OPTICAL SPECTROSCOPY OF CU+-DOPED BETA-ALUMINAS

Cu+-doped beta-aluminas were prepared by ion exchange of single crystals of Na+-beta-alumina. The emission spectrum of these crystals under UV excitation is complex and depends upon the nature and identity of other cations in the beta-alumina conduction plane. In the Na+ isomorph, emission is from isolated Cu+ ions in aBR sites (at 435 nm), and from Cu+-Cu+ dimers resulting from Cu+ ions occupying adjacent BR and aBR sites. The dimer emission is assigned on the basis of homoatomic d10 ion interactions. When the Na+ ions in the crystal are replaced by other cations (K+, Ag+, or Ca2+), changes in the emission spectrum result. These changes are the result of altered ion interactions and site occupancies in the beta-alumina conduction plane. The most notable of these is the formation of Cu+-Ag+ ion pairs via a mechanism similar to that which causes the Cu+-Cu+ dimers. The congruent melting nature of the beta-alumina host allows the growth of large, high-optical quality single crystals of these materials, suggesting a potential for application as solid-state tunable laser materials.