[17a-B301-1~12] 15.1 Bulk crystal growth

[17a-B301-6] Partitioning of Mg into Li Site and Nb Site in LiNbO₃ Crystal during Growth

〇Satoshi Uda¹, Yusuke Horie¹ (1.IMR, Tohoku Univ.)

Keywords:Lithium niobate, impurity partitioning, crystal site

The partitioning of Mg from the melt into Li site and Nb site was investigated during growth of congruent LiNbO₃ (LN) crystal doped with MgO. The equilibrium partition coefficient of Mg, k_E0, which is affected by the interface electric field, varied with the amount of MgO in the melt and a discontinuity in the k_E0 variation was found around 3.7 mol%. This is attributed to the change of Mg occupation site from Li site to Li site + Nb site where the crystal structure changes discontinuously, which surely changes the energy state of both Li site and Nb site. Applying the regular solution model to the chemical potential of Mg in Li site and Nb site, we found that the mixing enthalpy associated with Mg incorporation is several times larger in Nb site than in Li site, which might tell that the preferential site is Li site for Mg at the beginning of its incorporation into crystal.