Sintering Behavior and Dielectric Properties of Ca and Zr Doped Barium Titanate

• Main Authors: Huang, Mu-Chuan, 黃木全
• Other Authors: Tsang-Tse Fang
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/75179174036467881206

碩士 === 國立成功大學 === 材料科學(工程)學系 === 86 === Ca,Zr doped barium titanate (Ba,Ca)(Ti,Zr,Ca)O3 is a potential dielectric material that meets the need of Y5 and Z5 capacitors in MLC technology. So the purposes of this study were to evaluate the effect of Ca,Zr dopants on the sintering behavior and the dielectric properties.It is found that Ca(Ti site) dopant enhance the sintering and reduce the sintering activation energy from 1460kJ/mole (pure BaTiO3) to 800kJ/mole .The powders prepared by citric process will be densified at lower temperature than that by solid state reaction. The Ca(Ba site) dopant raise the sintering temperature at the liquid-enhanced sintering behavior but the preparation method ,the powder particle size ,and the green density have no obvious effect on liquid enhanced sintering .The CaTi ,ZrTi dopants affect the dielectric properties strongly .Both of them reduce the tetragonal-cubic phase transition temperature (Tc) and broaden the phase transition but Ca(Ti site) dopant reduces the dielectric constant and ZrTi dopant raises it. When Ca(Ti site) ,Zr dopants exist simultaneously ,the effect is stronger than the summation of them. The difference on dielectric constant of Ca(Ti site) doped BaTiO3 that prepared by different method may be related to the homogeneity of Ca(Ti site) dopant. We discuss the internal stress model about the movement of Tc ,too ,and we find it can not explain our result . We find a special phenomenon called dielectric unstableness near phase transition point at high frequency .The dielectric - temperaturerelation of barium titanate based materials will be unstable near the phase transition at frequency > 500 kHz ,but we can't observe the same phenomenon at CaTi doped BaTiO3 specimen .It may be related to the homogeneity of CaTi dopant,too . The long batch time of ball-mill in processes will affect the sintering behavior and dielectric properties ,and the preparation method f Zr solution in citric process were reported ,too .