Magnetic resonance study of Cr3+ and Fe3+ centers in hexagonal Cs2NaAlF6 and Cs2NaGaF6 crystals

In the search for new solid‐state laser materials, hexagonal Cs2NaAlF6 and Cs2NaGaF6 crystals doped with Cr3+ ions have been synthesized under hydrothermal conditions. Fe3+ ions have been found as unintentional impurities in these materials. Electron paramagnetic resonance and electron nuclear double resonance experiments of these elpasolite crystals have allowed unambiguously identifying the lattice sites for both Cr3+ and Fe3+ ions, by observing the interaction of the unpaired electrons with the nearest 19F and 23Na nuclei. The correlation between spin Hamiltonian parameters and crystallographic data is discussed. The results support the earlier identification of the Cr3+ centers in these crystals from optical measurements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)