Patent ID: 7662227

Claim:
A process for preparing a compound having the general formula M 5 (AO 4 ) 3 X, wherein M represents Ba, Sr, Ca or a mixture thereof and A represents P, V or a mixture thereof, and wherein the group M 5 (AO 4 ) 3 forms an apatite structure and X is situated in the hexagonal channels of the apatite structure and includes Cu-atoms, with the proviso that the compound is not Sr 5 (VO 4 ) 3 (CuO), or Sr 5 (VO 4 ) 3 (Cu 0.894 O 0.952 ), the process comprising the steps of: (i) mixing of compounds comprising the elements M, A and X; (ii) a first thermal treatment of the mixture in the range of 200 to 1700°C., wherein the thermal treatment is performed in ambient air; and (iii) a second thermal treatment of the mixture in the range of 500 to 900°C.