CORRELATION BETWEEN EU-151 MOSSBAUER ISOMER-SHIFT AND JUDD-OFELT OMEGA(6) PARAMETERS OF ND3+ IONS IN PHOSPHATE AND SILICATE LASER GLASSES

Eu-151 Mossbauer effect measurements were carried out for various sili cate and phosphate laser glasses doped with Eu3+ ions instead of Nd3+, for which Judd-Ofelt OMEGA(t) parameters are known. The isomer shift (IS) for the silicate glasses decreased with an increase in the electr onegativity of the network-modifying alkali and alkaline-earth metal i ons, indicating a decreased 6s electron density of the rare-earth R3ions, i.e., covalency of the R-0 chemical bond. On the other hand, in phosphate glasses the IS increased with increased electronegativity. A mong three OMEGA(t), parameters of Nd3+, OMEGA6, which dominates the r adiative transition probability and branching ratio of the 1.3 and 1.0 6 mum emissions, showed a good correlation with the IS of EU3+ ions in the corresponding glasses, independent of compositions. The results w ere explained by the more sensitive dependence of the THETA(s, t) term s in OMEGA6 on the overlap integrals of 4f and 5d orbitals of rare-ear th ions, compared with that in OMEGA2, which is sensitive to the odd-p arity terms of the crystal field, A(sp).