Study of ferroelectric phase transitions in solid solutions based on bismuth vanadate

Phase Transitions and Transport Properties of the Bismuth Vanadate-Based (Bi,La)4(V,Zr)2O11-zCeramics

“…In compositions with higher y values, parameter a increases slightly, parameter b decreases slightly, while parameters c and V do not change with increasing concentration of La 3+ cations. These results are consistent with the data obtained earlier for Zror La-doped bismuth vanadate solid solutions [6,9,10,[13][14][15][16][17][18][19].…”

“…It is believed that the main cause of such large temperature hysteresis of the α-β phase transition may be connected with the oxygen vacancies orderingdisordering in vanadium layers of the crystal structure and their "pinning" at the ferroelectric domain walls as well [18]. Samples with x > 0.1 which according to the X-ray data, have the ordered tetragonal γ -structure at the room temperature are characterized by the reversible γ -γ "order-disorder" phase transition at approximately 700 K. In the dielectric permittivity ε(t) and dielectric loss tan δ(t) versus temperature plots, peaks, corresponding to ferroelectric-paraelectric α-β phase transition, were observed only for the samples with x ≤ 0.05, y ≤ 0.05 [14] (Fig. 4a, c, Fig.…”

“…The parent bismuth vanadate compound undergoes phase transitions between α and β polymorphous modifications at approximately 700 K and between β-and tetragonal γ-phase at approximately 850 K [3][4][5]. Composition modifications by substitution of different valency cations for V 5+ and/or Bi 3+ cations were aimed at and succeeded in the stabilization of the tetragonal structure phase at the room temperature [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. However, the poor thermodynamic stability of these oxides in reducing atmospheres hinders their real applications and comprises the main task to be solved.…”

Solid solutions on the base of bismuth vanadate: Preparation, structure, phase transitions, dielectric and transport properties

“…Ceramic samples of (Bi 1-y La y ) 4 (V 1-x Me x ) 2 O 11-z with Me-Zr, Ga, Fe, Cu, x = 0-0.2, y = 0.0-0.16 were prepared by conventional solid-state reaction method from the preliminary dried oxides Bi 2 O 3, V 2 O 5 , La 2 O 3, ZrO 2 , Ga 2 O 3 , and Fe 2 O 3 of high purity (N99.9%) using procedures described previously [17,18]. Appropriate amounts of oxides were ground, pressed into pellets and calcined at temperatures 773-953 K for 10-30 h, cooled, and regrounded.…”

“…Poor thermodynamic stability of this oxide in reducing atmosphere comprises its main drawback and puts forward tasks to be solved. The modifications of the composition aimed to improve stability of oxides often lead to the stabilization of tetragonal phase at room temperature [11][12][13][14][15][16][17][18][19][20][21][22].…”