Abstract: An oxygen sensing element has a body of chromium-rich zinc chromite and electrodes in contact with it for sensing the electrical resistance. At elevated temperatures, the resistance varies with oxygen concentration. A rare earth oxide dopant, preferably 15% mole percent Lanthanum 10 oxide, stabilizes and improves performance.

Abstract: A process for preparing a heat-settable casting or moulding composition comprises forming a mixture of a refractory oxide, preferably alumina, and a polyvalent metal polyphosphate, the polyvalent metal being preferably magnesium, aluminium, cobalt or zinc. The mixture is preferably formed by precipitating the polyvalent metal polyphosphate from an aqueous solution of an alkali metal polyphosphate in the presence of the refractory oxide by the addition of a water soluble polyvalent metal salt to the solution.The compositions are useful in making encapsulated or "potted" components such as resistance thermometers and thermocouples.