A crystallographic study on the quantum spin liquid candidates Cu5–xZnx(VO4)2O2CsCl, x = 0, 1, 2

We propose to analyse the crystal structures of a new quantum (S=1/2) geometrically frustrated material based on the mineral averievite and its Zn-doped variants Zn_xCu_{5-x}Zn_x(VO_4)_2O_2CsCl, where x = 0, 1 and 2. The parent material has a magnetic lattice based on the pyrochlore slab (a kagome lattice sandwiched by two Cu^2+ hexagonal lattices) and Zn-doping on the hexagonal site is thought to form a S=1/2 kagome magnet (x=2) and a quantum spin liquid candidate. We propose to use HRPD to determine whether Zn-doping is only taking place on the Cu hexagonal lattice, and characterise the trigonal crystal structures and any weakly distorted structures.