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