Bismuth Titanate Research Articles

Effect of gamma rays irradiation in the structure, optical, and electrical properties of samarium doped bismuth titanate ceramics

AbstractCeramics have enormous potential in several emerging technologies, including nuclear reactors. Materials with chemical inertness, high-temperature operation, and physical properties stability under applied radiation with high energy are all desired in this field of technology. Given these broad specifications, bismuth titanate ceramics may prove to be a valuable material. Regarding this task, the effect of gamma rays on the structural, optical, and ferroelectric properties of samarium-modified bismuth titanate ceramics was investigated. The Bi3.15Sm0.85Ti3O12(BSmT) compound was irradiated for 0, 50, 100, and 200 kGy using a60Co gamma source at a dose rate of 10 kGy h−1. The phase structure confirmed the orthorhombic, single-phase nature even after gamma irradiation. The results show that the unit cell volume decreases from 966.39 to 962.38 Å3with an increase in gamma dose from 0 to 200 kGy. The X-ray photoelectron spectroscopy study shows an irradiation-induced defect in the host matrix. The results show that the bandgap energy, dielectric constant, Curie temperatures, and remnant polarization slightly decreased with an increase in gamma irradiation. According to the findings of this study, the BSmT exhibits adequate stability against gamma irradiation, which offers tremendous promise in their utilization in nuclear reactor technology.

Water flow promoted charge separation in piezoelectric Bi4Ti3O12 for the enhanced photocatalytic degradation of antibiotic

Addressing the issue of antibiotic residues in the environment is key to improving the quality of aquatic environments and reducing human health risks. In this study, piezoelectric bismuth titanate (Bi4Ti3O12) nanosheets are synthesized and employed to conduct antibiotic degradation. The piezoelectric potential induced by the water flow shear force is utilized to facilitate charge separation and migration in the photocatalytic process and enhance the catalytic degradation of antibiotic wastewater. As a result, 85% of tetracycline hydrochloride (TC) is degraded within 90 min. The piezo-photocatalytic process exhibits a 2.4 times faster reaction rate and a 15% higher mineralization rate than photocatalysis. Different environmental factors are investigated for their effects on the catalytic activity in piezo-photocatalysis. In situ electrochemical measurement and photoluminescence (PL) spectroscopy under stress demonstrated that the piezoelectric potential shifted the energy band of Bi4Ti3O12 and promoted the charge migration and separation, which produce more active species that favor the efficient catalytic degradation. Finally, the intermediate products of the tetracycline hydrochloride degradation process are analyzed and possible degradation pathways are suggested. This study elucidates the degradation mechanism of Bi4Ti3O12 as a piezo-photocatalyst for antibiotic pollutants, and meticulously investigates the charge transfer mechanism of the catalyst material in response to micro-stress. Hence, it provides an efficient solution for organic wastewater treatment and can potentially provide theoretical support for the development and performance optimization of catalyst materials applied in natural environments.

Characterization of Bismuth Titanate by Line Profile Analysis

Bismuth Titanate (BIT), Bi4Ti3O12, was synthesized using the solid-state reaction process from the oxide mixture of Bi2O3CO3 and TiO2. The characterization analysis of the prepared sample was done by X-ray diffraction technique. The X-ray diffraction data revealed an orthorhombic perovskite phase that was clearly explained. The Scherrer method, modified W-H analysis, and the SSP studies were conducted to figure out the crystallite size and micro strain in Bi4Ti3O12. Morphological studies included SEM and TEM analysis. FTIR spectral investigation supports the M-O coordination of the synthesized Bi4Ti3O12 sample. The phase formation patterns of Bi4Ti3O12 determined by different methods are highly connected.

Synthesis and Evaluation of Properties of an Additive Based on Bismuth Titanates for Cement Systems.

The development of modern building materials science involves the process of designing innovative materials that exhibit unique characteristics, such as energy efficiency, environmental friendliness, self-healing ability, and photocatalytic properties. This can be achieved by modifying cement with nano- and fine-dispersed additives that can give the material new properties. Such additives include a number of compounds based on the TiO2-Bi2O3 system. These compounds have photocatalytic activity in the near-UV and visible range of the spectrum, which can serve to create photocatalytic concretes. Here, the purpose of this scientific study was to synthesize compounds based on the TiO2-Bi2O3 system using two methods in order to identify the most optimal variant for creating a composite material and determine its properties. Within the framework of this article, two methods of obtaining a photocatalytically active additive based on the TiO2-Bi2O3 system are considered: the solid-state and citrate-based methods. The photocatalytic, mechanical and structural properties of composites containing the synthesized additive are investigated. In this study, it was found that for the creation of photocatalytic concretes, it is advisable to use cement compositions with a bismuth titanate content of 3-10 wt.%. of the cement content, regardless of the method of obtaining the additive. However, the most optimal composition is one containing 5 wt.% of the synthesized additive. It is noted that compositions containing 5% by weight of bismuth titanate demonstrate photocatalytic activity and also show an increase in strength on the first day of hardening by 10% for the solid-state method and 16% for the citrate method.

Co-regulation of phase-domain structure in Bi0.5Na0.5TiO3- based ferroelectrics to optimize energy storage properties

Sodium bismuth titanate (BNT)-based dielectric capacitors with excellent energy storage performance play an important role in electronics industry. (Sr1.05Bi0.3)ScO3 (SBS) is introduced into 0.85Bi0.5Na0.5TiO3-0.15NaNbO3 (BNT-NN) to achieve co-regulation of phase and domain structure. With the introduction of SBS, the dominated pseudocubic phase accompanied by a small percentage of rhombohedral phase are tend to form, and thus induce nanodomain structure with high-density domain walls. Under the excitation of a bias voltage, the induced nanodomains are easier to switch and effectively reduce the residual polarization. Additionally, the homogeneous nanodomains with high-density domain walls will promote large negative built-in voltage which are favorable to rise of breakdown field strength, and thus, optimize the energy storage performance. The co-regulation of phase-domain structure provides an idea for designing ferroelectrics with good energy storage performance.

Low temperature sintering, structure and electrical properties of BiFeO3-BaTiO3 based piezoelectric ceramics using CuO-B2O3 composite sintering aids

Piezoelectric ceramics usually have high sintering temperature, which cannot meet the low-temperature co-firing requirements of ceramics and metal electrodes in production of micro devices. Here, we studied the effects of CuO-B2O3 binary composite sintering aids on the sintering behavior, phase composition, microstructure, and electrical properties of the bismuth ferrite-barium titanate (0.7BiFeO3-0.3BaTiO3, BFO-BT) based lead-free piezoelectric ceramics. We found that the CuO-B2O3 sintering aids can effectively lower the sintering temperature of the BFO-BT ceramics to 880 ℃, which is far below the melting point of metal electrodes. The BFO-BT based ceramics with 0.5 wt% sintering aids exhibited excellent dielectric, ferroelectric, and piezoelectric properties (εm = 83029, Pm = 38.4 μC/cm2, Pr = 33.8 μC/cm2, d33 = 119 pC/N) with high Curie temperature (TC = 460 ℃). Meanwhile, this ceramic possessed high depolarization temperature (Td) near 300 ℃, demonstrating a good temperature stability of piezoelectricity. This study provides a feasible solution to improve the compatibility of lead-free piezoelectric materials and low-melting point metal electrodes for fabrication of micro piezoelectric devices.

Structural and Electrical Transport Features of Bi4Ti2.9Zr0.1O12

This paper reports the structural, dielectric, and electrical properties of Zr (10%) substituted bismuth titanate with the chemical formula Bi4Ti2.9Zr0.1O12. The material possesses a distorted orthorhombic structure and space group of B2cb at room temperature. The Zr-substituted bismuth titanate has a high Curie temperature and good dielectric constant. In any case, the dielectric constant of the Zr doped ceramic is higher than that of pure bismuth titanate. The study of impedance properties revealed the relaxation process, negative temperature coefficient of resistance behavior, grain and grain boundary formation, and the space charge effect in the high-frequency region of the material. The AC conductivity study explained the activation of charge carriers and the associated hopping mechanisms. A smaller activation energy (Ea) is observed at the low temperatures than in the high-temperature range. The ferroelectric property is confirmed through the P ∼ E hysteresis loop of the material at room temperature.

Effect of sintering time on electrical, ferroelectric, and piezoelectric performances of microwave synthesized sodium bismuth titanate ceramics

Herein, we report the synthesis of sodium bismuth titanate (Na0.5Bi0.5TiO3/NBT), a lead-free ceramic prepared via a cost and time-effective microwave synthesis route. This work presents the investigation of microstructural, electrical, and optical characteristics of NBT ceramics. The formation of a single-phase NBT sample sintered for 30 and 40 min (denoted as NBT 30 and NBT 40) is confirmed by Rietveld refinement and Raman measurement. FTIR spectroscopy is used to characterize the single-phase nature and to confirm the presence of desired vibrational spectra in the perovskite structure. Tightly packed micron-sized grains are observed from the field emission scanning electron microscopy. Due to the A-site disorder present in the lattice, two diffuse types of dielectric anomalies are present in the temperature-dependent dielectric plot for both samples. The maximum dielectric constant values of 1475 and 1628 are found for NBT 30 and NBT 40 samples at the transition temperature. From temperature-dependent AC conductivity measurement, NBT 40 samples show a higher value of conductivity in comparison to NBT 30. The PE hysteresis loops confirm the ferroelectric character present in both samples. An improved piezoelectric coefficient is observed with increasing sintering time and is found to be 80 pCN−1 for NBT 40. The optical bandgap of materials is 3.03 and 3.1 eV for NBT 30 and NBT 40, respectively.

Structural Refinement, Dielectric and Electromechanical Properties of (1-x)NBT-xKBT Piezoceramics in the Morphotropic Phase Boundary Region

Lead-free ferroelectric materials of sodium-potassium bismuth titanate, (1-x)NBT-xKBT systems were synthesized by a hydrothermal process. In this way, the appropriate conditions for the hydrothermal synthesis of NBT and KBT (i.e., concentrations of synthetic precursors, solution pH and temperature) are given graphically. Ceramics of (1-x)NBT-xKBT with (x(mol.%) = 0; 12; 16; 20; 30 and 100) were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The rhombohedral-tetragonal morphotropic phase boundary (MPB) was confirmed to be in the region of 0.12 ≤ x ≤ 0.20 for (1-x)NBT-xKBT at ambient temperature. Scherrer's formula and the Williamson-Hall (W-H) analysis were used to examine the average crystallite size and lattice strain. Raman spectroscopy was effectively applied to study the structural evolution of the (1-x)NBT-xKBT phase. The ceramics exhibited a high temperature of maximum dielectric permittivity at (Tmax = 343 °C at 100 kHz) along with electromechanical coupling factors (kp = 0.34, d33 = 147 pC/N). Based on the composition of all specimens, the results indicate a diffuse phase transition, probably of second order, between ferroelectric and paraelectric phases.

Heterophase of Bismuth Titanate as a Photocatalyst for Rhodamine B Degradation

Various studies have been made to obtain high efficiency photocatalysts. Auvirillius bismuth titanate oxide is known to have good photocatalytic activity to degrade dyestuffs. However, recombination is still an obstacle to photocatalytic efficiency. To overcome recombination and increase photocatalytic activity, it is proposed to synthesize bismuth titanate heterophase. Heterophase can enhance the formation of the synergistic effect of electrons, which effectively stimulates the transfer of electrons from 1 phase to another. This study aims to determine the photocatalytic ability of bismuth titanate heterophase for degradation of a rhodamine B. Bismuth titanate was synthesized by hydrothermal method using Bi2O3 and TiO2 precursors. The results of X-ray diffraction characterization showed that the synthesized bismuth titanate formed 2 phases, namely Bi4Ti3O12 (78.2 %) and Bi12Ti0.9O19.8 (21.8 %). In addition, it is also known that the volume of the synthesized bismuth titanate crystal lattice has a smaller volume than the standard synthesized in previous studies. The photocatalytic ability of bismuth titanate evaluated using 10 mg/L rhodamine B showed that it took 240 min to degrade 98 % of dye. Reaction kinetics studies showed that bismuth titanate has a reaction rate constant efficiency of 120 % better than TiO2 for the Langmuir- Hinshelwood 1st-order kinetic model. Then the reuse ability was evaluated, showing that after 3 times of uses, bismuth titanate only decreased 5 %, whereas TiO2 decreased by 7 % in degradation. HIGHLIGHTS Bismuth titanate heterophase Bi4Ti3O12/Bi12Ti9O19.8 has been synthesized using precursors Bi2O3 and TiO2 by hydrothermal method. Bismuth titanate heterophase has better photocatalytic ability than TiO2 in degrading rhodamine B. The ability to reuse bismuth titanate heterophase showed that after 3 uses there was no significant decrease in activity. GRAPHICAL ABSTRACT

Synthesis and Oxygen Mobility of Bismuth Cerates and Titanates with Pyrochlore Structure

Synthesis and study of materials based on bismuth cerates and titanates were carried out. Complex oxides Bi1.6Y0.4Ti2O7 were synthesized by the citrate route; Bi2Ce2O7 and Bi1.6Y0.4Ce2O7—by the Pechini method. The structural characteristics of materials after conventional sintering at 500–1300 °C were studied. It is demonstrated that the formation of a pure pyrochlore phase, Bi1.6Y0.4Ti2O7, occurs after high-temperature calcination. Complex oxides Bi2Ce2O7 and Bi1.6Y0.4Ce2O7 have a pyrochlore structure formed at low temperatures. Yttrium doping of bismuth cerate lowers the formation temperature of the pyrochlore phase. As a result of calcination at high temperatures, the pyrochlore phase transforms into the CeO2-like fluorite phase enriched by bismuth oxide. The influence of radiation-thermal sintering (RTS) conditions using e-beams was studied as well. In this case, dense ceramics are formed even at sufficiently low temperatures and short processing times. The transport characteristics of the obtained materials were studied. It has been shown that bismuth cerates have high oxygen conductivity. Conclusions are drawn about the oxygen diffusion mechanism for these systems. The materials studied are promising for use as oxygen-conducting layers in composite membranes.

Photodegradation behaviour of sol–gel synthesized Bi4Ti3O12 for water pollution disinfection

Minimization of water consumption and effective recycling of water by choosing the appropriate water treatment technique in industry are the most essential in this modern era. Nowadays, the usage of sol–gel synthesized nanomaterial to study the photo degradation behavior of disinfected water pollution is a promising way. Phase purity analysis, reusability test, photoarate constant of photo-catalytic and rate constant of photolysis reaction were examined. X-ray diffraction (XRD) results confirm the formation of Bi4Ti3O12 (BTO) with an orthorhombic structure. The phase purity of the catalyst is also analyzed using the Jana2006 refinement. The FESEM image revealed a hexagonally structured particle with an indistinguishable grain boundary. The degradation behaviour of Rhodamine-B (RhB) in sunlight is investigated under the influence of BTO nanoparticles. The rate constant of the photo-catalytic and photolysis reaction is found to be 0.0198 and 0.0008. Degradation efficiencies are found to be 91.3% for RhB. Overall results revealed that the sol–gel synthesized bismuth titanium oxide (Bi4Ti3O12) is best choice for water pollution disinfection.

Studies of structural, dielectric and impedance characteristics of Gd modified Bi4Ti3O12 Aurivillius ceramic

The synthesis and characterization (structure, dielectric, electrical properties) of ceramic technology prepared gadolinium modified bismuth titanate of a composition Bi4-x GdxTi3O12 (x = 0, 0.1) have been reported in this paper. The development of a single-phase orthorhombic structure with a space group Aba2 has been confirmed by analysing room temperature X-rays diffraction (XRD) patterns. The plate-like microstructures of the samples are revealed by scanning electron microscope, which confirmed the layered perovskite structure of Bi4-x GdxTi3O12 (x = 0,0.1). The crystallite size (D) and strain (ε), calculated from the W–H (Williamson-Hall) plots, are found to be 64 nm, 0.001, respectively for BIT (bismuth titanate, Bi4Ti3O12) and 53 nm, 0.009, respectively for Gd modified BIT. Some obtained electrical parameters (dielectric constant, conductivity, electrical impedance, and modulus) of BIT and Gd modified BIT have provided useful data on the conduction mechanism, structure-properties relationship, etc. The Nyquist plots confirm the contribution of grain boundary and the bulk effect to the properties (physical) of the materials.

Regulating the Electronic Structure of Bismuth Nanosheets by Titanium Doping to Boost CO2 Electroreduction and Zn-CO2 Batteries.

The electrochemical carbon dioxide reduction reaction (E-CO2 RR) to formate is a promising strategy for mitigating greenhouse gas emissions and addressing the global energy crisis. Developing low-cost and environmentally friendly electrocatalysts with high selectivity and industrial current densities for formate production is an ideal but challenging goal in the field of electrocatalysis. Herein, novel titanium-doped bismuth nanosheets (TiBi NSs) with enhanced E-CO2 RR performance are synthesized through one-step electrochemical reduction of bismuth titanate (Bi4 Ti3 O12 ).We comprehensively evaluated TiBi NSs using in situ Raman spectra, finite element method, and density functional theory. The results indicate that the ultrathin nanosheet structure of TiBi NSs can accelerate mass transfer, while the electron-rich properties can accelerate the production of *CO2 - and enhance the adsorption strength of *OCHO intermediate. The TiBi NSs deliver a high formate Faradaic efficiency (FEformate ) of 96.3% and a formate production rate of 4032µmolh-1 cm-2 at -1.01V versus RHE. An ultra-high current density of -338.3mA cm-2 is achieved at -1.25versus RHE, and simultaneously FEformate still reaches more than 90%. Furthermore, the rechargeable Zn-CO2 battery using TiBi NSs as a cathode catalyst achieves a maximum power density of 1.05mW cm-2 and excellent charging/discharging stability of 27 h.

Bismuth ferrite-barium titanate system studies around morphotropic phase boundary

Nowadays, the electro-electronic industry and scientific community have a great interest in improving memory devices. A candidate is the bismuth ferrite owing to the coexistence of ferroelectricity and anti-ferromagnetism at room temperature, however, a high leakage current harms their ferroelectric properties. Thus, bismuth ferrite and barium titanate solutions improve the ferroelectric properties of bismuth ferrite and optimize the magnetoelectric coupling factor. This system is called multiferroic, materials exhibit the coexistence of ferromagnetic, ferroelectric, or ferro-elastic orders, which is of interest to the scientific physics community and electronic industry. In this paper, bismuth ferrite-barium titanate system around the morphotropic phase boundary was studied and analyzed. It was observed changes in the structural properties in function of barium titanate content. Calcination temperature was determined from thermogravimetric analysis curves to powders of bismuth ferrite-barium titanate system. Ceramic bodies were densified conventionally. Archimedes’ method was used for density measure. Ceramics with densities greater than 95% were obtained. 93% of the perovskite phase was obtained from structural results. Finally, structural properties were presented and analyzed using Mossbauer spectroscopy as complementary technique. These analyses are very important in solid state physics because to contribute to understanding the phenomenology and synthesis process of multiferroic materials.

Structural, optical, electrical, and dielectric relaxation properties of rare earth containing sodium bismuth titanate [formula omitted] perovskite: Effect of ionic radius

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE3+ (RE = La, Sm, Dy, and Ho) on structural and various physical properties of sodium bismuth titanate (Na0.5Bi0.5TiO3, NBT) based perovskite nanomaterials. The X-ray diffraction data indicate the successful formation of the rhombohedral phase (space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site. The lattice parameters were found to increase linearly with the ionic radius of the dopant cation. The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions. The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius. Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry. The UV–Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap, which unfolds the application of NBT-based perovskite as photoactive material. The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius, i.e., La-doped NBT compound, exhibits the highest dc and bulk conductivity with the lowest activation energy. The frequency-dependent dielectric data follows Havriliak–Negami (HN) formalism and non-Debye type relaxation phenomena. Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value. Thus, this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural, optical, and electrical properties.

Characterization of Bismuth Titanate by Line Profile Analysis

Bismuth Titanate (BIT), Bi4Ti3O12, was synthesized using the solid-state reaction process from the oxide mixture of Bi2O3CO3 and TiO2. The characterization analysis of the prepared sample was done by X-ray diffraction technique. The X-ray diffraction data revealed an orthorhombic perovskite phase that was clearly explained. The Scherrer method, modified W-H analysis, and the SSP studies were conducted to figure out the crystallite size and micro strain in Bi4Ti3O12. Morphological studies included SEM and TEM analysis. FTIR spectral investigation supports the M-O coordination of the synthesized Bi4Ti3O12 sample. The phase formation patterns of Bi4Ti3O12 determined by different methods are highly connected.

Synthesis and characterization of Bismuth titanate perovskite materials for hydrogen production

In this work, a simple, low-cost, precursor free and a single step synthetic technique has been used for synthesis of Bismuth titanate (BT) perovskite nanomaterials, under surfactant free conditions. The powdered X-ray diffraction method has been employed for confirmation of crystal structure and surface morphology of synthesized nanoparticles were confirmed by FESEM analysis. The nanoparticles showed the band gap of 3.25 eV, calculated with the help of Tauc plot by diffused reflectance spectroscopy (DRS-UV). The efficiency of nanoparticles to act as photocatalyst was assessed by hydrogen evolution reaction carried out by water splitting, utilizing a photochemical cell reactor having xenon lamp. The reaction was carried out in the presence of triethanolamine (TEOA) and methanol acting as scavengers. It was reported that maximum hydrogen yield 39.24 µmol/g was obtained with methanol.

Effect of Electrical Poling on the Structural, Dielectric, and Photoluminescence Properties of Eu<sup>3+</sup> Substituted Eco-Friendly Ferroelectric Material Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>

In this work, the effect of electric field on structural, photoluminescence, dielectric, and piezo/ferroelectric properties of 2.5 mole % Eu3+substituted sodium bismuth titanate (Na0.5Bi0.475Eu0.025TiO3 abbreviated as NBT-Eu) ferroelectric material has been investigated. Rietveld refinement on the X-ray diffraction patterns of poled and unpoled ceramics suggested lower monoclinic symmetry (Cc) with 93.64% as major phase fraction and higher orthorhombic symmetry (Pbnm) with 6.36% as minor phase fraction. For the poled composition, the monoclinic (Cc) phase fraction decreased to 83.53%, and the orthorhombic (Pbnm) phase fraction increased to 16.47%. Improved ferroelectric and piezoelectric characteristics in comparison to pure NBT were found in Eu3+ substituted NBT. Moreover, the substitution with Eu3+ enabled observation of photoluminescence (PL) emission in the visible region under an excitation wavelength of 532 nm for electrically poled and unpoled ceramics, thereby enabling additional functionality for this material along with ferroelectric and dielectric properties. Intensities of PL emissions were tuned by the application of electric poling of the ceramic, which generates the possibility of using these materials in optoelectronics device applications.

A combined powder x-ray and neutron diffraction studies on (1-x) NaNbO3-x Na0.50Bi0.50TiO3 solid solution

Solid solution of sodium niobate and sodium bismuth titanate [(1-x)NaNbO3-x(Na0.5Bi0.5)TiO3: xNBT)] is an important lead-free eco-friendly piezo-ceramic material. In the present work, we report an investigation of the phase stabilities of this solid solution using powder x-ray and neutron diffraction techniques for the entire range of composition. We observed the disappearance of certain peaks and changes in the main perovskite peaks in the powder diffraction data suggesting structural phase transitions with composition. Rietveld analysis of combined x-ray and neutron powder diffraction data is performed to obtain single correct structural model wherever possible. Detailed analyses of powder diffraction data for composition range 0.0 ≤ x ​< ​0.15 revealed the coexistence of orthorhombic (Pbma) and (Pmc21) phases and an orthorhombic phase with space group Pbnm and cell dimensions √2ap ​× ​√2 bp ​× ​6 cp gets stabilized for 0.15 ≤ x ​< ​0.20. On further increasing NBT content in NaNbO3 matrix (0.20 ≤ x ​< ​0.60), a mixed orthorhombic (Pbnm) phase and tetragonal (P4bm) phase is confirmed by Rietveld refinement. Further, in the composition range 0.60 ≤ x ​≤ ​0.80, the tetragonal (P4bm) phase coexists with the ferroelectric rhombohedral (R3c) phase and finally for composition x ​> ​0.80, it completely transforms to rhombohedral (R3c) phase. The presence of phase coexistence in various composition ranges indicates the first order nature of these phase transitions. A detailed structural phase diagram of the system is presented at ambient conditions.