10:45 〜 11:00
▲ [17a-B301-7] Compositional uniformity in the MgO-doped LiNbO3 crystal that is concurrently congruent and stoichiometric
キーワード：LiNbO3, micro-pulling-down method, interface electric field
LiNbO3 (LN) crystals grown under the external electric field by μ-PD method have been studied. Doping a certain amount of MgO enables LN to be stoichiometric and congruent simultaneously (denoted as cs-MgO:LN, Li2O:Nb2O5:MgO = 45.3:50:4.7mol%). It is considered that no segregation of any ionic species takes place during crystal growth of cs-MgO:LN when an appropriate current is imposed, and thus makes it possible to obtain a high-quality LN crystal.
In the ternary system of Li2O-Nb2O5-MgO, the compositional variation of cs-MgO:LN crystal by external current injection was determined by Curie temperature. It was found that the current injection to the growth of cs-MgO:LN did not influence the bulk compositional in the grown crystal, that is, keff=1. However, the compositions at the interface varied in association with the interface electric field. Quenched samples that maintain the distribution of solute during crystal growth were analyzed by EPMA, therefore, the effect of electric field on the interface of solid-liquid could be directly observed. It was found that the intrinsic electric field or the forward current lead to the decrease of Mg concentration in the liquid at the interface, , while the reverse current increased . There exists a certain value of imposed current that was able to counterbalance the intrinsic electric field so that no segregation occurred at the interface.
In the ternary system of Li2O-Nb2O5-MgO, the compositional variation of cs-MgO:LN crystal by external current injection was determined by Curie temperature. It was found that the current injection to the growth of cs-MgO:LN did not influence the bulk compositional in the grown crystal, that is, keff=1. However, the compositions at the interface varied in association with the interface electric field. Quenched samples that maintain the distribution of solute during crystal growth were analyzed by EPMA, therefore, the effect of electric field on the interface of solid-liquid could be directly observed. It was found that the intrinsic electric field or the forward current lead to the decrease of Mg concentration in the liquid at the interface, , while the reverse current increased . There exists a certain value of imposed current that was able to counterbalance the intrinsic electric field so that no segregation occurred at the interface.