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 t he intermediates [M(II)M(IV)P2(X)x(SiMe3)x] with x = 0.3-0.8, which ar e converted to amorphous M(II)M(IV)P2 compounds by annealing at 250-35 0-degrees-C in vacuo. The amorphous compounds crystallize to the corre sponding 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 exp eriments on a nonspinning sample determine that T2 = 350 mus. These da ta are indistinguishable from data for glassy CdGeP2 obtained from con ventional melt quenching, suggesting that the amorphous CdGeP2 phases prepared by the two techniques have very similar or identical structur es. Analogies between the new organometallic syntheses and the sol-gel process for oxides are discussed.