LinbO₃단결정의 가열현상에 따른 자발분극 변화 및 초전계수

Abstract

LiNbO₃단결정의 자발분극 변화량 △Ps와 초전계수 ?????를 25℃∼300℃ 온도 영역에서 측정하였다. 전극은 시료의 양극면에 silver paste를 사용하여 0.15㎠ 되게 하였다. 일정한 stress상태에서 시료의 온도를 연속적으로 변화 시켰다.

온도변화에 따른 자발분극 변화량은 op amp를 이용하여 결정극면에 나타나는 전하를 콘덴서에 축적하여 측정 하였다. 결정극면에 전기장이 없을 때 자발분극 변화량은 연속적인 온도의 함수로 측정하였다.

측정한 초전계수와 계산한 secondary 초전계수?? 비교한 결과 LiNbO₃단결정의 초전성은 primary 초전현상에 기인하였다.

온도영역 100℃∼150℃ 사이에서 congruent한 c-plate시료에 나타나는 초전성의 불규칙한 변화는 분역들의 재정돈에 기인함이 확인되었다.

25℃∼300℃가지 LiNbO₃단결정의 자발분극 변화량은 2,858×10??C/㎠ 이었고 50℃에서 초전계수는 6.32×10??C/㎠℃ 이였다.

Measurements of spontaneous polarization, Ps, and pyroelectric coefficient, dPs/dΘ, of LiNbo₃have been made over the temperature range from 25℃ to 300℃.

Several crystals of typical surface area of 0.15㎠ were electroded with silver paste on the faces normal to the polar axis. The crystals were mounted in an unclamped manner and the temperature was varied continuously from 25℃ to 300℃.

The change of spontaneous polarization as a function of temperature was obtained by integration the charge which appear on the polar faces of the crystal with an operational amplifier. With this arrangement the field across the crystal is essentially zero at all times, and the spontaneous polarization change can be recorded continuously as a function of temperature.

After evaluating and comparing data, it becomes evident that the major pyroelectric properties of LiNbO₃, particulary in the temperature range, 25℃-300℃, belong to primary effect.

The anomalous change of pyroelectric effect in LiNbO₃as grown crystal of congruent c-plate in the temperature region between 100℃-150℃ was due to the domain rearrangements.

The change of spontaneous polarization is found to be 2.858×10??C/㎠ at 25℃-300℃ and pyroelectric coefficient for the LiNbo₃is measure to be 6.32×10??C/㎠℃ at 50℃.

Measurements of spontaneous polarization, Ps, and pyroelectric coefficient, dPs/dΘ, of LiNbo₃have been made over the temperature range from 25℃ to 300℃.

Several crystals of typical surface area of 0.15㎠ were electroded with silver paste on the faces normal to the polar axis. The crystals were mounted in an unclamped manner and the temperature was varied continuously from 25℃ to 300℃.

The change of spontaneous polarization as a function of temperature was obtained by integration the charge which appear on the polar faces of the crystal with an operational amplifier. With this arrangement the field across the crystal is essentially zero at all times, and the spontaneous polarization change can be recorded continuously as a function of temperature.

After evaluating and comparing data, it becomes evident that the major pyroelectric properties of LiNbO₃, particulary in the temperature range, 25℃-300℃, belong to primary effect.

The anomalous change of pyroelectric effect in LiNbO₃as grown crystal of congruent c-plate in the temperature region between 100℃-150℃ was due to the domain rearrangements.

The change of spontaneous polarization is found to be 2.858×10??C/㎠ at 25℃-300℃ and pyroelectric coefficient for the LiNbo₃is measure to be 6.32×10??C/㎠℃ at 50℃.