Abstract: Hg.sub.1-x Cd.sub.x Te is prepared in an improved directional solidification method in which a precast alloy sample containing predetermined amounts of Hg, Cd and Te is disposed in a sealed ampule (12) and a furnace (10) providing two controlled temperature zones (16, 18) is translated upward past the ampule so as to provide melting and resolidification. The present improvement is directed to maintaining the zones at temperatures determined in accordance with a prescribed formula providing a thermal barrier (32) between the zones with a maximum thickness and translating the furnace past the zones at a rate less than 0.31 .mu.m/sec.

Abstract: A method of preparing pseudobinary mercury, cadmium, telluride (HCT) crystals by controlled crystal growth in a fused silica ampule uses a modified Bridgman-Stockbarger method. In this method, the alloy is cast into one end of the ampule, inverted, heated to a temperature between the liquidus and solidus temperatures of the alloy and directionally solidified in a two zone furnace. The parameters of the solidification treatment are controlled according to the formulaT.sub.U.sup.4 -T.sub.I.sup.4 =T.sub.I.sup.4 -T.sub.L.sup.4,where T.sub.U =the temperature of the furnace upper zone, T.sub.L =the temperature of the furnace lower zone, and T.sub.I =the solidus temperature of the crystal composition. The rate of transfer of the crystal through the furnace and the size of the zone barrier are also controlled. The modified method imparts homogeneity to the crystal composition, both axially of the crystal and radially. The crystals produced by the method have superior properties and a much higher yield.

Abstract: Oxygen sensor incorporating a thin film electrolyte such as yttria stabilized zirconia sputtered onto a substrate produces an electrical signal in response to differences in oxygen partial pressures. The electrical signal changes rapidly enough for useful operation at temperatures which are substantially lower than those required by conventional oxygen sensors having a rigid, self-supporting thimble, tubular, or disc type electrolyte. For example, rapidly responding signals have been generated at temperatures below 200.degree. C whereas state of the art devices such as those used for sensing exhaust gases in automotive vehicles require temperatures higher than about 400.degree. C.