How is calcium molybdate (CaMoO4 ) formed in the MoOx /HAP catalyst and what influences its presence?

The XRD patterns of the MoOx/HAP catalysts indicate the formation of CaMoO4 ​but not MoO3 ​ .

A diffraction peak corresponding to CaMoO4 ​appears in the sample due to the partial substitution of P positions in the HAP structure by Mo atoms. The intensity of this peak increases with higher MoOx ​content, signifying greater incorporation into HAP's crystal structure. CaMoO4 ​begins to appear at calcination temperatures as low as 500 ℃, with its crystal diffraction peak intensifying as the calcination temperature rises, suggesting increased infiltration of Mo into the HAP lattice.