New Theoretical Insights into the Crystal-Field Splitting and Transition Mechanism for Nd3+-Doped Y3Al5O12

There has been considerable research interest paid to rare-earth transition-metal-doped Y3Al5O12, 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 Y3Al5O12 laser crystal by using the CALYPSO structure search method and our newly developed WEPMD method. A novel cage-like structure with a Nd3+ concentration of 4.16% is uncovered, which belongs to the standardized C-222 space group. Our results indicate that the impurity Nd3+ ions are likely to substitute the Y3+ at the central site of the host Y3Al5O12 crystal lattice. The laser emission F-4(3/2) -> I-4(11/2) occurring at 1077 nm is in accord with that of the experimental data. By introducing the proper correlation crystal field, three transitions, (4)G(5/2) -> I-4(9/2), F-4(7/2) -> I-4(9/2), and S-4(3/2) -> I-4(9/2), 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.