Lattice site location of Hf in LiNbO 3: Influence of dopant concentration and crystal stoichiometry

Abstract

The influence of dopant concentration and crystal stoichiometry on the lattice site of Hf in LiNbO 3 single crystals was studied combining ion beam and hyperfine interaction methods. Two cases were studied: A near-stoichiometric LiNbO 3 crystal doped with 1 mol% HfO 2 and a congruent crystal doped with 6 mol% HfO 2. In both cases it is shown that Hf occupies both Li and Nb sites, in contrast with the case of congruent crystals doped with a small amount of Hf, where it occupies only Li sites. The roles played by the stoichiometry of the crystal and the dopant concentration are discussed in the framework of the current models for the defect structure of lithium niobate.