ja035314b_si_002.cif (16.56 kB)

Combining Second-Order Jahn−Teller Distorted Cations to Create Highly Efficient SHG Materials:  Synthesis, Characterization, and NLO Properties of BaTeM2O9 (M = Mo6+ or W6+)

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posted on 10.06.2003, 00:00 by Hyun-Seup Ra, Kang Min Ok, P. Shiv Halasyamani
Two new oxides, BaTeMo2O9 and BaTeW2O9, have been synthesized, by standard solid-state techniques, that have strong SHG intensities of ∼600 × SiO2, on the order of LiNbO3. Both materials contain cations susceptible to second-order Jahn−Teller (SOJT) distortions, resulting in asymmetric coordination environments. The SOJT distortion polarizes the M6+−O and Te4+−O bonds. Equally importantly, these polarizations constructively add, resulting in the large SHG responses. Powder SHG measurements on BaTeM2O9 (M = Mo6+ or W6+) indicated that both materials are phase-matchable and have a 〈deffexp of 28 and 22 pm/V, respectively. Using bond hyperpolarizability values (β's) of 130 × 10-40 and 305 × 10-40 m4/V for Te4+−O and Mo6+−O respectively, we calculate a 〈deffcalc of 20pm/V for BaTeMo2O9. In addition, through the powder SHG measurements, we are able to give a more reasonable value for β(W6+−O), 230 × 10-40 m4/V. This value is consistent with the smaller polarizability and magnitude of the intra-octahedral distortion of W6+ compared with Mo6+.