Crystal-field study for the orthorhombic Yb3+ centers in Ca3Sc2Ge3O12 and Lu3Ga5O12 garnets

• Optical and EPR spectra for CaSGG:Yb3+ and LuGG:Yb3+ garnets were explained.
• The reliability and standardization of fitted CFPs were performed and discussed.
• The unavailability of SPM for LuGG:Yb3+ garnet was found and analyzed briefly.

The crystal-field modeling based on superposition model (SPM) for the orthorhombic Yb3+ centers in Ca3Sc2Ge3O12 (CaSGG) and Lu3Ga5O12 (LuGG) garnets has been employed to explain their recent experimental optical spectroscopy. Furthermore, the electron paramagnetic resonance (EPR) principal g values for orthorhombic Yb3+ centers in LuGG garnet have been interpreted and the predicted g factors for CaSGG:Yb3+ garnet are also given. Both calculated optical spectra and EPR g factors for the two Yb3+-doped garnets could be regarded as in reasonable agreement with the experimental ones. Two important facts about reliability and standardization of the fitted phenomenological crystal-field parameters (CFPs) have been discussed and the unexpected unavailability of direct parametric modeling by SPM for LuGG:Yb3+ garnet is also found and analyzed briefly.