体积应变对立方钛酸铅电子结构和光学性质的影响

本文利用第一性原理方法计算并分析了体积应变(-11%~11%)对立方顺电相PbTiO₃的结构、稳定性、电子结构和光学性质的影响。研究发现体积应变后PbTiO₃形成焓增大,稳定性下降,其中压应变对其稳定性的影响比拉应变大。当受到拉伸应变时,立方PbTiO₃由直接带隙半导体变为间接带隙半导体,且带隙随应变增大呈先增大后降低的趋势。在发生压应变时,从复介电函数、复折射率及吸收系数的分析结果可知,在自然光照下PbTiO₃的光吸收能力仅在个别波段有所增大,但总体呈减弱趋势,当产生拉伸应变时,介电峰、吸收峰红移,表明PbTiO₃在可见光范围内光吸收能力增强,并且当应变增大到11%时,PbTiO₃的吸收能力远高于本征立方相。

Effect of Volume Strain on Electronic Structure and Optical Properties of Cubic Lead Titanate

Effect of volume strain(-11%~11%)on the structure,stability,electronic structure and optical properties of cubic paraelectric phase PbTiO₃ was calculated and analyzed via first-principles method.It is found that formation enthalpy increases and stability decreases for PbTiO₃ after volume strain.And the influence of compressive strain on the stability of PbTiO₃ is greater than that of tensile strain.When subjected to tensile strain,cubic PbTiO₃ changes from direct bandgap semiconductor to indirect bandgap semiconductor,and bandgap increase first and then decrease with the increase of strain.When compressive strain occurs,from the analysis of complex dielectric function,complex refractive index and absorption coefficient,the light absorption capacity of PbTiO₃ weakens under natural light,with fluctuations in individual wavelength.When tensile strain occurs,dielectric peak and absorption peak redshifts,and light absorption capacity of PbTiO₃ in visible light range is enhanced.Furthermore,when strain increases to 11%,the aforementioned absorption capacity outclasses than that in intrinsic cubic phase.