Calculation of the g Factors and Local Angular Distortions for ZnO:Cu2+ Nanocrystals With Various Copper Concentrations

Based on the perturbation treatments for a tetragonally distorted tetrahedral 3d 9 cluster, the g factors and local angular distortions are calculated for ZnO:Cu2+ nanocrystals with various Cu2+ concentrations in different systems I and II under dissimilar experimental conditions. Because of the dynamic Jahn–Teller effect, the bond angles θ between the four equivalent Cu2+–O2– bonds and the C4 axis are about 1.5o larger than that (θ0 ≈ 54.736o) of an ideal tetrahedron. Consequently, the original slightly trigonally distorted oxygen tetrahedron of the host Zn2+ site is transformed into a tetragonally compressed one. The isotropy of g factors may be attributed to the appropriate angular distortions Δθ = θ – θ0 due to the dynamic Jahn-Teller effect. The slightly increasing (or decreasing) g factors with concentration x can be illustrated as the delicate increases (or decreases) of the angular distortions (Δθ) and the covalency factors (N) for system I (or II), respectively, under almost equivalent crystal-fi eld strengths (Dq).