Patent ID: 7691284

Claim:
A variable emissivity material having the formula M1 (1−(x+y)) M2 x M3 y MnO 3 wherein: M1 comprises lanthanum, scandium, yttrium, praseodymium, neodymium or samarium; M2 comprises an alkali earth metal; M3 comprises an alkali earth metal that is not M2, said M3 comprising Be; and x, y, and (x+y) are greater than zero and less than 1 and wherein M2 and M3 are each less than 0.4; and wherein the variable emissivity material has a critical temperature (Tc) in the range of about 270 to about 320 K and a transition width less than about 30 K, said critical temperature (Tc) and said transition width defining a phase change of said variable emissivity material from a ferromagnetic state to a paramagnetiC state.