Double orthovanadates Ca9R(VO4)7 (R=REE,Y,Bi) with whitlockite structure

Synthesis, X-ray diffraction and IR spectroscopic investigations of double vanadates of the composition Ca9R(VO4)7 have been carried out. Unit cell parameters are determined and it is ascertained that the compounds prepared are built on a trigonal basis and can be considered as derivatives of the structure of whitlockites natural mineral. The unit cell parameters of the double vanadates decrease with a decrease in rare earth element radius and undergo a bend on Eu-Gd interface. IR spectra of the compounds are similar to calcium orthovanadate spectrum