Prediction of Crystal Structure and Dielectric Properties of La(Zn_(1/2)Ti _(1/2))O_3(LZT) and Nd(Zn_(1/2)Ti_(1/2))O_3 (NZT)

摘要

For many years structural mineralogists have found Pauling's concept of bond strength or bond valence a useful tool in evaluating mineral structures. This is a powerful approach to predict the structure and properties of materials. Bond valences determined from experimentally measured bond lengths are used to calculate atomic valences which can be used to help in determination and evaluation of crystal structures. This method was used to determine the crystal structure of La(Ti_(1/2)Zn_(1/2))O_3 (LZT) and Nd((Ti_(1/2)Zn_(1/2))O_3 (NZT). The result indicates that LZT has monoclinic crystal structure. Nd~(+3) has much smaller ionic polarisability (5.01 A) than La~(+3) (6.03 A). The explanation for the increase can be attributed to the smaller size of Nd~(+3) (1.27 A) cation compared to La~(+3) (1.36 A), which increase the number of dipoles per unit volume and thus inflates ε_r despite the reduction in polarisability.