Positron Lifetime and Defects in Y‐doped (Ba^0.6Sr_0.4)TiO₃ Ceramics

Abstract

The positron lifetime spectra in Y-doped (Bao.6Sr0,4)Ti03 ceramics have been measured at room temperature for Y contents of 0-0.8 at. %. It was found from the experiments that with increasing Y content, the variation of the positron lifetime parameters is nonmonotonic, and the Y content corresponding to the knee is about 0.7 at. %, which is much larger than the La content corresponding to the knee in the La-doped BaTiO, (TANG 1994a). The experimental results show that the Y ions substitute predominantly for Sr ions, and this substitution induces a large number of Sr vacancies; when the Y content increases to about 0.7 at. %, the Y ions begin to substitute for Ba ions, and then the associated defects (2 YBaV&) and (2 YsrVi,) form gradually.

Dependence of the Electric Properties and the Positron Lifetimes on the Dopant Content in La‐doped SrTiO3

“…It is important to study the structure and defects and their variations in order to understand the influence of variable causes on the properties of these materials. Many methods arid techniques such as X-ray diffraction (RUDDLESDEN, POPPER), electron microscopy (HAANSTRA, IHRIG) internal friction (GRIDNER, DARINSKII), electron paramagnetic resonance (KUTTY et al), laser spectroscopy (COCKROFT et al), positron annihilation (TSUDA et al, HE et al;TANG 1994aTANG , 1994bTANG , 1995 have been used to study structure and defects of perovskite materials. Among these methods and techniques the positron annihilation is an important and sensitive technique for the stiidy of vacancy type defects.…”

The Defects, Grain Size and Electrical Property in the Non-stoichiometric BaTiO3 Ceramics

“…and small deviation in stoichiometry. Many subjects about them have been investigated by using X-ray diffraction (RUDDLESDEN et al1958), electron microscopy (HAANSTRA et al 1980), optical obsorption ), electron paramagnetic resonance (KUTTY et al 1985;KLEIN et al 1986;SCHWARTZ et al 1990;SCHWARTZ et al 1992;POSSENRIEDE et al 1992;SCHWARTZ et al 1993), laser spectroscopy (COCKROFT et al1991) and positron annihilation (TSUDA et al 1978;TANG 1994a;TANG 1994b;TANG et al 1995). These investigations took mainly aim at the influences of doping and preparation conditions.…”