학과 구성원 여러분의 많은 참석을 부탁 드립니다. 

         아             래  

     1. 일시: 2015년 2월 10일(화) 오후 2시 

     2. 장소: 삼성학술정보관 7층 Creative Learning Room

     3. 초청연사: Taras Kolodiazhnyi 박사님 (National Institute for Materials Science)

     4. 제목: Extrinsic dielectric loss in single phase, atomically ordered Ba(Mg1/3M2/3)O3 where M = Nb, Ta
 

     5. Abstract: I will address the compositional stability range, microwave dielectric properties, and defect chemistry of the title compounds within the BaO-MgO-Ta2O5(Nb2O5) ternary diagram. I will further demonstrate that the dense, atomically ordered BaMg1/3Ta2/3O3 and BaMg1/3Nb2/3O3 ceramics show large variation of dielectric loss within a single phase composition region– a clear message that the dielectric loss in practical ceramics is dominated by extrinsic sources and that the cation order alone is insufficient to achieve a minimum dielectric loss in the title compounds. The low-temperature dielectric relaxation studies point out that the extrinsic dielectric loss in the title compounds is due to the ‘rattling’ of the off-centered Mg2+ ions misplaced at the Ba sites. Controlled deviation from the BaMg1/3M2/3O3 stoichiometry toward the Mg-deficient region leads to suppression of the extrinsic dielectric loss as a result of the reduced chemical activity of Mg ion.