Combined X-ray and neutron powder diffraction study of magnesium-doped lithium niobate

Abstract

The nature of cation doping in the important optical material lithium niobate has been studied using a combination of X-ray and neutron powder diffraction methods. Samples of nominal composition Li_1–xMg_xNbO₃(x= 0.1, 0.2, 0.3) were studied. Magnesium was found to substitute exclusively at the Li site, with concommitant Li vacancies, and with no deviation from stoichiometry at the Nb position, i.e.[Li_1–xMg_x/2][Nb]O₃. This is the first detailed structural study of doped lithium niobate by diffraction methods and supports previous models obtained by local structural techniques and computational methods.