LOW-TEMPERATURE ORGANOMETALLIC SYNTHESIS OF CRYSTALLINE AND GLASSY TERNARY SEMICONDUCTORS M(II)M(IV)P(2) WHERE M(II) = ZN AND CD, AND M(IV) = GE AND SN

The first organometallic syntheses of the ternary phosphides M(II)M(IV)P2 (M(II) = Zn, Cd; M(IV) . Ge, Sn) are described. Reactions between the precursors {M(II)[P(SiMe3)2]2}2 and M(IV)X4 (X = OMe, Cl) afford the intermediates [M(II)M(IV)P2(X)x(SiMe3)x] with x = 0.3-0.8, which are converted to amorphous M(II)M(IV)P2 compounds by annealing at 250-350-degrees-C in vacuo. The amorphous compounds crystallize to the corresponding chalcopyrite phases at low temperatures, providing the lowest synthesis temperatures yet reported by any synthetic method: ZnGeP2, 700-800-degrees-C; CdGeP2, 500-650-degrees-C; ZnSnP2, 350-600-degrees-C; CdSnP2, 250-450-degrees-C. The solid-state MAS P-31 NMR spectrum of the amorphous CdGeP2 contains a single feature centered at - 104 ppm relative to H3PO4 (full width at half maximum, 160 ppm). Spin-echo experiments on a nonspinning sample determine that T2 = 350 mus. These data are indistinguishable from data for glassy CdGeP2 obtained from conventional melt quenching, suggesting that the amorphous CdGeP2 phases prepared by the two techniques have very similar or identical structures. Analogies between the new organometallic syntheses and the sol-gel process for oxides are discussed.