This is attributed to the fact that the film stoichiometry grown by the pulsed laser deposition
technique is very close to that of the target. The 4A2 to 4T1 band seems stronger than the 4A2 to 4T2 band in Fig. 6(a), while the situation is reversed in Fig. 6(b). It may be because Cr3+ experiences different crystal fields, which can be confirmed by the XRD results from Fig. 1. In addition, the luminescence intensity of the thin films is very low as compared to that of the powder sample. This is due to the internal reflection, small interaction volume between the incident beam and the solid.