Study On Processing And Characterization Of Strontium Titanate Zirconate

Strontium titanate zirconate (SrTixZr1-xO3) is very important dielectric material that can be applied in multilayer or grain boundary barrier layer capacitors (GBBLC), electroluminescent (EL) devices, etc. due to its high dielectric constant and low dielectric loss. SrTixZr1-xO3 is also very useful semiconductor material with potential of using as semiconductor electrodes to catalyze water photoelectrolysis into oxygen and hydrogen.In this paper processing and characterization of strontium titanate zirconate were studied. SrTixZr1-xO3 powders were synthesized by chemical coprecipitation method with strontium nitrate, zirconium oxychloride,titanium tetrachloride and sodium hydroxide as raw reactants. The react temperature, aging temperature and aging time were studied. Experiment shows react temperature has little effect on processing powders while aging temperature and aging time are major factors. SrTixZr1-xO3(x≥0.4)powders were prepared under the condition of 25℃for react temperature,90℃for aging temperature and 2h for aging time. Aging time is the major factor in synthesizing SrTixZr1-xO3(x≤0.3) and well crystallized powders can be obtained by extending aging time. Powders were characterized by X- ray powder fiffraction(XRD) and transmission electric microscope(TEM). Particle size of SrTi0.9Zr0.1O3 is 50～120nm and that of SrTi0.7Zr0.3O3 is 200～400nm.Strontium titanate zirconate powders were pressed into tablets by dry pressing process, then the tablets were sintered at ambient pressure for hours. The microstructure and dielectric properties were studied by scanning electron microscope(SEM) and impedance analyzer. The sinter programme was studied by thermogravimetric analysis and differential scanning calorimetry(TG-DSC). The sinter programme was finally ascertained with sintering temperature of 1400℃, heating rate of 3℃/min and sintering time of 2 hours.Dielectric properties of SrTi0.7Zr0.3O3 and SrTi0.5Zr0.5O3 ceramic tablets were tested by impedance analyzer. The dielectric constant of SrTi0.7Zr0.3O3 was 135.6 and dielectric loss was 0.0244 under the frequency of 1KHz. The dielectric constant of SrTi0.5Zr0.5O3 was 122.3 and dielectric loss was 0.1374 under the frequency of 1KHz.