Study Of The Photochromic Effect And Other Intelligent Characters In Perovskite-type Ferroelectric Relaxor Ceramics

Multifunctional perovskite-type ferroelectric ceramics belong to the group of smartmaterials. The electrical, thermal, and mechanical response of thoes materials havealready widely researched and applied in different fields, but it is still at the preliminarystage as the smart materials. As one of the most representative materials in this group,ferroelectric relaxor lead lanthanum zirconate titanate ceramics, photochromic effect hasobserved in this ceramics for many years, but it still lacks a thoroughly describtion andfurther researching about the mechanisms. PZT and PLZT ceramics, as a member of thevery smart materials, a thoroughly understanding and further researching about themechanisms is crucial not only for the application of its smart characters, but also forthe application of its other functionality, especially the development of micro-devicesand systems based on these materials is meaningful.This thesis takes PZT ceramics and rare earth doped PLZT optical ceramics asresearch object, a thoroughly understanding and further researching about themechanisms of photochromic effect has been taken. In the experiments, the refractiveindex of PLZT ceramics changes significantly after violet light (405nm) exposure, thisresult is very useful in developing relative smart devices.This thesis has been divided into three parts based on the purpose of the research.Firstly, the photochromic effect was described by the changes of transmission andreflectivity of non-transparent PZT ceramcis and transparent PLZT ceramcis after violetand infrared light exposure on the surface of the sample. The transmission andreflectivity of the ceramics will decrease after violet exposure, and the color of thesample will darken, while at this time, the transmission and reflectivity of the ceramicswill recover, and the color of the sample will brighten.In the second part, the dynamics of the intensity of the reflection light of thenontransparent PZT ceramics and the dynamics of transmission of the transparent PLZTwere used to calculate the violet and infrared light response time of these materials, ainverse proportion relationship was observed. This result is helpful in developing thedetectoin card for the ultraviolet and infrared light. For the researching of themicromechanisms of the photochromic effect in these materials, electrons trapsdistribution model was introduced to explain the macroscopical behavior of the effectfrom a microscopical view, and then a further analysis was taken to explore the rule ofthe traps distribution.In the third part, a polarized light at561nm was selected as the signal light, arelatively thick PLZT ceramic was exposed by405nm violet light, up to4percentageof the refractive index was observed after the405nm light exposure. A similar result was measured by the ellipsometer, which proves the validity of the experimental results.In addition, significant changes of the refractive index from400nm to600nm werealso measured by the ellipsometer.