Li+ ion conductivity in rock salt-structured nickel-doped Li3NbO4

摘要

Two mechanisms of doping Li3NbO4, which has an ordered, rock salt superstructure, have been established. In the 11 stoichiometric mechanism", the overall cation-to-anion ratio is maintained at 1: 1 by means of the substitution 3Li(+) + Nb5+ --> 4Ni(2+). In the "vacancy mechanism", Li+ ion vacancies are created by means of the substitution 2Li(+) --> Ni2+. Solid solution ranges have been determined for both mechanisms and a partial phase diagram constructed for the stoichiometric join. On the vacancy join, the substitution mechanism has been confirmed by powder neutron diffraction; associated with lithium vacancy creation, a dramatic increase in Li+ ion conductivity occurs with increasing Ni content, reaching a value of 5 x 10(-4) Omega(-1) cm(-1) at 300 degreesC for composition x = 0.1 in the formula Li3-2xNixNbO4. This is the first example of high Li+ ion conductivity in complex oxides with rock salt-related structures.