The parameters in the crystal structure of α-GeTe were determined by least-squares analysis of intensity data obtained with an automatic x-ray powder diffractometer. The rhombohedral cell containing 4 Ge and 4 Te atoms has a=5.996±0.001 Å, α=88.18°, and the single atom-position parameter x=0.237±0.002. The displacement of one sublattice with respect to the other from the relative position that would correspond to the NaCl structure (i.e., x=0.250) corroborates the predictions, based on band calculations, of Cohen, Falicov, and Golin.

SYNOPSIS IN INTERLINGUA FLUORURO DE CALCIUM IN AMALGAMA, PRO PREvENIR CARIE.—Esseva investigate le possibilitate de introducer fluoruro de calcium ad in amalgama con le objectivo de prevenir carie. Le thermodynamica del systema de CaF2-H 2O pare indicar que pulvere de fluoruro de calcium dispergite in amalgama de alligato a mercurio es possibilemente un acceptabile fonte de ion de fluoruro, providite que su presentia non causa effectos toxic. Le extrememente lente solution del fluoruro de calcium in le ambiente oral haberea nulle effecto adverse super le proprietates mechanic del restauration per amalgama de alligato a mercurio e promoverea le acceptation gradual de fluoruro e del iones de calcium ad in le email dental. Si le concentration de fluoruro de calcium in le alligato es tenite a 0,5 pro cento o minus, le resultante proprietates mechanic differe pauco ab illos de amalgama ordinari.

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