Preparation,Characterization And Properties Investigation Of Potassium Tantalum Niobate Materials

Materials,energy and information technology are three fundamental elements supporting the mankind civilization development in current society.Within the area of modern material science,functional material is a key example,which has gained great attention.With the development of science and technology,functional materials with superior and diverse properties are highly demanded.As an important functional material,piezoelectric and ferroelectric material has been widely investigated and gained great attention,due to its excellent dielectric,piezoelectric,pyroelectric and optoelectronic properties.As a representative of traditional piezoelectric and ferroelectric material,PZT has exhibited great potential in optoelectronic and absorption properties,due to its high responsive ability in the presence of light,electricity,mechanical force and temperature.However,PZT contains lead,thus may cause pollution to the environment,and further cause health problem to mankind and animals.Therefore,development of lead-free piezoelectric and ferroelectric material has drawn interest amongst scientists.As an important lead-free piezoelectric and ferroelectric material,KTN has shown certain potential in display,laser holographic storage and optoelectronic devices,due to its good nonlinear optical and pyroelectric properties.In order to meet the requirement for application,it is still challenging to reduce the preparation conditions and meanwhile realize the high performance of the material.Therefore,it is of significance for scientific research and the expansion of application fields of new materials to develop novel KTN and explore its basic properties.Based on previous report and state-of-art for KTN-based piezoelectric and ferroelectric material,this thesis mainly contains:1.We investigated the preparation conditions for alkali metal KTN materials,studied the thermal degradation and pyrolysis properties for the reagents of Li2CO3,K2CO3,Ta2O5 and Nb2O5 through the thermogravimetric analysis etc,explored the thermal gravity loss and thermal current properties in a temperature range between 20 and 1000 ℃ for KT,KN,KTN and LN in a stoichiometric ratio of the reagents and proposed the mechanism involved in the reactions,established the optimal preparation condition,and obtained corresponding KT,KN,KTN and LN materials.2.The crystalline structures of the as-prepared KT,KN,KTN and LN were investigated via X-ray diffraction(XRD),indicating KT,KN,KTN and LN have cubic,orthogonal,tetragonal and trigonal phase,respectively,and the parameters of these phases were systematically analyzed.SEM characterization of the materials indicated a powder state with a diameter range between nanometer and submicron meter regime,which locates at a microwave high frequency range,thus are promising to have good photoelectric effect.3.We simulate the geometry calculate the energy band density and the dielectric constants of KT,KN,KTN and LN,based on the first principle theory.The experimental data fits with the simulation results,further corroborates the reliability of the calculation results.Both the theoretical and the experimental results indicate KTN material series may have good dielectric characteristics in the high frequency range of microwave frequency,thus show potential for the application in optoelectronic fields.