Peculiarities of the Crystal Structure Evolution of BiFeO3–BaTiO3 Ceramics across Structural Phase Transitions

Abstract

Evolution of the crystal structure of ceramics BiFeO3–BaTiO3 across the morphotropic phase boundary was analyzed using the results of macroscopic measuring techniques such as X-ray diffraction, differential scanning calorimetry, and differential thermal analysis, as well as the data obtained by local scale methods of scanning probe microscopy. The obtained results allowed to specify the concentration and temperature regions of the single phase and phase coexistent regions as well as to clarify a modification of the structural parameters across the rhombohedral–cubic phase boundary. The structural data show unexpected strengthening of structural distortion specific for the rhombohedral phase, which occurs upon dopant concentration and temperature-driven phase transitions to the cubic phase. The obtained results point to the non-monotonous character of the phase evolution, which is specific for metastable phases. The compounds with metastable structural state are characterized by enhanced sensitivity to external stimuli, which significantly expands the perspectives of their particular use.

Impact of the Nanocarbon on Magnetic and Electrodynamic Properties of the Ferrite/Polymer Composites

“…To establish the influence of the type of carbon nanomaterials (CNT and CNF) on magnetic and electrodynamic parameters we produced ternary composites based on Al-substituted HF (BaFe 11.7 Al 0.3 O 19 ) in a polymer matrix (PVDF) with the addition of multilayer CNT and CNF. We have synthesized HF by the solid state reaction method [ 26 , 27 , 28 ] from initial oxides (Fe 2 O 3 , Al 2 O 3 ) and carbonate (BaCO 3 ) in accordance with the reaction: …”

Lead-Free BiFeO3–BaTiO3 Ceramics: An Overview

“…At 10 and 20% molar ratio of BTO, there is the existence of diffuse phase transition, whereas, when the composition of BTO ranges from 0.24 to 0.36, there is a simultaneous decrement in the coercive field and remnant polarization [66]. In the past few decades, research advancement is focused on the BTO-BFO crystal structure [67][68][69][70]. The simultaneous existence of pseudocubic, rhombohedral, and tetragonal phases was also reported [67].…”

Reasons for the High Electrical Conductivity of Bismuth Ferrite and Ways to Minimize It

“…At the same time, the most attractive are compositions containing transition metal ions, which cause magnetic phase transitions and ions with an unshared pair of s electrons capable of exhibiting a ferroelectric state, such as Bi, Pb, one of such compounds is BiFeO 3 [3]. BiFeO 3 has a relatively simple structure (rhombohedrally distorted perovskite, space group-R3c), high temperatures of ferroelectric (T c = 1083 K) and antiferromagnetic (T N = 643 K) transitions, which, in many respects, define it as the most convenient object of experimental research [4][5][6]. However, a number of features of this compound, high electrical conductivity and the presence of a spin modulation cell that is not commensurate with the period of the unit cell, make it extremely difficult to perform a comprehensive study of this material or put it into practice in the areas most in demand.…”