PRESSURE-INDUCED DEFECTS IN ZIRCONATES

摘要

Defects, e.g. vacancies and interstitials, play an important role on the physical properties of oxides, especially on their ionic transport. Those defects in oxides are generally controlled and analyzed as functions of dopant concentration, c, temperature, T, and oxygen chemical potential, □_(O_2), but not of total pressure, P. This is not surprising given that a molar volume, V_m, of solids is much smaller than that of gas phase by a factor of ≈1/1000. Meanwhile, under high pressure such as several GPa, the effect of total pressure on free energy, i.e. V_m□P, reaches 20～100 kJ/mol, which is high enough to affect the defect formation and migration in solids. In fact, pressure-induced phenomena are recently of great interest in solid state ionics. In this study, we focus on the pressure effects on the defect formation in some stabilized ZrO_2 and acceptor-doped BaZrO_3.