Patent ID: 6183716
Filing Date: 2001-02-06
Classification: C01G,C01P,G01K

Abstract:
A method for making substantially single-phase, crystalline NTE compounds having the formula: ##EQU11##where A.sup.4+ is Zr.sup.4+, Hf.sup.4+, or mixtures thereof, and M.sup.6+ is Mo.sup.6+, W.sup.6+, or mixtures thereof, the method comprising:forming a liquid mixture comprising stoichiometric amounts of (1) a soluble source of Zr.sup.4+, Hf.sup.4+, or mixtures thereof, and (2) a sodium-ion-free tungstate salt, a sodium-ion-free molybdate salt, or mixtures thereof;adding an acid to the liquid mixture to acidify the liquid mixture;refluxing the liquid mixture at ambient pressures for a period of about 48 hours or more, or at pressures greater than ambient for a period of from about 1 to about 24 hours;separating a solid fraction from the mixture; andheating the solid fraction to a temperature within the temperature range of from about 500.degree. C. to less than 700.degree. C. to form a compound having the formula ##EQU12##