Tetragonal distortions of some tetragonal Cr3+ centers in fluoroperovskite ABF3 crystals.
The tetragonal distortions [characterized by the displacement DeltaR of the F(-) ion intervening in Cr(3+) and V(B) (B(2+) vacancy) or M(+) ion in B(2+) site] for Cr(3+)-V(B) and Cr(3+)-Li(+) centers in Cr(3+)-doped fluoroperovskites KBF(3) (B=Mg, Zn) and ACdF(3) (A=K, Rb, Cs) and also for Cr(3+)-Na(+) center in KZnF(3) have been studied by calculating the EPR parameters D, g(parallel) and g(perpendicular) from the crystal-field theory. From the studies, an interesting trend is suggested, i.e., when the size of the co-doped monovalent impurity M(+) in the nearest neighbor B(2+) site is comparable to that of the replaced B(2+) ion, the displacement DeltaR of the intervening F(-) ion in Cr(3+)-M(+) center is smaller than that in Cr(3+)-V(B) center and if the M(+) iron is much smaller or much larger than that of the replaced B(2+) ion, the displacement DeltaR in Cr(3+)-M(+) center is greater than that in Cr(3+)-V(B) center. The causes of the trend are discussed.
Zhou
Qing
Q
Department of Material Science, Sichuan University, Chengdu 610064, PR China.
Wu
Hong-Ye
HY
Wu
Xiao-Xuan
XX
Zheng
Wen-Chen
WC
D002857:Chromium / Q000737:chemistry*; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D004583:Electrons; D005461:Fluorine / Q000737:chemistry*; D017611:Fluorine Compounds / Q000737:chemistry*; D007477:Ions; D007501:Iron / Q000737:chemistry; D008956:Models, Chemical; D015233:Models, Statistical; D015394:Molecular Structure
D017611:Fluorine Compounds; D007477:Ions; D002857:Chromium; D005461:Fluorine; D007501:Iron