Rietveld Refinement Technique Research Articles

Investigation of physicochemical characteristics of Dy3+ modified ZnO nanoparticles

In this report, pristine and Dy3+ modified ZnO nanoparticles [Zn(1-x)DyxO NPs, where x = 0, 0.05, and 0.10] were synthesized using the sol–gel route, and their physicochemical characteristics were investigated. x-ray diffractograms of all the compositions possess P63mc space group depicting hexagonal crystallinity with wurtzite-type crystal structure with no signature of impurities as confirmed using the Rietveld refinement technique. The granular microstructure displayed grain growth with Dy3+ incorporation in the ZnO crystal framework and an increment in average grain size was found to be 22.83 nm for x = 0 to 36.34 nm. The optical energy band gap also increased from 3.35 eV to 3.88 eV with Dy3+ doping in the host ZnO. Dy3+ substitution inhibits the conduction in ZnO and improves the resistivity (36 Ωcm–79 Ωcm) as carrier concentration diminishes from 7.36 × 1016 cm−3 to 4.23 × 1016 cm−3. Similarly, the mean free path length for ZnO and Dy3+ doped ZnO NPs declines from 0.0301 nm to 0.0198 nm. Dielectric properties of all the compositions were investigated using an LCR impedance analyzer and it was observed that Dy3+ substitution enhances the value of the dielectric constant from 32 to 91 with a low tangent loss at 50 Hz.

Understanding of the correlation of structural and microwave dielectric performance of (1-x)MgTiO3 - xCaTiO3 ceramics for dielectric resonator antenna applications

In this article, the effect of CaTiO3 on the structural and microwave dielectric characteristics of MgTiO3 has been discussed. The (1-x)MgTiO3 - xCaTiO3 (abbreviated as (1-x)MT- xCT) for x = 0.025, 0.05, 0.075, 0.1 ceramics have been developed using a solid-state reaction route. The structural as well as morphological characteristics of specimens have been observed by employing X-ray diffraction and scanning electron microscope methods. The Rietveld refinement technique of X-ray diffraction data have been conducted for the refinement of structural phases. It suggests that two crystallographic phases have been present in all materials. The SEM images display dense well-identified grains of (1-x)MT - xCT (for x = 0.025 - 0.1) ceramics. The Raman spectroscopy method has been employed to detect the symmetry of ceramics and modes of vibration of the materials. The microwave dielectric characteristics like dielectric permittivity (εr), loss (tanδ), quality factor (Q×f), and temperature coefficient at resonant frequency (τf) of (1-x)MT - xCT (for x = 0.025 - 0.1) ceramics have been thoroughly investigated. The bond strength, bond valency, bond energy, and tolerance factor of (1-x)MT - xCT (for x = 0.025 - 0.1) materials have been evaluated and their relation with microwave dielectric characteristics has been discussed. The (1-x)MT - xCT (for x = 0.025 - 0.1) ceramics show excellent dielectric properties with near to zero τf. In addition, DRAs have been designed with (1-x)MT - xCT (for x = 0.025 - 0.1) materials as dielectric resonators and various antenna properties have been studied with the help of HFSS software. This work suggests that (1-x)MT - xCT for (x=0.05) material can be a promising candidate for DRA applications working in the C band.

Investigation of structural, morphological, dielectric, optical, and ferroelectric-energy storage properties of [(1-x) BCT-(x) BZT] electroceramics

Extensive research and advancements have been progressed by the vast potential of eco-friendly dielectric capacitors in high-level electronic elements and high-performance pulsed power systems thus far. Ferroelectric ceramic materials exhibiting relaxor properties and significant dielectric constants are prime candidates for attaining exceptional energy storage capabilities. Herein, a lead-free (1-x) Ba0.9Ca0.1TiO3–xBaZr0.15Ti0.85O3 (abbreviated as (1-x) BCT-xBZT) solid solution system has been synthesized via the conventional solid-state reaction technique, with varying levels of BZT doping. The X-ray diffraction study confirmed pure perovskite structure formation in the prepared ceramics, and the coexistence of orthorhombic (O) (space group- Amm2) and tetragonal (T) (space group-P4mm) phases has been detected through the Rietveld refinement technique at room temperature. Rietveld refinement data and associated analysis highlight the gradual shift of crystal symmetry from Amm2 to P4mm as the x content increases. Replacing BZT in Ca-modified BaTiO3 has led to significant enhancements in microstructural properties and an increase in the width of the optical band gap. This, in turn, enhances energy storage capabilities compared to pure BCT. Incorporating BZT into BCT has led to the evolution of relaxor ceramics, a crucial development for achieving elevated levels of recoverable energy storage density. In this study, the solid solution comprising 0.6BCT-0.4BZT exhibits distinct traits, including a diffuse phase transition, high breakdown strength, shallow dielectric loss (tanδ <0.007), and significantly high dielectric constant. Due to enhanced electrical characteristics, the 0.6BCT-0.4BZT possesses very high saturation polarization of ∼48 μCcm−2, a total energy density of 1.71 J/cm3, and a recoverable energy density of 1.1 J/cm3. In addition, the optimized ceramics demonstrate concurrent achievement of high-frequency stability (10–250 Hz), fatigue resistance (up to 104 cycles), and favorable temperature stability (20–160°C). This study showcased a potential material candidate suitable for energy storage devices functioning within low to medium-electric fields.

Study of crystal structure and optical features of single-phase Ba2BiV3O11: Dy3+ nanophosphors for advanced solid-state illuminating applications

Urea-aided solution combustion (SC) method has been employed to generate monoclinic structure-based Dy (III) doped Ba2BiV3O11 nanophosphors. X-ray diffraction (XRD) and the Rietveld refinement techniques confirmed that the developed nanophosphors are crystallized in a monoclinic crystal system with space group as P21/a. The crystallite size was assessed via Scherrer's equation and Williamson-Hall (W–H) plot. SEM and TEM images confirm the agglomerated particle with a non-uniform shape lies in the nano range. An energy dispersive X-ray (EDAX) study is executed to assess various constitute elements and their relative dispersal was analyzed via mapping spectrum. The highly intense emission peak at 577 nm is ascribed to 4F9/2→6H13/2 electronic transition of the Dy3+ ion when energized at 327 nm wavelength. The band gap values for the host matrix and the optimized sample were measured using a DR spectrophotometer. Auzel's model was utilized to establish the values of quantum efficiency (68.21 %), non-radiative rates (597.08 s−1), and intrinsic lifetime (0.7803 ms). Furthermore, PL (photoluminescence) data is exercised to attain chromatic quantities viz. color coordinates (x and y), and correlated color temperature (CCT), which are strongly endorsed for their usage as near UV-based advanced solid-state illuminating devices.

Multiple relaxation mechanisms in SrBi2Nb2O9 ceramic tweaked by tin and samarium incorporation in assistance with single-step microwave sintering

Non-stoichiometric lead free polycrystalline Sr0.8Sn0.2Bi1.75Sm0.25Nb2O9 (SSBSN) ferroelectric ceramics were synthesized through conventional solid step route method by incorporating ball milling and microwave sintering method. X-ray diffraction along with the Rietveld refinement technique confirms the single-phase orthorhombic structure with A21 crystal symmetry. Additionally, the short-range ordering was confirmed by Raman spectroscopy. Doping induced crystallite size and strain were further calculated from the Williamson-Hall plot, which comes around 150 nm and 1.48 × 10–3 respectively. A plate like morphology with an average grain size of 0.41 μm was confirmed by scanning electron microscopy (SEM). A diffuse type ferroelectric to paraelectric phase transition was recorded at 395 °C, mostly arising due to structural heterogeneity at the inter-ferroelectric phase boundary. The temperature and frequency-dependent dielectric measurement of SSBSN ceramic reveal a Maxwell–Wagner relaxation, with prominent dielectric loss in a low frequency regime perhaps due to the generation of leakage current in the SSBSN system. Frequency dependent ac conductivity indicates the polaron assisted hopping mechanism in SSBSN, which further obeys Jonscher’s formulation. The intra and intergranular contributions to impedance in SSBSN ceramics were probed by the complex impedance spectroscopy (CIS) technique. A non-Debye type relaxation mechanism in SSBSN ceramics was indicated by the Cole–Cole plot, whereas the conduction mechanism and transport properties were briefly studied using modulus spectroscopy.

Evolution of Ni-induced orthorhombic phase in SnO2: Influence of Ni on the optical and photocatalytic properties

This paper presents the impact of nickel doping on the structural, optical and photocatalytic characteristics of Sn1-xNixO2 (x = 0, 0.3, 0.05, 0.07) nanoparticles. The samples are synthesized via the chemical co-precipitation method. Information on the structural properties of the samples is obtained via the Rietveld refinement technique. As the dopant concentration increases, a partially stable orthorhombic phase emerges and becomes prominent, indicating a correlation with the amount of Ni dopant. This orthorhombic phase arises during the transformation from the amorphous state to a more stable crystalline phase. The FESEM-EDAX analysis demonstrates the uniform distribution of agglomerated particles. Additionally, the Raman data provides information related to surface defects and vacancies. A minor increase in the band gap value is detected, and this observed blue shift can be attributed to the Burstein-Moss effect. The samples exhibit a strong blue emission, primarily attributed to surface defects and states, particularly due to the oxygen vacancies. The CIE coordinates show an increase in blue colour purity, making the samples suitable for blue components in white-light emitting diodes. However, the photocatalytic study reveals only partial degradation of methylene blue under visible light conditions.

COMPARATIVE THERMAL KINETIC ANALYSIS OF NICKEL HYDROXIDE NANOPARTICLES THROUGH CHEMICAL PRECIPITATION AND SOL–GEL ROUTES

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 [Formula: see text]-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.

Optimizing the White Light Emission of Pr3+ Activated SrCeO3 Perovskite by Controlling the Excitation Wavelength for High CRI wLED Applications.

The current research illustrates excitation energy-triggered photoluminescent characteristics of Pr3+ions in SrCeO3 providing a practical approach for developing high CRI wLED and its applications. SrCeO3: xPr3+ (x = 0, 0.005, 0.01, 0.02, 0.03 wt) perovskites synthesized by fuel excess gel combustion method generate high CRI (~98) for wLED applications. Crystalline phosphors with orthorhombic structures having space group Pnma were confirmed by XRD. The unit cell volume expansion occurred with an increase in Pr3+ concentration was verified through the Rietveld refinement technique. Surface morphology, particle distribution, and size were observed via FE-SEM imaging, and detected a well-defined regular distorted spherical structure with average grain size 0.826μm for Pr3+ doped SrCeO3. Elemental mapping and EDS analysis identified the uniform distribution and elemental purity of SrCeO3: 0.01 Pr3+. Further, the molecular vibrations and modes were analyzed from the Raman spectrum. Moreover, the average particle size assessed via TEM analysis was found to be ~83.2nm, consistent with XRD analysis. UV-visible absorption spectra for optical energy-band gap analysis showed a decrease in band gap energy with an increase in Pr3+ concentration, realizing an effective energy transfer from Ce4+ to Pr3+. PL measurements showed a huge variety of emission transitions, corresponding to excitations 290nm, 321nm, 373nm, and 449nm. The critical dopant concentration instigated by concentration quenching was 1 wt% Pr3+, ascribed to dipole-dipole interaction. The fluorescence lifetime of the optimal sample was 4.835μs. Commission International de I'Eclairage (CIE) diagram exposes the white light emanation of SrCeO3: Pr3+. Among which white light with high CRI (~98) and comparably low CCT (~6311K) was obtained for SrCeO3: 0.01 Pr3+ at 373nm excitation. The obtained results recommend that SrCeO3: Pr3+ perovskite as an efficient white phosphor for fabricating high-performance wLEDs.

Crystal structure and synchrotron X-ray powder reference pattern for the porous pillared cyanonickelate, Ni(3-amino-4,4′-bipyridine)[Ni(CN)4

The structure of Ni(3-amino-4,4′-bipyridine)[Ni(CN)4] (or known as Ni-BpyNH2) in powder form was determined using synchrotron X-ray diffraction and refined using the Rietveld refinement technique (R = 8.8%). The orthorhombic (Cmca) cell parameters were determined to be a = 14.7218(3) Å, b = 22.6615(3) Å, c = 12.3833(3) Å, V = 4131.29(9) Å3, and Z = 8. Ni-BpyNH2 forms a 3-D network, with a 2-D Ni(CN)4 net connecting to each other via the BpyNH2 ligands. There are two independent Ni sites on the net. The 2-D nets are connected to each other via the bonding of the pyridine “N” atom to Ni2. The Ni2 site is of six-fold coordination to N with relatively long Ni2–N distances (average of 2.118 Å) as compared to the four-fold coordinated Ni1–C distances (average of 1.850 Å). The Ni(CN)4 net is arranged in a wave-like fashion. The functional group, –NH2, is disordered and was found to be in the m-position relative to the N atom of the pyridine ring. Instead of having a unique position, N has ¼ site occupancy in each of the four m-positions. The powder reference diffraction pattern for Ni-BpyNH2 was prepared and submitted to the Powder Diffraction File (PDF) at the International Centre of Diffraction Data (ICDD).

Compatibility of LaFe13−x−yMnxSiyH1.6 and Eutectic Liquid GaInSn Alloy

The heat transfer rate of magnetocaloric regenerators is a topic of extensive research and the cyclability of these regenerators is critical to the operation of systems with a high coefficient of performance (e.g., potentially &gt;22, significantly higher than typical vapor compression cooling technologies). To enable a high operating frequency that will result in a high specific cooling power, the heat transfer fluid should have high thermal conductivity and lower specific heat, i.e., higher thermal diffusivity. Eutectic metal alloys possess these qualities, such as gallium–indium–tin (Galinstan), whose thermal diffusivity has been found to be approximately an order of magnitude higher than water. For this study, the effects of eutectic liquid Galinstan exposure on the phase stability of LaFe13−x−yMnxSiyH1.6 magnetocaloric powders in an active magnetic regenerator device were investigated. The powders were characterized before and after exposure to Galinstan using X-ray diffraction, in which the phases were determined using the Rietveld refinement technique and X-ray fluorescence. It was found that after Galinstan exposure, hydrogen containing phases were present in the powder, suggesting that the hydrogen was lost from the magnetocaloric phase. The magnetocaloric phase degradation indicates that the powder was incompatible with the Galinstan metal in an environment with moisture.

New Solid-Solutions of Substitution Strontium (Sr) for Lead (Pb) in Apatite Structure

Strontium substitution for lead in Pb(8-x)SrxNa2(PO4)6 was analyzed using XRD, SEM, and Rietveld refinement techniques. All samples were synthesized using ceramic and semi-ceramic technologies. Pure apatite was formed in the composition from x=0.00 up to x=2.75. The results indicate that the samples’ collected compositions agree with the values calculated.

The modifications in structural, optical, and electro-magnetic phase transition of Vanadium-doped La-based manganite ceramics La0.7Pb0.3Mn1−yVyO3 (y = 0 – 0.1)

The present paper is centred around the investigation of the structural, electrical, and magnetic properties displayed by the novel perovskite polycrystalline La0.7Pb0.3Mn1−yVyO3 (y = 0 – 0.1) prepared via the conventional solid-state technique. The structural properties of the samples were assessed through the utilisation of X-ray diffraction (XRD) analysis. Subsequently, the obtained diffraction data underwent refinement employing Rietveld refinement techniques in order to determine the structural parameters of the samples a, b, c, V and Mn–O bond length and angle. The study of X-ray diffraction (XRD) peaks reveals that all the samples exhibited crystallization in a single phase, devoid of any impurities. All of the samples exist in rhombohedral orientation with a space group of R-3c. The tolerance factor of the samples was calculated in order to assess the severity of lattice distortion, decrease from 0.872 (y = 0) to 0.831 (y = 0.1). The microstructural characteristics of the samples were analysed using a field-emission scanning electron microscope (FESEM). The morphology results reveal that a rise in the amount of V leads stimulates the grain growth in the sample, as evidenced by the increase in grain size from 2.17 µm (y = 0) to 3.71 µm (y = 0.1). The Fourier transform infrared (FTIR) analysis revealed an absorption range of 500 – 600 cm-1, which is indicative of the Mn–O bond deformation vibration. This observation suggests the presence of a MnO6 bond in the sample. The Tauc plots derived from the UV-Vis spectroscopy data reveal a notable increase in the optical bandgap (Eopt) as the concentration of V increases. Specifically, the Eopt values rise from 1.71 eV (y = 0) to 2.30 eV (y = 0.1), falling within the range typically observed for semiconductor materials. A distinct metal-insulator transition was observed in all of the samples, exhibiting a range of TMI values ranging from 250 K to 292 K. The scattering model was employed to determine the itinerant eg behaviour in the low temperature region, whilst the SPH model was used to explore the conduction behaviour in the high temperature region. The magnetic characteristic of the samples was investigated using the Alternating Current Susceptibility (ACS) and Vibrating Sample Magnetometer (VSM) techniques, which confirms the existence of a shift in phase from ferromagnetic (FM) to paramagnetic (PM). The TC value exhibits a declining trend from 298.8 K (y = 0) to 274.8 K (y = 0.1).

Extending the modified steel slag cement into the hydrophobic and anti-icing application

Steel slag cement is commonly used as a non-load-bearing building material because of its low long-term strength. To promote its large-scale recycling, the new application of steel slag cement is significantly attractive. In this study, a new type of hydrophobic steel slag cement modified by Polydimethylsiloxane (PDMS) was prepared. α-C2S, β-C2S, C3A, C3S, C4AF, Aft, and CH were found in the samples by XRD. The Rietveld refinement technique was used to quantitatively analyze the content of hydration products. SEM and EDS analysis revealed the effect of PDMS and steel slag on the morphology of hydration products. The increase in the steel slag content, resulted in a smoother the surface due to the decrease in hydration products. It was found that PDMS covered the surface of hydration products, resulting in excellent hydrophobic properties. FTIR and XPS analysis showed that the main reason for the good hydrophobicity of the sample was that PDMS crosslinked on the surface of cement particles and filled the pores. With hydrophobic modification, the contact angle could reach 143.7°. The hydrophobically modified cement exhibited excellent self-cleaning ability, low water absorption, good photothermal properties, remarkable anti-icing properties, certain mechanical strength and high durability.

Unraveling the potential of sonochemically achieved DyMnO3/Dy2O3 nanocomposites as highly efficient visible-light-driven photocatalysts in decolorization of organic contamination

In the present day, the widespread presence of lingering contaminants in ecosystems has prompted scientists to develop novel semiconductor nanoarchitectures that assist in photocatalytic reactions mediated by visible light. As a result, we propose to prepare a series of Dy-Mn-O based nano-catalysts using a sonochemical approach utilizing various ionic phases of surfactants as structure-directing agents. In this study, X-ray diffraction (XRD) and Rietveld refinement techniques were used to explore the fundamental effects of surfactants on the compositional-structural features of the materials. In terms of morphological profiles, DyMnO3/Dy2O3 (DM) nanostructures fabricated with Triton X-80 as a structure-directing agent showed the best uniformity with an acceptable size range between 14.14 and 52.35 nm. In the visible-light-driven photocatalytic domain, these nanocomposites provide high responsiveness based on their optical band gap value of 2.0 eV. According to our findings, two individual factors affect dye activity, namely dye type and concentration, which is why a high decomposition efficiency of 78.8% was obtained for 10 ppm Acid violet (AV) using DyMnO3/Dy2O3 nanocomposites after 120 min of exposure to visible light. Furthermore, radical quenching test confirmation confirmed the mechanistic behind the degradation process. This indicates that active species of O2•− and •OH may play a significant role in photocatalysis. As a result of repeated processes over three consecutive cycles, binary DyMnO3/Dy2O3 nanocomposites had an efficiency of 64.4% in removing dyes from the environment, indicating their high stability.

Investigation of magnetocaloric effect in Holmium substituted Dysprosium iron garnet for magnetic refrigeration applications

The Dy1-xHox3Fe5O12(Ho-DyIG) with x=0.0 to 1.0 garnet samples are prepared by solid-state reaction route by sintering them at 1200 °C for 24 hours followed by calcination. The samples have simple cubic structure with Ia3¯d space group. The lattice constant is obtained from the Rietveld refinement technique and is found to be decreased from 12.4181Å to 12.3858Å with Ho doping. All the samples exhibit ferrimagnetic behavior below their transition temperature of 555K(x=0.0) to 545Kx=1.0. This drop in transition temperature is attributed to the dilution of Fea-O-Fed networks. All the samples show magnetic compensation because of the strong anisotropy induced at lower temperatures. In addition, we have also observed spin reorientation in all the samples of Ho-DyIG series. We have performed magnetocaloric measurements for x=0.4 and 0.8 samples and observed that the magnetic entropy is improved from 3.92 to 4.30J/kgK when measured at a maximum applied field of 5T around their respective Belov tranistion temperature i.e. TB. We have seen both normal and inverse magnetocaloric effects in these samples. To test the extent of magnetic refrigeration capacity, we have calculated the Relative Cooling Power, which comes out to be 364.6J/kg for x=0.4 and 313.0J/kg for x=0.8 samples at 5T magnetic field. The Arrott plots are also investigated and they have positive slope suggesting the presence of second-order phase transition in our samples.

Structural and magnetocaloric properties of Gd2-xMnxO3 nanoparticles

Magnetic cooling is considered to be an important component of future green refrigeration. On this subject, rare earth oxides (RE2O3) are seen as a promising class of magnetic materials for low-temperature magnetic cooling technology. In this work, we report the influence of Mn substitution on the structural, magnetic and magnetocaloric characteristics of Gd2O3 powders synthesized by sol–gel route. Structural analysis using Rietveld refinement technique confirmed the cubic-bixbyite structure with the Ia3¯ space group. The lattice parameter slightly decreases with the Mn doping degree. Temperature dependent magnetization measurements demonstrated a paramagnetic behavior sustained in Gd2-xMnxO3 in the whole temperature range of 2–400 K and the presence of weak antiferromagnetic interactions at low temperature (≤2K). The measured hysteresis loops are linear and completely reversible (2 K), which is typical for paramagnetic system and suitable for cryogenics magnetic refrigeration. The variation of the magnetic entropy was measured indirectly using the Maxwell approach with increasing magnetic field.

Structural, optical and electrical characteristics of samarium molybdate nanoceramic

The 1:1 composition of R2O3–MoO3 rare earth molybdates forms an interesting class for research, as the compounds in the system crystallize in three structures, namely, tetragonal I4‾2m, monoclinic C2/c and cubic Fm3m with Sm2MoO6 existing at the boarder of transition from tetragonal to monoclinic structure. In the present study, single phase Sm2MoO6 nanoceramic is synthesized through auto ignited combustion method and its structure and optical and electrical properties are investigated. The crystal structure and lattice parameters of the compound are analyzed using X-ray diffraction and Rietveld refinement techniques which implies that the compound crystallizes in the monoclinic system with space group C2/c. The vibrational spectroscopic analysis substantiates the existence of trigonal bipyramidal MoO5 units in the sample. Morphological study is carried out using FESEM and TEM. The material shows high absorption in the UV region and the optical band gap energy is 2.97 eV. The impedance spectroscopic analysis corroborates that the compound has a conductivity of 0.15 × 10−5 S/cm and 1.71 × 10−5 S/cm at 550 °C and 850 °C, respectively, at1 MHz frequency.

Exploration of the Structural, Dielectric, Ferroelectric, and Piezoelectric Properties in Non-stoichiometric Sr1−XBi2+2X/3Nb2O9 Ceramics

In this study, the authors focused on the preparation and characterization of Lead-free ferroelectric ceramics known as Sr1−XBi2+2X/3Nb2O9: SBBNX, where 0.0≤ × ≤0.4. The ceramics were synthesized using a conventional solid-state reaction route. The researchers performed X-ray diffraction (XRD) analysis to confirm the phase formation and employed the Rietveld refinement technique. The results indicated that the prepared SBBNX ceramics exhibited a single phase with an orthorhombic structure, specifically belonging to the A21am space group. All samples were subjected to analysis using field emission scanning electron microscopy (FESEM) to investigate their surface morphology. The micrographs revealed a uniform distribution of grains (of size 2–4 μm ) on the surface, with distinct grain boundaries. An increasing trend in both the dielectric constant (from 99 to 220 at room temperature) and transition temperature (from 396 °C to 490 °C) was noted with an increase of Bi content in SBN. The researchers estimated the activation energies by analyzing the Arrhenius plots of the ac conductivity. The obtained values ranged from 0.62 to 1.25 eV, indicating the presence of motion of oxygen vacancies in the SBBNX ceramics. The primary objective of this study was to optimize the Sr/Bi ratio in SBBNX ceramics to enhance their potential use in non-volatile random access memory (NVRAM) applications and high-temperature piezoelectric devices.

Influence of Bi3+ 6s2 lone pair hybridization on the La0.7Pb0.3-xBixMnO3 (x = 0–0.04) crystal structure and electro-magnetic phase transition behaviour

Current manuscript focuses on the variations in structural, electrical, and magnetic behaviour exhibited by the new perovskite compound of La0.7Pb0.3-xBixMnO3 (x = 0–0.04). The samples were synthesized using the conventional solid state preparation method. The sample structural properties were determined using X-ray diffraction (XRD), and the diffraction data was refined using Rietveld refinement techniques to determine the samples structural parameters. The XRD analysis shows that the x = 0–0.02 samples crystallized as a single-phase sample, whereas x = 0.04 indicates secondary phase formation of Mn3O4 impurities. Though, all the sample crystallized in a rhombohedral structure with a space group of R-3c. The tolerance factor of the sample was calculated to determine the distortion severity of the structure. Scanning electron microscope (SEM) was used to study the samples' morphological properties. Fourier transform infrared (FTIR) indicates absorption range within 450–600 cm−1 which corresponds with absorption range of Mn–O bond formation. Ultraviolet–visible spectroscopy (UV–Vis) analysis of the sample exhibited an optical energy bandgap within the range of 1.71 eV–2.16 eV. The samples exhibit a clear metal-insulator transition with various TMI values ranging from 256 K until 292 K. Conduction mechanisms at low temperatures (T < TMI) were suggested due to grain or domain boundaries, electron-electron, and electron–magnon mechanisms, while SPH analysis were done to determine the electron conductivity behaviour at high temperatures (T > TMI). The AC susceptibility and Vibrating-sample Magnetometer (VSM) were done to study the magnetic properties of the samples and confirm the transition from ferromagnetic (FM) to paramagnetic (PM) with variation of TC value from 298 K (x = 0) to 289 (x = 0.02) and 287 (x = 0.04).

An investigation about the ability to change color and the way energy is transferred of NaYMgWO6:RE3+ (RE3+ = Tm3+, Dy3+, Tm3+/Dy3+): A new type of single-phase white phosphor for WLEDs

Novel NaYMgWO6:Tm3+, Dy3+ phosphor is synthesized by solid-state reaction method in air. The phase structure was meticulously analyzed through XRD and Rietveld refinement techniques. Dy3+ doped NaYMgWO6 phosphors emitted yellowish-white light, which was observed. Surprisingly, the introduction of Tm3+ ions resulted in white-emitting, which was further studied with the aid of a spectrometer. By fixing the concentration of Tm3+ ions and subsequently adjusting the co-doping concentration of Dy3+ ions or altering the excitation wavelength, the CIE coordinates of NaYMgWO6:Dy3+, Tm3+ phosphors shifted from the blue-violet region to the yellowish-white region. In particular, when b = 0.2 mol, there was efficient energy transfer from Tm3+ to Dy3+, with an energy transfer efficiency of 95.1 %. The gradual decrease of the lifetime at 454 nm monitoring implies that there is indeed an energy transfer process from Tm3+ to Dy3+ and that the probability of energy transfer from Tm3+ to Dy3+ gradually increases with increasing Dy3+ concentration. These findings indicate that NaYMgWO6: aTm3+, bDy3+ phosphors offer a novel approach to researching single-phase white phosphors.