By using the superposition model,the tetragonal field parameters Ds and Dt are calculated from the structural data of（TiO6）9- cluster in SrTiO3 crystal.Based on these values,the EPR g factors of the rhombic Ti3+ center in SrTiO3 are calculated by use of only one adjustable parameter.The results show good agreement with the observed values.
The tetragonal distortions of Gd 3+-VB and Gd 3+-M + centers in fluoroperovskites ABF3 （A=K,Rb,Cs;B= Cd,Ca） are studied by calculating the EPR zero-field splitting b 02. From the studies,an interesting trend is found,i.e., when the size of M + ion is close to that of the replaced host ion,the tetragonal distortion ΔR in Gd 3+-M + centers is smaller than that in Gd 3+-VB center,whereas when the size of M + ion is much smaller than that of the replaced host ion,the distortion ΔR becomes larger. The causes of the trend are discussed.
