(中國石油大學(xué)(華東)機(jī)電工程學(xué)院，青島 266580)
摘 要: 通過原子環(huán)境計(jì)算分析正交相SrBi4Ti4O15(SBTi)的空間鍵絡(luò)結(jié)構(gòu)，根據(jù)固體與分子經(jīng)驗(yàn)電子理論(EET)計(jì)算正交相SrBi4Ti4O15(SBTi)的價(jià)電子結(jié)構(gòu)，進(jìn)而求得晶體中各原子的有效價(jià)電子數(shù)。根據(jù)空間群理論構(gòu)建SBTi鐵電-順電相變過程中的正交順電結(jié)構(gòu)(Aama)和四方順電結(jié)構(gòu)(I4/mmm)，并通過原子坐標(biāo)分析得到相變過程中晶體內(nèi)各原子的原子位移。最后根據(jù)自發(fā)極化與原子位移和原子有效價(jià)電子數(shù)之間的關(guān)系，求得正交相SBTi沿a軸方向的自發(fā)極化強(qiáng)度為25.81 μC/cm2，與實(shí)驗(yàn)結(jié)果和其他理論參考值吻合較好。
關(guān)鍵字: 價(jià)電子結(jié)構(gòu)；經(jīng)驗(yàn)電子理論；鐵電相變；原子位移；自發(fā)極化
（College of Mechanic and Electronic Engineering,
China University of Petroleum (East China）
Abstract:The chemical bonds structures were analyzed by the atomic environment calculation method, and the valence electron structure of orthorhombic phase SrBi4Ti4O15 was calculated according to the EET theory, the numbers of the effective valence electrons of each atom in SrBi4Ti4O15 were obtained. Furthermore, according to the theory of crystal space group, the structures of orthogonal paraelectric phase (Aama) and the tetragonal paraelectric phase (I4/mmm) in the ferroelectric-paraelectric phase transition were constructed, and the atomic displacements in the phase transition were calculated by the atomic coordinate analysis. The spontaneous polarization in SrBi4Ti4O15 was studied based on the atomic displacements and atomic effective valence electrons numbers. The calculated spontaneous polarization strength in ferroelectric SrBi4Ti4O15 along the a axis is 25.81 μC/cm2, which is in good agreement with the experimental and other theoretical results.
Key words: valence electron structure; empirical electron theory; ferroelectric phase transition; atomic displacement; spontaneous polarization
