A RAMAN AND INFRARED STUDY OF (NH4)(2)ZRF6

The infrared and polarized Raman spectra of diammonium hexafluorozirco nate, (NH4)(2)ZrF6, are reported over a wide temperature range. It is shown that the Raman spectrum of (NH4)(2)ZrF6 is characteristic of a c ompound containing Zr2F12 chains and both Zr-F(terminal) and Zr-F(brid ging) modes have been identified in the Zr-F stretching frequency rang e. The N-D stretching modes of isolated NH3D+-ions in the lattice reve al only four distinct absorption peaks at lower temperatures instead o f the four quartets predicted. Weak shoulders and the breadth of the i nfrared bands, however, suggest the presence of an undetermined number of features in the infrared spectra of the isolated NH3D+-goups. The NH4+-ions, or some of them, display dynamic behavior and the strength of the hydrogen bonds varies from weak to medium/strong and both norma l and bifurcated bonds are present in (NH4)(2)ZrF6. The changes which occur in the infrared and Raman spectra of (NH4)(2)ZrF6 upon heating t he samples are reported and the final decomposition product ZrO2 is ob tained in a very pure and well-characterized state.