Crystal chemistry of α-(Zn,M)2V2O7 solid solutions correlation between preference for five-coordination and extension of solid solubility

Abstract Solid solutions of M 2 V 2 O 7 in α-Zn 2 V 2 O 7 have been prepared and equilibrated at 600°C ( M = Mg, Ca, Mn, Co, Ni, Cu, Zn, and Cd ). The crystal structure of α-Zn 2 V 2 O 7 contains only one type of metal site, which is five-coordinated by a somewhat distorted trigonal bipyramid ZnO 5 (Gopal & Calvo, 1973). The solubility range is largest for Cu 2+ and Co 2+ which can substitute for about 35% of the zinc atoms. The cations can be arranged in the following sequence with respect to their solubility in α-Zn 2 V 2 O 7 , which accords well with these ions' preference for five-coordination: Zn 2+ >> (Cu 2+ ,Co 2+ ) > Mg 2+ >(Ni 2+ , Mn 2+ ) > Cd 2+