The equations of state and axial moduli of the CaBO3 perovskites (B=Zr,Sn,Ti,Ge) and CaFeO2.5 with the brownmillerite structure have been determined using high-pressure, single-crystal X-ray diffraction. The bulk modulus-specific volume relationship for the Ca-perovskites is nonlinear, with CaSnO3 and CaZrO3 displaying anomalous stiffening (higher bulk moduli) than previously reported and predicted [1,2]. The axial moduli of the a- and c-axes decrease steadily by ∼30% from the least-distorted of the Pbnm perovskites, CaGeO3, to the most distorted, CaZrO3, while the b-axis shows little change. The net result is a threefold increase in the anisotropy of the axial moduli of CaSnO3 and CaZrO3 (∼21%) relative to CaGeO3 and CaTiO3 (∼ 4-8%). The bulk modulus of CaFeO2.5 falls significantly below the trend for the stoichiometric perovskites. The introduction of 1/6 vacancies, on the oxygen positions softens the perovskite structure by 25%.
|頁（從 - 到）||115-119|
|期刊||Materials Research Society Symposium - Proceedings|
|出版狀態||Published - 2002 1月 1|
|事件||Perovskite Materials - San Francisco, CA, United States|
持續時間: 2002 4月 1 → 2002 4月 5
All Science Journal Classification (ASJC) codes