R3c Phase Research Articles

Tuning ferroelectric domains and polarization properties of flexible BiFeO3 thin films by phase transition engineering

In the present investigation, thin films of flexible (Bi1-xSmx)(Fe0.95Mn0.05)O3 (denoted as BSFM0, BSFM4, BSFM8, and BSFM12 for x=0 %, 4 %, 8 %, and 12 %, respectively) were synthesized on metallic Ni-Cr substrates via the sol-gel technique. A comprehensive examination was conducted to elucidate the influence of varying concentrations of Sm3+ substitution on the phase constitution, oxygen vacancy concentration, and leakage behavior of the (Bi1-xSmx)(Fe0.95Mn0.05)O3 films. Utilizing X-ray diffraction (XRD) and Raman spectrometry, it was ascertained that all films exhibited a composite structure comprising orthorhombic (Pnma) and rhombohedral (R3c) phases. An augmentation in Sm3+ doping led to a non-monotonic variation in the R3c phase content, initially increasing and subsequently decreasing, while the nonpolar Pnma phase demonstrated a progressive enhancement. The distorted R3c phase was found to promote the flipping of the domain architecture, thereby augmenting the polarization attributes. Notably, at a Sm doping level of 4 %, the maximum polarization (Pmax) attained was 95 μC/cm2, with a remnant polarization (Pr) of 78 μC/cm2. The incorporation of a judicious amount of Sm was observed to curtail film leakage and decelerate the aging phenomenon. The compositional stability of this doping level was evaluated across a frequency spectrum of 0.1–12 kHz and a temperature gradient of 25–200 °C, revealing no propensity for degradation under conditions of polarization, a holding duration of 104 s, or fatigue scenarios involving a curvature of 5 mm and 108 switching cycles subjected to 103 instances of bending. These findings provide innovative insights for the development of next-generation lead-free transducer apparatus and flexible information storage mediums.

Broad temperature range with stable permittivity and low dielectric loss in (1–2x)Na0.5Bi0.5TiO3-xNaNbO3-xGdFeO3 system

High-temperature capacitors have garnered increasing attention in current research due to the inability of commercially available capacitors to meet the evolving industry demands. In this study, a Na0.5Bi0.5TiO3 based ternary system, denoted as [(1–2x)(Na0.5Bi0.5TiO3) -x(NaNbO3) -x(GdFeO3): x=0.01–0.09], was synthesised through solid-state reaction route. The influence of NaNbO3 and GdFeO3 on phase structure, dielectric, and ferroelectric properties are investigated. A fall of polar R3c phase % from X-ray refinement studies, diminishing macroscopic polarization, increasing breakdown strength, and flattening of temperature-dependent dielectric permittivity curves are perceived with the increase of substituent concentration. Temperature stable permittivity of (1–2x)(Na0.5Bi0.5TiO3) -x(NaNbO3) -x(GdFeO3) calculated ε'r/ε'r [250℃] at 1, 10, 100, 500 kHz with 10 % tolerance. Remarkably, (Δε′/ε′250°C ≤ ± 10 %) with x = 0.07 and 0.09 showed stable permittivity in the wide temperature range of (30°C to 600°C) at 500 kHz and a minimal dielectric loss (tan δ ≤ 0.01) measured at 250°C makes it a promising candidate for high-temperature dielectric capacitor applications.

Comprehensive investigation into the influence of oxygen vacancies on the ferroelectric properties of spin coated bismuth ferrite thin films

Bismuth ferrite (BFO) is a prime candidate for room-temperature magnetoelectric coupling and multiferroic applications. The rhombohedral R3c phase of BFO is the source of many properties, but the phase purity and oxygen vacancies are still the biggest obstacles to its real-world application. Considering these facts, the present work investigates the effects of oxygen vacancies on the functional properties through manipulation of drying temperatures of spin-cast films, especially at temperatures around 280 °C, where both the secondary phase and oxygen vacancies are prevalent. One of the biggest sources of oxygen vacancy is bismuth volatilisation, and our work deals with the situation head-on, uncovering the effect of bismuth volatilisation on functional properties. The structural properties were studied using x-ray diffraction (XRD), and deeper insights into the surface topography of the samples were obtained using AFM imaging. The electrical and dielectric characteristics help distinguish and analyse the samples in terms of the presence of resistive switching. PUND studies were performed to determine the ferroelectric properties of the samples. A fifty percent reduction in the oxygen vacancies in the presence of secondary phases was observed when compared with the phase-pure sample, as shown by the XPS analysis. Deeper insights were provided into the valence band spectra by first-principles studies. This work shows that phase purity may not be the singular condition for enhancing functional properties, and fine-tuning the presence of secondary phases and oxygen vacancies may be the way forward. The ferroelectric polarisation in one of the samples exhibits a notably higher value when using chemical solution deposition methods, making it a promising candidate for memory devices.

Effect of different ionic valence state doping on the structure and characteristic of BiFeO3‐BaTiO3‐based ceramics

AbstractBiFeO3‐BaTiO3‐based ceramics are promising multiferroic materials for a wide range of applications. In this paper, the effects of different ionic valence state((Ga0.5Ta0.5)4+, Ta5+) doping on the structure and properties of 0.73BiFeO3‐0.27BaTi1‐y(Ga1‐xTax)yO3 ceramics were investigated. X‐ray diffraction analysis showed that all samples were determined by rhombohedral R3c phase and tetragonal P4mm phase. A frequency‐independent dielectric anomaly with obvious thermal hysteresis was detected in all samples, indicating the first‐order ferroelectric phase transition, and the Curie temperatures were all above 600°C. The ferroelectric analysis found that the doping of donor element Ta reduced the coercive field, with a slight decrease of remanent polarization, which can be attributed to the soft effect of Ta element. Meanwhile, the magnetic properties were enhanced for all samples, with a maximum in 15T (x = 1, y = .015) sample, where Mr = .13 emu/g. According to relevant analysis, high‐valence element substitution can enhance the magnetic properties and reduce the coercive field of BiFeO3, while low‐valence element substitution can reduce dielectric loss. This result points out a way for us to choose appropriate doping elements to improve the performance of BiFeO3 ceramics.

Elucidating the Mn-Doping Induced Phase Transition from Orthorhombic Pnma to Rhombohedral R3c in LaFeO3: Insights from Mössbauer Spectroscopy

LaFe1-xMnxO3 (0≤x≤0.9) samples were synthesized through the sol-gel method. According to X-ray diffraction (XRD) results, with the increase of Mn doping, the crystal structure of the sample changes from orthogonal Pnma structure to rhombohedral R3c structure, and a two-phase coexistence phenomenon exists within the range of 0.4≤x≤0.7. Using Mössbauer spectroscopy, the coexistence range of the two phases and the iron content in each phase were identified. At x=0.4, the Pnma phase contribution (91.1%) dominates, with only a slight R3c phase contribution (8.9%). As the amount of Mn doping gradually increases, the R3c phase becomes dominant at x=0.6 (74.6%), and the Pnma phase completely disappears at x=0.8. This work will provide an important perspective for future researchers studying similar phase coexistence systems.

Significantly enhancing piezoelectric temperature stability of BNT-based ceramics by constructing the successive ferroelectric-relaxor phase transition

Bi0.5Na0.5TiO3 (BNT)-based piezoceramics with the morphotropic phase boundary MPB are confronted with some critical challenges for practical applications, such as the low depolarization temperature Td, the poor thermal shock resistance and the high fluctuation of the real-time piezoelectric coefficient d33. Herein, an ingenious strategy that integrating quenching process and successive ferroelectric-relaxor phase transition is proposed to enhance piezoelectric temperature stability of BNT-based ceramics. The multilayer ceramic composites (0.93Bi0.5Na0.5TiO3-0.07BaTiO3/0.89Bi0.5Na0.5TiO3-0.11BaTiO3/0.85Bi0.5Na0.5TiO3-0.15BaTiO3-0.2 g/0.25 g/0.15 g-Q, abbreviated as BNT-7/11/15BT-0.2 g/0.25 g/0.15 g-Q, the Q refer the quenching process and the 0.2 g/0.25 g/0.15 g refers the mass of each layer) feature the relatively large d33 (130pC/N) and near the Curie point Td (244℃), which jumps out of the d33-Td trade-off boundary of BNT-based ceramics. Besides, the BNT-7/11/15BT-0.2 g/0.25 g/0.15 g-Q ceramic composite also shows the superior thermal shock resistance and decent temperature stability of real-time d33 over the temperature region from 25℃ to 235℃. Enhanced piezoelectric temperature stability should be attributed to the development of tetragonal P4mm and P4bm phase gradients caused by the successive ferroelectric-relaxor phase transition and the development of bamboo-shaped domain based on Ba2+ diffusion layer. In addition, the relatively large d33 stems from the coexistence of rhombohedral R3c phase and tetragonal P4bm and P4mm phases and the formation of lamellar domain. Therefore, this strategy provides a good design methodology for the practical application of BNT-based materials.

Quenching-driven advancements in functional properties of high-temperature lead-free Sc, Ga modified 0.67BiFeO3-0.33BaTiO3 relaxor ceramics

The processing method is one of the most important deciding factors in the fabrication of BiFeO3–BaTiO3 (BF-BT) based piezoceramics because of the Bi2O3 volatization. It significantly influences the functional properties, including the piezoelectric coefficients, dielectric properties, and microstructure. This study presents a significant advancement in the realm of high-temperature lead-free piezoelectric ceramics in terms of understanding effects of processing method on functional properties. In this light, a novel ceramic solid-solution, 0.67{Bi(Fe0.97Ga0.03)1-xScxO3}-0.33(BaTiO3) with x ≤ 0.07, incorporating Scandium (Sc) and Gallium (Ga) modifications, was meticulously designed and synthesized. Impact of two distinct sintering methods, namely air quenching (AQ) and closed sintering (CS) on the structure and properties of the developed materials are investigated. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analysis verified the formation of pure perovskite phases with successful incorporation of Sc and Ga into the 0.67BF-0.33BT lattice. The FTIR analysis revealed a sharp absorptive band in the 590-604 cm−1 range, corresponding to the signature of stretching and bending vibrations of (Ti/Fe)O6 octahedra. Rietveld structure refinement confirmed the coexistence of pseudocubic (Pm-3m) and rhombohedral (R3c) phases in AQ samples, with predominantly pseudocubic phase, while CS samples closely approximated the pseudocubic phase. The microstructure of the samples exhibits small average grain size distribution (<2 μm). Temperature-dependent dielectric measurements show strong frequency dispersion in the dielectric permittivity with broadened transition peaks. The ferroelectric studies reveal low Pr and Ec values. These observations suggest a ferroelectric relaxor-like behavior of the developed materials. Moreover, the permittivity peaks maxima (Tm) temperature corresponding to CS samples for 0.04<x < 0.07 is less than 390 °C at 10 Hz while it is above 400 °C for AQ samples. The results of our study reveal that AQ samples exhibit superior electrical and ferroelectric properties as compared to the CS samples. The AQ samples demonstrate improvements in Tm (>400 °C), d33(∼35 pC/N), Pr (∼4–11 μC/cm2), PS (∼8–21 μC/cm2), Ec (∼13–25 kV/cm) with reduced dielectric loss, and a better dielectric constant over a wide temperature range.

Control of physical properties in BiFeO3nanoparticles via Sm3+and Co2+ion doping.

Highly crystalline BiFeO3(BFO), Bi0.97Sm0.03FeO3(Sm-BFO) and BiFe0.97Co0.03O3(Co-BFO) nanoparticles (NPs) were utilized as potential magnetic hyperthermia agents at two different frequencies in the radiofrequency (RF) range, and the effect of Sm3+and Co2+ion doping on the physical properties of the material was examined. The thermal behaviour of the as-prepared powders disclosed that the crystallization temperature of the powders is affected by the incorporation of the dopants into the BFO lattice and the Curie transition temperature is decreased upon doping. Vibrational analysis confirmed the formation of the R3c phase in all compounds through the characteristic FT-IR absorbance bands assigned to O-Fe-O bending vibration and Fe-O stretching of the octahedral FeO6group in the perovskite, as well as through Raman spectroscopy. The shift of the Raman-active phonon modes in Sm-BFO and Co-BFO NPs indicated structural distortion of the BFO lattice, which resulted in increased local polarization and enhanced visible light absorption. The aqueous dispersion of Co-BFO NPs showed the highest magnetic hyperthermia performance at 30 mT/765 kHz, entering the therapeutic temperature window for cancer treatment, whereas the heating efficiency of all samples was increased with increasing frequency from 375 to 765 kHz, making our doped nanoparticles to be suitable candidates for potential biomedical applications.

Cation substitution and size confinement effects on structure, magnetism and magnetic hyperthermia of BiFeO3-based multiferroic nanoparticles and hydrogels

Highly crystalline BiFeO3 (BFO), Bi0.97Sm0.03FeO3 and BiFe0.97Co0.03O3 nanoparticles are synthesized via the chemical co-precipitation method after calcination at 600 °C in air for 2 h. The effect of cation substitution, Sm for Bi and Co for Fe, on the structural and magnetic properties of BFO nanoparticles is investigated, whereas their magnetically induced heating efficiency in radio frequency alternating magnetic fields is examined. X-ray diffraction indicates the formation of the R3c phase in all compounds, while the corresponding Rietveld refinement reveals a variation of the lattice parameters upon doping, suggesting structural distortion within the BFO lattice due to the ionic radii mismatch between doped and host elements. Transmission electron microscopy unveils smaller particle sizes for the doped nanoparticles, owing to the frustrated particle growth induced by the dopants, whose presence is verified by X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. The combined effect of cation substitution and size confinement results in the suppression of the spiral spin structure of BFO, leading to the significantly enhanced magnetic features of the doped nanoparticles at room temperature. For possible applications in the biomedical sector, we tested them as heating agents in magnetic hyperthermia. The dispersion of BiFe0.97Co0.03O3 nanoparticles in water at a concentration of 4 mg/mL could reach the therapeutic window of 41–45 °C for cancer treatment in 50 mT at 375 kHz, whereas the remarkable temperature increase of the BFO-based multiferroic hydrogels, under the same conditions, is auspicious for an effective local treatment at reduced toxicity.

Antiferroelectric-like BiFeO3-SrTiO3 based ceramics with high breakdown strength and energy-storage density

Herein, an outstanding excellent energy storage performance (ESP) (Wrec∼4.4 J/cm3; η∼72%; ΔP = 38.1 μC/cm2) was obtained in environmentally friendly 0.52BiFeO3-0.4SrTiO3-0.08NaNbO3 lead-free ceramic. First, the addition of NaNbO3 (NN) lead to composition and charge disorder of A- and B- sites, generating random electric field that induce the emergence of small-sized polar nano-regions (PNRs) to enhance ΔP (Pmax-Pr). Rietveld refinement analysis showed that introducing NN reduces the content of polar R3c phase from 81.8% to 24.4%, and the non-polar Pm3m phase increased. When x ≥ 0.08, the antiferroelectric-like double P-E loops were acquired due to field-induced phase transition, and further lower Pr and Ec were obtained. Then, the introduction of NN greatly improved the breakdown strength of BFO-STO ceramics. That is, enhances electrical homogeneity, increases energy gap (Eg) and refines grain size (from 1.05 to 0.75 µm). Through domain engineering, antiferroelectric-like design and other multi-factors to achieve the optimization of ESP, providing a feasible strategy for lead-free pulse energy storage capacitors. Additionally, the good temperature (20–120 °C) and frequency (1–100 Hz) stability acquired to less than 15% in favor of practical applications.

Revival of rhombohedral structure and complex magnetic response in (La,Cr) codoped BiFeO3

The polycrystalline ceramics of Bi0.83La0.17Fe1-xCrxO3 (BLFCO) have been synthesized by the solid-state reaction method to investigate the features of structural phase coexistence and complex magnetic response. The coexistence of the R3c rhombohedral and Pbam orthorhombic structures has been revealed by X-ray diffraction and Rietveld refinement. Selected-area Raman scattering spectra are used to further confirm a mixed phase state as both phonon vibrations of these phases are detectable. An unusual revival of the R3c phase is observed with increasing chromium concentration. The compound displays an intriguing weak magnetic response and some unique phenomena, such as the magnetic aging and field step-dependent hysteresis loop. The electric-field-controlled magnetism shows a complex behavior due to the interplay of the phase boundary ferromagnetism and structural phase transition.

Synergy of morphotropic phase boundary and internal bias fields to achieve high d33 and d33* simultaneously in lead-free BNT-based ceramics

It is difficult to obtain high d33 and d33* simultaneously in one piezoelectric ceramic system via a conventional method due to the conflicting structure–properties responding mechanism between the direct piezoelectric and converse piezoelectric effects. In this work, a synergistic approach of constructing morphotropic phase boundary and introducing the internal bias fields in (Bi0.5Na0.5)TiO3 ceramics is proposed through Sr2+ and Li+ doping for mitigating the conflict between d33 and d33*. By this strategy, both high d33 (197 pC/N) and d33* (1500 p.m./V) are realized in Srx(Bi1-xNa0.97-xLi0.03)0.5TiO3 when x = 0.24. The large d33 stems from rhombohedral and tetragonal (R3c and P4bm) phase coexistence. The internal bias field introduced by defect dipoles tends to counteract the effects of depolarization field, thus greatly aiding the external fields with higher actual excitation fields. The superposition of internal bias field, depolarization field and external fields yields strong asymmetry bipolar strain curves, thereby contributing to the large d33*. Thus, this work opens a new door for developing lead-free ceramics with excellent piezoelectric performance.

The pressure-induced crystal structure transformations in the high-pressure annealed Bi1− xTbxFeO3 compounds (x = 0.05, 0.1, and 0.3)

The substitution of Bi by rare-earth ions is one of the common approaches for improving the electrical, magnetic, and multiferroic properties of the most studied multiferroic material BiFeO3. In this work, Bi1−xTbxFeO3 compounds with x = 0.05, 0.1, and 0.3 were synthesized using a two-step process: standard solid-state synthesis and high-pressure annealing. The obtained samples were studied by means of x-ray diffraction at normal pressure and neutron powder diffraction at high pressure. It was shown that high-pressure annealing could increase the Tb solubility limit to 10 at. %. It is proposed that the maximum solubility limit is even higher and could be achieved with high-pressure annealing in bulk samples. The transition from the R3c phase to the Pnma phase for the compounds with x = 0.05, 0.1 occurs through a two-phase region and starts at P≈4.4 and 1.7 GPa, respectively. The Pnma phase is stable in the compound with x = 0.3 up to P≈3.2 GPa. The values of Fe magnetic moments decrease with an increase in the Tb concentration or with external pressure for the compounds with x=0.05,0.3 in one-phase regions. The results will help to optimize the synthesis of multiferroic materials with improved magnetoelectric coupling for use in technological applications.

Simultaneously enhanced piezoelectric response and depolarization temperature in BNT-7BT ceramics with simple composition via optimizing sintering temperature

For (Bi0.5Na0.5)TiO3-based ceramics, one of the obstacles limiting their actual application is the incompatibility of a large piezoelectric response d33 with a low depolarization temperature Td. In this work, a high d33 of 186 pC/N and a Td of 133 °C are achieved simultaneously in unmodified 0.93(Bi0.5Na0.5) TiO3–0.07BaTiO3 (BNT-7BT) ceramics only via optimizing sintering temperature. Structural and microstructural analyses show that grain size and relative content of P4bm and R3c phases in BNT-7BT ceramics can be regulated by tuning the sintering temperature (Tsinter = 1100 °C, 1120 °C, 1140 °C, 1160 °C, and 1180 °C). Thus, high sintering temperature is not only able to increase the grain size to promote the domains switching for higher the piezoelectric response, but also to enhance the ratio of R3c/P4bm phase so as to improve ferroelectric-relaxor transition temperature that defer the depolarization. Hence, the present work provides a simple and effective method for optimizing the piezoelectric properties of (Bi0.5Na0.5)TiO3-based ceramics.

Structural mechanisms of large piezoelectric responses in BiFeO3-PbTiO3 based solid-solution ceramics

Achieving large piezoelectric response and high Curie temperature, simultaneously, are of great demand but have been rarely achieved in BiFeO3-PbTiO3 (BF-PT) based morphotropic phase boundary (MPB) systems. In this work, in-situ synchrotron x-ray diffraction and transmission electron microscopy were carried out in BF-PT-0.19Ba(Zr,Ti)O3 high-temperature piezoceramic, a recently reported MPB composition with high piezoelectric coefficient, to elucidate the underlying structural mechanism. A field induced irreversible transition from tetragonal (T) P4mm phase to rhombohedral (R) R3c phase is identified although R and T phases are still coexisted after poling. This induces the significantly enhanced irreversible domain switching of both R and T phases and the reversible domain switching of R phase but only a slightly enhanced reversible switching of T phase of as compared with other BF-PT-x Ba(Zr,Ti)O3 MPB compositions, leading to the significant increase of lattice strain up to ∼0.15% but only a slightly increase of strain from extrinsic domain switching due to the strong coupling between lattice strain and domain switching in both R and T phases, although the strain contribution seems to be composition independent after the field induced irreversible phase transition. The present study demonstrates a new performance enhancement mechanism to design the high-performance BF-PT based high-temperature piezoelectric ceramics in terms of the different roles of R and T phases within MPB.

The Influence of BaTiO3 Content on the Energy Storage Properties of Bi0.5Na0.5TiO3-Bi(Mg2/3Nb1/3)O3 Lead-Free Ceramics

Na0.5Bi0.5TiO3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications due to their outstanding dielectric and ferroelectric properties derived from large polarization. However, the high coercive field and large remnant polarization are unfavorable for practical applications, and thus NBT-based ceramics with relaxation behavior via doping/forming solid solutions with other elements/components have been widely studied. In this work, BaTiO3 (BT) was introduced to the 0.94Na0.5Bi0.5TiO3-0.06Bi(Mg2/3Nb1/3)O3 system by a conventional solid-state reaction to form a homogeneous solid solution of 0.94[(1−x)Na0.5Bi0.51TiO3-xBaTiO3]-0.06Bi(Mg2/3Nb1/3)O3 (BNT-100xBT-BMN). As the BT content increased, the proportion of the rhombohedral R3c phase increased while that of the tetragonal P4bm phase decreased, leading to the maximum Pmax (38.29 μC/cm2) and Eb (80 kV/cm) obtained in BNT-7BT-BMN (x = 0.07) composition. Specifically, the optimal energy storage properties of Wrec ~ 1.02 J/cm3 and η ~ 62.91% under 80 kV/cm were obtained in BNT-7BT-BMN ceramics, along with good temperature stability up to 200 °C, which are promising factors for future pulse power 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.

Synchrotron X-ray powder diffraction under high pressures up to 33 MPa for mechanoresponsive materials.

Equipment for synchrotron X-ray diffraction at high pressures up to 33 MPa with an accuracy of ±0.1 MPa using a liquid as a pressure-transmitting medium has been developed. This equipment enables atomic-scale observation of the structural change of mechanoresponsive materials under applied pressures. The validity of the equipment is demonstrated by observation of the pressure dependence of the lattice parameters of copper. The observed bulk modulus of copper was found to be 139 (13) GPa which is a good agreement with the literature value. The developed equipment was subsequently applied to a repeatable mechanoluminescence material, Li0.12Na0.88NbO3:Pr3+. The bulk modulus and compressibility along the a and c axes were determined as 79 (9) GPa, 0.0048 (6) GPa-1 and 0.0030 (9) GPa-1, respectively, for the R3c phase. The advance of high-pressure X-ray diffraction will play an important role in understanding mechanoresponsive materials towards their atomic-scale design.

Room temperature magneto-dielectric coupling in the CaMnO3 modified NBT lead-free ceramics

The sol–gel prepared (1-x)Na0.5Bi0.5TiO3-(x) CaMnO3 (x = 0, 0.03, 0.06, 0.12) compositions show a Rhombohedral (R3c) phase up to x = 0.06 while a mixed rhombohedral (R3c) and orthorhombic (Pnma) phases for the x = 0.12. The lattice volume consistently decreased with an increase in the CaMnO3 content. The phase transition temperature (Tc) decreased with an increase in the CaMnO3 compositions. The room temperature dielectric constant increased, and loss decreased for the x = 0.03 composition due to a decrease in the oxygen vacancy and Bi loss confirmed by the valence state study (XPS). All the compositions show a variation of the room temperature dielectric property with an application of magnetic field confirming a magnetodielectric coupling. The x = 0.06 composition shows the highest negative magnetodielectric coupling constant (MD%) of 3.69 at 100 kHz at an applied field of 5 kG.

Effect of introducing Sr2+/Hf4+ on phase structures, bandgaps, and energy storage performance in Bi0.47Na0.47Ba0.06TiO3-based ferroelectric ceramic

Dielectric energy storage ceramic capacitors have garnered wide attraction in recent years due to their splendid integrated energy storage properties. However, difficulties in obtaining splendid integrated properties limit their industrial application. This work achieved splendid integrated energy storage properties by doping Sr2+/Hf4+ into the Bi0.47Na0.47Ba0.06TiO3 ceramics. The R3c and P4bm phases were simultaneously induced and the short-range ordered polar nanoregions were formed, thereby generating a large polarization D-value by maintaining the large maximum polarization of the Bi0.47Na0.47Ba0.06TiO3 ceramics and greatly reducing the remnant polarization. By increasing both the density of the grain boundaries and the difficulty of electrons leaping out of the valence band to the conduction band, the breakdown electric fields of the ceramics were greatly improved. Eventually, a high Wrec of 5.83 J/cm3, a moderate η of 83.67%, a stable frequency (Wrec ≈ 2.84 ± 2.1% J/cm3, η ≈ 80.7 ± 2.8%, 1–200 Hz), excellent temperature stability (Wrec ≈ 2.89 ± 1.4% J/cm3, η ≈ 83.7 ± 1.0%, 20–140 °C), and a fast discharge rate (8 μs) were simultaneously obtained in the 0.8Bi0.47Na0.47Ba0.06TiO3-0.2SrHfO3 relaxor ferroelectric ceramics. These results suggested that the co-doping of A/B sites could significantly improve the energy storage properties of the Bi0.47Na0.47Ba0.06TiO3 ceramics. Furthermore, the excellent integrated properties indicate that the 0.8Bi0.47Na0.47Ba0.06TiO3-0.2SrHfO3 ceramics are expected to meet the application requirements of dielectric capacitors under complex conditions in the future.