Preparation And Propeties Of K_0.82Ba_0.18TaO₃

Ferroelectric material has become a very active branch in the field of thenational hi-tech materials,with its excellent ferroelectric, piezoelectric, pyroelectricand optical propertiescurrently, and all its researches are developing rapidly towardspractical application. As a kind of functional material, the application of ferroelectricmaterials is also very wide, ferroelectric memory, infrared detector, a spatial lightmodulator and optical sensors，also other aspects have important applications.Ferroelectricity refers to some of the materials, which is under the action of appliedelectric-field within a certain temperature range can produce spontaneous polarization,and the direction of spontaneous polarization is opposite to the applied electric-field’s.Quantum paraelectrics also called incipient ferroelectrics, and it is extremelysimilar to the traditional electrical properties of ferroelectric and in a certaintemperature range, the dielectric changes consistent with Curie-Weiss law. KTaO3asa kind of Incipient ferroelectrics, has the typical structure which is the ABO3perovskite octahedral structure.as early as70s of last century, scholars haveconducted in-depth research on the various special electrical properties, the recentstudies found that we can get a new type of ferroelectrics by replacing the A, Belements, so that to reduce the overall symmetry of the crystal.This article is justbased on the idea, that is through hydrothermal synthesis method, on the basis of theoriginal compound KTaO3to make the target product obtain ferroelectric withchemical doping.The first chapter is the introduction part of the thesis, firstly, inducing somebasic concepts involved in article, including: ferroelectric, quantum paraelectricsand Curie-Weiss law etc., then referring the background of KTaO3and thedevelopment of material polarization,finally expounding the purpose andsignificance of this researchThe second chapter mainly introduce the preparing of perovskite type oxidestructure K0.82Ba0.18TaO3with the method of hydro-thermal synthesis. compared withthe traditional solid phase synthesis method,Hydrothermal synthesis method has the characteristics such as reaction at relatively low temperature, and prepared sample hasgood crystallinity, crystal morphology of high purity.Through The basic phaseanalysis to determine the sample belongs to Pm-3m space group by X-ray diffractionexperiments. By SEM and TEM we can observe the sample crystal shaped like asmall cube about120nm in size. Meanwhile the samples were tested by XPS test,spectrum results determine the doping ratio of samples, and the valence of elements.Finally, the samples were tested by DSC thermal analysis.The third chapter is the electrical testing of samples. Through the Curie-Weisslaw and dielectric temperature spectra we determine the sample Curie point453K,which is consistent with the second chapter of the thermal analysis test.Finallythrough the electrode test obtained the hysteresis loop sample,(PMax) is about0.0123μC/cm2, it proves that the sample has ferroelectricity.The research of this paper reflects the advantages of the current situation ofinterdisciplinary on chemistry, physics and materials science, these national popularobjects. The K0.82Ba0.18TaO3oxide has ferroelectric, which prepared by the authorthrough hydrothermal synthesis method, and summarizes the related electrical laws, itis not only rich variety of ferroelectric materials but also pave the way for China’sscholars in this research field and accumulate important experimental data for furtherresearch.