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To design novel materials suitable for high-temperature electromechanical applications, a bismuth-based ternary solid solution system, (1- x - y)BiScO 3 - y Pb(Sc 1/2 Nb 1/2)O 3 - x PbTiO 3 , with compositions situated around the morphotropic phase boundary, were designed and synthesized in the form of ceramic. The crystal structure, microstructure, dielectric, ferroelectric and piezoelectric properties, and the local polar domain structure of the ceramics were investigated in detail. The examined ceramics exhibit large grain sizes ranging from 20 μm to 45 μm, along with noteworthy characteristics, including a relatively large strain of 0.21 %, a high large-signal piezoelectric coefficient (d 33 * = 368 pm/V), a low dielectric loss (tanδ = 1.7 %), and a high Curie temperature (T C ∼ 423 °C). These enhanced properties signify the suitability of the designed ternary ceramics for future high-temperature electromechanical applications. This work demonstrates an effective approach for designing ferro-/piezoelectric materials characterized by substantial strain and low dielectric loss. [ABSTRACT FROM AUTHOR]

Morphotropic phase boundary of ferroelectric solid solutions attracts interest with respect to not only improved piezoelectric properties but also the electrocaloric effect, which is attractive to build new-generation cooling devices. In the present study, the electrocaloric effect in (1 − x − y)Na0.5Bi0.5TiO3–xBaTiO3–yNaNbO3 near its morphotropic phase boundary is studied by direct measurements of temperature change ΔT. ΔT maximum is observed in the region of depolarization temperature, where the major contribution comes from an entropy jump at the electric field-induced phase transition. Differences between ΔT values measured when an electric field pulse is applied and removed are explained by slow domain rearrangement in the ferroelectric phase and metastability of phases close to the depolarization temperature. Among studied compositions, the highest value of ΔT is obtained for the compositions 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 and 0.93Na0.5Bi0.5TiO3–0.06BaTiO3–0.01NaNbO3 in the region of depolarization temperature. Examples of the comparison of the directly measured values of ΔT and the values calculated using the Maxwell relation revealing inconsistency between the two methods in the ferroelectric and the nonferroelectric phase are presented. [ABSTRACT FROM AUTHOR]

X-ray diffraction and dielectric studies were performed on synthesized ceramic samples of the section (1–x) (0.8PbMg 1 ∕ 3 Nb 2 ∕ 3 O 3 ⋅ 0. 2 BiScO3)⋅ x(0.8PbTiO 3 ⋅ 0. 2 BiScO3) with x = 0 –1 of the ternary BiScO3–PbTiO3–PbMg 1 ∕ 3 Nb 2 ∕ 3 O3 (BS–PT–PMN) system, including the temperature dependence of thermally stimulated depolarization currents (TSDC). It was found that the samples are solid solutions with a perovskite structure, which have cubic symmetry in the range of x = 0–0.587 and tetragonal symmetry in the range of x = 0.680–1. In the intermediate composition range of x = 0.587–0.680 (morphotropic region — MR), the samples consist of a mixture of solid solutions of different symmetries. Data on the change in dielectric properties and TSDC(T) dependencies of solid solutions with a change in their composition were obtained. It was found that samples of compositions x =0–0.625 and 0.6875–1 exhibit relaxor-ferroelectric and conventional ferroelectric properties, respectively, while samples of compositions x = 0.625–0.6875 combine ferroelectric and relaxor-ferroelectric properties. [ABSTRACT FROM AUTHOR]

As the two typical basic binary solid solutions of the relaxor-PbTiO3 family, Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) has been widely investigated, whereas Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) has not. Here, 1.5 mol% Sm-doped (1 − x)Pb(Ni1/3Nb2/3)O3–xPbTiO3, (1 − x)PNN–xPT:0.015Sm with x = 0.33–0.39, ceramics have been prepared and the chemical composition-induced evolution of crystal structure, domain, and electrical properties investigated systematically. With increasing PT content, evolution of the rhombohedral–tetragonal structure was observed. A rhombohedral–tetragonal morphotropic phase boundary occurred around x = 0.36–0.37, which showed a peak piezoelectric property with piezoelectric constant d33 = 531 pC N−1 and planar electromechanical coupling factor kp = 0.37 at room temperature. At the same time, the x = 0.36 composition showed improved ferroelectric behavior with remanent polarization Pr = 13.4 μC cm−2 and coercive field Ec = 3.2 kV cm−1. Interestingly, different from its PMN-PT counterpart, there is no temperature-driven phase transition between room temperature and the Curie temperature for (1 − x)PNN–xPT:0.015Sm. These parameters indicated that the PNN-PT system is worthy of more attention and is a promising platform for further development of high-performance piezo/ferroelectric materials. [ABSTRACT FROM AUTHOR]

As the two typical basic binary solid solutions of the relaxor-PbTiO3 family, Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) has been widely investigated, whereas Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) has not. Here, 1.5 mol% Sm-doped (1 − x)Pb(Ni1/3Nb2/3)O3–xPbTiO3, (1 − x)PNN–xPT:0.015Sm with x = 0.33–0.39, ceramics have been prepared and the chemical composition-induced evolution of crystal structure, domain, and electrical properties investigated systematically. With increasing PT content, evolution of the rhombohedral–tetragonal structure was observed. A rhombohedral–tetragonal morphotropic phase boundary occurred around x = 0.36–0.37, which showed a peak piezoelectric property with piezoelectric constant d33 = 531 pC N−1 and planar electromechanical coupling factor kp = 0.37 at room temperature. At the same time, the x = 0.36 composition showed improved ferroelectric behavior with remanent polarization Pr = 13.4 μC cm−2 and coercive field Ec = 3.2 kV cm−1. Interestingly, different from its PMN-PT counterpart, there is no temperature-driven phase transition between room temperature and the Curie temperature for (1 − x)PNN–xPT:0.015Sm. These parameters indicated that the PNN-PT system is worthy of more attention and is a promising platform for further development of high-performance piezo/ferroelectric materials. [ABSTRACT FROM AUTHOR]

An X-ray diffraction study of ceramic samples of the BiScO3–PbTiO3–PbMg⅓Nb⅔O3 system with compositions close to the morphotropic phase boundary was carried out at room temperature. The existence of wide areas of solid solutions has been established. The symmetry of the PbTiO3-based solid solutions is tetragonal (space group P4mm). The symmetry of the PbMg⅓Nb⅔O3-based solid solutions is cubic (space group Pm3‾m). Near the BiScO3 side, the solid solutions are rhombohedral (space group R3m). During the morphotropic phase transition from the cubic solid solutions to the tetragonal ones, additional phases appear. If a tetragonal phase prevails ((1 − 2x)BiScO3–xPbTiO3–xPbMg⅓Nb⅔O3x = 0.46; (1 − 2x)BiScO3–1.1xPbTiO3–0.9xPbMg⅓Nb⅔O3x = 0.45 and 0.42), a satisfactory model is a model with a minority cubic phase (space group Pm3‾m). If a cubic phase prevails ((1 − 2x)BiScO3–1.1xPbTiO3–0.9xPbMg⅓Nb⅔O3x = 0.39 and 0.36; (1 − 2x)BiScO3–0.8xPbTiO3–1.2xPbMg⅓Nb⅔O3x = 0.4), a model with a minority monoclinic phase (space group Cm) or with two minority phases: tetragonal (space group P4mm) and monoclinic (space group Cm) is satisfactory. [ABSTRACT FROM AUTHOR]

Ferroelectric Pb 5 Nb 10 O 30 (PN) tetragonal tungsten bronze (TTB) forms solid solutions that exhibit morphotropic phase boundaries (MPBs). Successful replacement of PN with TTBs containing Bi could advance lead-free TTB MPBs. The most studied Bi containing TTB, K 4 Bi 2 Nb 10 O 30 , was recently demonstrated to be paraelectric, and we have systematically explored the possibility to increase the Bi-content beyond two Bi3+ ions per unit cell aiming to induce ferroelectricity. Higher Bi content was incorporated by either increasing the cation vacancy concentration on the A-site or by B-site substitution with lower valency cations. An additional pyrochlore phase was found in almost all the explored compositions exceeding two Bi3+ per unit cell. The instability of the TTB structure with higher Bi3+ concentrations was investigated in terms of first-principles calculations, combined with chemical considerations and including the tolerance factor. Consequently, an in-plane polarisation found in PN is unlikely to exist in Bi-based TTBs, meaning that Bi3+ cannot fully replace Pb2+ in ferroelectric TTBs. [ABSTRACT FROM AUTHOR]

A strategy is developed to enhance the energy storage properties of lead-free Bi 0.5 Na 0.5 TiO 3 -based solid solutions, which is implemented through coupling the lattice instability in 0.94(Bi 0.5 Na 0.5)TiO 3 -0.06BaTiO 3 (0.94BNT-0.06BT) ferroelectric with a composition at its morphotropic phase boundary with the chemical disorder in (Bi 0.2 Na 0.2 K 0.2 La 0.2 Sr 0.2)TiO 3 (BNKLST) high-entropy ceramic (HEC). The addition of BNKLST in 0.94BNT-0.06BT could suppress the relaxor behaviors in the resulting solid solutions (1-x)(0.94BNT-0.06BT)-xBNKLST. With increasing content x, BNKLST may triggers more polar nano-regions which are in ergodic states at elevated temperatures. As a result, the thermal stability for energy storage properties is increased. In particular, the solid solution with x = 0.3 not only possesses large dielectric constants but also has a low content of oxygen vacancies, beneficial to its dielectric properties; It exhibits an excellent recoverable energy storage density of 2.24 J/cm3 under an electric field of 140 kV/cm, and a good thermal stability at 50 kV/cm with energy storage efficiency η >80 % up to 200 °C. The results demonstrate that the synergy effect of lattice instability and chemical disorder in the solid solutions is effective in enhancing energy storage properties of HECs, facilitating the design and optimization of dielectric energy storage devices. [ABSTRACT FROM AUTHOR]

Multiferroic (BiFeO3)1−x-(PbTiO3)x (1−x)BF−xPT thin films exhibit very high electromechanical properties in the vicinity of the morphotropic phase boundary (MPB), making them important candidates for use in several modern device applications. However, preparing high-quality (1−x)BF−xPT thin films is challenging due to the high conductivity caused by oxygen vacancies produced during the synthesis process. This study aims to understand the effect of size and porosity density on the electrical properties of (1−x)BF−xPT thin films. A series of (1−x)BF−xPT solid solution thin films were fabricated using the spin-coating method on Pt/TiO2/SiO2/Si(100) substrates through chemical solution deposition. X-ray diffraction studies revealed a polycrystalline structure. Surface SEM images showed that the films have a uniform surface with average grain sizes ranging between 50 and 200 nm and an average film thickness of 1.5 μm. A decrease in average pore size and an increase in the number of pores were observed with the increase in PT concentration in the prepared films. Ferroelectric characterization revealed that the films exhibit room-temperature ferroelectric hysteresis loops. Sources of various contributions to polarization were extracted from hysteresis loops, including true ferroelectric switching and space charge contributions. Thin films with 0.30 < x < 0.45 show higher remanent and saturation polarization values, suggesting that these compositions exhibit the MPB. The highest remanent polarization value (PR = 16.68 μC/cm2) was observed for the thin film with x = 0.40. The correlation between the phase, composition, film morphology, and ferroelectric response is described and discussed. [ABSTRACT FROM AUTHOR]

Temperature–field phase diagrams in the [001]c and [011]c directions in the cubic coordinate in 24%Pb(In1/2Nb1/2)O3–46%Pb(Mg1/3Nb2/3)O3–30%PbTiO3 (24PIN–46PMN–30PT) and 31PIN–43PMN–26PT near the morphotropic phase boundary have been clarified by measuring the temperature dependences of permittivity under an electric field. Field-induced intermediate orthorhombic and tetragonal phases have been newly found in 24PIN–46PMN–30PT and 31PIN–43PMN–26PT, respectively. The temperature dependences of the remanent polarization have also been determined by polarization–electric field (P–E) hysteresis loop evaluation. On the basis of our experimental results, the phase transition and dielectric anisotropy in PIN–PMN–PT have been discussed. [ABSTRACT FROM AUTHOR]

We report the structural, piezoelectric, multiferroic and magnetoelectric (ME) properties of the ternary 0.65BiFeO3–0.35[(1 − x)Bi0.5K0.5TiO3 − xBaTiO3] (0.0 ≤ x ≤ 1.0) (BF–BKT–BT) solid solutions. These samples show a rhombohedral to pseudo-cubic structure transition in the vicinity of x ~ 0.4, i.e., the morphotropic phase boundary (MPB), where the maximum piezoelectric coefficient d33 occurs. In addition, maximum electric-field (E) induced strain is also observed for x ~ 0.4 near the MPB. All the samples show good ferroelectricity and basically antiferromagnets at room temperature. The room-temperature E control of magnetization, i.e., converse ME effect, increases with increasing x, reaches a maximum near x = 0.6, and decreases again with x ≥ 0.8. In-situ X-ray diffraction studies at different applied E demonstrate an important role of E-induced variation in the phase fraction, Fe–O bond length and Fe–O–Fe bond angle in the converse ME effect. These results reveal a possible effective route to obtain multi-functional devices with both good piezoelectricity and ME effect in the BF–BKT–BT based systems. [ABSTRACT FROM AUTHOR]

Origins of the unipolar strain, strain hysteresis, and remnant strain of Mn-modified BF-BT ceramics near the pseudo-cubic and rhombohedral (PC-R) phase boundary, before and after poling treatments, were investigated by high-energy synchrotron X-ray diffraction. The largest unipolar strain of BF-BT ceramics was found to occur at the composition with a single pseudo-cubic phase, rather than the phase boundary composition, owing to the synergetic contributions from the reversible phase transition of PC-R phase, non-180° domain switching, and lattice distortion. It is interesting to find that the phase boundary composition exhibits an irreversible PC-R phase transition, where its unipolar strain after poling is attributed to the lattice distortion. The lowest strain hysteresis and remnant strain were observed in BF-BT ceramics with rhombohedral phase, due to the fact that the reversible lattice distortion dominates the strain level. These new findings on BF-BT solid solutions are expected to provide new insights on the strain mechanisms of perovskite-structured ferroelectric materials. [ABSTRACT FROM AUTHOR]

High dielectric and piezoelectric properties of solid-solution ferroelectrics around a morphotropic phase boundary (MPB) have attracted considerable attention in the last 60 years. Previous studies on MPB generally focused on a phase boundary between two ferroelectric phases, attributing enhanced dielectric/piezoelectric response to both intrinsic and extrinsic contribution. However, contribution from interfacial effects among the regions with different ferroelectric phases has not been fully considered. Therefore, it is valuable to study dielectric/piezoelectric responses in a ferroelectric-paraelectric system, where interfaces among different polar states may have a strong influence on the averaged free energy profile. In this paper, the piezoelectric response of a ferroelectric-paraelectric nanocomposite, i.e., the xSrTiO3-(1−x)BaTiO3 system, is systematically studied. By phase-field simulations, domain evolution of the xST-(1−x)BT composite poled along the [001] and [011] axis is presented with respect to the applied electric field. The piezoelectric strain coefficient of the xSrTiO3-(1−x)BaTiO3 composites is found to first increase and then decrease with increasing the parameter x, which is similar to that observed in ferroelectric solid solutions with a MPB. Finally, the temperature-dependent piezoelectric responses of the composites are also simulated, where a compromise between the room-temperature piezoelectricity and the thermal stability is observed. This work may benefit the design of the ferroelectric-paraelectric composite. [ABSTRACT FROM AUTHOR]

To analyze the effect of PFN content on the microstructure and electrical properties of x Pb(Fe 0.5 Nb 0.5)O 3 –(0.57− x)Pb(Ni 1/3 Nb 2/3)O 3 –0.43Pb(Zr 0.3 Ti 0.7)O 3 , the doping of x PFN–PNN–PZT) were systematically studied with 0.015 ≤ x ≤ 0.075. XRD patterns and Raman spectra analysis reveal that PFN diffuses into PNN–PZT perovskite lattice and forms new quaternary solid solution. With the increase of PFN content x , the proportion of rhombohedral (R) phase decreases gradually, whereas the proportion of tetragonal (T) phase displays a contrary trend. In particular, R – T coexistence near MPB was observed at x = 0.045. Meanwhile, optimized electrical properties of d 33 = 961 pC/N, k p = 0.716, ε r = 6298, and tan δ = 3.1% are achieved for the 0.045PFN–PNN–PZT ceramics. Moreover, the ceramics at MPB showed larger remnant polarization P r = 24.55 μC/cm2, smaller coercive field E c = 0.36 kV/mm, and lower dielectric relaxor degree γ = 1.813. All these results reveal that the enhanced electrical properties could be attributed to synergistic phase boundary motion, dielectric relaxor behavior and ferroelectric hysteresis effect. [ABSTRACT FROM AUTHOR]

The morphotropic phase boundary (MPB) region of the BFO-BTO solid solution is studied by comprehensive macroscopic and local methods, focusing on the synthesis conditions that influence the final phase composition and functional response. The difference between the phase distribution and local switching behavior in two sets of the BFO-BTO solid solutions prepared with different applied pressures is revealed and attributed to the local chemical inhomogeneity forming due to certain differences in the solid-state sintering reactions. More homogeneous mixing of the polar and non-polar phases stimulates the non-polar-to-polar phase transition and widening the MPB region. [ABSTRACT FROM AUTHOR]

The structural, electromechanical, and dielectric properties of (1 − x)(0.8Na0.5Bi0.5TiO3-0.2BaTiO3)-xCaTiO3 [(1 − x) (0.8NBT-0.2BT)-xCT] ceramics are studied as candidates for room temperature actuators with high field-induced strain. The choice of 0.8NBT-0.2BT as a starting composition is motivated by the large tetragonality in this concentration range, even though it is located far away from the morphotropic phase boundary. CaTiO3 was chosen as a third component to decrease the depolarization temperature and achieve a high field-induced strain at room temperature. The measured strains at the field-induced phase transition are remarkably lower than might be expected from the jump in unit cell parameters at the phase transition. This inconsistency could be related to an incomplete field-induced phase transition from the ferroelectric phase to the nonpolar phase. Among all of the manufactured samples, the phase transition is close to room temperature in the composition with x = 0.100, which allows obtaining unipolar strains up to 0.23% at E = 65 kV/cm. Electrostrictive-like strain was observed not only above the depolarization temperature but also in the region of field-induced phase transition. [ABSTRACT FROM AUTHOR]

To develop high‐performance piezo‐/ferroelectric materials, Bi(Zn½Ti½)O3–PbZrO3–PbTiO3 (BZT–PZ–PT) ternary solid solution with compositions around the morphotropic phase boundary (MPB) is synthesized by solid‐state reaction. The crystal structure and electric properties are investigated systematically by X‐ray powder diffraction (XRD), dielectric spectroscopy, and ferroelectric and piezoelectric measurements. On the basis of the results of the XRD, dielectric and ferroelectric measurements, the pseudo‐binary phase diagram of the yBi(Zn½Ti½)O3–(1 − y)[(1 − x)PbZrO3–xPbTiO3] system has been constructed for three series, namely, y = 0.05, 0.10, and 0.15. It is found that the introduction of BZT into the PZT system makes the paraelectric to ferroelectric phase transition more diffuse, brings the MPB to a lower PT content, and enlarges the MPB region. The best properties with an improved dielectric constant ε' = 1248, and a large remnant polarization Pr = 33 μC/cm2, as well as a relatively high TC = 286°C, and a high coercive field Ec = 23 kV/cm was achieved in the y = 0.15 series with MPB composition x = 0.425, making it a promising material for high‐power piezoelectric applications. [ABSTRACT FROM AUTHOR]

We present an ultrasonic study of relaxor-based solid solution (1−x) PbFe2/3W1/3O3–x PbTiO3 (0.25 ≤ x ≤ 0.35) located within the morphotropic phase boundary (MPB). The longitudinal ultrasonic wave velocity and attenuation have been measured by the ultrasonic pulse-echo technique at a frequency of 10 MHz in a wide temperature range from 200 to 800 K. Attenuation peaks have been observed at characteristic temperatures, namely, at Burns temperature TB and the additional distinctive temperature T*. To explain the experimental results, we consider a modified polar nanoregions (PNRs) model taking into account fluctuation corrections of ultrasonic wave velocity and attenuation in the vicinity of both TB and T*. The obtained results confirm the dynamic nature of MPB effects which determine the physical properties of relaxor-based solid solutions. [ABSTRACT FROM AUTHOR]

The best piezoelectric properties of any perovskite oxide known are found in the solid solution of the relaxor Pb(Mg 1/3 Nb 2/3)O 3 and ferroelectric PbTiO 3. Despite its impressive properties, this system has limited analogy. We present the compositional exploration of the Pb-free analogue (1-x)(K 1/2 Bi 1/2)(Mg 1/3 Nb 2/3)O 3 -x(K 1/2 Bi 1/2)TiO 3 (KBMN-KBT). We locate the morphotropic phase boundary between x = 0.86 and 0.88 changing from Cm to Pm symmetry and the optimally performing composition at x = 0.88. We report a piezoelectric figure of merit (d 33 *) of 192 pm V−1 from strain measurements. Diffraction methods reveal disordered displacements of K+ and Bi3+ which persist from the KBMN endmember through multiple changes in symmetry. Rearrangement of the Bi3+ displacements along the uncommon [011] c direction drives the physical response. Ferroelectric, dielectric, and piezoresponse force microscopy are used to study the progression of physical properties through the MPB and attribute the mechanism to a polarization rotation. Taking account for local, short-range, and average structural features yield a balanced perspective on the structure and properties of this system, isolating the driving force within this system to the Bi3+ bonding configuration. This work yields a strong analogy to the Pb-based analogue, and provides strategies for further optimization. [Display omitted] [ABSTRACT FROM AUTHOR]

Sample x=0.15, exhibits moderate leakage current density & highest dielectric constant. [Display omitted] • An attempt to investigate the thermo-dielectric behaviour of BSFO – BZT system. • Visualize the role of BZT content within the structural stability of the perovskite. • The variations of microstructural features validated structural transformations. • Dielectric anomalies correlated with possible transitions and conduction mechanisms. • Electrical heterogeneities elucidated by frequency dependent impedance characteristics. • Confirming the existence of a NTCR behavior in all samples. Lead-free solid solution of (1-x) Bi 0.9 Sm 0.1 FeO 3 − (x) BaZr 0.15 Ti 0.85 O 3 (BSFO − BZT) (x = 0.0, 0.10, 0.15, 0.20, 0.25, 0.50) ceramics were prepared using solid-state reaction method. The structural, morphological, temperature-dependent dielectric properties and leakage current were investigated. The structural investigation revealed the formation of perovskite structure coexisting with tetragonal and rhombohedral phases within (BSFO–BZT) ceramics. The dielectric measurements (within 303 K-773 K) confirmed the existence of a morphotropic phase boundary at x = 0.15 for the (BSFO–BZT) system. The frequency and temperature dependent electrical behavior were explained using Ac conductivity and impedance analysis. The leakage current behavior for all these samples was investigated using both space charge-limited conduction (SCLC) for bulk and Schottky emission (SE) for limited interface conduction approach, whereas the pure BSFO sample was found to be dominated by ohmic conduction, while the BZT-doped samples were dominated by grain boundary-limited conduction. The sample (0.80)Bi 0.9 Sm 0.1 FeO 3 -(0.15)BaZr 0.15 Ti 0.85 O 3 achieved largest dielectric constant 330 at 10 KHz along with a moderate leakage current density value of 3.54 × 10-5A/cm2 (which is quite lower than pure BSFO) proven its candidacy to develop a stable photovoltaic, multilayer actuators, and ferroelectric memory devices. [ABSTRACT FROM AUTHOR]

Multiferroics materials processing ferroelectric and magnetic properties are being explored widely for device applications around the world. Herein, a composite multiferroic material was designed which is expected to show enhanced magnetoelectric (ME) multiferroic properties. In this unique idea, a lead free (0.7)BiFeO 3 -(0.3)BaTiO 3 system with ferroelectric morphotropic phase boundary (MPB) was chosen and a magnetic MPB is induced through Nd incorporation. The MPB was confirmed through X-ray diffraction and Raman studies. The hysteresis loops confirmed the ferroelectric nature of solid solutions and the increase in polarization is related to the induced structural changes. A consistent increase in magnetization with Nd content indicates weaking of R 3 c symmetry of BiFeO 3 due to continuous suppression of the spiral spin structure leading to transition from antiferromagnetic to ferromagnetic response. The presence of ferroelectric and ferromagnetic nature along with the existence of MPB indicates that solid solutions are promising candidates for magnetoelectric multiferroic applications. [ABSTRACT FROM AUTHOR]

The understanding of structure-property co-relations is a key to utilising the materials for their best performances. This paper focuses on the physical property characterization of a new binary solid solution series with formula (1-x)Ba(Cu 1/3 Nb 2/3)O 3 -xPbTiO 3. A unique type of crystal structure evolution as a function of composition has been observed for this solid solution series, where a two-phase coexistence is observed in a very large span of compositions at room temperatures. The microstructure, piezoelectric, ferroelectric and dielectric properties along with their entanglement with crystal structure, have been investigated in detail. The compositional homogeneity of selected compositions has been verified with EDS and XPS. The higher responses in the physical properties have been observed near morphotropic phase boundary compositions. On heating above room temperature, peaks in dielectric permittivity responses have been observed that correspond to the phase transitions of non-centrosymmetric phases. The solid solution's best piezoelectric and ferroelectric responses are observed for the x = 0.70 composition showing higher densification, larger grain size and low dielectric losses, and lies near the morphotropic phase boundary region. The solid solution has enormous potential in piezoelectric industries as it possesses morphotropic phase boundary and high-temperature piezoelectricity. Fig. (a) Room temperature XRD pattern of (111), (200) and (220) reflection of (1-x)Ba(Cu 1/3 Nb 2/3)O 3 -(x)PbTiO 3 ceramics sintered at 1050°C for composition x = 0, 0.20, 0.40, 0.59, 0.60, 0.65, 0.70, 0.95 and 1. Fig. (b) P-E hysteresis loop of (1-x)Ba(Cu 1/3 Nb 2/3)O 3 -(x)PbTiO 3 ceramic for composition x = 0.70, 0.85, 0.90 and 0.95 at 50 Hz at room temperature. [Display omitted] • The comprehensive dielectric, ferroelectric and piezoelectric studies were done for (1-x)Ba(Cu 1/3 Nb 2/3)O 3 -(x)PbTiO 3 ceramics. • The solid solution studied exhibit multiple phase boundaries where high responses of physical properties can be found. • Profound correlations of the solid msolution's physical properties have been established with crystal and microstructure. [ABSTRACT FROM AUTHOR]

Density functional theory was used to inspect the structural properties and morphotropic phase boundaries (MPBs) of Ag1-xKxNbO3 (AKN) solid solutions. Structural properties of pristine AgNbO3 in Pbcm and Pmc21 phases were firstly investigated. The obtained crystal structures were found to be in good agreement with those from experiments. From the formation energy calculation of AKN solid solutions, the coexistences between Pbcm and Pmc21 phases and between Bmm2 and Pm phases were found to be in the composition ranges of x<"0.46" and x>"0.46," respectively. Therefore, the MPB separating the antiferroelectric and the ferroelectric phases can be specified at x ≈ "0.46." This theoretical study provides x ≈ "0.46" as a suggestive composition probably useful to acquire superior piezoelectricity for the utilization of AKN with reduced volatility of alkali elements at the A-site. [ABSTRACT FROM AUTHOR]

Abstract: The ferromagnetic perovskite oxide BiMnO3 is a highly topical material, and the solid solutions it forms with antiferromagnetic/ferroelectric BiFeO3 and with ferroelectric PbTiO3 result in distinctive polar/nonpolar morphotropic phase boundaries (MPBs). The exploitation of such a type of MPBs could be a novel approach to engineer novel multiferroics with phase‐change magnetoelectric responses, in addition to ferroelectrics with enhanced electromechanical performance. Here, the interplay among crystal structure, point defects, and multiferroic properties of the BiMnO3–BiFeO3–PbTiO3 ternary system at its line of MPBs between polymorphs of tetragonal P4mm (polar) and orthorhombic Pnma (antipolar) symmetries is reported. A strong dependence of the phase coexistence on thermal history is found: phase percentage significantly changes whether the material is quenched or slowly cooled from high temperature. The origin of this phenomenon is investigated with temperature‐dependent structural and physical property characterizations. A major role of the complex defect chemistry, where a Bi/Pb‐deficiency allows Mn and Fe ions to have a mixed‐valence state, in the delicate balance between polymorphs is proposed, and its influence in the magnetic and electric ferroic orders is defined. [ABSTRACT FROM AUTHOR]

(1- x- z)NaNbO · xKNbO · zCuNbO ( x = 0.05-0.50, z = 0.025−0.050) ceramics have been prepared by solid-state reactions followed by sintering using standard ceramic processing. Phase relations in a portion of the NaNbO-KNbO-CuNbO system have been studied for the first time, and property-structure-composition relationships have been established for solid solutions in this system. The effect of KNbO content on the main electrical and physical parameters of the solid solutions has been shown to correlate with the position of the morphotropic phase boundaries in this system and the observed structural anomalies. The solid solutions have been demonstrated to be potentially attractive for use in ultrasonic devices. [ABSTRACT FROM AUTHOR]

The MPB phase of La doped BiFeO 3 , which has a homogeneous composition but an inhomogeneous structure, exhibits much better gas sensitivity than undoped samples. • The morphotropic phase boundaries strategy was first used for the design of high-performance sensors. • The Bi 1-x La x FeO 3 samples located at the morphotropic phase boundaries have superior gas sensitivity. • The Bi 0.9 La 0.1 FeO 3 exhibited ultralow concentration detection of acetone even in high humidity. • The as-prepared gas sensor exhibit high selectivity and fast response/recovery time. • The characteristics of morphotropic phase boundaries are the completely homogeneous chemical composition but distinct symmetry. An unsolved yet important issue related to chemiresistive sensors is the lack of ultralow detection capability, i.e., ppb-level detection. Here, we propose a novel strategy to further improve gas sensor performance by introducing morphotropic phase boundaries that have a homogeneous chemical composition but inhomogeneous structures to regulate the band structure and interfaces. The Bi 1-x La x FeO 3 samples located at the morphotropic phase boundary have good selectivity for acetone and showed better gas sensitivity than undoped samples. It is worth noting that the morphotropic phase boundary phase Bi 0.9 La 0.1 FeO 3 exhibited ultralow concentration detection of 50 ppb acetone. The mechanism is that the morphotropic phase boundary phase provides a more efficient carrier and variation in hole accumulation layer. This work provides an alternative strategy for designing high-performance sensors in addition to traditional chemical and physical modifications. [ABSTRACT FROM AUTHOR]