Effect of Yttrium Doping on Microstructure and Temperature Resistance Characteristics of Barium Strontium Titanate Ferroelectric Ceramics

The negative temperature coefficient (NTC) effect of DC cable material can make the cable material internal and external electric field distortion, causing hidden insulation dangers. It is a new idea to suppress the NTC effect of DC cable insulation material by adding the barium titanate ceramics with positive temperature coefficient (PTC) electrical resistivity. Curie temperature and resistivity at room temperature are important parameters for NTC effect control, which are affected by preparation technology. In this paper,
$\mathrm{Y}_{x}-\text{Ba}_{0.7}\text{Sr}_{0.3}\text{TiO}_{3}\ (\mathrm{x}=0, 0.0008,\ 0.0016,\ 0.0024,\ 0.0032$
, referred to as BST, BYST08, BYST16, BYST24 and BYST32) lead-free ceramics were prepared by solid-phase method. The Curie temperature and resistivity at room temperature of BST ceramics were regulated by doping with different contents of Y
2
O
3
. The results show that the ceramics are pure perovskite and belong to tetragonal phase crystal system. The density of ceramic is above 91%. The grain size decreases with the increase of the Y element. With the increase of sintering temperature, the Curie temperature of BYST08 decreases gradually. The Curie temperature and resistivity of BYST08 at a sintering temperature of 1350°C meet the basic requirements and can be used as an alternative filler to suppress the NTC effect.