Dielectric Study on Pressure-Induced Phases in Ca 2 Ba(C 2 H 3 COO) 6 (DBA) and Ca 2 Ba(C 3 H 7 COO) 6 (DBB)

The effect of hydrostatic pressure on the structural phase transitions in two isomorphic crystals of Ca 2 Ba(C 2 H 3 COO) 6 (DBA) and Ca 2 Ba(C 3 H 7 COO) 6 (DBB) have been studied by dielectric measurements. The pressure ( p )-temperature ( T ) phase diagrams were obtained. As pressure increases the I-II transition temperatures (at 1 atm, 355 K in DBA, 329 K in DBB) linearly increase with rates of 0.53 K/MPa and 0.50 K/MPa for DBA and DBB, respectively. The lower temperature II-III transition temperature in DBB (212 K at 1 atm) nonlinearly increases with increasing pressure. Two pres- sure-induced phases respectively exist both in DBA and in DBB. Unlike Ca 2 Ba(C 2 H 5 COO) 6 (DBP), pressure-induced ferroelectric phase is not observed both in DBA and in DBB.

Keywords:

• Ca 2 Ba(C 2 H 3 COO) 6
• Ca 2 Ba(C 3 H 7 COO) 6
• dielectric
• phase Transition
• phase Diagram
• high Pressure