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Lead-free piezoelectric ceramics of (1 − x)K0.5Na0.5NbO3-xCaTiO3 were fabricated, and their crystal structure, microstructure, and electrical properties were systematically studied. Rietveld refinement of the x-ray diffraction data and Raman spectroscopic analyses revealed a composition-dependent structural phase transition: three phase transitions, namely, from a pure orthorhombic phase for x ≤ 0.02 to a mixed phase of orthorhombic and tetragonal phases (0.03 ≤ x ≤ 0.08) and finally another mixed phase of tetragonal + cubic for x = 0.10 and 0.15 at room temperature (RT). The morphological study reveals a decrease in grain size along with a more uniform distribution of grains as the concentration of CaTiO3 (CT) increases; notably, a homogeneous distribution of grains is observed for x = 0.05. The temperature-dependent dielectric properties show two phase transitions, from orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), for unmodified K0.5Na0.5NbO3 (KNN). However, both the phase transition temperatures (TO-T and TC) decrease, and the transition peaks broaden with an increase in CT substitution, and for x > 0.06, the TO-T shifted below RT. The broadening of the transition peak at TO-T may be due to the relaxation behavior. Among the prepared samples, the 5 mol. % CT-modified KNN shows the optimum electrical properties (d33 = 114 pC/N, ɛr = 412, and 2Pr = 15.25 μC/cm2) at RT. The enhanced electrical properties for x = 0.05 are due to the coexistence of orthorhombic and tetragonal phases, facilitating easy polarization rotation and flattening of the free energy profile. A phase diagram has been constructed based on the information gathered from the temperature-dependent dielectric measurements, RT x-ray diffraction, and Raman spectroscopy data and is discussed in detail. [ABSTRACT FROM AUTHOR]

(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba2+ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases' transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases' transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature. [ABSTRACT FROM AUTHOR]

Chemical pressure is widely applied to antiferroelectrics (AFEs) as a criterion to enhance their antiferroelectricity. However, NaNbO3 (NN)-based ceramic with well-defined double polarization hysteresis (P–E) loops was rarely reported based on this strategy, and the effect of chemical pressure on antiferroelectricity remains to be understood. In this work, the Me cations (Me is Ti, Sn, Zr) with different ionic radii were introduced into the component system 0.76NaNbO3–0.20AgNbO3–0.04CaMeO3 to tune the negative chemical pressure and investigate its effect on antiferroelectricity. The enhancement of negative chemical pressure can effectively stabilize the AFE phase and reduce hysteresis, as revealed by the P–E loops and dielectric properties, which is further confirmed by the change in crystal lattice parameters and in situ Raman spectra. Rietveld refinement of x-ray powder diffraction reveals that the enhanced negative chemical pressure mainly reduces the cation off-centering displacement and [BO6] octahedral tilting angles. As a result, the 0.76NaNbO3–0.20AgNbO3–0.04CaZrO3 exhibits good reversibility of the electric field-induced antiferroelectric–ferroelectric phase transition and well-defined double P–E loops. This work reveals the underlying mechanism of chemical pressure and provides an effective way of discovering new NN-based AFEs. [ABSTRACT FROM AUTHOR]

We report an unexplored type-II multiferroic order in NiMn 2 O 4 , exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼ 100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼ 535 μ C/m 2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼ 21 %) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼ 100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound. [ABSTRACT FROM AUTHOR]

We report an unexplored type-II multiferroic order in NiMn 2 O 4 , exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼ 100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼ 535 μ C/m 2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼ 21 %) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼ 100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound. [ABSTRACT FROM AUTHOR]

A temperature factor is one of the main parameters in the synthesis of nanoparticles and can affect considerably the arrangement of atoms in the lattice. In the system of magnetically hard CoFe2O4 spinel ferrite, the distribution of cations directly determines the magnetic properties of the sample. It was studied, on products of co-precipitation synthesis followed by a temperature dependent sinterization, by x-ray diffraction (XRD), x-ray absorption (XAS) using synchrotron radiation, vibrating sample magnetometry, and 57Fe Mössbauer spectroscopy (MS). From the Rietveld refinement of XRD patterns, the site occupancies reveal the following trend: with a decrease in the sintering temperature, the inversion degree parameter γ, which is a fraction of Co ions residing in the octahedral sites, decreases. For the highest sintering temperature explored in this work, 1000 °C, γ ≈ 0.83 giving rise to (Co0.17Fe0.83)A[Co0.83Fe1.27]BO4 formulation. For the lowest sintering temperature explored, 500 °C, the inversion degree is approximately 0.69 giving rise to (Co0.31Fe0.69)A[Co0.69Fe1.31]BO4 formulation. The propensity for the cationic arrangement was also confirmed by MS. Qualitative analysis of XAS at Co L3,2 edges strongly supports the tendency observed by XRD: the lower the sintering temperature, the more Co ions tend to occupy the tetrahedral sites. The magnetic behavior of the samples is consistent with the particle size which was determined by transmission/scanning electron microscopies. The particle size is the product of different sintering temperatures after the primary synthesis. [ABSTRACT FROM AUTHOR]

Pr 2 NiO 4+δ -based materials are considered as promising air electrodes for proton ceramic electrochemical cells due to their wide range of attractive properties. In the present work, the basic functional properties of Pr 2 NiO 4+δ are optimized by substituting Pr-cations with isovalent La- and Nd-ions. The synthesized samples are characterized by X-ray diffraction analysis, thermogravimetry in oxidizing and reducing environments, dilatometry, and four-probe conductivity measurements. As a result, the relationships between crystal and defect structures on the one hand and their electrotransport and thermomechanical properties on the other hand are revealed. The PrLaNiO 4+δ , Pr 1.5 La 0.5 NiO 4+δ , and PrLa 0.5 Nd 0.5 NiO 4+δ compositions are stabilized by the large lanthanum cation and do not show the phase transition (from Fmmm to I 4/ mmm space group) typical of the other studied compounds. The conductivity values of the studied materials remain practically unchanged for most of the compositions, but the La-doping reduces the activation energies of hole transfer. Based on the obtained data, two optimal compositions (Pr 1.5 La 0.5 NiO 4+δ and PrLa 0.5 Nd 0.5 NiO 4+δ) can be identified for their further application in electrochemical cells. [Display omitted] • (Pr x La y Nd z)PrNiO 4+δ (x + y + z = 1) are synthesized by citrate-nitrate method. • Doped materials obtained have orthorhombic structure of Pr 2 NiO 4+δ. • Doping with La or Nd results in a decrease of oxygen content of Pr 2 NiO 4+δ. • Nd- and La-doping have the opposite effect on thermal expansion of Pr 2 NiO 4+δ. • Doping with lanthanum reduces the activation energy of hole mobility. [ABSTRACT FROM AUTHOR]

The present study reveals the synthesis of Iron oxide nanoparticles (IONPs) by varying the molar ratio of ferric (Fe3+) to ferrous (Fe2+) ions via chemical coprecipitation method for the study of cationic distribution of Fe‐ions and its potential application for magnetic hyperthermia therapy (MHT). X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS), were used to characterize the physicochemical properties. Several structural parameters were estimated using the Rietveld refinement, resulting in structural modelling verified by magnetic characteristics. A vibrating sample magnetometer (VSM) assessed the magnetic hysteresis loop at room temperature in a field range of ±15 kOe, revealing superparamagnetic behavior for the ratio Fe2+/Fe3+ 1:2. The saturation magnetization (Ms) of IONPs increased with the increasing Fe2+ concentration and attained a maximum value of 60.21 emu g−1 at a molar ratio of 2:1. The potential of the inductive heating capability of IONPs in an alternating current magnetic field (AMF) was studied to treat localized MHT. The changes in magnetic properties and inductive heating properties of IONPs are associated with the cationic distribution of Fe2+ at the tetrahedral (A) and octahedral (B) sites of crystal structure. The variation in cationic properties at the A and B sites may result in varying/tuneable magnetic properties, affecting the overall heating profiles of hyperthermia. [ABSTRACT FROM AUTHOR]

The structural and electromagnetic properties of various Ba1−x(Sr0.5Ni0.5)xTiO3 are extensively investigated. X‐ray diffraction and Rietveld refinement are used to perform a structural study. With doping substances, bulk and theoretical densities decrease. The crystallite size is calculated using Scherrer and Williamson–Hall method. The microstructural properties are examined using images from field‐emission scanning electron microscope. The observed values of dielectric constants are found to agree with the porosity‐corrected dielectric constants. The nonlinear modified Debye equation (NLMDE) displays a reasonable goodness of fit value for the first five samples. A small polaron hopping mechanism may be responsible for the frequency‐dependent AC conductivity observed in all samples confirming the Jonscher power law. It is discovered that permeability initially increases and then decreases with doping substances. Initial permeability, experimental data from the magnetic hysteresis (M–H) curve, and law‐of‐approach‐to‐saturation techniques show that Ba0.85(Sr0.5Ni0.5)0.15TiO3 and Ba0.75(Sr0.5Ni0.5)0.25TiO3 ceramics have enhanced electromagnetic properties. These ceramics are useful for fabricating electromagnetic sensors. [ABSTRACT FROM AUTHOR]

Herein, the temperature‐dependent magnetic structure and sign reversal exchange bias in CeCrO3 using magnetization data and time‐of‐flight neutron diffraction data which is given less attention among RCrO3 are investigated. While nuclear structural analysis using Rietveld refinement exhibits distorted orthorhombic structure within Pnma space group, temperature dependence of the magnetic structure using neutron diffraction reveals possible spin configurations, namely, Γ4, Γ2, and Γ1, within the temperature range of 6–300 K. Temperature‐dependent magnetization shows compensation temperature, Tcomp, at 58 K, spin reorientation temperature, TSR, at 15 K along with a Neel temperature, TN, at 260 K which is the outcome of the competition between canted antiferromagnetic ordering of Cr3+ ions and Ce3+ ions in CeCrO3. Furthermore, the magnetization versus magnetic field (M vs H) measurements indicate transition of the Γ4 spin structure to Γ2 spin structure around TSR which is further supported by reversible‐to‐irreversible changes observed in temperature‐dependent MFCC and MFCW. Moreover, a temperature‐driven sign reversal of exchange bias in CeCrO3 is observed, resulting from the competition between antiferromagnetic coupling between chromium moment (MCr) and cerium moment (MCe) in these nanoparticles. This intriguing behavior holds significant potential for the development of thermally assisted magnetic random access memory. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) are porous materials with numerous chemical and structural possibilities. Due to their ease of modification, well‐organized structure, and diverse guest molecule chemistry, MOFs are ideal platforms for uncovering improved functional material design characteristics. Quantitative analysis of glucose is crucial, especially in some food products, for quality control as well as evaluation of the glucose levels helps diagnose and treat diabetes. Recent glucose sensing devices have relied heavily on MOFs and other nanomaterials to enable user‐friendly and safe non‐invasive sensing methods. Nevertheless, the conventional synthesis methods involve multi‐day reactions, cooling, and depressurization processes. This study demonstrates the unprecedented high‐power laser‐induced rapid synthesis (LIRS) of Ni‐based MOF nanospheres with interconnected nano‐rods and noncentrosymmetric primitive triclinic crystalline structure, highlighting their multifunctional usage in sensing and gas sorption applications. Ab initio simulations show excellent agreement with the experimental physical and gas sorption properties. Furthermore, the Ni‐MOF‐based biosensor accurately measures glucose real‐life beverage samples, yielding promising glucose detection biosensor results with a low limit of the detection (LOD) of 13.96 µM and high sensitivity of 120.606 µA mM−1 cm−2. [ABSTRACT FROM AUTHOR]

The Gd and Zr co-doped ceria electrolyte Gd 0.1 Ce 0.9- x Zr x O 1.95 (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15, labeled as GDC, Zr0.03GDC, Zr0.06GDC, Zr0.09GDC, Zr0.12GDC, Zr0.15GDC) was synthesized by solid-state reaction. The XRD and Rietveld refinements reveal that Zr x GDC is in a cubic fluorite phase with the cell parameters a decrease from 5.4186(1) to 5.3728(1) Å and cell volume V decreases 159.10(2) to 155.09(2) Å3 as the x increases from 0 to 0.15. SEM studies confirm a dense microstructure with well-defined grains in a size of 10–20 μm. The Raman spectra agree with the fact that a solid solution is formed and the blue-shift of Raman modes is observed as expected. XPS analysis shows that Ce4+ is more stable in Zr doped GDC. The conductivity of Zr0.03GDC reaches 1.2 × 10−3 S/cm at 450 °C. The bond valence of Ce4+ is constrained to a higher one as the Ce4+ is substituted by Zr4+ in the solid solution, and a higher stability in the reducing atmosphere was achieved. The electronic conductivity decreases from 14.8% of GDC to 0.1% of Zr0.03GDC at 400 °C. The oxygen ion transference number of Zr0.03GDC is improved significantly to > 0.93 in 3% H 2 /Ar at 700 °C. [ABSTRACT FROM AUTHOR]

In order to solve the problem of signal delay, a novel low-K Ca 3 Cr 2 Ge 3 O 12 ceramic for 5G and millimeter-wave communication was prepared by a solid-state reaction method. XRD and Rietveld refinement results confirm that it belongs to the garnet structure with the Ia-3d space group. The shrinkage rate of the sample sintered at 1350 °C reached 11.9 %, and the relative density exceeded 94.3 %. Excellent microwave dielectric properties were obtained. The permittivity was 8.38, the quality factor was 23,107 GHz, and the temperature coefficient of resonant frequency was −43.57 ppm/°C. The relationship between the crystal structure and microwave dielectric properties of ceramics was further studied. The results show that lattice vibration, stacking fraction and bond strength have a great influence on the Q × f value of ceramics, and the bond valence parameter is the key factor affecting the temperature stability. In addition, the theoretical quality factor of the ceramic can reach ∼13,0000 GHz by far-infrared reflection spectroscopy, and the ceramic has great research potential. The development of Ca 3 Cr 2 Ge 3 O 12 ceramics and the study of microwave dielectric properties have filled the research gap of related systems. The excellent microwave dielectric properties indicate that it can be used as an alternative material for the preparation of components in the field of communication. [ABSTRACT FROM AUTHOR]

The geopolymerization reaction is a chemical process involving the dissolution of amorphous, semi-crystalline and crystalline phases following alkaline or acid attack at ambient or at low temperature (T˂100 °C). Together with precondensed entities of the used activator solution the dissolved parts form a geopolymer network which glues together all remaining unreacted parts as ingredients of the artificial stone. The fate of the mineralogical phases present in the precursors used in the synthesis of alkaline and acid geopolymers is reviewed in this article. The different starting materials used in the synthesis of geopolymers and the different techniques used to modify the reactivity of these materials are reported. The mineralogical evolution of the amorphous, semi-crystalline and crystalline phases after activation at ambient and at low temperatures (T < 100 °C) is also reported. This study shows that for the mineralogical investigation of raw material, precursors and geopolymers, XRD is the most widely used analytical method. The most commonly used method to confirm the participation of crystalline phases in geopolymerization is the comparison of the diffractograms of the raw material to those of the products. It also indicates that, in addition to the amorphous aluminosilicate phases, certain semi-crystalline, and crystalline phases participate in this geopolymerization dynamic either by undergoing total or partial dissolution to form an inorganic macromolecule with an amorphous structure of the zeolitic type and other new minerals. The composition of the phases formed depends on the base material. Increasing the synthesis temperature promotes the dissolution of phases, the formation of geopolymer networks, and in some cases, the formation of new phases such as sodalities, zeolite A and zeolite P. Little work has been done to quantify the mineralogical phases before and after precursor activation, making it impossible to assess dissolution, the degree of geopolymerization, and mineral formation. The exact structure of the phases formed is often questionable, as most of the papers do not mention their reference structure number. There is also a lack of quantification of the amorphous phase resulting from the hardening of the activating solution and the evaluation of the fraction of the amorphous phase contained in the precursor remains unreacted. The mineralogical investigation must also extend to the quantification of phases using Rietveld refinement with internal standards to correlate these with the physical and mechanical properties of geopolymer products. Additional mineralogical study techniques, such as thin sections, should be used in future work for in-depth mineralogical investigation of geopolymers. [ABSTRACT FROM AUTHOR]

The structural, microstructural, dielectric, optical, ferroelectric, and magnetic properties of cobalt doped barium calcium titanate (BCT) (Ba 0.80 Ca 0.20 Ti 1-x Co x O 3 with x = 0.000, 0.005, 0.010, 0.015, and 0.020) ceramics have been reported in this paper. The ceramic samples were prepared by the conventional solid-state reaction method. For all of the prepared samples, the tetragonal structure with the space group P 4 mm has been confirmed using the refinement method through Rietveld refinement of X-ray diffraction patterns. Field Emission Scanning Electron Microscopy (FESEM) micrographs revealed that the average particle size exists in micrometre range (0.3–0.8) μm. Optical studies revealed a gradual decrease in the energy bandgap from 3.31 eV to 2.71 eV with increasing doping concentration. A decreasing trend was observed in the dielectric characteristics of the material with changing frequencies at room temperature. Ferroelectric (P-E loops) analysis displayed an increase in both remnant polarization and maximum polarization of the ceramic with the increasing applied electric field. The highest value for the energy storage efficiency (η) was calculated to be 20.51 %. Magnetic analysis conducted at room temperature revealed the enhancement in ferromagnetism with the increase in doping concentration. [ABSTRACT FROM AUTHOR]

A series of (Mg 1- x Zn x) 3 (PO 4) 2 (x = 0.02–0.10) microwave dielectric ceramics were fabricated by the solid-state reaction method and investigated in terms of crystal structure, chemical bond properties, and dielectric properties were analyzed. The XRD data indicates that (Mg 1- x Zn x) 3 (PO 4) 2 samples belong to the monoclinic crystal with P 2 1 /c space group and no detectable secondary phases. The Rietveld refinement was employed to obtain crystal parameters. In addition, the results of chemical bond properties reveal that the lattice energy and ionicity of Mg (2)–O (3) bonds play a primary effect on the dielectric loss and dielectric constant, respectively. The bond energy of Mg(l)-O (2) bonds plays a dominant role in thermal stability. The far-infrared spectroscopy was employed to explore the intrinsic dielectric parameters, and the results showed that peaks below 400 cm-l contributed 78.9 % to ε′ and 99.1 % to ε″. The Raman data demonstrated that the Raman shift and FWHM exhibit an important influence on Q × f. The optimal performance was achieved in (Mg 0.94 Zn 0.06) 3 (PO 4) 2 ceramics: ε r = 5.00, Q × f = 84,674 GHz, τ f = −59.98 ppm/°C. [ABSTRACT FROM AUTHOR]

Two series of LiF-doped Li 4 CaSr(SiO 4) 2 (LCSS) ceramics with different LiF contents were synthesized by SSR and RS methods. The formation of single-phase LCSS + x wt% LiF (x = 0–4, SSR) (LCSSL 04) and LCSS + y wt% LiF (y = 0–8, RS) (LCSSF 08)ceramics with an orthorhombic structure (Pbcm space group) was confirmed by the Rietveld refinement of their XRD data. The addition of LiF improved the relative density and microwave dielectric properties of LCSS + x wt% LiF (0 < x ≤ 2, SSR) and LCSS + y wt% LiF (0 < y ≤ 3, RS). The LCSS +2 wt% LiF (SSR) ceramic exhibited good properties, presenting a dielectric permittivity (ε r) of 7.03, quality factor (Q × f) of 62,195 GHz (at 11.6 GHz), and temperature coefficient of resonant frequency (τ f) of −76 ppm/°C. Further, the LCSS +3 wt% LiF (RS) ceramic exhibited outstanding performances, with an ε r of 6.1, Q × f of 103,086 GHz (at 15.8 GHz), and τ f of −67 ppm/°C. The chemical compatibility with silver suggests that both of them are potential candidates for low temperature co-fired ceramic (LTCC) devices. [ABSTRACT FROM AUTHOR]

Herein, Mg1−xNixZrTa2O8 (x = 0, 0.1, 0.3, 0.5, 0.8, 1) ceramics are synthesized using a solid‐phase reaction method. Ni2+ replacing Mg2+ improves the drawback of high sintering temperature and poor temperature stability. The samples have a relative density above 95% at the optimal sintering temperature. The sintering temperature of Mg1−xNixZrTa2O8 reduces from 1475 to 1400 °C. And single‐phase Mg1−xNixZrTa2O8 ceramics with monoclinic wolframite structures are analyzed. According to the Rietveld refinement results, with the doping of Ni2+, the transformation of unit cell volume leads to the shift of the main peak in the X‐Ray diffraction pattern to a higher angle in 0 ≤ x ≤ 0.3 and a lower angle in 0.5 ≤ x ≤ 1. The εr of Mg1−xNixZrTa2O8 is comparable to MgZrTa2O8. At 1400 °C, the Q × f is increased from 10 598 GHz in the undoped sample to 43 041 GHz in Mg0.9Ni0.1ZrTa2O8 ceramic. The absolute values of τf of ceramic samples decrease with the excessive Ni2+. The desirable dielectric properties (εr = 20.79, Q × f = 43 041 GHz, τf = −33.04 ppm °C−1) are obtained at 1400 °C. Ni substitution is effective for MgZrTa2O8 ceramic to optimize densification temperature and retain the high Q × f value. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray–induced multicolor long afterglow and photostimulated luminescence from Sr3(PO4)2: Pr3+ was reported. The Rietveld refinement results have confirmed the as‐prepared sample was pure Sr3(PO4)2 phase with hexagonal crystal system. And Sr3(PO4)2: Pr3+ showed an excellent X‐ray–induced long afterglow luminescent performance. Under the excitation of X‐ray, the sample showed multicolor long afterglow luminescence from UVC to red region located at 268, 359, 466, 548, 604.3 and 685 nm, which can be ascribed to 4f5d‐3H4, 4f5d‐ 1D2, 4f5d‐3P0, 3P0→3H5 and 1D2→3H4, respectively. And the strongest afterglow emission intensity appeared at 468 nm. Furthermore, only 30 s X‐ray irradiation can induce 12 h afterglow emission, which afterglow emission intensity of 468 nm still reached 3.71 × 104 cps and was about 37.1 times stronger than the background intensity. In particular, the relation between 268 nm afterglow emission intensity and 468 nm afterglow emission intensity showed good linearity. And the UVC afterglow emission can be easily “observed” via the visible afterglow light. Furthermore, Sr3(PO4)2: Pr3+ possessed an excellent photostimulated luminescence (PSL) under the excitation of 980 nm NIR laser and the PSL intensity of the 12 circle still arrived at 1.26 × 105 cps, which was about 37.1 times stronger than the afterglow emission intensity after 5 h decay. All these results showed that the as‐prepared Sr3(PO4)2: Pr3+ phosphor was an excellent X‐ray–induced long afterglow luminescence phosphor, which possessed large potential applications in the medical field. [ABSTRACT FROM AUTHOR]

The crystal structures of both Pb2PbO4 (Pb3O4) and Pb2SnO4 at room temperature can be described using mullite-type setting in the space groups P42/mbc and Pbam, respectively. At what chemical extend the crystal structure prefers either of the space groups would be an excellent playground in the Pb2(Pb1−xSnx)O4 solid solution. Members of the solid solutions have been prepared by solid-state reactions carried out in sealed quartz tubes. Each sample has been found to be phase pure confirmed by X-ray powder diffraction data Rietveld refinement. Samples with higher tin content require higher synthesis temperatures, and controlled decomposition of Pb3O4 serves as the source for both Pb2+ and Pb4+ cations. Since the Pb4+ cation is larger than Sn4+, the MO6 polyhedral volume decreases with increasing Sn-content. As such, each metric parameter shows a linear trend following Vegard's rule. The concomitant contraction of the MO6 octahedra and the high stereo-chemical activity of the 6s2 lone electron pairs of lead in the Pb2+O4 distorted pyramid results in symmetry reduction. DFT suggests dynamical instability of the tetragonal Pb3O4 while Pb2SnO4 keeps orthorhombic symmetry at low temperatures, which agrees well with the experimental findings. The global blue shift of the vibrational mode frequencies is explained by the quasi-harmonic approach. The indirect band-gap linearly increases from 2.1(1) eV (x = 0) to a maximum value of 2.5(1) eV for x = 0.8 followed by a sharp drop towards Pb2SnO4. Thermogravimetric analysis demonstrates higher thermal stability with increasing Sn-content, which is explained in terms of higher bond strength of Sn–O than that of Pb–O in the MO6 octahedra. [ABSTRACT FROM AUTHOR]

Iodine eluent is a type of secondary waste that adsorbs radioactive iodine during the reprocessing of used nuclear fuel. To better deal with it, Na2SiO3 and NaAlO2 were used to immobilize iodine eluents by synthesizing iodosodalite via a hydrothermal method. Orthogonal experiments were designed to investigate the effects of four factors: mass ratio of iodine eluent, Al/Si ratio, temperature, and aging time. Powder X-ray diffraction with Rietveld refinements was performed to characterize the structures and phases of the samples, of which iodosodalite and hydrosodalite are the primary phases that immobilize iodine effluents. Fourier-transform infrared spectroscopy and scanning electron microscopy results demonstrated a cage-like sample structure. Energy-dispersive X-ray spectroscopy revealed a homogeneous distribution of Na, Al, Si, O, and I on the sample surfaces. X-ray photoelectron spectroscopy indicated the presence of both iodide and iodate in the synthesized products. The optimal synthesis process is a reaction temperature of 190 ℃, NaI + NaIO3:Na2SiO3 + NaAlO2 ratio of 1:5, Si/Al ratio of 1:1, and aging time of 7 d. The leaching rate of iodine (including I− and IO3−) indicates considerable chemical durability of the optimized sample. [ABSTRACT FROM AUTHOR]

The effect of specimen displacement in X‐ray powder diffraction experiments with laboratory diffractometers has been revisited and new expressions have been derived for several commonly used experimental configurations, including Bragg–Brentano parafocusing geometry and flat‐plate transmission geometry. The results presented in this work allow the analysis of data from samples with relatively large displacements. This may open the possibility to study samples with dimensions that are difficult to accommodate with the sample‐handling capabilities of standard laboratory diffractometers. [ABSTRACT FROM AUTHOR]

High‐pressure neutron powder diffraction data from PbNCN were collected on the high‐pressure diffraction beamline SNAP located at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory (Tennessee, USA). The diffraction data were analyzed using the novel method of multidimensional (two dimensions for now, potentially more in the future) Rietveld refinement and, for comparison, employing the conventional Rietveld method. To achieve two‐dimensional analysis, a detailed description of the SNAP instrument characteristics was created, serving as an instrument parameter file, and then yielding both cell and spatial parameters as refined under pressure for the first time for solid‐state cyanamides/carbodiimides. The bulk modulus B0 = 25.1 (15) GPa and its derivative B′0 = 11.1 (8) were extracted for PbNCN following the Vinet equation of state. Surprisingly, an internal transition was observed beyond 2.0 (2) GPa, resulting from switching the bond multiplicities (and bending direction) of the NCN2− complex anion. The results were corroborated using electronic structure calculation from first principles, highlighting both local structural and chemical bonding details. [ABSTRACT FROM AUTHOR]

FullProfAPP is a software tool for data processing, refinement and visualization of large collections of powder diffraction patterns. Featuring an intuitive graphical user interface, it seamlessly facilitates a variety of tasks. These include conducting full‐profile phase searches, sequential and high‐throughput Rietveld refinements, and managing background (and peak) detection. FullProfAPP also provides convenient interaction with crystallographic databases and supports the visualization and export of high‐quality pixel and vector graphics depicting the refinement results, among other functionalities. FullProfAPP wraps around the refinement program FullProf [Rodríguez‐Carvajal (1993), Physica B, 192, 55–69] and offers the flexibility of user‐defined workflows by accessing and editing FullProf's input files and triggering its execution as necessary. FullProfAPP is distributed as open‐source software and is presently available for Windows and Linux operating systems. [ABSTRACT FROM AUTHOR]

The embedded call to a special version of the web‐based Bilbao Crystallographic Server tool k‐SUBGROUPSMAG from within GSAS‐II to form a list of all possible commensurate magnetic subgroups of a parent magnetic grey group is described. It facilitates the selection and refinement of the best commensurate magnetic structure model by having all the analysis tools including Rietveld refinement in one place as part of GSAS‐II. It also provides the chosen magnetic space group as one of the 1421 possible standard Belov–Neronova–Smirnova forms or equivalent non‐standard versions. [ABSTRACT FROM AUTHOR]

In most of the chemical methods, the as-prepared NPs have a metal hydroxide form. The calcination temperature is very important to prepare the metal oxide from metal hydroxide. Thus, in this work, the chemical precipitation and sol–gel routes were employed to produce the Nickel hydroxide nanoparticles and analyze their functional, structural, thermal, and morphological behavior of prepared NPs. The formation of Ni(OH)2 is confirmed by FTIR analysis including both techniques. Rietveld refinement techniques were used to diffraction patterns by the program FullProf. The well-matched XRD patterns reveal that prepared NPs have β -Ni(OH)2 phase and hexagonal structure (HCP) with a space group of P3m1 for both the methods. The kinetic factors were calculated using different models. The Phadnis–Deshpande model is employed to identify the mechanism of solid state kinetic reaction. Solid state kinetic model observes nucleation and nuclei growth (Avrami–Erofeev nuclei growth) and 2D diffusion mechanism for chemical precipitation and sol–gel, respectively. From the FESEM analysis, flower-shaped architectures and nanosheet morphology are presented in the prepared sample by chemical precipitation and sol–gel, respectively. From the kinetic parameters, we conclude that the decomposition of Ni(OH)2 to NiO is thermally stable, has slow reaction and spontaneous process at 300∘C. The results show that the chemical precipitation method is more suitable for energy storage application compare to the Sol–gel method. [ABSTRACT FROM AUTHOR]

The development of new electrocatalysts for the oxygen evolution reaction (OER) is fundamental for water-splitting devices. In this work, a novel composite based on Ca3Co4O9 (C349) and Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF) was synthesized and characterized using XRD with Rietveld refinement, SEM, EDX, and FTIR. The electrochemical properties were evaluated in a KOH alkaline medium. The composite exhibited exceptional OER electrocatalytic activity, showing an overpotential of 389 mV at 10 mA cm−2, which is lower than the pristine BSCF and C349 samples. Tafel slope of 77 mV dec−1 and double-layer capacitance (Cdl) of 4.37 mF were obtained, indicating an ECSA of 109.25 cm2. The composite also demonstrated a high turnover frequency (TOF) of 1.9 × 10−3 mol O2 s−1, underscoring its superior catalytic efficiency. Impedance spectroscopy revealed that the C349 and BSCF samples exhibited greater limitations in charge transfer compared to the composite. These results highlight the composite's potential as a highly effective OER electrocatalyst, leveraging the synergistic effects of C349 and BSCF. [ABSTRACT FROM AUTHOR]

High-entropy ceramics have sparked renewed interest in compositionally complex ceramics since the first introduction in 2015. The kaleidoscopic array of compositions and structures harnessed by this idea has unlocked an unprecedented opportunity to tailor materials for specific applications, including catalysis, thermal barriers, and electrochemical energy storage. Within the family of oxides, a competition exists between rock-salt and spinel structures. The rock-salt structure is highly symmetrical, consisting of a single cation sublattice, while the spinel structure offers more flexibility to accommodate various cations in two distinct sublattices. Herein, we aimed at stabilizing and expanding the thermal stability range of the spinel-structured oxide, successfully synthesizing novel, single-phase, compositionally complex materials by capitalizing on entropy stabilization, all while avoiding the ubiquitous use of nickel and chrome, notorious for their negative environmental impact. The right combination of cations resulted in the synthesis of a seven-metal oxide that is thermally stable up to the remarkable temperature of 1473 K. [ABSTRACT FROM AUTHOR]

This paper represents a study of the effect of Al-substitutions on structural, magnetic, and dielectric properties of Sr 0·8 Ce 0·2 Fe 12- x Al x O 19 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) ferrites synthesized in presence of yellow bell leaves extract. All samples were synthesized using the sol-gel combustion technique with the influence of green synthesis by using leaves of Tecomastans (yellow bell) plant. These samples were preheated at 550 °C for 4 h and finally calcinated at 1150 °C for 6h. These samples were characterized using XRD, FTIR spectroscopy, SEM, VSM, LCR measurements, and VNA measurements. XRD analysis confirm the formation of a magnetoplumbite M-phase (hexagonal) with a minor impurity phase of CeO 2 in all samples. Lattice parameters a and c are obtained from rietveld refinement, which are found in the range from 5.859 Å to 5.883 Å, and 22.96 Å to 23.05 Å respectively. FTIR spectra confirm the absence of organic compounds and the presence of an absorption band in the fingerprint region, which are linked to the stretching of the metal-oxygen bond at the octahedral and tetrahedral sites. The surface morphology of these samples is analyzed using SEM images. Grains with hexagonal plate shapes were observed in each sample. The average grain size varies in the range of 0.565 μm–1.455 μm. EDS data confirms the presence of desired elements in the respective sample. VSM analysis shows hard magnetic behavior in all samples. Magnetic parameters were found in the range, M s : 36.281–43.397 emu/g, M r : 12.297–19.841 emu/g, H c : 2.0987–3.814 kOe. In low-frequency (20 Hz-2 MHz) dielectric measurements, the dielectric constant is high at low frequencies, which rapidly falls as frequency increases. Loss tangent curve shows a relaxation peak for each sample above 200 kHz. AC conductivity is very low in the order of 10−5 S/m in plateau region below 2 kHz, which increases as frequency increases. Cole-Cole plot suggests the effect of grain boundary contribution is higher in non-substituted sample compared to Al-substituted samples. In high-frequency (0.2 GHz–20 GHz) measurements, the dielectric constant remains almost constant. These values are found in the range 5–7.5. Low loss tangent of 0–0.16 were observed in every sample in this frequency domain, with AC conductivity of the order of 10−2 S/m. [ABSTRACT FROM AUTHOR]

The presence of organic contaminants in aquatic environments, such as antibiotics, induces the proliferation of resistant pathogens, giving rise to the need to develop new materials with antimicrobial action. Therefore, in this work, we report new results to purified Palygorskite (P-Pal) clay with a surface impregnated with alpha-silver tungstate (α-Ag 2 WO 4) microcrystals abbreviated as AWO, and its structural, photoluminescence (PL) and antibacterial investigation for inactivation of gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacterial strains at concentrations of P-Pal/ x %/AWO from x = 4–32%. X-ray diffraction patterns, Rietveld refinement data, and Fourier transform infrared spectroscopy confirmed that the P-Pal is composed of two crystal phases (Mg 2.074 Al 1.026) (Si 4 O 10.48) 2 (OH) 2 (H 2 O) 10.68 with an orthorhombic structure and α-SiO 2 with a rhombohedral structure; already the AWO microcrystals are single-phase with an orthorhombic structure and their vibrational modes. Ultraviolet–visible spectroscopy shows an increase in the E gap values for mixed systems compared to the isolated materials, indicating a synergistic interaction between the energy levels of both materials. Field emission scanning electron microscopy images display the presence of several elongated fibers and hexagonal crystals in the P-Pal clay and rod-like AWO microcrystals. In contrast, P-Pal clay/AWO microcrystals exhibit the presence of all three crystal shapes. Photoluminescence spectra show a high emission for the P-Pal clay/4% AWO microcrystals, indicating a better energy band gap synergistic. Finally, the microbiological tests show that as the proportion of AWO crystals on the P-Pal clay surface increases, there is a rise in antibacterial activity. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age‐related magnesium out‐diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age‐related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm−1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X‐ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age‐related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content. [ABSTRACT FROM AUTHOR]

The ternary material Mn2SiTe4 was synthesized by direct fusion using the annealing method. X-ray powder diffraction analysis indicated that this material crystallizes in the olivine-type structure, space group Pnma, Z = 4, with unit cell parameters: a = 13.905(2) Å, b = 8.128(1) Å, c = 6.526(1) Å, V = 737.6(2) Å3. This olivine structure can be described from a hexagonal close-packing of selenium atoms where manganese atoms occupy ½ of the octahedral sites while silicon atoms lay in ⅛ of the tetrahedra. The magnetic susceptibility curve indicate a possible antiferromagnetic behavior for this material. This compound is related to the ternary layered Mn3Si2Te6 recently studied as possible two-dimensional (2D) magnetic material. [ABSTRACT FROM AUTHOR]

High‐nickel cathode materials are widely used in lithium‐ion batteries because of their advantages of high energy density and high safety. High‐nickel cathode materials need to further improve cycling stability because they are prone to structural changes and capacity degradation. This paper proposes a method to improve high‐nickel cathode materials by Mg doping. XRD proves that Mg‐doped high‐nickel materials still have R‐3 m spatial structural characteristics; Rietveld refinement confirms that the c‐axis gradually increases with the increase of Mg content. Combined with DFT calculations, the presence of Mg can inhibit structural collapse during charge and discharge, reduce Li/Ni antisite defects, improve the electronic conductivity of the material, and improve the cyclic stability of the material. The 0.6 mol % Mg‐doped sample has an initial discharge capacity of 233 mAh g−1 at 0.1 C in the range of 2.7–4.3 V, a capacity retention rate of 91.0 % after 50 cycles at 1 C, still retains 79.9 % after 100 cycles. The dQ/dV curves further indicate that the presence of Mg improves the structural stability of the material. [ABSTRACT FROM AUTHOR]

In this work, the synthesis of Ho3+-doped calcium titanate perovskite (CaTiO3) revealed significant photoluminescence (PL) properties, predominantly displaying a distinct green emission. The investigation explored Ho3+-doped CaTiO3 perovskite synthesized via the sol–gel method. Structural analysis confirmed an orthorhombic crystal structure through powder x-ray diffraction (XRD) and Rietveld refinement, while Fourier transform infrared (FT-IR) spectroscopy confirmed the presence of functional groups in Ho3+-doped CaTiO3. Diffuse reflectance spectroscopy (DRS) revealed a charge transfer band between O2− and Ho3+ ions in the range of 250–350 nm, supported by photoluminescence excitation (PLE) spectra. A bandgap of 3.39 eV was found for Ho3+-doped CaTiO3. At 0.03 mol Ho3+, the PLE band intensity was saturated, indicating optimal excitation efficiency. Emission spectra revealed distinct intra 4f–4f transitions, particularly a green emission at 545 nm under 454 nm excitation corresponding to 5F4 + 5S2 → 5I8 transition. The PL intensity reached its peak at 0.03 mol Ho3+ and then decreased due to concentration quenching. Color purity reached ~90%, highlighting its potential in applications requiring precise green emission. The results of the study suggest that this perovskite is well suited for optoelectronics, lighting, displays, or industries that require specific green light emission properties. [ABSTRACT FROM AUTHOR]

In this study, BiFeO3 (BFO) and Er3+-, La3+-, and Nd3+-substituted BFO were synthesized using Pechini's modified sol–gel auto-combustion route. Comprehensive investigations were conducted on the structural, magnetic, and optical properties of the samples. X-ray diffraction and Rietveld refinement analysis provided insights into the crystal structure, which was found to be distorted rhombohedral for all the samples except for BEFO (Bi0.95Er0.05FeO3), which was orthorhombic. The crystallite size and strain were calculated by strain-size plots. Fourier transform infrared spectroscopy confirmed the crystallinity and characteristic FeO6 peaks of perovskites in all the samples. Microstructural investigations using field-emission scanning electron microscopy imaging revealed the morphological features and particle size distribution. The magnetization–hysteresis (M–H) loop demonstrated that the Ms and Mr values decreased after the incorporation of rare earth (RE) ions in the BFO lattice, while electron paramagnetic resonance analysis elucidated the magnetic interactions within the materials. In addition, UV direct reflectance spectroscopy coupled with Kubelka–Munk plot analysis facilitated the determination of band gap energy values, which were in the range of 2.11–2.22 eV. The integration of these diverse characterization techniques offers a holistic understanding of the structural, morphological, magnetic, and optical properties of BFO and its RE-substituted variants. This multifaceted approach not only enriches our knowledge of these materials but also paves the way for their diverse applications in sensors, spintronics, actuators, and photocatalysts for environmental remediation. [ABSTRACT FROM AUTHOR]

Ba3Ca2(PO4)3F, having been proven beneficial for ancient geological surveys, was also found to be an efficient fluorescence emitter when doped with various rare-earth and transition ions. Advancing the respective properties further, dysprosium (Dy3+) was added as an activator into the Ba3Ca2(PO4)3F host lattice. The Dy ion in its trivalent form possesses emission in two regions, blue at 481 nm and green at 575 nm, opening a new window towards its plausible use in white-light-emitting diode (LED) lighting appliances. Subsequent analyses including x-ray diffraction, Rietveld refinement, photoluminescence, and lifetime observed in milliseconds (ms) revealed a similar nature of the decay curves as given in the literature. Further, a CIE coordinate calculation predicted near-ideal white light emission. [ABSTRACT FROM AUTHOR]

This article describes the synthesis of CoFe2O4 nanoparticles, which can be used to form an anode for supercapacitor applications. The CoFe2O4 nanoparticles were synthesized via a hydrothermal route. The structural parameters of the prepared samples were characterized by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), and the supercapacitive behavior was evaluated by cyclic voltammetry plots, galvanostatic charge–discharge plots, and electrochemical impedance spectroscopy (EIS). Rietveld refinement confirmed the spinel structure of the CoFe2O4 nanoparticles with space group Fd3m. The FE-SEM micrographs confirmed the spherical shape of the CoFe2O4 nanoparticles, with a mean particle size of 58 nm. The electrochemical performance of the samples was checked in different aqueous electrolytes: Na2SO4 and KOH. The nanoparticles exhibited differences in capacitive behavior in different aqueous electrolytes, with higher specific capacitance (362 F/g) in the KOH electrolyte due to its greater molar ionic conductivity in comparison to the Na2SO4, and a low resistance value obtained from impedance measurements was observed for CoFe2O4 nanoparticles. The cyclic stability of CoFe2O4 in KOH electrolyte, with 82.16% retention after 2000 cycles at current density of 1 A/g, evidenced its outstanding performance, with exceptionally high specific capacitance of 314 F/g. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive inquiry into the structural refinement and Raman spectroscopy of natural barium strontium sulfate, characterized as Sr0.967(2)Ba0.030(2)U0.0022(6)Y0.0012(6)SO4. The crystal structure of orthorhombic sulfate celestine is meticulously refined using Rietveld methods with conventional powder X-ray diffraction data, optimizing the structural model within space group Pnma (Z = 4). The ultimate reliability factors, namely χ2 = 5.6, RF = 3.6, and RBragg = 4.65, confirm the outstanding quality of the refinement process. These factors serve as indicators of the degree to which the refined crystal structure in alignment with the experimental data. In this case, the values suggest a high level of accuracy and precision in the refinement, reinforcing the reliability of the obtained structural model for the celestine crystal. The resulting unit cell parameters are reported as a = 8.372(9) Å, b = 5.357(6) Å, c = 6.877(7) Å, and V = 308.42(7) Å3. The average Vinograd et al. (Appl. Geochem. 89, 59–74, 2018) distance is 2.832(6) Å, while the corresponding average Baker and Bloomer (Geochim. Cosmochim. 52, 335–339, 1988) distance is 1.497(4) Å. This investigation confirms the isostructural nature of the celestine solid solution with pure SrSO4 and barite (BaSO4). Chemical analysis through X-ray fluorescence provides the empirical formula for celestine as (Sr0.979Ba0.013U0.001Y0.005)SO4. Additionally, the application of Vegard’s law for unit cell parameters consistently aligns with the chemical formulas obtained from Rietveld refinement and X-ray fluorescence analysis, underscoring the reliability of Vegard’s law in predicting compound composition. Distinctive vibrational modes in natural celestine are unveiled through Raman spectroscopy, revealing a composition diverging from typical celestine. The observed shift in Raman bands is ascribed to the incorporation of Ba, U, and Y into the celestine lattice, resulting in a solid solution denoted as Sr1-x (Ba, U, Y)ₓSO4. The chemical formula derived through the application of Vegard’s law for ν1(SO4) is reported as Sr0.977 Ba0.023SO4. This formula closely corresponds to the formulation presented earlier. [ABSTRACT FROM AUTHOR]

Complex oxides La 0. 9 7 Ba 0. 0 3 MnO3, La 0. 7 3 Ba 0. 2 7 MnO3 and La 0. 5 Ba 0. 5 MnO3 were synthesized and their structural properties were studied. The structural investigation of the samples is done by incorporating X-ray diffraction (XRD) and scanning electron microscope (SEM) technique at room temperature. The Rietveld method was successfully used for the analysis of the obtained diffraction spectra. It was determined that these compounds have a perovskite structure. Partial substitutions La→Ba do not disturb the ideal perovskite structure and the cubic crystal structure with the space group Pm-3m is preserved. Crystallographic parameters, lattice parameters and interatomic distances were determined for each compound. As a result of SEM studies, it was determined that the size of crystallites in LaxBa 1 − x MnO3 solid solutions ranged from 2 to 10 μ m. [ABSTRACT FROM AUTHOR]

Crystals of Ca10.5−xTMx(VO4)7 (TM = Co, Cu), belonging to the whitlockite family, were synthesized by solid-state reaction and studied as a function of the TM content (x) for the first time. The structure was refined at ambient conditions and at high temperatures up to 1200 K using the Rietveld method. The unit cell size significantly decreases with increasing TM content up to the solubility limit, xlim, which is 0.78(3) for TM = Co and 0.75(4) for TM = Cu. Occupancy factors show a preference for the M5 site by Co/Cu. The unit cell size varies smoothly with temperature, while the axial ratio exhibits nonlinear behaviour above approximately 800 K. The thermal expansion coefficient was determined from 300–1100 K. Atomic arrangement modifications at higher temperatures are indicated by changes in the axial ratio, the thermal expansion coefficient, and the reduction of fractional TM occupancy at the M5 site at specific temperatures. [ABSTRACT FROM AUTHOR]

ZnO nanostructures with various aspect ratios have been synthesized for H 2 gas detection applications. The thermal-decomposition method was employed at different annealing temperatures (350, 450, and 550 °C) and its impact on various shapes/sizes of ZnO nanostructures is demonstrated. Thermal decomposition performed at 350 °C exhibited a maximum (∼6.25) aspect ratio among them. Its capability of H 2 sensing was also observed to be maximum by realizing ∼483% of sensor response at 180 °C under H 2 gas concentration of 80 ppm. The sensor response is ∼3 times (∼177%) and ∼9 times (∼53%) higher at ZnO nanostructure synthesized at 350 °C than at 450 °C, and 550 °C, respectively. The higher sensor response has been attributed to the increased availability of active surface area for adsorption/desorption of gas molecules. ZnO@350 nanostructure showed significantly higher selectivity towards H 2 gas than other target chemical inputs. We have also studied H 2 -induced metallization on the surface of ZnO nanostructures which plays an important role for improving the selectivity and sensor response. This study provides insight into the role of aspect-ratio-controlled shape/sized ZnO in improving H 2 gas sensing. [Display omitted] • Aspect-ratio-controlled ZnO nanostructures for H 2 gas sensing was examined. • The maximum sensor response (∼483%) for ∼6.25 aspect ratio ZnO was observed. • ZnO-nanorods pose higher active surface area than NPs that reduced operating temperature. • The sensor response is ∼3 times and ∼9 times higher at 350 °C than at 450 °C, and 550 °C. • H 2 -induced metallization on ZnO surface significantly improved the sensor selectivity. [ABSTRACT FROM AUTHOR]

This study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd2NiTiO6 synthesized through the sol–gel citrate auto‐ignition method. The Rietveld refinement of the X‐ray diffraction patterns confirmed a monoclinic symmetry (space group P21/n) with an ordered arrangement of alternate NiO6 and TiO6 octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye‐type relaxation mechanism and semi‐conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature‐ and frequency‐dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal‐ and field‐dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni2+ ions via Ti4+ ions and the rare‐earth cation (Nd3+) moment. [ABSTRACT FROM AUTHOR]

Samples with compositions of Sr2Sn1−xMnxO4(SSM) with 0 ≤ x ≤ 0.10 are prepared by conventional ceramic route via heat treatment at 1350 °C. Phase and crystal structure analysis is studied using X‐ray diffraction and Rietveld refinement to confirm the crystallization of samples in the tetragonal structure under space group I4/mmm. The size‐strain plot method is employed to identify the role of Mn on crystallite size/microstrain/dislocation density. The scanning electron microscope and energy‐dispersive X‐ray spectroscopy analysis confirm a significant change in the grain size and compositional homogeneity of all samples with Mn‐doping. Dielectric properties of samples are explained in terms of interfacial and orientation polarization of dipoles SnSn4+2+″−VO⋅⋅;2Mn2Mn3+2+′−VO⋅⋅$S n_{\left(\text{Sn}\right)^{4 &amp;amp;amp;amp;amp;plus;}}^{2 &amp;amp;amp;amp;amp;plus;} ^{&amp;amp;amp;amp;amp;aposx; &amp;amp;amp;amp;amp;aposx;} - V_{O}^{\cdot \cdot} ; 2 M n_{2 \left(\text{Mn}\right)^{3 &amp;amp;amp;amp;amp;plus;}}^{2 &amp;amp;amp;amp;amp;plus;} ^{&amp;amp;amp;amp;amp;aposx;} - V_{\text{O}}^{\cdot \cdot}$. Modulus studies show the exclusion of electrode contribution from the electrical properties. The single‐segment circular dielectric resonator antenna is designed with the help of experimental dielectric parameters and showed two major resonant frequencies at 3.6 and 6.7 GHz. The reduction in the S11 parameter and −10 dB reflection coefficient bandwidth with Mn‐doping observed due to overlapping of the E‐field line suggests the application in patch array antenna for radar and satellite communication applications. This study also enables to explore Sr2SnO4‐based Ruddlesden Popper oxide for antenna and mm‐wave communication applications. [ABSTRACT FROM AUTHOR]

In the present work, the sintering of bismuth germanate through hot pressing and the improvement of scintillator performance were investigated. The linear shrinkage, crystalline structure, microstructure, transparency degree, and radioluminescence (RL) were studied as functions of the sintering pressure. X‐ray diffraction revealed that the samples were predominantly composed of the Bi4Ge3O12 phase, accompanied by small amounts of Bi12GeO20, with concentrations varying according to the sintering parameters. These concentrations were quantified through Rietveld refinement, which also indicated a tendency for the cell parameters to shrink as the sintering pressure increased. The microstructure of the ceramic pellets produced under varying hot‐pressing parameters was investigated using scanning electron microscopy (SEM), revealing that while the grain size was preserved, the porosity and grain boundary thickness were reduced by the hot pressing, forming a quasicontinuum in some areas of the sample. The RL of all the samples exhibited a green color, with a maximum at 540 nm, ascribed to the transitions from the 3P0,1,21P1 excited states to the fundamental 1S0 state of the Bi3+ ions. For samples sintered under a pressure of .18 MPa, the enhancement in the optical transmittance, accompanied by a 61.36% increase in light output at the maximum wavelength, was observed. [ABSTRACT FROM AUTHOR]

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na 0.5 Bi 0.5 TiO 3) and Co–Ti substituted Barium Hexaferrite (BaFe 12-2x Co x Ti x O 19 ; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63 / mmc hexagonal phases corresponding to Na 0.5 Bi 0.5 TiO 3 and BaFe 12-2x Co x Ti x O 19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x ≠ 0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future. [ABSTRACT FROM AUTHOR]

In this work, non-ordered and ordered CeO2-based catalysts are proposed for CO2 conversion to dimethyl carbonate (DMC). Particularly, non-ordered mesoporous CeO2, consisting of small nanoparticles of about 8 nm, is compared with two highly porous (635–722 m2/g) ordered CeO2@SBA-15 nanocomposites obtained by two different impregnation strategies (a two-solvent impregnation method (TS) and a self-combustion (SC) method), with a final CeO2 loading of 10 wt%. Rietveld analyses on XRD data combined with TEM imaging evidence the influence of the impregnation strategy on the dispersion of the active phase as follows: nanoparticles of 8 nm for the TS composite vs. 3 nm for the SC composite. The catalytic results show comparable activities for the mesoporous ceria and the CeO2@SBA-15_SC nanocomposite, while a lower DMC yield is found for the CeO2@SBA-15_TS nanocomposite. This finding can presumably be ascribed to a partial obstruction of the pores by the CeO2 nanoparticles in the case of the TS composite, leading to a reduced accessibility of the active phase. On the other hand, in the case of the SC composite, where the CeO2 particle size is much lower than the pore size, there is an improved accessibility of the active phase to the molecules of the reactants. [ABSTRACT FROM AUTHOR]

Nitridophosphates are in the focus of current research interest due to their structural versatility and properties, such as ion conductivity, ultra‐incompressibility and luminescent properties when doped with suitable activator ions. Multinary representatives often require thorough investigation due to the competition with the thermodynamically more stable binary and ternary compounds. Another point of concern is the synthetic control of structural details, which is usually limited by conventional bottom‐up syntheses. In this study, we report on the synthesis and characterization of the quaternary nitridophosphate CaLi2PN3. Various synthesis protocols were used for the preparation of CaLi2PN3, including the novel nitridophosphate double salt approach. The crystal structure was solved and refined from single‐crystal X‐ray diffraction data and confirmed by Rietveld refinement, solid‐state NMR spectroscopy, EDX measurements and low‐cost crystallographic calculations. The experimental results were corroborated by DFT calculations, which revealed the electronic band structure. Formation energy calculations allowed conclusions to be drawn about the stability in comparison to the initial ternary nitridophosphates. The synthesis of CaLi2PN3 exemplifies the enormous potential of medium‐pressure syntheses in the field of nitridophosphate research. Furthermore, the presented new synthesis route allows a certain degree of structural control, which is a promising addition to previous synthesis strategies in nitridophosphate chemistry. [ABSTRACT FROM AUTHOR]

This research investigates the mechanical activation of kaolin as a supplementary cementitious material at the laboratory scale, aiming to optimize milling parameters using the response surface methodology. The study evaluated the effects of rotation speed and milling time on the amorphous phase content, the reduction in crystalline kaolinite, and impurity incorporation into the activated clay through the Rietveld method. The results demonstrated that adjusting milling parameters effectively enhanced clay activation, which is crucial for its use in low-carbon cements. High rotation speeds (300/350 rpm) and prolonged grinding times (90/120 min) in a planetary ball mill increased the pozzolanic activity by boosting the formation of amorphous phases from kaolinite and illite and reducing the particle size. However, the results evidenced that intermediate milling parameters are sufficient for reaching substantial degrees of amorphization and pozzolanic activity, avoiding the need for intensive grinding. Exceedingly aggressive milling introduced impurities like ZrO2 from the milling equipment wear, underscoring the need for a balanced approach to optimizing reactivity while minimizing impurities, energy consumption, and equipment wear. Achieving this balance is essential for efficient mechanical activation, ensuring the prepared clay's suitability as supplementary cementitious materials without excessive costs or compromised equipment integrity. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of speed sintering and glazing on the flexural strength and microstructure of multilayered 5 mol% yttria-stabilized (5Y-) zirconia, which remains unknown. Bar-shaped specimens (N = 600) were fabricated from 5Y-zirconia (FX; Ceramill Zolid FX ML, ST; Katana STML) by cutting, polishing, sintering (conventional and speed sintering), and then glazing. A flexural strength test (n = 30/group), field emission scanning electron microscopy (FE-SEM) observation (n = 2/group), and an X-ray diffraction (XRD) study with Rietveld refinement (n = 1/group) were performed. The flexural strength was analyzed using three-way ANOVA and a post hoc Scheffé test. The grain size was analyzed using the Kruskal–Wallis H test and Bonferroni–Dunn post hoc test. Flexural strength slightly decreased in the nonglazed FX after speed sintering (p < 0.05). Glazing with and without glazing paste did not affect flexural strength at both sintering speeds (p > 0.05). Speed sintering and glazing minimally changed the Weibull modulus and phase fraction, and did not affect grain size (p > 0.05). ST had a larger grain size and lower tetragonal phase content than FX and had a lower flexural strength than FX in most groups (p < 0.05). Overall, the multilayered 5Y-zirconia is considered suitable for dental application using speed sintering and glazing. [ABSTRACT FROM AUTHOR]

A novel high-entropy M 4 AlC 3 phase ceramic (M=Ti, V, Mo, Nb, Ta) was synthesized by three-step solid phase sintering, and the textured high-entropy M 4 AlC 3 composites were prepared for the first time by SPS uniaxial pressing of nano flakes generated via reactive ball milling. The microstructure were characterized in detail and Maud software was used for Rietveld refinement analysis of phase composition content. The results showed that Ti, V, Mo, Nb, Ta were successfully dissolved in M 4 AlC 3. On this basis, the density, hardness and mechanical properties before and after texture were tested. The results showed that the textured composite achieved 12.1 GPa Vickers hardness (//C-axis), 2.2 GPa compressive strength (//C-axis), 8.8 fracture toughness of MPa m1/2 (//C-axis) and 726 MPa bending strength (//C-axis). Dispersively distributed nano-Al 2 O 3 and texturization played a key role in strengthening and toughening. This work can provide an important reference for the subsequent preparation and texturing of high-entropy MAX ceramics. [ABSTRACT FROM AUTHOR]