铌酸锶钡晶体的铁电及光学性能研究

Study on Ferroelectric and Optical Properties of Strontium Barium Niobate Crystal

采用Czochralski方法生长了铌酸锶钡晶体(Sr0.62Ba0.38Nb2O6),研究了其铁电及光学性能。通过测量电滞回线,介电常数随温度的变化,得到晶体自发极化强度为0.294 c/m2,轿顽场为72.4 V/mm,居里温度为74℃,其相变属弥散性铁电相变。由透射光谱得出,晶体吸收边位于375 nm,大于500 nm波段的透过率均在60%以上。由椭偏光谱得出,其no和ne均随着波长增大而减小,波长632.8 nm处的值分别为2.288和2.261。no大于ne,是负单轴晶体。

The strontium barium niobate crystal （Sr0.62 Ba0.38 Nb2O6 ） was grown by the Czochralski method, and the ferroelectric and optical properties were studied. Through the measurement of the variation of dielectric constant with temperature and the Ferroelectric hysteresis loop, it is obtained that the value of spontaneous polarization intensity Ps=0. 294 c/ m^2, coercive field Ec=72.4V/mm and Curie temperature Tc=74 ℃, as this processs of transition belongs to relaxor phase-transition. The transmittance spectrum measurement results reveal that the Crystal absorption edge lies at 375 nm, and the transmittance above 500 nm-band is more than 60 %. Obtained by the ellipsometry method, the dispersion show that both refractive indexes no and ne decrease with the increasing wavelength, obtaining 2.288 and 2.261, respectively. As no is larger than he, so the crystal is optically negative uniaxial.