The effect of K defect clusters on the ferroelectric phase transitions in NaCaF3

We have performed a number of molecular dynamics computations on 320 ion samples of NaCaF3 containing K substitutional defects in various concentrations and configurations. Ab initio potentials with no adjustable parameters were used to obtain the short range interactions between ion pairs. Our results indicate that the presence of these defects, in most cases has a profound effect on the characteristics of the polar state, including a diminished sharpness of the transition temperature. We believe that these results may lend some insight into the mechanisms which produce “relaxor” ferroelectrics.

Keywords:

• ferroelectrics
• perovskites
• molecular dynamics
• defects