Analysis of low symmetry aspects revealed by the zero-field splitting parameters and the crystal field parameters for Cr3+ ions doped into yttrium aluminum borate YAl3(BO3)4 crystal

• A structure modeling for Cr3+ doped YAl3(BO3) is firstly carried out through the zero-field splitting (ZFS) parameters.
• Analysis of low symmetry aspects revealed by the ZFS parameters is carried out.
• It is suggested that the Cr3+ ion substitutes for Al3+ ion in YAB with feasible distortions.
• It is shown that angular distortions can be essentially associated with the elongation of the (CrO6)9− octahedron.

Structural modeling has been carried out for Cr3+ centers in YAl3(BO3), YAB, single crystal, which is a potential laser host material. Superposition model (SPM) analysis is applied to predict the zero-field splitting parameters (ZFSPs) the as well as the crystal field parameters (CFPs) for Cr3+ ions located at possible cation sites in YAB. Our analysis of the crystal structure data and the available EPR spectra has revealed considerable low symmetry features. These findings indicate an approximated nature of the previous interpretation of EPR spectra and necessitate their reconsideration taking into account low symmetry aspects. The theoretically predicted ZFSPs and CFPs corroborate the significance of low symmetry aspects. Comparison of the theoretical and experimental ZFSP values obtained from EPR measurements enables analysis of the structural distortions at the Y3+ and Al3+ sites. It is shown that the ZFSPs of the six-coordinated Cr3+ centers are well described by a structural model for the Y3+ and Al3+ sites based on the angular distortions of the surrounding oxygens. The results obtained from our SPM analysis support the earlier finding that Cr3+ ions substitute for Al3+ ions in YAl3(BO3). The predicted ZFSPs and CFPs may be useful in future studies aimed at technological applications of the Huntite-type borates with the formula RM3(BO3)4.