J. Korean Ceram. Soc. > Volume 34(12); 1997 > Article
 Journal of the Korean Ceramic Society 1997;34(12): 1235.
 편광 현미경을 이용한 Sodium Niobate 단결정의 분역 구조 관찰 정선태 삼성전자 정보통신연구소 In Situ Observation of Domain Structure of $NaNbO_3$ Using Polarizing Microscope ABSTRACT Sodium niobate single crystals were grown by high temperature solution growth with Na2O/B2O3 flux. The phase transitions and domain structures of sodium niobate were observed using transmission polarizing microscope from room temperature to $650^{circ}C$. There was imperfect extinction region within as-grown crystals and this area could be removed by heat treatment. The area existed within crystal till 3$65^{circ}C$, in which temperature the space group of sodium niobate is changed from Pbma to Pmnm. The phase transition from Pbma to Pmnm happened abruptly with changing domain structure. At 48$0^{circ}C$, 52$0^{circ}C$ and 572$^{circ}C$, the colors and walls of domains were changed. All domains disappeared and the space group of sodium niobate was changed from P4/mbm to Pm3m at 64$0^{circ}C$. When sodium niobate changed from high temperature phase to low temperature phase, the memory effect of domain structure was not observed. Key words: Sodium niobate, Domain structure, Phase transition, Polarizing microscope
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