An electron paramagnetic resonance study on Sm3+ and Yb3+ in KY3F10 crystals

Electron paramagnetic resonance (EPR) spectra of Sm3+ and Yb3+ ions in KY3F 10 single crystals have been measured at X-band microwave frequencies and l ow temperatures. The EPR lines have been fitted to a tetragonal spin Hamilt onian to determine effective g-values (g(//), g(perpendicular to)). The obs erved g-values, ((g//) = 0.714(2), g(perpendicular to) = 0.11(1)), for Sm3 are in agreement with those calculated via crystal-field J-mixing of the f irst excited-state multiplet H-6(7/2) into the groundstate multiplet H-6(5/ 2) Of Sm3+ as the second-order perturbation. On the other hand, the observe d g-values, (g(//) = 5.363(5), g(perpendicular to) = 1.306(2)) for Yb3+ are coincident with those calculated via mixing in only the groundstate multip let F-2(7/2) as the first-order perturbation because the first excited-stat e multiplet F-2(5/2) lies above similar to 10 000 cm(-1) from the groundsta te. The groundstate eigenfunctions of Sm3+ and Yb3+ obtained from the EPR r esults are close to those calculated from a C-4v, symmetry crystal-field an alysis applied to their optical transitions. The distortions of the Sm3+ an d Yb3+ complexes in KY3F10 are discussed in the term of the crystal-field H amiltonian in comparison with LiYF4.