X-ray powder diffraction of Ag2Te at temperatures up to 1123 K

J. Schneider and H. Schulz

Abstract

X-ray powder diffraction was performed on β-Ag2Te at room temperature, on ion conducting α-Ag2Te at 523 K, 723 K and 923 K respectively and on γ-Ag2Te at 1123 K.

Rietveld profile refinement of β-Ag2Te confirmed the space group P21/c and the positional parameters of the model of Frueh (Z. Kristallogr. 112 (1959) 44–52).

For the α-modification in space group Fm[unk]m, best results were obtained for a model with a statistical distribution of Ag ions: about 60% of the available Ag ions were placed into 32f(xxx) positions around the tetrahedral 8c(¼ ¼ ¼) sites and the remainder on the 48i(xx½) positions. The probability density function (PDF) calculated with these formal structure parameters suggests next neighbour jumps of Ag ions via the 48i sites.

The first structure refinement of γ-Ag2Te showed it to crystalize in space group Im[unk]m and to be iso-structural to α-AgI. Third order anharmonic coefficients of the temperature factor of the Ag ions could be refined from our X-ray powder data. Corresponding PDF maps show Ag-densities bridging next nearest as well as second next nearest neighbours.

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Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.

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