BaTiO_3单晶压痕裂纹的畴变和裂纹扩展的原位观察

IN SITU OBSERVATION OF DOMAIN SWITCHING AND INDENTATION CRACK PROPAGATING IN BaTiO_3 SINGLE CRYSTAL

金相显微镜原位观察了面内极化的BaTiO3单晶在瞬时电场作用下的畴变和裂纹形核、扩展的关系以及未极化BaTiO3单晶在恒电场下Vickers压痕裂纹扩展和电致畴变的关系．结果表明,畴变是裂纹形核、扩展的先决条件,但不存在直接的关系．在恒电场下,未极化的BaTiO3单晶卸载压痕裂纹的滞后扩展可以导致畴变区的扩大．

Instant electric field-induced domain switching, crack initiation and propagation in a poled BaTiO3 single crystal, as well as sustained field-induced indentation crack propagation and 90° domain switching in an unpoled BaTiO3 single crystal have been investigated in situ using optical microscopy. The results show that the domain switching is a prerequisite for instant field-induced crack initiation and propagation, but there is no direct relation between crack initiation and propagation and the domain switching. Delayed propagation of unloaded indentation crack under sustained field can result in an enlargement of the indentation-induced domain switching zones.