. Conventional sintering techniques for Ca-α-sialon ceramics employ nitrogen-containing additives to facilitate the Si–N bond substitution mechanism with Al–O and Al–N bonds. In this work, calcium aluminate additives are utilized, leading to the formation of Ca-α-sialon ceramics via carbothermal reduction processes and partial nitridation of aluminum oxide. The influence of varying calcium aluminate content (5, 10, 15, 30, and 40 wt%) on the phase composition of Ca-α-sialon ceramics, produced by hot pressing at 1650 °C in a nitrogen atmosphere, was investigated. Results indicate that increasing the calcium aluminate content leads to the formation of a β-sialon phase, which subsequently transforms into Ca-α-sialon. At 40 wt% calcium aluminate, complete conversion of α-Si 3 N 4 to Ca-α-sialon is achieved, with significant glassy phase formation at the grain boundaries. The study elucidates the relationship between calcium aluminate content, phase composition, lattice parameters, mechanical properties, oxidation resistance, and thermal expansion of the ceramics. [ABSTRACT FROM AUTHOR]

Ceramics of Li 2 Mg 2 GaTi 2 O 8 F (LMGTOF) were prepared by the traditional solid-state method. XRD and TEM results confirmed that a single phase of Li 2 Mg 2 GaTi 2 O 8 F, with an Fd-3m space group and a cubic spinel structure, was formed by the ceramics. It was shown by the results that the lattice parameters of the ceramics at 1050 °C were measured as a = b = c = 8.36576 Å, with a volume of V = 585.485549 Å3. Furthermore, it was observed through the analysis of the Raman peak at 718 cm−1 that an inverse relationship was exhibited between the Raman shift and ε r. Similarly, an opposing trend was also demonstrated between the Q × f value and FWHM. By bond valence analysis, it was shown that Mg2+, Ga3+, and Ti4+ ions were in a "rattling" state, and the large positive deviation between ε corr and ε theo was attributed to the strong "rattling" effect induced by the cations. At 1050 °C, the best microwave dielectric properties (ε r = 14.58, Q × f = 76,689 GHz, and τ f = −52 ppm/°C) were exhibited by LMGTOF ceramics. [ABSTRACT FROM AUTHOR]

The (Al 1-x Cr x) 2 O 3 solid solution (ACS) is expected to be an low pollution chromium source for high-performance alumina-chromium oxide refractory materials. In this work, the effects of Cr 2 O 3 content and reaction conditions on the solid solution behavior in the Al 2 O 3 -Cr 2 O 3 system were explored and the mechanism was revealed. The relationship between the lattice parameters of the formed ACS phase and the content of Cr 2 O 3 was closer to a linear one as the temperature rose, serving as an indicator for a higher degree of reaction. The solid solution reaction between Al 2 O 3 and Cr 2 O 3 was governed by the diffusion processes of Al3+ and Cr3+ at 1300–1500 °C and 1200 °C, respectively, and thus the increase of Cr 2 O 3 content slowed the solid solution reaction at a low temperature whereas promoted it at elevated temperatures. The diffusion process of solid solution reaction within the Al 2 O 3 -Cr 2 O 3 system was consistent with the Cater model; The diffusion activation energy (E a) decreased as the content of Cr 2 O 3 increased at 1300–1500 °C. When the content of Cr 2 O 3 increased from 25 to 60 mol%, the diffusion activation energy decreased from 92.48 to 86.49 kJ/mol−1, which was attributed to the augmentation in the diffusion rate of Cr3+ caused by the increase of Cr 2 O 3 content and its vapor-phase transport mechanism at high temperatures. [ABSTRACT FROM AUTHOR]

The coalescence of nanocrystals that occurs during low-temperature thermal treatments during the purification of hydroxyapatite from pigs has not yet been studied in the context of low-temperature environmentally friendly purification. To preserve the nature of hydroxyapatite, two extraction methods were investigated: Route 1 (autoclave and Soxhlet) and Route 2 (calcination at low temperatures with different times). The focus is on observing the effectiveness of removing fats and proteins while maintaining crystallite size and morphology. DSC showed that coalescence of crystallites occurred at 452, 566, 648, and 704 °C. Raw has a higher IR FWHM (phosphate band) due to the organic material; R1 had a lower FWHM (partial removal of lipids and proteins). Increasing the calcination temperature decreases the FWHM, indicating a shift in vibrational states from surface to bulk, leading to an increase in apparent crystallite size due to coalescence. For 20–80 h at quasi-stable temperatures of 400 and 500 °C, no significant changes occur in the IR spectrum. X-ray diffraction indicates the removal of organic material during calcination, as the peaks become clearer with increasing temperature. The crystallite size is not affected and remains in similar ranges. Purification with hydroxide shows an increase in both lattice parameters, in addition to the fluctuations that occur due to the ionic substitutions that naturally occur in biogenic HAp. And the TEM study confirms that the changes in apparent size from 2D to 3D are the result of the phenomenon of interplanar coalescence at low temperatures that occurs in sintering processes. [ABSTRACT FROM AUTHOR]

In this study, the element substitution technique was utilized to create a solid solution, which in turn allowed for the manipulation of lattice parameters. The microwave dielectric properties of Mg 1.8 R 0.2 Al 4 Si 5 O 18 (R=Mg, Ni, Zn, Cu, Sr, Ca, Ba) ceramics were investigated following the substitution of Mg2+ ions. The influence of microstructural alterations on these properties was also examined. A cordierite solid solution was formed when R = Ni, Cu, Sr, or Ba; however, an additional phase emerged when R = Zn, Sr, or Ca. The complete substitution influenced the relative dielectric constant of Mg 1.8 R 0.2 Al 4 Si 5 O 18 due to the ionic polarizability and the average ionic property of the R ion. The Q × f value was found to be related to the crystal lattice energy, while the τ f value was primarily affected by octahedral distortion. The appearance of a secondary phase altered the primary factors influencing the dielectric properties of the Mg 1.8 R 0.2 Al 4 Si 5 O 18 ceramics. Among the substitutions tested, Mg 1.8 Ni 0.2 Al 4 Si 5 O 18 exhibited superior microwave dielectric properties with ε r = 4.64, Q × f = 44,770 GHz, and τ f = −32 ppm/°C. [ABSTRACT FROM AUTHOR]

Wafer-scale Mesoporous GaN (MP-GaN) distributed Bragg reflectors (DBRs) with high reflectivity (>99 %) are prepared by electrochemical etching, and then are used as the substrate in growth of large-area europium (Eu) doped Ga 2 O 3 thin films via the pulsed laser deposition (PLD) technology. X-ray diffraction analysis shows that all Ga 2 O 3 thin films with different doping concentration have monoclinic β-Ga 2 O 3 structures with [−201] orientation. The angle of β-Ga 2 O 3 (−201) peak decreases as Eu contents increases, which is due to the fact that Eu3+ substituting for Ga3+ rises the lattice constant of β-Ga 2 O 3. With the increase of Eu doping, the photoluminescence (PL) of the Ga 2 O 3 thin film is enhanced. The epitaxial relationship is β-Ga 2 O 3 (−201) || GaN (0001) with β-Ga 2 O 3 [010] || GaN [-12-10]. Compared to the sample without DBRs, wafer-scale Ga 2 O 3 thin films with MP-GaN DBRs exhibit a markedly increased PL intensity, which is attributed to improved internal quantum efficiency (IQE) of Ga 2 O 3 thin films and enhanced light extraction efficiency (LEE) related to the light reflection effect of MP-GaN DBRs. [ABSTRACT FROM AUTHOR]

Crystalline Sm3+ substituted V-type hexaferrites Sr 1-x Sm x Fe 8 SnO 15 with composition (x = 0.00, 0.02, 0.06, 0.10) were synthesized using hydrothermal method. With the substitution of Sm3+ ions, the lattice constant 'c' experienced a decrement from 54.4600 Å to 53.0200 Å while the value of lattice constant 'a' firstly increased and then decreased. The crystallite size varied from 37.95 to 50.86 nm. The spherical shape of particles was analyzed by Atomic Force Microscopy (AFM). The VSM analysis revealed that the samples inherent the soft magnetic properties as evidenced by the coercivity value being below 1 k Oe which exemplifies its usefulness in the field of microwave absorption properties. The successive production of heat during hyperthermia analysis indicated the use of this material in cancer cell treatment. The UV visible spectroscopy technique was utilized to investigate many parameter including absorption, Urbach-energy, and band gap. It can be affirmed that the prepared material might be useful for photo-catalytic purposes and hyperthermia applications. [ABSTRACT FROM AUTHOR]

In this study, Ca substitution and carrier doping effect on phase formation temperature and physical/superconducting properties of (Eu 0.9-x Ca x La 0.1)(Fe 0.97 Co 0.03)As 2 ((Eu,Ca)112, x = 0–0.4) compounds were investigated. The best synthesis condition for obtaining pure phases vary (850–900 °C) depending on the Ca substitution amount. Ca substitution in the EuFeAs 2 structure induced a structural transformation from orthorhombic I 2 mm to monoclinic P 2 1 / m symmetry. Single crystals of EuFeAs 2 and (Eu 0.9 La 0.1)FeAs 2 were grown and their crystal structures were determined. Density functional theory calculations confirmed the transformation and stability of the La-doped Eu112 crystal structure with Ca substitution. Compared with the parent compound EuFeAs 2 , the effective substitution of Ca reduced the lattice constants. The magnetic and transport properties of (Eu 0.9- x Ca x La 0.1)(Fe 0.97 Co 0.03)As 2 compounds were studied using the temperature and field dependence of the magnetization and electrical resistivity measurements. Ca substitution suppressed the magnetic ordering of Eu and gradually reduced the Néel temperature T N Eu. As determined by the magnetization and electrical resistivity data, the onset of critical temperature (T c) values increased with Ca substitution increment from 26 K to 32.2 K and 31 K–34.8 K, respectively. Ca substitution slightly increased the upper critical field values, while the coherence length ξ values were slightly decreased. The Ca substitution and sintering temperature dependence of superconductivity, upper critical fields, lower critical fields, and Eu-related magnetic transitions were extracted. The new series of Eu-containing iron-based superconductors with high T c provides an interesting playground in this field. [ABSTRACT FROM AUTHOR]

Recently it was found that doped barium stannates have proton conductivity and can be used for various electrochemical applications. In this study, we investigated the effect of lutetium doping of the tin sublattice on the functional performance of oxides BaSn 1-х Lu х O 3 (х = 0, 0.05, 0.1, 0.15). Oxides with the concentration of lutetium up to 10% mol. were found to be single-phase, crystallizing in a cubic structure with a space group Pm 3 m. The lattice parameter increases linearly with the concentration of lutetium. The oxide with 15 % mol. of lutetium contains an additional phase of Lu 2 Sn 2 O 7. Electrical conductivity of the oxides was studied by the 4-probe DC method and impedance spectroscopy. Experiments were carried out in H 2 O and D 2 O - containing air atmospheres, as well as under dry air conditions. It was found that electrical conductivity of BaSnO 3 does not depend on humidity, while for Lu-doped oxides tends to decrease with increase in the humidity. Impedance data analysis has shown that change in the humidity mostly affects the grain boundary resistance. It is shown for the first time that the conductivity of BaSn 1-х Lu х O 3-δ in D 2 O-containing air is higher than in H 2 O-containing air, which was explained by the thermodynamic isotope effect. [ABSTRACT FROM AUTHOR]

Using first principles calculations, the hydrogen storage, mechanical, dynamic, thermodynamic, electronic and optical properties of YCrH 3 (Y = Ca, Sr, Ba) materials are studied for the first time. The lattice constants of CaCrH 3 , SrCrH 3 and BaCrH 3 are 3.70, 3.88 and 4.07 Å, respectively. Exploration of the mechanical properties shows that both CaCrH 3 and BaCrH 3 are brittle, whereas SrCrH 3 is ductile. In addition, all compounds are metallic, thus facilitating efficient charge transfer during hydrogen storage and release. According to the Bader partial net charges, the charge transfer in the YCrH 3 materials is analyzed. The electron density distributions show that the CaCrH 3 hydride contains ionic and covalent bonds, whereas SrCrH 3 and BaCrH 3 are ionic hydrides. Studies of optical properties reveal that CaCrH 3 has the largest static refractive index and dielectric constant. Notably, all the studied hydrides exhibit dynamic, thermodynamic and mechanical stability. The gravimetric hydrogen storage capacities are 3.08, 2.08 and 1.55 wt% for CaCrH 3 , SrCrH 3 and BaCrH 3 , respectively. These investigations provide an important theoretical basis for further exploring the application of hydride materials in the field of hydrogen storage. [ABSTRACT FROM AUTHOR]

This study investigates the magnetic response of Ho3+ doped Ni 0.4 Cu 0.6 Ho y Fe 2-y O 4 (y = 0.0, 0.02, 0.04, 0.06, and 0.08) spinel ferrites (SFs) and their correlation with crystallite size. The synthesis was achieved using a sol-gel auto-combustion (SGAC) route and performed different characterizations, including X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive x-ray (EDX), Inductively coupled plasma atomic emission spectroscopy (ICP-AES), and vibrating sample magnetometer (VSM) analysis. The cubic spinel phase was verified via XRD in pure NCF and Ho3+ doped NCF samples. The lattice constant (a) was improved from 8.344 Å to 8.378 Å. The substitution of Ho3+ ions led to a decrease in porosity from 42.22 % to 39.54 %. The introduction of Ho3+ ions also reduced the crystallite size (D) from 37.05 nm to 27.72 nm. The specific surface area (S) was increased from 27.44 g/cm2 to 36.14 g/cm2 with the doping of Ho3+. The average particle size (D S) was decreased from 54 nm to 35 nm. The EDX and ICP-AES analyses confirmed the good agreement with the theoretical composition. The VSM measurements provided insights into their magnetic properties. Furthermore, the doping of Ho3+ ions enhanced coercivity (H C), while reducing saturation magnetization (M S) from 64.35 emu/g to 16.22 emu/g. The decrease in crystalline anisotropy (K) observed at higher concentrations of Ho3+ may result from the increase in coercivity, potentially attributable to the smaller crystallite size of the single-domain SFs particles. The single-phase matrix and their magnetic behaviour showed that the Ho3+ doped Ni–Cu SFs samples are suitable for high-frequency applications. [Display omitted] • Ni 0.4 Cu 0.6 Ho y Fe 2-y O 4 was prepared via the sol-gel auto-combustion technique. • The crystallite size was the minimum (27.72 nm) for the y = 0.08 (NCHF4) sample. • The sample has y = 0.08 (NCHF4) and contains maximum coercivity (1031.44 Oe). • The sample has y = 0.08 (NCHF4) and is best-suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

A series of Cr 2− x Fe x O 3 (0.0 ≤ x ≤ 0.3) nanoparticles were successfully synthesized using a sol-gel-based method. Analysis through XRD and SAED of both pure and Fe-doped Cr 2 O 3 nanoparticles revealed a rhombohedral structure belonging to the R 3 ‾ c D 3 d 6 space group, without the formation of secondary phases or Fe clusters. Fe ions were well integrated, as indicated by fluctuations in lattice parameters, and lattice strain. The crystallite size decreased from 38.42 to 27.54 nm with increasing doping concentration. HRTEM images depicted evenly distributed nanoparticles. At lower dopant concentrations (x = 0.1), smaller and more heterogeneous nanorod-like structures emerged, with average sizes and lengths of 36.56 and 39 nm, respectively. Increasing the doping content to x = 0.2 resulted in a morphological shift towards semi-spherical and ellipsoidal shapes, with average dimensions of 22.84 and 31 nm, respectively. At higher doping levels (x = 0.3), nanoparticles grew to 66.5 nm in size and exhibited a spherical morphology. Raman and Fourier transform infrared spectra showed red-shifting of absorption bands with increasing Fe content, attributed to variations in bond length and Cr/Fe–O–Cr/Fe structural perturbation. XPS and Mössbauer spectroscopy analyses confirmed the oxidation states of Fe3+ and ionized oxygen vacancies in the crystal lattice of Cr 2 O 3 nanoparticles. Higher values of quadrupolar splitting Δ indicated greater structural disorder induced by Fe3+ in octahedral positions and in an oxygen-deficient environment. Atomistic simulations confirmed that Fe3+ dopants can induce the presence of vacancy-complexes, forming a stable double-defect configuration with vacant Cr sites along the c-axis, proximal to oxygen vacancies with a single positive charge. These findings offer both experimental and theoretical insights into the dynamics of structural defects in trivalent transition metal doping of Cr 2 O 3 nanoparticles, which holds significant implications for spintronics research. [ABSTRACT FROM AUTHOR]

We have synthesized (G d 0.2 Y 0.2 N d 0.2 D y 0.2 R 0.2) 3 F e 5 O 12 (R = E r , S m and Pr) high entropy garnet ceramic samples via solid-state reaction route for the first time. All the samples are formed in a single phase and exhibit a simple cubic crystal structure with an I a 3 ‾ d space group. The lattice constant of these samples varies as per the ionic radii of the substituted element and ranges in between 12.4458 Å to 12.5062 Å. The morphology and elemental contributions are also investigated for all the high entropy samples. Additionally, magnetization data reveal a similar value of room temperature saturation magnetization i.e., ∼ 16 e m u / g for (G d 0.2 Y 0.2 N d 0.2 D y 0.2 R 0.2) 3 F e 5 O 12 (R = S m and Pr) samples and it becomes 13.67 e m u / g for Er doped sample. This variation is understood with Dionne's sublattice magnetization model where the molecular weight of the substituent will affect the saturation magnetization. Furthermore, a deviation from ideal Debye-type relaxation behavior is noticed in room temperature Nyquist plots for all three samples. An anomaly in the dielectric plot around ferrimagnetic transition temperature indicates the multiferroic behavior of these high entropy ceramic materials. [ABSTRACT FROM AUTHOR]

In this study, a novel solid electrolyte system consisting of co-doped cubic phase stabilised bismuth oxide was successfully synthesized via the sol-gel method. X-ray diffraction (XRD) analysis revealed that all synthesized samples exhibited stable cubic fluorite-type structures. Notably, as the dopant ion radius decreased, a trend of increasing full width half maximum (FWHM) of the main (111) peak and crystal microstrain, along with a decrease in the average crystallite size and lattice constant, was observed. Interestingly, the sample Bi 1.8 Gd 0.1 Er 0.05 Pr 0.05 O 3 , possessing a dopant ion radius closest to Bi3+ (1.17 Å), exhibited exceptional electrical properties, achieving a high conductivity of 0.347 S cm−1 at 800 °C and a low activation energy of 0.20 eV for the high-temperature regions (HTR). This superior performance was attributed to the significant role played by the grain boundary volume and conductivity in facilitating ionic conduction, thus explaining the variations in conductivity among the different samples. [ABSTRACT FROM AUTHOR]

Optical ceramics with 50 at.% Sc in both dodecahedral ({Y 1·17 Er 0.03 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12 , {Y 1.2 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12) and octahedral ({Y 2·52 Er 0.03 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12 , {Y 2.55 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12) sites of the garnet structure were synthesized using the non-reactive vacuum sintering method. Analysis of the phase composition, thermal diffusivity, transmission in the visible and IR regions of the spectrum, as well as luminescent properties (Stokes and anti-Stokes luminescence, luminescence decay kinetics) revealed clear correlations with the chemical composition of ceramics. It has been determined that solid solutions in which Y3+ cations are partially replaced by Sc3+ cations, compared to solid solutions in which Al3+ cations in the octahedral site are partially replaced by Sc3+, are characterized by lower crystal lattice parameters (11.883 ± 0.004 Å and 12.153 ± 0.005 Å); lower thermal conductivity values (4.72 W/(m·K) and 5.9 W/(m·K)); higher characteristic vibration frequencies of structural groups; shorter lifetimes of excited states of Yb3+ (1.41 μs and 1.56 μs for YSAG:Yb; 0.42 μs and 0.65 μs for YSAG:Yb,Er) and Er3+ (8.6 μs and 9.2 μs) cations; higher efficiency of energy transfer from Yb3+ to Er3+. The results clearly indicate that solid solutions with high concentrations of Sc3+ cations in the dodecahedral site can also be effective matrices for Yb3+ and Er3+ cations compared to solid solutions with a predominant introduction of scandium in the octahedral site. [ABSTRACT FROM AUTHOR]

A series of Zr4+-Co2+ substituted U-type hexaferrites (Ba 4 Zn 2 Fe 36-2x Zr x Co x O 60 (0.0 ≤ x ≤ 1.0, having Δx = 0.25)) were synthesized via sol-gel auto-combustion method. The samples were sintered at 1200 ° C for 6 h. The impact of Zr–Co substitution on phase, structure, morphology, and dielectric behavior were investigated through XRD, FTIR, SEM, XPS and VNA. XRD studies shows that the U-type hexaferrite phase has been developed and the increase in lattice constants (a & c), cell volume, c/a ratio, and percentage porosity was observed. Sample with x = 0.25 exhibited the smallest crystallite size (34.5 nm). The existence of signature metal-oxygen vibrational bands for hexaferrites was observed by FTIR spectra. SEM analysis reflects that the substitution produces a significant effect on morphology and grain size of the samples. X-ray photoelectron spectra (XPS) of sample x = 1.0 confirmed the chemical and elemental composition. The dielectric constant, dielectric loss, and ac conductivity increases with increasing frequency and decreases with Zr–Co substitution. The lowest reflection loss of R L = −64.5 dB (with MW absorption >99.9 %) was observed for the composition x = 0.5 with pellet thickness of 1.73 mm at 1.05 GHz frequency. Due to the improved bandwidth and better absorption, these hexaferrites can be used in microwave and high frequency applications. [ABSTRACT FROM AUTHOR]

We report the structure and physical properties of a new rare-earth (RE) high-entropy boride (HEB) (Dy 0.2 Ho 0.2 Er 0.2 Tm 0.2 Lu 0.2)(Rh 0.85 Ru 0.15) 4 B 4. The as-cast HEB consists of a highly crystallized, body-centered-tetragonal phase (I 4 1 / a c d , a = 7.460 Å and c = 14.860 Å); here, all the RE elements share the same crystallographic site and are distributed uniformly on both macroscopic and microscopic scales. At high temperature, the HEB shows a paramagnetic behavior with a large effective moment p eff yet it becomes a bulk superconductor upon cooling below 6.0 K. Remarkably, a peculiar cocktail effect of properties is observed: while the lattice parameters, T c and p eff of the HEB agree reasonably well with the compositional averages of the individual pseudo-ternary counterparts, the increased RE mixing entropy tends to suppress the superconductivity even without the magnetic exchange interactions, and a reentrant resistive transition is induced at magnetic fields above 0.8 T. Our results indicate that the high-entropy design of the RE sublattice is a viable way to tune the electrical and magnetic properties in RE intermetallics. [ABSTRACT FROM AUTHOR]

A novel quaternary medium-entropy rock-salt oxide (Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25)O (MERO) was predicted using first-principles calculation and prepared through solid-state reaction. The first-principles study demonstrated that the mixing enthalpy and entropy values of the MERO are 2.377 kJ/mol and 0.693–1.040 R, respectively. The single-phase MERO can be obtained from 1000 °C to 1200 °C, demonstrating good thermal stability, whereas a completely disordered occupancy of different metal cations can be confirmed by Raman spectroscopy. The Transition Electron Microscope (TEM) analysis reveals that the MERO exhibits an FCC structure with a lattice parameter of 4.384 Å. The dielectric permittivity ε r of MERO prepared at 1200 °C shows relatively high values of 6.4 × 103 and 18.40 corresponding to frequencies of 100 Hz and 1 MHz at room temperature, exhibiting a potential for application in electrode materials and capacitors. [ABSTRACT FROM AUTHOR]

Double perovskite oxide Pr 1-x Nd x BaFe 2 O 5+δ (PNBFx, x = 0.0–0.3) nanofiber were prepared using electrospinning and were evaluated as cathodes for solid oxide fuel cells (SOFCs). The crystalline structure, microstructure, and electrochemical performance of PNBFx were thoroughly investigated and discussed. The PNBFx nanofiber cathodes obtained after sintering at 800 °C crystallized in a tetragonal structure with the space group P 4/ mmm and had good chemical compatibility with SDC electrolytes at 900 °C for 4 h. Nd doping was found to increase the lattice parameter, while the average valence of praseodymium and iron content increased steadily in PNBFx. The Pr 0.8 Nd 0.2 BaFe 2 O 5+δ (PNBF02) nanofiber cathode exhibited the best performance with a polarization resistance (R p) of 0.072 Ω cm2 at 750 °C. When PNBF02 nanofiber was used as a single-cell cathode, the peak power density reached 1.52 W cm2 at 750 °C. All results indicate that double perovskite PNBF02 is a promising cathode material for SOFCs. [ABSTRACT FROM AUTHOR]

In this paper, cordierite ceramics with high far-infrared emission properties are synthesized by a high-temperature solid-phase method using molybdenum tailings and vanadium-titanium magnetite tailings. The microstructure, physical properties and far-infrared emission mechanism of ceramics are investigated. The results show that the ceramics synthesized with 10 wt% molybdenum tailings and 30 wt% vanadium-titanium magnetite tailings have a flexural strength of 67 MPa, a bulk density of 2.531 g/cm3 and a maximum far-infrared emissivity of 0.958 when the sintering temperature is 1200 °C. The crystal phase of the ceramic are 21.4 % cordierite and 58.7 % magnesia-alumina spinel. In the sintering process, the Fe3+ in vanadium-titanium magnetite tailings doped into the cordierite to substitute the Mg2+, which has the similar ionic radius with Fe3+, to form a substitutional solute. Ionic substitution causes the lattice parameters of cordierite larger, reducing the symmetry of the lattice vibrations and leading to lattice distortion. In addition, the composition of a large amount of magnesia-aluminum spinel is attributed to the far-infrared emission properties of ceramics. [ABSTRACT FROM AUTHOR]

An experimental and theoretical investigation of the magnetic properties of Ti-doped barium hexaferrite (BaM) is conducted. Polycrystalline samples of BaFe 12 − x Ti x O 19 with x ≤ 0.2 were synthesized using the solid-state reaction method. X-ray diffraction (XRD) analyses, along with Rietveld refinement, confirmed the presence of BaFe 12 O 19 as the predominant BaM phase and a minor amount of hematite in all samples. Structural analysis revealed a slight increase in lattice parameters a and c for x = 0. 2. A result mostly related to the preferential occupation of Ti 4 + ions at the 4f 2 and 12k sites, coupled with the reduction of Fe3＋ ions to Fe2＋. It was also found that the magnetic response of samples is affected by Ti 4 + substitution. Saturation magnetization slightly decreased from ∼ 45 (x = 0) to ∼ 44 emu/g (x = 0.2), the anisotropy constant from ∼ 4. 08 × 105 to ∼ 4. 06 × 105 erg/g 2 , while coercivity slightly increased from ∼ 2456 to ∼ 2468 Oe, and the anisotropy field from ∼ 18.2 to ∼ 18.6 kOe. The magnetic features of the samples were analyzed in terms of a proposed model based on the mean-field theory. Results indicated that the substitution of Ti 4 + ions resulted in a decrease in the magnetic moment of the 2b sublattice. Such behavior is influenced by its closest neighboring sites 12k and 4f 2 sublattices, which are the preferred occupancy sites for the Ti 4 + cations. [ABSTRACT FROM AUTHOR]

Element-modified La 0.67 Ca 0.33 MnO 3 (LCMO) ceramics have been a major research subject in the past decades due to their various electromagnetic properties and potential applications in infrared detection and magnetic storage devices. However, its electromagnetic transport mechanism has not been fully elucidated and its properties need to be further optimized for practical applications. Here, we report the effect of Ni2+ doping on the structural, magnetic, the temperature coefficient of resistivity (TCR) and magnetoresistance (MR) properties of La 0.67 Ca 0.33 Mn 1- x Ni x O 3 (LCMNO) ceramics. All samples were synthesized by the sol-gel method and were in pure phase. XRD refinement results show a decrease in lattice constants and cell volume of LCMNO ceramics with increasing Ni2+ content. The XPS study confirms the reduction of the Mn3+/Mn4+ ratio and indicates that oxygen vacancies occur in LCMNO ceramics due to the Ni2+ doping. Curie-Weiss fitting results suggest ferromagnetic superexchange coupling between Ni2+ and Mn3+(4+) ions. The electrical transport properties of LCMNO ceramics were further investigated using the spin polaron hopping model in the high temperature range and the various competing scattering mechanisms in the low temperature range. In addition, double resistivity peak behavior is observed at x = 0.04 and 0.05. Furthermore, the TCR of the LCMNO ceramics increased to 45.4 %·K−1 (x = 0.01), while the MR increased to 67.9 % (x = 0.03), respectively. Our studies contribute to a better understanding of the electromagnetic properties of LCMNO ceramics. [ABSTRACT FROM AUTHOR]

Sol-gel auto ignition route was utilized to synthesize a series of Zn-doped Cd–Mg spinel ferrites with composition Cd 0.5-x Mg 0.5 Zn x Fe 2 O 4 (x = 0.0, 0.1, 0.2, and 0.3). All of the prepared nanomaterials that were annealed for 4 h at 900 °C had a cubic structure and were spinel, according to X-ray diffraction studies. The lattice constant decreased as the Zn concentration increased. This is because of the substituent's lower radii. The W–H plot, Size strain plot, and Sherrer Formula were used to calculate the crystallite size, which was in the range of a nanometer. Vibrational spectroscopy studies have also shown that M − O bonds are present in every processed sample and that a spinel cubic structure has formed. Additionally, the cationic distribution and cubic spinel structure were validated by Rietveld refinement of the XRD data. The analysis using X-ray photoelectron spectroscopy (XPS) has confirmed the presence of all metal ions in their respective electronic states. The dielectric characteristics in the 1 MHz-6 GHz range of frequencies were ascertained using an impedance analyzer. Jonscher's power law validated the conduction mechanism in the synthesized ferrite samples. The relaxation time constant calculated from impedance Cole-Cole plots shows that the conduction in all the synthesized nanomaterials was due to the grains rather than the grain boundaries. The minimum reflection loss of −36.54 dB was achieved for Zn-doped Cd–Mg ferrites at x = 0.3. The prepared Zn-doped Cd–Mg spinel ferrites would be an excellent material for high-frequency microwave absorption applications. [ABSTRACT FROM AUTHOR]

The thermosensitive ceramics of negative temperature coefficient (NTC), SrCo 1- x Ru x O 3 (0 ≤ x ≤ 0.8), were synthesized using the solid-phase method. The research systematically explored the phase structure, microstructure, elemental chemical states, electrical properties, and aging performance. X-ray diffraction (XRD) data indicates that with the increase of Ru content, the lattice parameter increases. Scanning electron microscopy (SEM) images reveal a dense and uniform microstructure. X-ray photoelectron spectroscopy (XPS) data indicates the presence of Co2+/Co3+ and Ru4+/Ru5+ ion pairs. Resistive temperature data indicates its potential use as a low-temperature thermosensitive resistance material in the range of 2–300 K. Fitting the resistance-temperature curve using the thermally activated band conduction model and Mott's 3D variable range hopping model. Proposed the Ru–O2--Co hopping model, elucidating the hole hopping transport mechanism in NTC ceramics. Impedance spectroscopy analysis indicates that grain boundary resistance dominates the overall resistance of the sample. After aging at 77 K for 864 h, the maximum aging drift rate of the ceramic material is 1.55 %. Proposed a novel cationic vacancy diffusion model to explain aging phenomena, offering a new perspective for designing high-stability low-temperature NTC thermistors. [ABSTRACT FROM AUTHOR]

Zirconolite ceramics have been proven to be a promising matrix for high-level waste immobilization, especially for minor actinides. In this study, a series of CaZr 1-2x REE 2x Ti 2-x Mo x O 7 (REE = Nd, Sm, Gd, Ho, Yb) samples were prepared to investigate the formation of zirconolite REE as surrogates of minor actinides and Mo6+ as charge compensator. Synchrotron and in-house powder X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were used to study their solid solubility, phase evolution, and structural details. XRD results show that the formation of zirconolite-2M can be up to x = 0.15 in the CaZr 1-2x Nd 2x Ti 2-x Mo x O 7 samples when co-existence of 2 M and 4 M was observed at x = 0.20 and 0.25. The "yellow phase" appears when x exceeds 0.4. The phase evolutions of CaZr 1-2x Sm 2x Ti 2-x Mo x O 7 , CaZr 1-2x Gd 2x Ti 2-x Mo x O 7 , CaZr 1-2x Ho 2x Ti 2-x Mo x O 7 and CaZr 1-2x Yb 2x Ti 2-x Mo x O 7 solid solutions are similar to each other: (1) zirconolite-2M in x = 0.05 and 0.10; (2) co-existence of 2 M and 4 M and then formation of 4 M phase from x = 0.15 to 0.25; (3) formation of "yellow phase" and pyrochlore when x ≥ 0.30. Interestingly, perovskite exits in all the ceramic samples, and its lattice parameters slightly change when increasing the dopants. Rietveld refinement results reveal that Sm/Ho mainly incorporates into 8f (Wyckoff position) Zr-sites while Mo replaces the 8f (Wyckoff position) Ti-sites. XANES results further confirm the occupation of Mo in TiO5 coordination environments. Furthermore, there is a considerable amount of Sm/Ho incorporated into 8f Ca-sites, demonstrating a different substitution mechanism from the preliminary design. [ABSTRACT FROM AUTHOR]

We thoroughly investigated the effects of Sm³⁺ doping on the magnetic, structural, hyperfine, and vibrational properties of Sr 1-x Sm x Fe 12 O 19 (0 ≤ x ≤ 0.15) nanoparticles, which were synthesized using the proteic sol-gel process. The Rietveld refined XRD patterns confirmed the presence of M-type SrFe 12 O 19 , alongside a minor fraction of α-Fe 2 O 3. As Sm³⁺ doping increased, the unit cell volume fluctuated, decreasing from 691.73 ų at x = 0 to 690.67 ų at x = 0.10 and slightly rising thereafter. The incorporation of Sm³⁺ induced a conversion of Fe3+ to Fe2+, affecting lattice parameters and crystallinity. At x = 0.10, maximum crystallite size (56.48 nm) and X-ray density (4.83 g/cm³) were attained, alongside decreased microstrain, indicating improved crystallinity and reduced defects. However, at x = 0.15, an increase in microstrain suggested lattice instability. FTIR confirmed that bands in the range 400–600 cm⁻1 might be due to the stretching vibration of oxygen and metal (Fe–O) ions, confirming the formation of hexaferrite. Temperature-dependent Raman spectroscopy studies confirmed the presence of spin-phonon coupling in all samples in the ferrimagnetic transition at ∼725-735 K. Mössbauer spectroscopy elucidated that the substitution of Sr2+ by Sm3+ induced the most pronounced effect on the 12 k , 4 f 2 , and 2 a sites, corroborating the evolution of the lattice constants and the fact that these three sites have Sr sites in their close vicinity. The room-temperature hysteresis loops exhibited narrow features, indicative of soft magnetic behavior. Saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc) varied with Sm3+ doping content (x). Ms initially decreased from 62.62 emu/g and 22.03 emu/g at x = 0.00 to 54.96 emu/g and 19.63 emu/g at x = 0.10, respectively, and then increase to 59.77 emu/g and 21.86 emu/g at x = 0.15. Conversely, Mr and Hc showed a non-monotonic trend with x, suggesting complex interactions between dopant concentration and magnetic properties. [ABSTRACT FROM AUTHOR]

Hexagonal ferrites have gained much attraction due to extensive applications in telecommunication and stealth fields. R-type hexagonal ferrites are rare hexagonal ferrites used in various technological applications. In the current work, the sol-gel auto-combustion method was used to prepare samples of R-type hexagonal ferrites with the chemical formula BaZr 2 Fe 4-x Pr x O 11 (x = 0.00, 0.03, 0.06, and 0.09) respectively. The impact of substituting Praseodymium (Pr) on its structural, electrical, dielectric, and magnetic properties was investigated. X-ray diffraction (XRD) patterns suggest all samples exhibit a single phase. The lattice parameters and unit cell volume experienced alterations with varying Praseodymium (Pr3+) substitution levels. The atomic dynamics study of the Pr-doped R-type hexagonal ferrites was evaluated using FTIR analysis. Two absorption bands in the infrared spectroscopy were utilized to designate the tetrahedral and octahedral sites. X-ray photoelectron spectroscopy (XPS) findings verified the presence of all metal ions alongside their respective electronic states. Jonscher's power law elucidates the conduction mechanism of charge carriers in the synthesized ferrite samples. Impedance analysis was employed to investigate the influence of relaxation time and grain boundaries on the electrical characteristics of the fabricated nanomaterials. Impedance Cole-Cole plots provide evidence that all samples demonstrate multiple relaxation processes of a non-Debye nature. The minimum reflection loss (RL) of −32.46 dB at 3.27 GHz was achieved for x = 0.09. Pr-doped R-type hexagonal ferrite has potential applications in microwave high-frequency applications. [ABSTRACT FROM AUTHOR]

High-energy ball milling was employed to fabricate LiMnPO 4 coated with varying carbon ratios (3%wt, 7%wt, and 10%wt), using glucose as a carbon source. The process involved pre-milling of LiMnPO 4 precursors, followed by granulation through high-energy ball milling at 270 rpm for 2 h, and subsequent calcination at 700 °C without an inert gas flow. XRD analysis discerned the phases and structure of LiMnPO 4 , confirming the successful attainment of a single-phase LiMnPO 4 without impurities. Rietveld refinement of the XRD data elucidated the crystallographic details, affirming the material's orthorhombic olivine structure with precise lattice parameters, thereby underpinning the structural integrity essential for electrochemical applications. FE-SEM analysis revealed uniformly distributed semi-sphere particles, with sizes ranging from 130 nm for LM to 183 nm for LM-10%C. FTIR analysis delineated the internal modes of vibration in the olivine structure and verified the presence of carbon on the powder surface. Electrical measurements conducted within the frequency range of 20 Hz–100 kHz demonstrated an increase in electrical conductivity with an escalation in carbon concentration, ranging from 31 μΩ−1m−1 to 75 μΩ−1m−1 for 0%C and 10%C, respectively. A temperature-dependent study spanning 30–160 °C revealed stable electrical conductivity behavior for the samples, with a marginal increase observed at elevated temperatures. [ABSTRACT FROM AUTHOR]

Near-white emission phosphors of the Bi3+/Sm3+ co-doped double-perovskite Ca 2 YTaO 6 were successfully prepared via a simple solid-state reaction. The crystal structures and lattice parameters as functions of doping ion type and its content were analyzed. Note that all the prepared samples have the monoclinic structure with the space group of P 21/n (14). Their lattice parameters were enlarged with the increment of doping ion content since the Y3+ ion with the smaller radius was substituted by the Bi3+ and Sm3+ ions. The photoluminescence (PL) properties of single Bi3+-doped and Bi3+/Sm3+ co-doped Ca 2 YTaO 6 phosphors were fully investigated in terms of PL emission spectrum, emission intensity, energy transfer mechanism, chromaticity coordinate, decay curve, thermal stability, and internal quantum yield. Interestingly, the Ca 2 YTaO 6 :0.015Bi3+/0.07Sm3+ phosphor exhibited a high quantum yield (70.71%). Furthermore, the relative sensitivity based on the dual-emission centers (Bi3+ and Sm3+) was also analyzed. It is demonstrated that high-efficiency near-white Ca 2 YTaO 6 :Bi3+/Sm3+ phosphor with good sensing properties is expected to be a candidate in the field of optical thermometry. [ABSTRACT FROM AUTHOR]

We investigated the effects of various transition metal dopants on the changes in B-site ion-oxygen (B–O) bonding characteristics and the subsequent effects on the electrochemical properties of PrCoO 3 (PCMe, PrCo 0.9 Me 0.1 O 3-δ , Me = Cu, Mn, Nb). The lattice constants of Mn, Cu, and Nb-doped PrCoO 3 were increased compared with that of pure PrCoO 3 (PCO), and the B–O–B bond angles were determined to be 163.709°, 167.323°, 165.149°, and 161.765° for PCO, PCCu, PCMn, and PCNb, respectively, by Rietveld refinement. The pre-edge peak of the O K-edge shifted to 0.7 eV of lower energy in PCCu as compared with PCO, and to 0.2 eV of lower energy in PCMn. By contrast, PCNb shifted to 0.3 eV of higher energy. Considering the B–O–B bond angle and pre-edge peak shift, the overlap between B 3d and O 2p orbitals can be expected to be the largest in PCCu, indicating the strongest covalency, whereas PCNb has the weakest covalency. The polarization resistance, as an indicator of the ORR activity, was 7.63, 6.67, 8.05, and 9.56 Ω cm2 in PCO, PCCu, PCMn and PCNb, respectively. [ABSTRACT FROM AUTHOR]

Al x In 0.05− x Ta 0.05 Ti 0.9 O 2 ceramics with x ranging from 0 to 0.05 were synthesized using a conventional solid–state reaction method. All samples achieved a pure rutile–TiO 2 phase. Additionally, the lattice parameters of the samples increased with higher Al doping concentrations. The ceramics exhibited a dense microstructure and uniform dispersion of dopants. Raman spectroscopy revealed a decrease in oxygen vacancies in the structure with increasing Al3+ concentration. The presence of Ti3+ in the structure was confirmed by X–ray photoelectron spectroscopy. The dielectric properties of all samples were investigated as functions of frequency and temperature. The triple–doped AITTO ceramics demonstrated a high dielectric constant (ε′) of ∼2×104 and low dielectric loss (tanδ) ranging from 0.029 to 0.04, along with excellent temperature stability of ε′ at 1 kHz, showing a Δε′/ε′ 30 of less than ±15% over a temperature range of −60 to 210 °C. Notably, the tanδ of the triple–doped AITTO ceramics remained below 0.04 even at 200 °C. Impedance spectroscopy was utilized to analyze the electrical properties of the grains and grain boundaries. The observed dielectric properties are attributed to the formation of electron–pinned defect–dipoles, along with the impacts of both internal and surface barrier layer capacitors. [ABSTRACT FROM AUTHOR]

Compositions of Ce 1-x-y Gd x Sr y O 2-δ (x = 0.1, 0.2, and y = 0.025, 0.05, 0.075) are prepared using the sol-gel auto combustion method. The as-prepared powders are calcined at 500 °C for 2 h, followed by pelletization and sintering at 1450 °C for 4 h. Phase identification, defect distribution, microstructural analysis, and conductivity are examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy and impedance spectroscopy, respectively. A single crystalline phase is formed, and the lattice parameter variation with dopant concentration exhibits anomalous behavior. All the samples show relative densities higher than 92 %. The partial liquid phase sintering is also observed. In co-doped samples, the doping of 10 % Gd with 2.5 % Sr exhibits the highest conductivity, i.e., 1.20 × 10−2 S cm−1 at 600 °C. The developed materials are used in anode-supported cell testing. It shows a maximum power density of 112.7 mW cm−2 and a current density of 288.7 mA cm−2 at 600 °C with wet hydrogen and air on the anode and cathode side, respectively. [ABSTRACT FROM AUTHOR]

Solar thermal energy regulation is important for sustainable development, comfortable housing, and living. Black compounds are usually considered as an absorber of solar heat. This work reports a series of black near-infrared reflective pigments, Ca 2-y Mg y Mn(1) 1-x Mn(2) x O 4 (x = 0–1, y = 0–0.5), which show strong near-infrared (NIR) reflectivity. Comprehensive analyses were carried out to characterize the obtained pigments including X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and UV–Vis–NIR spectrophotometry. Through the substitution of MnO 2 with Mn 2 O 3 , NIR solar reflectance of the black pigment can be enhanced by 13%, which might be mainly attributed to differences in particle size and lattice parameters. Meanwhile, through Mg doping, the obtained pigment Ca 1.8 Mg 0.2 MnO 4 shows excellent color performances (L* = 43, a* = 0.36, b* = −0.37) and NIR solar reflectance (R*, ∼60%). EnergyPlus simulation results show that for a warm city (Haikou), using the Ca 1.8 Mg 0.2 MnO 4 coating (L* = 25, R* = 51%) can reduce annual cooling energy consumption by 21%. [ABSTRACT FROM AUTHOR]

Er3+, Ho3+ or Sm3+ single-doped hexaluminate CaAl 12 O 19 phosphors were successfully synthesized by a simple polyacrylamide gel method. Low concentration of Er3+, Ho3+ or Sm3+ ions doped CaAl 12 O 19 changed the lattice parameters of CaAl 12 O 19 but did not change its phase structure. A variety of characterization techniques confirmed that the Er3+, Ho3+ or Sm3+ ions occupied part of the position of Ca2+ ions and transformed the surface morphology from the lamellar CaAl 12 O 19 to nanoparticles. The color, optical properties and photoluminescence properties of CaAl 12 O 19 : Er, Ho, Sm phosphors are affected by different rare earth ions and their contents. Er3+, Ho3+ or Sm3+ ions introduces CaAl 12 O 19 which changes its color to bright white and decreases the Eg value. The nonlinear dependence between the reflectance of CaAl 12 O 19 : Er, Ho, Sm phosphors and the content of rare earth ions makes the back propagation neural network model play a great advantage in predicting their color properties. The CaAl 12 O 19 : Er, CaAl 12 O 19 : Ho, and CaAl 12 O 19 : Sm phosphors exhibits obvious emission peaks at 472, 533 and 418 nm with the excitation wavelengths of 310, 370 and 251 nm, respectively. Compared with the literature, CaAl 12 O 19 : Er, CaAl 12 O 19 : Ho, and CaAl 12 O 19 : Sm phosphors show novel luminescence phenomena and are strongly dependent on synthesis methods. The fluorescence emission intensity of CaAl 12 O 19 : Er, CaAl 12 O 19 : Ho, and CaAl 12 O 19 : Sm phosphors increased with the increasing of Er3+, Ho3+ or Sm3+ ion content. Anti-counterfeiting applications show that the CaAl 12 O 19 : Er, CaAl 12 O 19 : Ho, and CaAl 12 O 19 : Sm phosphors have potential applications in the fields of sky blue, green and dark blue luminescence, respectively. [ABSTRACT FROM AUTHOR]

TiC-14 wt%TiC 0.4 and TiC-7.63 wt%Ti ceramics were fabricated by spark plasma sintering (SPS) at a sintering temperature of 1600 °C and an applied pressure of 40 MPa. The impact of ex-situ addition and in-situ formation of vacancies on the microstructures and mechanical properties of TiC composites were investigated. The microstructures were analysed by XRD, SEM, EDS and TEM. The results reveal that TiC 1-x phases with different Ti/C ratios exist in the TiC-14 wt%TiC 0.4 ceramics, which have the same crystal structure and similar lattice parameters. In contrast, only a single phase of TiC 1-y exists in the TiC-7.63 wt%Ti ceramics. The introduced carbon vacancies not only lowered the sintering temperature, but also had a toughening effect on the material. At a sintering temperature of 1600 °C, the TiC-14 wt%TiC 0.4 and TiC-7.63 wt%Ti materials had densities of 98.5% and 99.2%, both materials exhibited excellent mechanical properties Vickers hardness and fracture toughness of 22.5 GPa, 5.2 MPa m1/2 and 23.5 GPa, 4.9 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

Zr x Ta 2 O 2x+5 (ZTOx) was systematically studied to determine ideal solid-state synthesis and pressureless sintering conditions. For Zr 6 Ta 2 O 17 (ZTO6) and other compositions with values of x in ZTOx the optimal synthesis temperature of 1100 °C with 1 h dwell time was optimal. XRD phase analysis of the homologous series indicated that for ZTOx, x = 5, 6, 7, and 8 were within the phase stability field while x = 4 and x = 9 were outside the phase stability field. Unit cell lattice parameters changed anisotropically with Zr:Ta ratio with an overall <0.1% change in unit cell volume across the solid solution. Some Raman modes red shifted while others blue shifted, indicating competing tensile and compressive strains. Sintering of ZTOx required a progressively higher temperature as Zr-content increased despite the same starting powder grain sizes and synthesis temperature. Higher Vickers hardness for Zr-rich (12.7–12.8 GPa) than Ta-rich Zr x Ta 2 O 2x+5 (11.6–11.7 GPa) disappeared when accounting for different sintering temperatures. Indentation toughness was similar for all compositions (1.2–1.4 MPa m1/2). Properties of Zr x Ta 2 O 2x+5 series indicate tunability of Zr:Ta composition ratio while maintaining the structure and room temperature mechanical properties comparable to Hf 6 Ta 2 O 17 and 8 mol% yttria stabilized zirconia ceramics. [ABSTRACT FROM AUTHOR]

Ti 2 GaC is a novel ternary layered ceramic with unique physical and chemical properties such as excellent thermal conductivity, low density, high-temperature oxidation resistance, and corrosion resistance. However, the relatively low strength and hardness of Ti 2 GaC hinder its practical applications as a structural component. To strengthen the mechanical properties of Ti 2 GaC and extend its application range, in this study, (Ti 1-x V x) 2 GaC MAX phase solid solutions with x ranging up to 0.25 were successfully synthesized using a two-step sintering method. (Ti 1-x V x) 2 GaC solid solutions grains showed a typical lamellar structure, where the a lattice constant of (Ti 1-x V x) 2 GaC decreased from 3.0660 to 3.0326 Å and c decreased from 13.3223 to 13.1520 Å. The effects of V content on the solid solution microstructure, crystal structure, mechanical strength, and resistance to friction and wear were evaluated in detail. In addition, the solid solution formation mechanism and fracture damage modes of these materials were discussed. The crystal structure, mechanical properties, electronic properties, and chemical bonding of (Ti 1-x V x) 2 GaC continuous solid solution at x = 0–1 were calculated by DFT. The solid solution enhancement mechanism of (Ti 1-x V x) 2 GaC was explained by analyzing the relationship between the structure and properties. [ABSTRACT FROM AUTHOR]

Mg 1−x O:Bi x (x = 0.01–0.5 mol%) nanophosphors have been prepared using the solution combustion method and subsequent annealing at 1173 K in air. Rietveld refinement on X-ray diffraction (XRD) data confirmed the rock-salt phase formation in pure and Bi3+ doped MgO (space group; F m ‾ 3 m). Lower Bi3+ ion concentrations in Mg 1−x O:Bi x (x = 0.01 and 0.05 mol%) lead to tensile strain and increased lattice parameters of MgO. Higher doping concentrations of Bi3+ ions (x = 0.1–0.5 mol%) lead to a decrease in the lattice strain, unit cell parameters, and Mg–O bond length. Transmission electron microscopy (TEM) images along with selected area electron diffraction (SAED) patterns confirmed the crystalline nature of Mg 1−x O:Bix samples with an average particle size of ∼37.5 nm. X-ray absorption spectroscopy (XAS) results at the Mg K-edge and Bi L-edge confirmed the Mg2+ ions and Bi3+ ions in Mg 1−x O:Bi x samples throughout the Bi doping range. O–K edge XAS conveys the hybridization of the frontier orbitals of O and Bi atoms. UV–visible absorption spectroscopy measurements convey the defect-induced absorption peak shifting in Mg 1−x O:Bi x compounds. Dopant and host defect-assisted PL emission is observed, with prominent emission in the blue region owing to the transition between 3P 1 to 1S 0 and 3P 0 to 1S 0 of Bi3+. The quenching effect on PL properties has been observed beyond 0.05 mol% doping of Bi3+ ions. The presence of various defect states and their stability with re-trapping and charge transfer behaviour have been analyzed by thermoluminescence studies of gamma-irradiated samples, which enable the Mg 1−x O:Bi x samples for potential applications in display device dosimetry. [ABSTRACT FROM AUTHOR]

The paper discusses the structural, morphological, and chromatic characteristics of La3+ substituted Fe3+ in Zn–Co–La ferrite embedded in a SiO 2 matrix, synthesized through a sol-gel method. The thermal behavior of reactants during the synthesis process revealed the formation of metallic oxalate up to 200 °C and their decomposition into metal oxides that further react and form ferrites. The rate constants of oxalate decomposition into ferrites calculated using the isotherms at 160, 200, 240, and 280 °C decrease with increasing temperature and depend on the Fe3+ substitution with La3+ in Zn–Co–La ferrite. The XRD patterns showed a nano-crystalline, single-phase structure formation. The lattice constant increased from 8.431 Å to 8.466 Å, and the crystallite size registered a growth from 35 to 64 nm with the increase in La3+ cations concentration. FT-IR spectra revealed the existence of the M − O stretching bands from Zn–Co–La ferrite and the formation of SiO 2 matrix. Transmission electron microscopy revealed spherically-shaped ferrite particles,with particle sizeraging from,38 to 67 nm. The particle size increases with increasing the La content. The lightness of pigments is low and increases by embedding in opaque ceramic glazes. Synthesized NCs were tested for their potential application as pigments in the ceramic industry through their incorporation into glazes. This evaluation included assessing their color using CIELAB coordinates. [ABSTRACT FROM AUTHOR]

A series of Ce 2 (Zr 1− x B x) 3 (MoO 4) 9 ceramics, where B Cd 1/3 Nb 2/3 , Cd 1/3 Ta 2/3 (abbreviated as CZ 1− x N x , CZ 1− x T x), were synthesized using the classical solid-state reaction method. This study focused on the intrinsic mechanisms affected by doping in terms of chemical bond parameters, polarizability, lattice parameters, and bond valence. X-ray diffraction (XRD) results showed that Cd/Nb and Cd/Ta were solidly dissolved into the matrix lattice, which crystallized in a pure trigonal structure (Space group of R -3c, No. 167). According to the Phillips-van Vechten-Levine (P–V-L) theory, the chemical bond features have been parameterized for exploring the relationships between crystal structure and property. Interestingly, the findings indicated that the dielectric parameters varied closely with the chemical bond features of Zr1–O4. Far-infrared reflectivity (FIR) spectrum and terahertz time-domain (THz-TD) were used to obtain information on lattice vibration. The results showed that the complex permittivity extrapolated from THz-TD was closer to the measured value (at microwave) than the former. The relaxation polarization mechanism may be a key intrinsic factor affecting dielectric loss. Additionally, the bond valence results showed a linear relationship between Zr1–O4 and τ f. CZ 1− x N x and CZ 1− x T x exhibited Qf values that were 2.86 and 5.46 times greater than the matrix, respectively, with low permittivity (ε r , roughly 10) suitable for high-frequency communication materials. Notably, CZ 0.94 T 0.06 ceramic achieved excellent performance with Qf = 103,974 GHz, ε r = 10.63, and τ f = −17.68 ppm/°C at 725 °C. [ABSTRACT FROM AUTHOR]

Rare earth metal Neodymium (Nd3+) doped nano-crystalline Copper-Cobalt (Cu-Co) spinel ferrites which are represented as Cu 0.5 Co 0.5 Nd x Fe 2-x O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) chemically were prepared through "sol-gel auto-combustion method". The structural/mechanical, morphological and infrared characteristics were studied in comprehension in the light of Nd3+ doping, using industrial standard techniques. For all of the prepared samples, an X-ray investigation confirms the production of cubic spinel structures in a single phase without the presence of any secondary or impurity phases. Crystallite size and the lattice parameter of Cu 0.5 Co 0.5 Nd 0 Fe 2-0 O 4 found 40 nm and 8.361 Å respectively. The findings demonstrate a clear correlation between increasing Nd3+ content and a decrease in both the crystallite size and lattice parameter. Surface texture and morphology was examined through Scanning Electron Microscopy. According to the results of SEM investigation, the grain size ranged from 13 nm to 0.2 μm. The stretching modes of vibrations at 466 cm−1, 660 cm−1, and 274 cm−1, which are typical modes of spinel ferrites, were discovered via micro-Raman spectroscopy. Optical behaviour of ferrite material observed by UV–Visible spectroscopy. For undoped samples, UV–vis indicated a maximum wavelength of 249 nm, but for doped samples, which are varied through 0.1, 0.2, 0.3, 0.4, and 0.5, the wavelength ranges from 230 to 237 nm. The saturation magnetization was observed to increase with a further increase in Nd3+ concentration (x = 0.5), which may be helpful in storage devices. [ABSTRACT FROM AUTHOR]

Ceramic samples of Na 1-x K x NbO 3 , (0.460 ≤ x ≤ 0.485) were prepared by using the double sintering solid-state reaction method. The grain size and porosity were found to vary with composition. The dielectric constant of the material phase was obtained from the measured dielectric constant of the prepared ceramic pellets by applying porosity correction. Among the prepared compositions, the dielectric constant was observed to be minimum for x = 0.475. The temperature variation of the dielectric constant and lattice parameters was measured for the samples with x = 0.475, in the range from room temperature (RT) to 500 °C. Three distinct phase transitions, monoclinic to tetragonal, at about 205 °C; tetragonal to tetragonal, at about 410 °C; and tetragonal to cubic, at 460 °C, were observed from the dielectric constant and high-temperature X-ray diffraction (HT-XRD) measurements of the prepared compositions. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the influence of annealing temperature on the grain growth of zinc oxide nanocrystals synthesized in ethylene glycol and isothermally calcined at T a : 300 °C, 500 °C, 700 °C for 60 min at the ambient atmosphere. The effect of polyvinylpyrrolidone (PVP) addition and annealing temperature on ZnO nanocrystal's phase composition, structural (scattering domain size of nanocrystallites L , unit lattice parameters a , c , and unit volume V unit , theoretical density ρ x) parameters, morphological (size, shape, specific surface area SSA) features, chemical composition, and grain growth kinetics were determined. It was found that T a caused the increase in L of single-phase ZnO nanocrystals from 18 nm to 40 nm (with adding PVP) and to 45 nm (without adding PVP). Despite the surfactant composition, submicron grain sizes (D = 120–150 nm) were observed at T a = 700 °C. The activation energy of grain growth was Q = 121.4 kJ/mol (without adding PVP) and Q = 126.4 kJ/mol (with adding PVP), while grain growth exponent was n = 1.9 (without adding PVP) and n = 2.0 (with adding PVP). ZnO nanocrystals annealed at 700 °C are forthcoming in the design of the active layers of solar cells, and at (300–500) °C are suitable for thermoelectric converters. [ABSTRACT FROM AUTHOR]

In this paper, Sm3+-activated K 2 BaPO 4 F red phosphors were prepared by a traditional solid-state reaction method. The crystal structure and emission enhancement mechanism of the materials were systematically investigated. The photoluminescence intensity, chromaticity, lifetime, and fluorescence thermal stability were evaluated in detail. The emission intensity and quantum efficiency were significantly improved by the introduction of Na + ions. The lattice parameters of the K 2 BaPO 4 F, K 2 Ba 0.975 PO 4 F:0.025Sm3+, and Na-doped K 2 Ba 0.975 PO 4 F:0.025Sm3+ phosphors were investigated through the Rietveld refinement method. With the occupation of K+ sites by Na+ ions, the reduced volume of the unit cell increased the quantum efficiency of Sm3+ ions about 2.5 times. The present work demonstrates that the modified K 2-2x Na 2x Ba 0.975 PO 4 F:0.025Sm3+ orange-red phosphors are expected to be used in white light-emitting diodes (w-LEDs). [ABSTRACT FROM AUTHOR]

In this paper, Sm3+-activated K 2 BaPO 4 F red phosphors were prepared by a traditional solid-state reaction method. The crystal structure and emission enhancement mechanism of the materials were systematically investigated. The photoluminescence intensity, chromaticity, lifetime, and fluorescence thermal stability were evaluated in detail. The emission intensity and quantum efficiency were significantly improved by the introduction of Na + ions. The lattice parameters of the K 2 BaPO 4 F, K 2 Ba 0.975 PO 4 F:0.025Sm3+, and Na-doped K 2 Ba 0.975 PO 4 F:0.025Sm3+ phosphors were investigated through the Rietveld refinement method. With the occupation of K+ sites by Na+ ions, the reduced volume of the unit cell increased the quantum efficiency of Sm3+ ions about 2.5 times. The present work demonstrates that the modified K 2-2x Na 2x Ba 0.975 PO 4 F:0.025Sm3+ orange-red phosphors are expected to be used in white light-emitting diodes (w-LEDs). [ABSTRACT FROM AUTHOR]