| In the thesis, BaxCa1-xTiyZr1-yO3(BCZT) based dielectric barium titanatematerials were prepared and characterized. A brief overview of barium titanate-basedferroelectric ceramics was first summarized. The influence of temperature on themicrostructure and properties of the proposed BCZT based ceramics wereinvestigated. The impact of Al2O3doping and chemical modification on themicrostructure and properties of BCZT was compared in detail. The main results areas follows:（1）With increasing calcining temperature, the cube of the powders graduallyincreased, but the high temperature will burn ceramic powder into a porcelainobviously. The raise of calcining temperature will intensify the interaction of atomswithin the BCZT crystal lattice, increasing its activation energy.（2）An appropriate doping of Al2O3will drive the Curie temperature of BCZTceramics to lower temperature and increase their electrical insulation. The obtainedmaximum insulation resistance is: in air atmosphere,6.7E+11cm, and in reducingatmosphere,1.88E+12cm. Both were20-30times higher than those of theundoped BCZT. An appropriate doping of Al2O3would improve the breakdown fieldstrength of BCZT porcelain powder, and the largest breakdown field strength is: in air,5.2KV/mm, and in a reducing atmosphere,7.3KV/mm.（3）With the gradually increased amount of Al2O3-coated, the grain size of thesamples sintered both in air and in reducing atmosphere first dropped down,indicating that a small amount of doping will inhibit the growth of BCTZ grains.Because the increase of Al2O3doping could reduce the sintering temperature ofBCZT, the grain size thus increased. An appropriate chemical coating of Al2O3canimprove the breakdown field strength of BCZT porcelain powder, and the maximumbreakdown field strength is: in air,2.8KV/mm, and in a reducing atmosphere,8.6KV/mm, which is double higher than those of the uncoated samples. |
