2004 Germanium I 4700 51- 025 From Yellow to Black: New Semiconducting Ba Chalcogeno-Germanates. — Three samples of the new germanates Ba2GeSe4-δTeδ with δ = 0, 2, and 2.47 are prepared by reaction of the elements at 800 °C (evacuated silica tube, 5 d; cooling rate of 1 °C/h). These germanates are isotypic with Sr2GeS4 and crystallize in the monoclinic space group P21/m with Z = 2 (single crystal XRD). The yellow color of Ba2GeSe4 indicates semiconducting behavior with an activation energy of 2.6—3.0 eV and the black appearance of the seleno-telluro-germanates points towards band gaps below 1.7 eV. — (ASSOUD, A.; SOHEILNIA, N.; KLEINKE*, H.; Z. Naturforsch., B: Chem. Sci. 59 (2004) 9, 975-979; Dep. Chem., Univ. Waterloo, Waterloo, Ont. N2L 3G1, Can.; Eng.) — Schramke
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