Spectroscopic and crystal field studies of (NH4)2BeF4 : Co2+

Detailed studies of the optical spectra of new synthesized (NH4)2BeF4:Co2+crystals are presented. First consistent theoretical simulations of the absorption spectra were performed using exchange charge model of crystal field (CF). As a result, we obtained the values of crystal field parameters (CFPs) and Co2+ energy levels; these results were used for absorption bands assignments up to 25 000 cm−1 in the experimental spectrum. Good agreement between calculated and observed energy levels supports reliability of the obtained CFPs values and Racah parameters. The method used in the present paper may be readily applied for the prediction and analysis of the spectroscopic features for new synthesized nonoxide materials doped with transition metal ions.