Research On Microscopic Theory Of The Ternary System PZT Ferroelectric Thin Film

The ferroelectric thin film is a kind of important functional materials in the related applications. The lead zirconate titanate(PZT) based ferroelectric thin films are more extensively used, which own excellent properties, such as ferroelectrics and piezoelectrics. With the development of the micro-device and micro-nano technology, the traditional ferroelectric thin films can not keep up with the developing requirements. For getting some new excellent ferroelectric thin films, we modified the PZT based ferroelectric thin films with different elements doped The research on the micro mechanism of the excellent properties of the multi compound ferroelectric thin films has become the focus of this research field.The research on microscopic mechanism of the ternary PZT based ferroelectric thin films is made. The CASTEP module is used to study on the doping effects of Pb(Mn1/3Nb2/3)O3 into PZT, and theoretical model of PMn N-PZT is built. The calculations of the geometric structure and electronic structure of PMn N-PZT with the first principles method based on density functional theory are made. The analyzation on the property of pure PZT films and the PZT doped with different proportion of PMn N are done, such as the density of the state, band structure. The effects of addition of PMn N into PZT are studied on. The main results are the following:(1) The proper doping ratio of PMn N into PZT causes the crystal constant changing, which doesn’t change the crystal phase. Based on the results of comparison of different proportion PMn N addition to the same Zr/Ti ratio PZT, and the doping ratio of PMn N into PZT should be smaller than 10 percent.Otherwise the optimization can’t convergence.(2) With the increasing of PMnN doping percent, the Mn and Nb tend to substitute Zr and Ti positions, which changes the structure based on the analysis of the total density of states and the points of the density wave state of PZT, 0.06 PMn N-0.94 PZT and 0.1PMn N-0.9PZT. It also shows that the bandwidth decreases, and the conductive ability of PMn N-PZT system increases.The results of this paper are very consistent with the existing relevant theoretical calculations and the data of the experiments. It owns some guiding values for the microscopic mechanism of the PZT ternary ferroelectric thin films.