Strontium Bismuth Niobate Research Articles

Synthesis, characterization, and dielectric properties of Y-doped strontium bismuth niobate (SrBi2−xYxNb2O9) ceramics: a lead-free ferroelectric alternative with enhanced performance

Synthesis, characterization, and dielectric properties of Y-doped strontium bismuth niobate (SrBi2−xYxNb2O9) ceramics: a lead-free ferroelectric alternative with enhanced performance

Effect of annealing temperature and thickness on the structural and optical properties of strontium bismuth niobate films

Strontium Bismuth Niobate (SBN) thin films were prepared by metal organic decomposition method. The effects of post deposition annealing temperature (500–900 °C) and thickness (200–650 nm) on the structural and optical properties have been discussed. X-ray diffraction studies indicate the formation of single phase structure at annealing temperature of 800°C. The crystallinity of the samples improved with the increase in film thickness (200–500 nm), however, structural changes were observed beyond film thickness 500 nm. The changes in surface morphology of the films have been discussed as a function of annealing temperature and thickness. Although well-defined Raman spectra were obtained at higher annealing temperature (≥700 °C) for low thickness film, low frequency Raman modes were observed for higher thickness film (≥500 nm). The optical transmittance of the film decreases with increase in thickness from 200 to 650 nm. The energy band gap and refractive index have been estimated as a function of annealing temperature and film thickness. The band gap values decreased from 4.38 to 3.88 eV with the increase in film thickness. The correlation between structural and optical properties has been done in order to optimize annealing temperature and film thickness at 800 °C/ 500 nm.

Study of relaxor behaviour of rare-earth-doped strontium bismuth niobate doped with europium, gadolinium and neodymium

Study of relaxor behaviour of rare-earth-doped strontium bismuth niobate doped with europium, gadolinium and neodymium

Conduction mechanism in excess Bismuth doped Strontium Bismuth Niobate ceramics

Strontium Bismuth Niobate ceramics with excess Bismuth doping (0%wt – 20%wt) were prepared using solid state reaction method. X-ray diffraction studies reveal the decrease in c-axis orientation as bismuth content increases up to 5 ​wt%, beyond that it increases. The dielectric studies were carried out at room temperature as well as at higher temperatures. The ferroelectric properties were found to improve with excess bismuth doping to some extent (5%), indicating compensation for bismuth losses during heat treatment. Temperature dependent dc conductivity studies were done and attempts were made to explain extrinsic and intrinsic conduction mechanisms in Strontium Bismuth Niobate. In low temperature region, the activation energy was found to be very low (0.08eV–0.16eV), which increases (1.07eV–1.14eV) due to introduction of intrinsic defects. A detailed conduction mechanism is presented with excess bismuth doping in Strontium Bismuth Niobate.

Structural, Mechanical and Magnetic Characterization of Rare Earth Double Doped SrBi2Nb2O9 lead Free Ceramics

Lead free dielectric materials of Strontium Bismuth Niobate SrBi2Nb2O9 (SBN) and rare earth double doped SrBi1.8Pr0.1Gd0.1Nb2O9 (SBPGN), SrBi1.8Pr0.1Y0.1Nb2O9 (SBPYN), SrBi1.8Eu0.1Gd0.1Nb2O9 (SBEGN) and SrBi1.8Eu0.1Y0.1Nb2O9 (SBEYN) were prepared by two-stage solid-state reaction route. The XRD studies have confirmed the formation of single-phase orthorhombic crystal structure. The microstructural analysis showed the formation of plausible needle shaped grains in the prepared ceramics. The FTIR study was used to investigate the effect of preparation and doping processes on the band intensities of the spectra. Mechanical studies showed that SBEGN and SBEYN ceramics exhibited mild wear (<10−6 mm3 Nm−1) compared to others. The low friction coefficient values of SBPYN (0.044), SBEGN (0.058) and SBEYN (0.002) to that of SBN necessitate lattice strain in these materials. The VSM studies on the rare earth double doped SBN ceramic materials confirmed the induction and existence of magnetic order in SBPGN and SBEGN.

Structural, Ferroelectric, Dielectric and Piezoelectric Studies of Yttrium Substituted SrBi2Nb2O9 Lead-free Relaxor Ceramics

Ferroelectric ceramic compositions SrBi2–xYxNb2O9 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) were prepared via conventional solid-state route with high density (92-99%) establishing the sintering conditions. X-ray diffraction studies confirmed the orthorhombic structure. The micrographs obtained from scanning electron microscopy showed the presence of well packed and randomly oriented needle-shaped grains with an average grain size of 1.624 μm. FTIR and Raman studies on these samples indicated the growth of single phase perovskite material. From the dielectric studies, the phase transition temperature (T c) of strontium bismuth niobate (SBN) was found to be 430oC, whereas the Tc of yttrium substituted SBN (SBYN) was found to decrease from 400° to 370°C. The transition was diffuse and frequency dependent which is a characteristic behavior of relaxor material. The diffuseness parameter (γ) was computed for all the compositions. P-E loop measurements showed a decrease in the parameters P s, P r and E c in yttrium substituted SBN compared to SBN. Piezoelectric studies in SBN and SBYN estimated k p, d 33, g 33 and Qm values. Cole-Cole plots were obtained from studies on SBN and SBYN at different temperatures in the frequency range 50 Hz to 1 MHz. The activation energy values were computed.

Microwave derived porosity in tin-doped Sr1-xSnxBi1.95La0.05Nb2O9nano materials for non-Debye conduction and photocatalytic activity

Microwave synthesized strontium bismuth niobate Sr1-xSnxBi1.95La0.05Nb2O9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn2+) and layer bismuth (Bi3+) generate optimal lattice strain. Lattice oxygen, that is critical in photocatalytic applications, is observed to fold along a-c plane on introducing tin. SSBLN compositions possess higher porosity with reduced dimensions. Porosity derived capacitive boundaries promote polaronic hopping in SSBLN materials over diffused ionic conduction. The visible spectrum photocatalytic response is better after doping tin in SSBLN compositions. Mesoporous network and electron-hole pair generation play crucial role in augmented photocatalytic behaviour of SSBLN materials.

Study of structural and mechanical aspects of Praseodymium and Europium doped SrBi2Nb2O9 ceramics

Abstract Bismuth Layer Structured Ferroelectrics (BLSFs) have prominent technological applications as electronic materials. Strontium Bismuth Niobate (SBN) ceramics doped of rare earth elements SrBi2−xRxNb2O9 (R = Pr, Eu and x = 0.0, 0.2) have been synthesized by solid state reaction method between corresponding oxides and carbonate. The prepared ceramic samples are analysed by X-Ray Diffraction (XRD) technique to conform the formation of single phase layered perovskite. Further, XRD studies at room temperature revealed orthorhombic structure with lattice parameters a = 5.5023 A, b = 5.5083 A and c = 25.0985 A for SBN. Scanning Electron Microscopy (SEM) envisage a slight change in the morphology of the doped samples compared to SBN. Energy Dispersive X-ray Spectroscopy (EDAX) confirms the elements making of the samples being analysed. Fourier Transform Infrared (FTIR) spectra showed a significant shift in the band position for doped samples in comparison with SBN. The density and volume of the studied ceramic samples has been identified varying with rare earth element doping in SBN. The Vickers hardness of the samples is measured under a load of 500 g with dwell time of 20 s using Vickers hardness tester for the first time.

Synthesis, DC conductivity and Dielectric studies on double doped Strontium Bismuth Niobate Ceramics

The Strontium Bismuth Niobate SrBi2Nb2O9 (SBN), K0.025Sr0.95Gd0.025Bi2Nb2O9 (KSGBN1) and K0.05Sr0.9Gd0.05Bi2Nb2O9 (KSGBN2) ceramics were prepared by two stage solid state reaction method. Crystal structure of sintered samples was studied by powder X - ray diffraction technique. XRD patterns well matched with reported data (ICSD #82280).The lattice parameters of the samples were calculated using POWD Software. Pellets of 10mm diameter and thickness about 1mm∼2mm were prepared and final sintered in the temperature range 900°C ∼950°C for four hours. The surface morphology of the samples was studied from Scanning electron Microscope pictures. The Temperature dependence of DC conductivity and dielectric properties were obtained and analyzed. Conclusions arrived at are presented.

Role of higher valent substituent on the dielectric and optical properties of Sr0.8Bi2.2Nb2O9 ceramics

Abstract The synthesis, structure, optical and dielectric properties of strontium deficient bismuth excess strontium bismuth niobate Sr0.8Bi2.2Nb2O9 (SBNex) ceramics were systematically studied with tungsten and molybdenum as a doping element. The ceramics were prepared with a two-step solid-state method with ∼ 98 % of relative density. The XRD spectrum established that the orthorhombic crystal structure of the Aurivillius oxides was formed and doped with 2.5 at. % of W and Mo resulted in a near phase transition to the tetragonal phase. The energy dispersive X-ray spectra confirmed the formation of the desired compound of strontium deficient bismuth excess SBNex ceramic. The W doped SBNex ceramics exhibited the maximum value of dielectric constant ∼ 270 at the lower frequencies. The dielectric study suggested that the relaxation mechanism be of Debye model with free from any space polarization. The complex modulus plots presented to establish the dielectric relaxation at higher frequency side of the spectra. The band-gap energy (Eg) decreased with Mo and W doping, being 3.00 and 2.85 eV respectively. The enhanced dielectric properties in W and Mo doped SBNex ceramics entitled them for the application to produce high density RAM.

Phase evolution of strontium bismuth niobate ceramics by conventional solid-state reaction method

In the present study, formation of single-phase Strontium Bismuth Niobate (SBN) composition is investigated and the phase evolution is understood by studying the reaction mechanism between the raw materials and their combinations. The ceramics compositions were prepared using conventional solid-state reaction method. TG/DTA studies of all the constituents of SBN and the combination of its components have been carried out. X ray diffraction studies reveal the evolution of different phases among the raw powders thermally treated in different temperature ranges. FTIR studies reveal how different phases evolve as a function of calcination temperature. In the present study, an attempt is made to understand the effect of thermal treatment on the reaction mechanism for the formation of single-phase SBN.

Influence of lone pair on structural and electrical properties of Sb substituted Bismuth layered SrBi2Nb2O9 ceramics

Antimony (Sb) substituted Strontium Bismuth Niobate ceramics with chemical formula SrBi2-xSbx Nb2O9 (SBSN) have been prepared through conventional solid state reaction method with varying Sb content in the range (x = 0.0 to 0.5). Limited solubility of Sb content in SBN ceramics were revealed through X-ray diffraction studies which indicates secondary phases of Sb2O3 in prepared ceramics for Sb content x > 0.2. Formation of single phase with orthorhombic structure were confirmed for compositions having x = 0.0 to 0.2. Increase in c-axis of lattice crystal are analyzed and correlated to the ionic structure and existence of lone pair in Sb. Dielectric properties of all SBSN ceramics compositions are studied as a function of temperature over the frequency range of 100 Hz–1 MHz. Increase in Sb incorporation shows insignificant shift in Ferroelectric to Paraelectric Phase transition Temperature in SBSN ceramics. Sb substitution results in the increase in ferroelectricity (2Pr = 15.4 μC/cm2) and poiezoelectric coefficient (d33 = 20 pC/N) for composition having x = 0.1 in SBSN ceramic. Sb substitution results in increase of piezoelectric coefficients (d33) whereas piezoelectric charge coefficient values for composition SrSb0.1Bi1.9Nb2O9 was found to be comparable to that of PZT at room temperature. Existence of lone pair of electron in Antimony were correlated with high piezoelectric coefficient in SBSN ceramics.

Co-precipitation-hydrothermal preparation of SrBi2Nb2O9

Strontium Bismuth Niobate (SrBi2Nb2O9) was synthesized by co-precipitation-hydrothermal method. Precipitation step was first carried out at room temperature at which the powder was prepared from aqueous solution of Bi(NO3)3, Sr(NO3)2 and Nb2O5. Then the process is completed by hydrothermal treatment. The compound crystallized in the orthorhombic structure. The characteristic bands, at approximately 619cm−1 and 816cm−1 were observed. The grain size is around 1µm. The dielectric properties at room temperature show low loss values at higher frequencies which makes it suitable for ferroelectric random access memory applications.

Synthesis and Dielectric Properties of Nanocrystalline Strontium Bismuth Niobate.

Herein, we report the synthesis, characterization and dielectric properties of nanocrystalline ferroelectric ceramic of strontium bismuth niobate (SrBi₂Nb₂O₉; SBN). The material was prepared by simple sol–gel combustion route using strontium nitrate, bismuth nitrate pentahydrate and niobium oxide in presence of sucrose. During synthesis, the sucrose played dual role, i.e., as the gelling agent and combustion fuel. The prepared material was characterized in detail using several techniques such as differential thermal analysis and thermogravimetric (DTA-TG), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscope (SEM). These techniques were utilized to describe the thermal stability, crystal structure, crystallite size and morphologies of the prepared material. Further, the dielectric properties of the prepared SBN sample were investigated at various frequencies and temperatures.

Effect of Microwave Sintering on Electrical Properties of Sr-deficient and Bi-rich Strontium Bismuth Niobate (Sr0.8Bi2.2Nb2O9) Ferroelectric Ceramic

Nonstoichiometric strontium bismuth niobate (Sr0.8Bi2.2Nb2O9: SBN) ceramic was prepared using conventional solid-state reaction and microwave sintering methods. Complex impedance spectroscopy (CIS) has been used to investigate the intra and intergranular contribution to the impedance SBN ceramics as a function of temperature and frequency. Complex impedance Cole‑Cole plots were used to interpret the relaxation mechanism in SBN ceramic which showed a non-Debye relaxation. The grain and grain boundary contribution to conductivity have been estimated from the Cole‑Cole plots. The bulk (grain) resistance of both samples was found to decrease with rise in temperature indicating negative temperature coefficient of resistance (NTCR) type behavior like that of semiconductors. The microwave sintered SBN was found to have low value of bulk resistance indicating more increase in conductivity as compared to conventionally sintered SBN. The temperature dependence of the relaxation time was found to obey the Arrhenius law. Studies of electrical modulus show the presence of hoping conduction mechanism in SBN.

Microwave-assisted sintering of non-stoichiometric strontium bismuth niobate ceramic: Structural and dielectric properties

In recent years the microwave sintering has been utilized for the synthesis of materials in enhancement of the properties. In this paper strontium bismuth niobate (Sr0.8Bi2.2Nb2O9:SBN) bulk ceramic has been synthesized by microwave reactive sintering and conventional heating techniques. A relative density of 99.6% has been achieved for microwave sintered SBN, which is higher than that of (98.81%) conventionally sintered SBN. The phase formation of SBN synthesized by both processes has been confirmed by X-ray diffraction (XRD). The surface morphology of SBN was observed by scanning electron microscopy (SEM). The microstructure was found to be more uniform in case of SBN sintered by microwave sintering. The dielectric properties of SBN were studied as a function of frequency in the temperature range of 30–500°C. Both the samples synthesized by two different processes were found to follow Curie–Weiss law above the transition temperature. The Curie temperature was found to be higher for microwave sintered SBN. The dielectric constant and the transition temperature were observed to be higher for SBN ceramic synthesized by microwave sintering technique. The ac and dc activation energy values were also found to be higher for microwave sintered SBN as compared to conventional sintering technique.

Preparation and electrical properties of SrBi2−x Sm x Nb2O9 lead-free piezoelectric ceramics

Sm-doped strontium bismuth niobate SrBi2−x Sm x Nb2O9 (0 ≤ x ≤ 0.10) ceramics were prepared by a conventional solid-state reaction method. The X-ray diffraction study showed that the ceramics possess a pure structure and no secondary phase can be detected. The scanning electron microscopy indicates that the grains of all the samples are all well-defined. The dielectric, ferroelectric and piezoelectric properties of the SBSN-x ceramics were investigated and found that the optimum electrical properties can be obtained at x = 0.03, which are as follows: 2P r = 14 μC cm−2, d 33 = 19 pC/N, T c = 435 °C. In addition, after annealing at 400 °C, the piezoelectric constant (d 33) of this component ceramic sample remains 18 pC/N, so it has good temperature stability for high temperature applications.

Enhanced up-conversion photoluminescence and dielectric properties of Er- and Zr-codoped strontium bismuth niobate ceramics

Er- and Zr-codoped strontium bismuth niobate ceramics, Sr0.97Er0.03Bi2Nb2−xZrxO9 (SBNx) with different x (0≤x≤0.1), were synthesized by the solid state reaction method. Their structural, up-conversion (UC) photoluminescence, and dielectric properties were investigated. By Rietveld structural refinement, all SBNx samples exhibited a polycrystalline bismuth-layered perovskite structure with space group A21am. With deliberate introduction of Zr4+ ions in the bismuth-layered perovskite structure, SBNx samples presented simultaneously enhanced UC photoluminescence and dielectric properties. The UC photoluminescence was investigated as a function of Zr4+ concentration and incident pump power. Under the 980nm near infrared (NIR) excitation, bright UC green and weak red emissions were observed which corresponded to the transitions from 2H11/2/4S3/2 and 4F9/2 to 4I15/2 level, respectively. With x increase, the UC luminescence improvement of SBNx can be attributed to the local distortion of crystal field surrounding the Er3+ activator which induced by different ionic radii of Zr4+ and Nb5+ ions. The dependence of UC emission intensity on pumping power showed that two photon energy transfer process was involved in the UC green and red emissions. Furthermore, electrical measurements indicated that the introduction of Zr4+ distinctly increased the ferroelectric to paraelectric phase transition temperature (TC) of SBNx ceramics from 724K to 762K as x ranging from 0.0 to 0.1. It is believed that B site doping in SBNx by large Zr4+ ion is an effective method to improve UC luminescence and electrical properties of this potentially multifunctional optical-electro material.

Structural, dielectric and piezoelectric properties of SrBi2Nb2O9 and Sr0.8Bi2.2Nb2O9 ceramics

Lead free polycrystalline materials SrBi2Nb2O9 and Sr0.8Bi2.2Nb2O9 were synthesized by conventional solid-state reaction process. X-ray diffraction studies confirm the single phase compound in the orthorhombic crystal system. Raman spectroscopy was used to understand the lattice vibrational characteristics of sintered pellets for SrBi2Nb2O9 and Sr0.8Bi2.2Nb2O9 ceramics. The morphology was observed by scanning electron microscopy. The Sr-deficient and Bi-excess SBN (deficient Strontium bismuth niobate: Sr0.8Bi2.2Nb2O9) was found to have better density and least porosity. The dielectric and electrical response of SBN ceramics have been studied in the frequency range of 20Hz–1MHz and in the temperature range 30–500°C. The transition temperature (Tc) was found to gradually increase from 401°C for SrBi2Nb2O9 (SBN1A) to 440°C for Sr0.8Bi2.2Nb2O9 (SBN2A). The ac conductivity (σac) of both samples SBN1A and SBN2A was found to follow the universal Joncher׳s power law. The piezoelectric coefficient (d33) 20pC/N has been achieved for Sr deficient and Bi excess SBN.

Synthesis and Dielectric Characterization of Barium Substituted Strontium Bismuth Niobate Layered Perovskite Oxides

The strontium bismuth niobate, SrBi 2Nb2O9 (SBN) is a bismuth layered perovskite oxide compound with potentially useful ferroelectric properties which offer several advantages suchas fatigue free, lead free, low operating voltages , relatively high Curie temperature; and most importantly, their ferroelectric properties are independent of film thickness.These materials are also important forFe-RAM applications having large remanent polarization and low coercivity accomp anied by high Curie temperature for better performance and reliable operation.Present paper describes synthesis, dielectric properties and impedance studies to reveal the important properties of barium substituted str ontium bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).