Sagrario M. Montemayor, A. Alvarez Mendez, A. Martínez-de la Cruz, Antonio F. Fuentes and Leticia M. Torres-Martínez
A study of lithium insertion in two tetragonal tungsten bronze (TTB) type phases of general formula M8W9O47 (M=Nb and Ta), is presented. The electrochemical insertion of up to 20 lithium atoms per formula unit in Nb8W9O47 (Li/ΣM=1.2) proceeds through a reversible reaction with several single phase and one two-phase domains, while in Ta8W9O47 the reversibility of lithium insertion is limited to 15 atoms (Li/Sigma;M=0.9). Structural changes on Nb8W9O47 as a function of the number of lithium atoms inserted have been studied by X-ray powder diffraction.