Microstructure and Dielectric Properties in $30Pb(Mg_{1/3}Nb_{2/3})O_3-20PbTiO_3-50Pb(Mg_{1/2}W_{1/2})O_3$ Ceramics with Excess MgO Addition

MgO가 과잉첨가된 $30Pb(Mg_{1/3}Nb_{2/3})O_3-20PbTiO_3-50Pb(Mg_{1/2}W_{1/2})O_3$계 세라믹스의 미세구조와 유전특성

  • 길영배 (한양대학교 무기재료공학과) ;
  • 이응상 (한양대학교 무기재료공학과)
  • Published : 1997.01.01

Abstract

The effects of 0 to 10mol% excess MgO addition on the microstructure and dielectric properties in 30Pb(Mg1/3Nb2/3)O3-20PbTiO3-50Pb(Mg1/2W1/2)O3 ternary system were investigated. Samples were prepared by mixed oxide and precursor methods to compare the role of excess MgO. Excess MgO enhanced grain growth and increased dielectric constant. The dielectric constant and tesmperature dependence of dielectric constant of the sample sintered at 100$0^{\circ}C$ with 5mol% MgO were above 5,000 and +25% to -50% from - 55$^{\circ}C$ to 1$25^{\circ}C$, respectively. For these specimens the phases percent were mainly perovskite and Pb2WO5, which was confirmed by XRD analysis. Also the amount of cubic pyrochlore Pb3Nb4O13 and PbWO4 were de-creased with sintering temperature and MgO addition. BSE image showed the chemical inhomogeneous dis-tribution. Crystal phase formed at each sintering temperature and the chemical inhomogeneous distribution caused the decrease of the temperature dependence of dielectric constant.

Keywords

Dielectric properties;Microstructure;Temperature dependence of dielectric constant;Excess MgO ad-dition

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