Crystal structure of A(VO2)(HPO4) (A=NH+4,K+,Rb+) solved from X-ray powder diffraction

Abstract

The cell is orthorhombic (space group Pbca,Z=8) with a=6.7550(3), b=9.1026(4) and c=17.0808(6) A for A=K + ; a=6.8064(6), b=9.2567(7) and c=17.732(2) A for A=NH +4 ; a=6.8182(8), b=9.291(1) and c=17.631(2) A for A=Rb + . The reliability factors (%) are R 1 =4.35, R wp =8.53 for A=K + ; R 1 =4.79, R wp =10.13 for A=NH 4 ; and R 1 =4.50, R wp =10.40 for A=Rb + . The structure consists of isolated chains of VO 5 square pyramids running along the a axis. The VO 5 units in each chain are linked by HPO 4 groups. The compounds are found to be double hydrogenophosphates of dioxovanadium(V) and alkaline metals