New Theoretical Insights into the Crystal-Field Splitting and Transition Mechanism for Nd-Doped YAlO.

There has been considerable research interest paid to rare-earth transition-metal-doped YAlO, which has great potential for application as a laser crystal of new-type laser devices because of its unique optoelectronic and photophysical properties. Here, we present new research conducted on the structural evolution and crystal-field characteristics of a rare-earth Nd-doped YAlO laser crystal by using the CALYPSO structure search method and our newly developed WEPMD method. A novel cage-like structure with a Nd concentration of 4.16% is uncovered, which belongs to the standardized C space group. Our results indicate that the impurity Nd ions are likely to substitute the Y at the central site of the host YAlO crystal lattice. The laser emission F → I occurring at 1077 nm is in accord with that of the experimental data. By introducing the proper correlation crystal field, three transitions, G → I, F → I, and S → I, are predicted to be good candidates for laser action. These findings can provide powerful guidelines for further experiments of rare-earth-metal-doped laser crystals.