气相法对BaTiO_3陶瓷扩渗Gd元素及其电性能研究

Gaseous Penetration of Gd into BaTiO_3 Ceramics and Their Electric Characteristics

采用气相法对BaTiO3 陶瓷扩渗Gd元素 ,使BaTiO3 陶瓷的导电性发生了显著变化 ,其室温电阻率从 4 .0× 10 12 Ω·m下降为 2 .76× 10 3 Ω·m ,而且随着频率增大和温度升高 ,交流电导逐渐增大 ,BaTiO3 陶瓷的导电性更强。Gd扩渗后BaTiO3 陶瓷的晶粒电阻随着温度的变化 ,呈现NTCR效应 ,而晶界电阻随着温度的变化 ,呈现PTCR效应 ,且晶界电阻远远大于晶粒电阻 ,说明该材料的PTCR效应是由晶界效应引起的。Gd扩渗使BaTiO3 陶瓷的介电常数显著降低 ,且随频率的增大而逐渐减小 ,介电常数随温度的变化呈PTC效应 ,并使BaTiO3 陶瓷的居里温度升高为 130 .6°C。

The gaseous penetration of Gd element into BaTiO 3 ceramics was reported in this paper. The penetration conditions and effects on electric characteristics of BaTiO 3 ceramics were studied. The results showed that the electric characteristics of BaTiO 3 ceramics changed obviously through the gaseous penetration of Gd element. The resistivity decreased obviously, when the Gd element content was 2%(wt), the penetration temperature was 860 °C and the penetration time was 4h, the resistivity was changed from 4.0×10 12 Ω·m to 2.76×10 13 Ω·m, and the conductance increased with increase of frequency and temperature. The grain resistance of Gd-penetration BaTiO 3 ceramics exhibited NTCR effect, but the grain boundary resistance showed PTCR effect, and the grain boundary resistance was too much larger than the grain resistance, so the PTCR effect originated from the grain boundary. The dielectric constant of Gd-penetration BaTiO 3 ceramics decreased visibly with increase of frequency, the dielectric constant exhibited PTC effect, and the Curie-temperature had gone up to 130.6 °C .