Conventional Solid-state Reaction Technique Research Articles

Electrical resistivity and magnetoresistance of Sr3Fe2+xMo1–xO9–3x/2 (x = 0.45, 0.60, and 1.00) prepared by the solid-state reaction

In this paper, we focus on understanding the behavior of the temperature dependence of electrical resistivity (ρ) and magnetoresistance (MR) in Sr3Fe2+xMo1–xO9–3x/2 perovskites with x = 0.45, 0.60, and 1.00. Three polycrystalline materials were synthesized using conventional solid-state reaction techniques. Rietveld analysis of room-temperature X-ray diffraction data reveals that all three compositions crystallize in tetragonal symmetry; where x = 0.45 and 0.60 undergo an I4/mcm space group, while x = 1.00 adopts a P4/mmm space group. Electrical resistivity measurements carried out at magnetic fields (0 and 1 T) reveal the presence of a transition from the ferromagnetic phase to the paramagnetic phase in the vicinity of the TMI. The metal-insulator transition temperature (TMI) decreases with increasing Fe content and rises slightly with changing magnetic field from 0 to 1 T. The magnetoresistance (MR) of the SrFeO3–δ sample (x = 1.00) has a large value of about 63.6 %, indicating that it can be exploited for certain devices. A variety of theoretical models are used to study the behavior of electrical resistivity in various temperature ranges, showing excellent agreement with experimental results.

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.

Novel sr-doped NdMn0.5Cr0.5O3-δ electrodes for symmetrical solid oxide fuel cell

Solid oxide fuel cells (SOFCs) have emerged as promising energy conversion devices, offering high efficiency and environmental sustainability. Efficient electrode materials are crucial for the overall cell performance of SOFCs. Perovskite type Nd1-xSrxMn0.5Cr0.5O3-δ (x = 0.25, 0.5) (NSCM25, NSCM50) was synthesized via conventional solid-state reaction technique. Structural, thermal and electrochemical characterizations were performed using X-ray diffraction, thermogravimetric analysis, conductivity measurements, scanning electron microscope, thermal expansion coefficient analysis and impedance spectroscopy. Structural analysis revealed that both compositions exhibit orthorhombic symmetry in the Pbnm space group. Thermogravimetric analysis (TGA) indicated minimal weight changes in both pre-reduced and as-prepared samples. The electrical conductivities in air at 600 ℃ were found to be 1.69 S/cm for NSCM25 and 4.91 S/cm for NSCM50, with a decrease observed under reduced oxygen partial pressure. Polarization resistance (Rp) analysis was conducted on symmetrical cells composed of NSCM25|GDC|NSCM25, NSCM50|GDC|NSCM50, NSCM25|YSZ|NSCM25, and NSCM50|YSZ|NSCM50. At 900 ℃, the polarization resistances were 0.12 Ωcm2, 0.21 Ωcm2, 0.11 Ωcm2, and 0.67 Ωcm2, respectively. The results suggest that NSCM25 and NSCM50 hold promise as electrode materials for symmetrical solid oxide fuel cells (SSOFC) employing YSZ or GDC electrolyte.

Optimizing the Structure and Optical Properties of Lanthanum Aluminate Perovskite through Nb5+ Doping.

This work involves the introduction of niobium oxide into lanthanum aluminate (LaAlO3) via a conventional solid-state reaction technique to yield LaAlO3:Nb (LaNbxAl1-xO3+δ) samples with Nb5+ doping levels ranging from 0.00 to 0.25 mol%. This study presents a comprehensive investigation of the effects of niobium doping on the phase evolution, defect control, and reflectance of LaNbxAl1-xO3+δ powder. Powder X-ray diffraction (XRD) analysis confirms the perovskite structure in all powders, and XRD and transmission electron microscopy (TEM) reveal successful doping of Nb5+ into LaNbxAl1-xO3+δ. The surface morphology was analyzed by scanning electron microscopy (SEM), and the results show that increasing the doping concentration of niobium leads to fewer microstructural defects. Oxygen vacancy defects in different compositions are analyzed at 300 K, and as the doping level increases, a clear trend of defect reduction is observed. Notably, LaNbxAl1-xO3+δ with 0.15 mol% Nb5+ exhibits excellent reflectance properties, with a maximum infrared reflectance of 99.7%. This study shows that LaNbxAl1-xO3+δ powder materials have wide application potential in the field of high reflectivity coating materials due to their extremely low microstructural defects and oxygen vacancy defects.

Investigation of Structural, Morphological and Luminescent Features of Eu&lt;sup&gt;3+&lt;/sup&gt; Activated Molybdate Based Phosphor for W-LED Applications

In the present work, NaBi(MoO4)2 (NBM) phosphor has been successfully synthesized by doping 1.0 mol% of Eu3+ via the conventional solid state reaction technique. The undoped synthesized NBM sample and 1.0 mol% Eu3+ doped phosphor were characterized to explore crystal structure, morphology, photoluminescence (PL) and colorimetric properties using various characterization techniques. The structural properties were analysed via x-ray diffraction and diffraction peaks were compared with the standard JCPDS (card no. 79-2240) pattern. The morphological studies of the sample have been done through FE-SEM micrograph. From the photoluminescence emission spectra, it has been observed that an intense peak was obtained in the at 615 nm under blue excitation. Colorimetric property of 1.0 mol% of Eu3+ doped NBM phosphor has been investigated and traced in the red region with high color purity of 92.79%. The aforementioned characteristics demonstrate that the NaBi(MoO4)2: 1.0Eu3+ phosphor has great potential in the field of w-LED applications.

Preparation and study of La-doped bismuth sodium potassium titanate -strontium titanate piezoelectric ceramics to enhance energy storage properties

This study involves the introduction of lanthanum oxide into bismuth sodium potassium titanate, alongside strontium titanate, denoted by the La2O3-doped BNKT-ST samples with varied x values ranging from 0.000 to 0.030 mol % prepared by conventional solid-state reaction technique. The research comprehensively investigates the impact of lanthanum incorporation on the phase evolution, dielectric properties, scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDAX), ferroelectric behavior, piezoelectric response, and energy storage density of the Bi0.5(Na0.84K0.16)0.5TiO3-SrTiO3 (BNKT-BST) ceramics. Powder X-ray diffraction analysis reveals a tetragonal phase structure in all ceramics. Scanning Electron Microscopy (SEM) is employed for surface morphology analysis, indicating that higher concentrations of lanthanum result in reduced grain sizes. The ceramic material demonstrates remarkable P-E hysteresis loops, featuring a prominent peak at an electric field intensity of 3 kV/cm. The trends in residual polarization (Pr) and coercive field (Ec) show ascending, descending, and subsequent ascending patterns with increasing lanthanum concentration. Dielectric measurement was carried out for different composition at various temperatures. The maximum dielectric constant (εr) ∼ 4553 was observed at 348 °C. The sample was poled at a voltage of 3-5 kV. Notably, at a La doping level of 0.020 mol%, the doped samples exhibit favorable performance, as evidenced by the highest piezoelectric coefficient (d33) of 121 pC/N observed in the poled samples. The 0.97BNKT-0.030ST ceramics showcase exceptional energy storage capacity, marked by an elevated energy storage density (W) of 0.26 J/cm3 and a notable energy storage efficiency of 58 %. This study suggests the promising application potential of lanthanum-doped BNKT-ST ceramic capacitors, which are lead-free and exhibit high power density energy storage. Consequently, the BNKT-ST ceramic material emerges as a prospective candidate for further development in actuator and energy storage applications.

Color-tunable luminescence and temperature sensing properties of Bi3+/Sm3+ or Bi3+/Eu3+ codoped Ba2Gd2Ge4O13 phosphors.

Novel temperature-sensitive luminescent materials, Ba2Gd2Ge4O13 doped with Bi3+, Bi3+/Sm3+ or Bi3+/Eu3+ ions, have been prepared using a conventional solid-state reaction technique. The XRPD study has verified that all the synthesized germanates crystallize in the monoclinic system (space group C2/c, Z = 4). The crystal lattice of the compounds consists of zigzag chains of edge-sharing Me2O7 (Me = Bi3+, Eu3+ or Sm3+) dimers, [Ge4O13] units, and ten-coordinated Ba atoms. Under UV excitation the powders exhibit the luminescence corresponding to the 3P1 → 1S0 (310-550 nm) transition in Bi3+ and 4G5/2 → 6HJ (550-730 nm) in Sm3+ or 5D0 → 7FJ (570-720 nm) transitions in Eu3+ ions. Heating of Ba2Gd1.94Bi0.01Sm0.05Ge4O13 and Ba2Gd1.89Bi0.01Eu0.1Ge4O13 phosphors leads to an irregular decrease in the intensity of the main emission lines. It has been found that the fluorescence intensity ratio between a wide band in the 310-530 nm region and peaks at longer wavelengths may be successfully used as a temperature-dependent characteristic. Absolute/relative sensitivity values for Ba2Gd1.94Bi0.01Sm0.05Ge4O13 and Ba2Gd1.89Bi0.01Eu0.1Ge4O13 germanates reach 0.19% K-1/0.80% K-1 and 2.21% K-1/0.58% K-1, respectively. The above parameters indicate that Ba2Gd2Ge4O13:Bi3+/Sm3+ or Bi3+/Eu3+ samples can be used as potential luminescent materials for non-contact temperature measurement.

A comparative study by mechanical activation and conventional processes of BaTi0.95W0.05O3 ferroelectric ceramic

BaTi0.95W0.05O3 is synthesized by both mechanical activation process and conventional solid-state reaction technique for comparative study. The prepared sample is characterized by XRD and SEM. There is proper formation of perovskite structure in BTW from both of the methods confirmed by XRD. Scanning electron microscopy (SEM) depicts that the micro-grains obtained by the mechanical activation method had comparatively fine structure compared to that of the conventional solid-state process. The mechanically activated samples display enhanced electrical properties showing a high value of the dielectric constant and a low value of the dielectric loss. The remnant polarization (Pr) value and d33 values were also high in samples synthesized by the mechanical method.

Microwave Assisted Sintering of Sr-doped Zinc Titanate (Sr0.2Zn0.8TiO3) Nano-ceramics

Sr0.2Zn0.8TiO3 (SZT) ternary nanopowders of perovskite structure samples were prepared by conventional solid state reaction technique using ultra-pure metal oxide powders. SrCO3, ZnO and TiO2 powders were used as a source of Strontium, Zinc, and Titanium. The calcination temperature of the samples is 820 °C and sintered at different temperatures ranging from 850 °C to 1000 °C in conventional and microwave furnaces for 2 hours and 30 min., respectively. The synthesized nano-powders were characterized using XRD, SEM, XPS and their dielectric properties were studied by temperature dependent LCR meter. The dielectric constant increases with an increase in sintering temperature until 950 °C and it decreases with a further increase of frequency.

Multi-color tunable emission of Bi3+,Eu3+ co-doped Ca3LiZnV3O12 phosphors for warm white light-emitting diodes

Bi3+,Eu3+ co-doped Ca3LiZnV3O12 (CLZV) phosphors were manufactured by conventional high-temperature solid-state reaction technique to explore their application for solid-state lighting. Their crystal structure, luminescent properties, energy transfer processes and quantum efficiency were investigated in detailed. CLZV host can be efficiently excited by 345 nm near-ultraviolet light and exhibit self-activating blue emission. When Bi3+ ions are introduced into CLZV, VO43− and Bi3+ can be co-excited by 345 nm light. Benefiting from energy transfer from VO43− to Eu3+ and Bi3+ to Eu3+, multi-color tuning emission from green to yellow can be observed in CLZV:Bi3+,Eu3+ phosphors. Warm white emission was achieved in CLZV:0.015Bi3+,0.01Eu3+ and CLZV:0.015Bi3+,0.02Eu3+ phosphors. Importantly, their internal quantum efficiencies are 35.2 % and 39.6 %, respectively. Our results indicate that CLZV: Bi3+,Eu3+ phosphors might be promising candidates for white light emitting diodes under ultraviolet excitation.

Investigation of conventional exchange bias in (Nd1-xHox)2CoMnO6 (x = 0.0–0.4) double perovskite

In this article, we have investigated the characteristics related to structure, magnetism and exchange bias behavior in single phased polycrystalline samples of (Nd1-xHox)2CoMnO6 (x = 0.0–0.4) (NHCMO) series. The samples were prepared using the conventional solid state reaction technique and they crystalize in monoclinic structure with P21/n space group. The x = 0.0 sample shows the ferromagnetic transitions at TC1 = 139K and TC2 = 170K. These values decrease to 136K and 160K respectively for x = 0.1 sample. However, for other Ho substituted samples we observed only one transition. For x = 0.2, TC is 129K which decreases to 118K for x = 0.4 sample. The ferromagnetic super exchange interaction that arises within the network of Co2+ and Mn4+ ions bridged by O2− ions is the reason of occurring of these transitions. The presence of anti-site defects with antiferromagnetic interactions and subsequent formation of anti-phase boundaries within the system cannot be ignored. To gain a deeper insight into the underlying magnetic interactions, the M − T plots, under both the ZFC and FC conditions, were measured by applying different external magnetic fields. Saturation magnetization (MS) value of 3.68 μB/f.u. is observed in parent sample. The MS value increases to 7.22 μB/f.u. for x = 0.4 sample. Such mixed magnetic ground state of the samples motivates us to perform the exchange bias field measurement revealing an exchange bias field of 725Oe is found for x = 0.0 sample at 5K.

Compositional induced structural phase transitions in (1 − x)(K0.5Na0.5)NbO3–x(Ba0.5Sr0.5)TiO3 ferroelectric solid solutions

Ferroelectric materials exhibiting switchable and spontaneous polarization have strong potential to be utilized in various novel electronic devices. Solid solutions of different perovskite structures induce the coexistence of various phases and enhance the physical functionalities around the phase coexistence region. The construction of phase diagrams is important as they describe the material properties, which are linked to the underpinning physics determining the system. Here we present the phase diagram of (K0.5Na0.5NbO3)–(Ba0.5Sr0.5TiO3) (KNN-BST) system as a function of composition and their associated physical properties. Lead-free (1 − x)KNN–xBST (0 ≤ x ≤ 0.3) solid solution ceramics were synthesized by conventional solid-state reaction technique. The X-ray diffraction and Raman spectroscopic studies indicate composition-dependent structural phase transitions from an orthorhombic phase for x = 0 to orthorhombic + tetragonal dual-phase (for 0.025 ≤ x ≤ 0.15), then a tetragonal + cubic dual-phase (x = 0.2) and finally a cubic single phase for x ≥ 0.25 at room temperature (RT). Among these, the orthorhombic + tetragonal dual-phase system shows an enhanced value of the dielectric constant at room temperature. The phase transition temperatures, orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), decrease with the increase in BST concentrations. The ferroelectric studies show a decrease of both 2Pr and EC values with a rise in BST concentration and x = 0.025 showed a maximum piezoelectric coefficient.

Influence of Zn-substitution on structural, magnetic, dielectric, and electric properties of Li–Ni–Cu ferrites

The polycrystalline Li0.15Ni0.6-xZnxCu0.1Fe2.15O4 ferrites are fabricated by the method of conventional solid-state reaction technique. The X-ray diffraction (XRD) confirms that the structure of the composition is a single-phase cubic spinel structure for all samples. The particle size of the compositions is varied from 36 to 52 nm. The lattice parameter and densities are found to increase with enhancing Zn content, as the ionic radius and atomic weight of Zn are greater than Ni. The porosity exhibits a decreasing trend. The average grain size determined using Field Emission Scanning Microscopy (FESEM) increases until x = 0.40, then declines. The Energy-Dispersive Spectroscopy (EDS) examination revealed that the percentage of obtained elements is well matched with the stoichiometric elements. The addition of Zn content acts as an accelerator for enhancing the value of the real part of initial permeability and the highest value is obtained (μiʹ = 276) for the x = 0.40 sample, as well as the highest relative quality factor (RQF) of around 3000. The loss factor for the Zn substituted composition is nine times lower than for the parent composition. The optimum saturation magnetization of around 77.49 emu/g is found for the x = 0.40 sample. The maximum dielectric constant (εʹ = 2.85 × 103) is found for x = 0.10 samples at 10 kHz. Further, from impedance studies, the non-Debye type dielectric relaxation is seen for the Zn-substituted samples. The observed region of the imaginary electric modulus peak signifies the transition of charge carrier mobility from a larger range to a short-range distance. The phenomenon of ac conductivity is attributed to the process of the small polaron hopping mechanism.

Impedance spectroscopic study of temperature and frequency dependent conduction behaviour of xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 , x = 0.50, 0.55, 0.70, 0.85 ceramic

Here, we report on structural, impedance, modulus and conductivity analyses of xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 (x = 0.50, 0.55, 0.70 and 0.85) polycrystalline ceramic prepared using conventional solid state reaction technique. The X-ray diffraction (XRD) pattern for all the synthesised polycrystalline samples confirmed the formation of pure perovskite phase. A slight variation in the lattice parameters were observed with varying concentration of x in BCZT ceramic. Composition dependence of average crystalline size and lattice strain of the synthesised samples were evaluated by Williamson-Hall plot. The samples near the Morphotropic phase boundary (MPB) were much strained with large crystallite size. The impedance spectroscopic study was done to evaluate the conduction behaviour of the BCZT samples with varying concentration of x in wide temperature and frequency range. All the samples were found to exhibit Negative temperature coefficient of resistance suggestive semiconducting nature of the synthesised samples. A comparative detail conduction behaviour with grain and grain boundary contribution is presented and discussed in detail.

Porous pyroelectric material for waste heat harvesting

The utilization of pyroelectric materials to harvest waste heat from the ambient environment has gained much interest. However, pyroelectric energy harvesting technology still faces the challenge of low output voltage. In this paper, a porous pyroelectric ceramic with 0.3 wt.% poly(methyl methacrylate) (PMMA) as the additive was prepared via a conventional solid-state reaction technique. Our experimental results indicated that the porous PMN–PMS–PZT:0.3PMMA ceramic had a decrease in both relative permittivity and volume heat capacity at a temperature of 44ˆ∘C, compared to that of the dense sample. Additionally, the porous ceramic demonstrated an enhanced voltage responsivity from 0.50 to 0.52 m2/C and a higher figure of merit from 0.64 to 0.65 nm3/J for energy harvesting, compared to the dense sample. When 0.3 wt.% PMMA was added, the voltage generated by the device increased by 17.01% due to the presence of pores, which suggests a potential application in the field of waste heat harvesting and sensing.

Structure, photoluminescence, Judd-Ofelt analysis, and thermal stability studies of Eu3+-doped Ba2Tb8(SiO4)6O2 red phosphor with high color purity

In this study, a series of Eu3+-doped Ba2Tb8(SiO4)6O2 red-emitting phosphors were developed by using a conventional solid-state reaction technique. The crystalline structure, surface morphology, photoluminescence properties, energy transfer processes, and thermal behavior of the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors were studied. The X-ray diffraction patterns confirmed the formation of the phase, and the Rietveld refinement study revealed that the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors have a hexagonal crystal structure with the space group P63/m. Energy-dispersive X-ray analysis confirmed the homogenous distribution of Eu3+ ions over the Tb3+ sites. Photoluminescence (PL) spectroscopy was used to test the luminescent properties of the synthesized phosphors. The PL spectra showed that upon UV and blue light exposure, the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors exhibited red emission associated with the 5D0→7FJ transitions. The mechanisms of concentration quenching and energy transfer were analyzed using Blasse and Dexter's formula. Judd-Ofelt parameters (Ω2, Ω4) and other radiative parameters were analyzed using PL emission spectra to investigate the luminescence behavior of Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors. The results of the thermal stability studies show that Eu3+-doped Ba2Tb8(SiO4)6O2 has good thermal properties with a high activation energy of approximately 0.23 eV. The calculated Commission International del'Eclairage coordinates (x = 0.62 and y = 0.36) of the prepared phosphors confirm that the emitted light is in the red portion with a high color purity of about 99.9%. These findings show that Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors are a viable option for solid-state lighting technology.

Phase transition and thermodynamic properties of CaV2O6 at high temperature

CaV2O6 is widely utilized in optoelectronic materials, dielectric ceramics, magnetic candidates, and catalytic materials due to its unique physical and chemical properties. CaV2O6 was synthesized by a conventional solid-state reaction technique in this study. The CaV2O6 crystallizes in a monoclinic system belonging to space group C2/m, with the lattice parameters of a = 10.06 Å, b = 3.675 Å, c = 7.039 Å, and β = 104.843°. The congruent melting of CaV2O6 was detected at 1045 K by performing DSC. Enthalpy increments of CaV2O6 were experimentally measured for temperatures ranging from 573 K to 1023 K employing drop calorimetry for the first time. The temperature dependence of the molar heat capacity of CaV2O6 was then calculated on the basis of the enthalpy increments results. Thermodynamic properties (enthalpy change, entropy, and Gibbs free energy) were also calculated in the temperature range of 300–1000 K.

High electric field-induced strain properties in La-doped Pb(In1/2Nb1/2)O3–PbZrO3–PbTiO3 relaxor ferroelectric ceramics

Piezoelectric ceramics with high strain response and low hysteresis are highly in demand for high-performance actuator applications. Unfortunately, the trade-off relationship between large field-induced strain and low hysteresis in piezoelectric ceramics is a key challenge for designing high-performance piezoelectric actuators. Herein, ymol%La-doped 0.10 Pb(In1/2Nb1/2)O3-xPbZrO3-(0.90–x)PbTiO3 [0.10PIN-xPZ-(0.90-x)PT: ymol%La] ternary relaxor ferroelectric ceramics were prepared by conventional solid-state reaction technique. Pb(In1/2Nb1/2)O3 (PIN) as a relaxor end member was introduced into (Pb,La) (Zr,Ti)O3 (PLZT) system to improve relaxor characteristics and strain properties. A giant strain of 0.23% was obtained in 0.10PIN-0.59PZ-0.31 PT: 8mol%La ceramic at the electric field of 20 kV/cm, with a high piezoelectric d33* of 1150 pm/V and low hysteresis Hy of 6.4%, exhibiting a potential application in high-performance piezoelectric actuators. Furthermore, the effects of La ion doping and components on the ferroelectric, dielectric and electric field-induced strain properties were investigated, and provides a new way for improve the strain properties of piezoelectric materials.

Investigation of structure, thermal and dielectric study of Dy0.05Ba0.7Sr0.25TiO3/polystyrene nanocomposites

In the present study, Dy0.05Ba0.7Sr0.25TiO3 (Dy-BST) nanoparticles were prepared using the conventional solid-state reaction technique. Different volume fractions of Dy-BST (0, 5, 10, 15 & 20) were immersed in the polystyrene (PS) matrix, forming PS/Dy-BST nanocomposites, then their crystal structure, morphology, topography, thermal properties, electrical properties, breakdown voltage, and energy storage were investigated. X-ray diffraction (XRD) validates the cubic phase of Dy-BST nanoparticles incorporated in PS/Dy-BST nanocomposites. The size of Dy-BST nanoparticles was in the range (8–18 nm) using HRTEM. Incorporating Dy-BST NPs into the polymer matrix improved the thermal stability and limited the thermal degradation of the nanocomposite. The loading of Dy-BST in PS has a positive effect on dielectric properties and breakdown strength. The permittivity (ε′) enhanced from 2 to 10 at a constant frequency of 105 Hz while a relatively high loss (tanδ) decreased from 0.0015 to 0.0011 with the increase of Dy-BST content in the PS matrix. Finally, dielectric strengths of PS/Dy-BST nanocomposites were evaluated using high voltage testing; then their corresponding energy densities were obtained. The energy density increased to 133% at a 10 vol.% loading of Dy-BST compared to pure polystyrene.

Structural, dielectric, and morphological properties of (1-x)Ba0.65Sr0.35TiO3-xBi(Mg2/3Nb1/3)O3

Compared to other electrical energy storage devices, dielectric capacitors provide advantages like high power density, fast charge and discharge times, thermal stability, excellent mechanical strength, and a long cycling lifetime. Amongst the various dielectric materials, relaxor ferroelectric materials offer low remanent polarization and high energy efficiency. Previous research has shown that (i) doping Bi3+ ions into perovskite material can achieve improved results because its valence electronic configuration is close to that of Pb2+ and its ionic radius is also comparable to that of Ba2+, and (ii) introducing complex ions at the B-site can reduce the long-range ferroelectric order and result in the occurrence of polar nano regions.The present work aims at (i) incorporating both these strategies for the synthesis of the dielectric ceramic material and (ii) studying the structural, morphological, and dielectric properties of the prepared material. We have successfully synthesized (1-x) Ba0.65Sr0.35TiO3 – x BiMg2/3Nb1/3O3 with the help of a conventional solid-state reaction technique. The XRD analysis demonstrates the formation of cubic perovskite structure with space group Pm3m. The diffraction peaks shift towards lower 2θ angles with an increasing concentration of BMN, indicating a regular increase in unit cell volumes owing to the substitution of the smaller Ti4+ ions with bigger Mg2+ and Nb5+ ions. FESEM images illustrate the development of a homogeneous and dense microstructure. Element mapping analysis confirms the uniform distribution of all the elements within the prepared sample. From the dielectric measurements, we found that with the increase in doping, the dielectric peak broadens, and the frequency dispersion increases, indicating a rise in the relaxor behavior, which may be attributed to the increase in cation disorder due to the substitution of Bi3+ and [Mg2/3Nb1/3]4+ at the A- and B-site, respectively. The excellent dielectric properties indicate that (1-x)BST-xBMN is a promising ceramic material for use as a dielectric in capacitors for advanced pulsed power applications and consumer electronic devices.