Spectroscopic and crystal field studies of (Ce,Gd)Sc3 (BO3)4:Cr3+ crystals

Complex spectroscopic studies of (Ce,Gd)Sc3(BO3)4:Cr3+ (CSB:Cr3+) crystals (crystal growth, absorption and luminescence spectroscopy, crystal field calculations, analysis of the radiative and non-radiative decays) are presented. The main results of the paper include calculations of crystal field parameters and energy level scheme for Cr3+ at distorted octahedral Sc3+ sites, evaluation of the Huang-Rhys factor, effective phonon frequency, zero-phonon line energy, and parameters of radiative and non-radiative decays. Comparison with experimental results and other literature data is discussed. A very unusual value of the frequency factor (related to the non-radiative processes) is explained as being due to heterodesmic nature of chemical bonds in the CSB crystal. Cr3+-doped CSB crystals (with Cr3+ concentration 5.1×1019 cm−3 or 1%) are suggested as promising candidates for potential applications as active media for solid state lasers.