Preparation And Pyroelectric Properties Of NKBT Lead-free Ferroelectric Thin Films

It is well known that lead based ferroelectric materials such as lead titanate and lead titanate have excellent dielectric properties, piezoelectric properties,ferroelectric and pyroelectric properties.Therefore, lead based ferroelectric materials are widely used in electronic devices, and have become an indispensable functional material. However, the preparation of these materials requires high temperature treatment, while the high temperature will lead to serious volatilization of lead.This phenomenon not only causes damage to the performance of the material itself, but also causes serious pollution to the environment during the preparation and application of the material.Lead-free(Na_0.85K_0.15)_0.5Bi_0.5TiO₃?NKBT?thin films with different spin-coating layers were fabricated by a sol-gel process using a Pb_0.8La_0.1Ca_0.1Ti_0.975O₃?PLCT? and LaNiO₃?LNO?seed layer. Ferroelectric thin films with high temperature and low crystallization temperature were successfully prepared. At the same time, the effect of multilayer structure of PLCT/NKBT multilayer composite film on the thin film was also studied. The seed layer, the multilayer structure, and the annealing temperature have important influence on the properties of the films. How to control the annealing temperature is an important research direction of high performance films. The crystallization temperature of NKBT ferroelectric thin films was successfully reduced by the introduction of PLCT seed layer. It is found that the optimized NKBT films have lower dielectric constant and higher pyroelectric coefficient at 550? crystallization, thus obtaining a higher Fd. PLCT/NKBT multilayer composite films have low dielectric constant, low dielectric loss and high pyroelectric coefficient when annealed at 500?, which makes it a very high value for Fd. In order to obtain the real lead free thin film, the LNO optimized NKBT thin film was further studied on the basis of the study of the optimized KNBT thin film of PLCT. The study found that the composite films annealed at 500? in all of the NKBT/LNO composite film showed a stronger?100? orientation. In addition, thecomposite films annealed at 500? can effectively reduce the occurrence of interfacial diffusion, thereby improving the electrical properties of the films. Also found strong orientation is conducive to improve the electrical properties of the composite film, effectively reduce dielectric constant ? dielectric loss and leakage current density of the composite film, increase the relative thin film pyroelectric coefficient of electric, have attained a high detection quality films.