本文選題：密度泛函理論 + BiFeO3��； 參考：《青島大學(xué)》2015年碩士論文

【摘要】：BiFeO3是多鐵材料的一種,具有鐵電性、鐵磁性和反鐵磁性,在傳感器、鐵電存貯器等方面有很好的潛在應(yīng)用價值,近年來BiFeO3在光伏領(lǐng)域又有了新的研究進(jìn)展,因此其光電特性成為了研究熱點(diǎn)。本論文采用第一性原理方法計算研究了多鐵材料中BiFeO3在純相和摻雜兩種情況下的幾何結(jié)構(gòu),電子特性,光學(xué)性質(zhì)。重點(diǎn)討論了單相BiFeO3陶瓷的光吸收以及稀土元素?fù)诫s對其吸收光譜的影響。我們首先運(yùn)用了第一性原理密度泛函理論中的局域自旋密度近似加U(LSDA+U)方法對單相BiFeO3的帶隙進(jìn)行了調(diào)節(jié),計算結(jié)果顯示,當(dāng)U值等于16.5ev時,BFO的帶隙值為2.418ev且為間接帶隙,這與實(shí)驗(yàn)測試值2.5ev左右相符。在此基礎(chǔ)上我們分別計算了其電子結(jié)構(gòu)及光學(xué)性質(zhì)。結(jié)果發(fā)現(xiàn),紫外區(qū)域的吸收效果非常好,在可見光范圍內(nèi)當(dāng)入射光波長在400nm左右時吸收效果最好,根據(jù)可見光光譜范圍其對應(yīng)的入射光是紫光,對應(yīng)著從O 2p(向上)態(tài)到Fe 3d(向下)態(tài)的電子躍遷。第四章是有關(guān)稀土元素Co對鐵電體BiFeO3斜六方相B位摻雜對其態(tài)密度以及光學(xué)吸收影響的研究。結(jié)果發(fā)現(xiàn),摻雜以后吸收光譜的范圍從可見光變到了紫外區(qū)域。這可以從側(cè)面說明Co元素B位摻雜BiFeO3對其光吸收光譜的影響是發(fā)生藍(lán)移。
[Abstract]:BiFeO3 is a kind of multi-iron material, which has ferroelectricity, ferromagnetism and antiferromagnetism. It has good potential application value in sensor, ferroelectric memory and so on. In recent years, BiFeO3 has made new progress in photovoltaic field. Therefore, its photoelectric characteristics have become a research hotspot. In this paper, the geometrical structure, electronic properties and optical properties of BiFeO3 in pure phase and doped multiferric materials have been calculated and studied by first-principle method. The light absorption of single phase BiFeO3 ceramics and the effect of rare earth element doping on their absorption spectra were discussed. We first use the local spin density approximation plus U(LSDA U) method in the first principle density functional theory to adjust the band gap of the single-phase BiFeO3. The calculated results show that the band gap of the single phase BiFeO3 is 2.418ev and indirect band gap when the U value is equal to 16.5ev. This is consistent with the experimental value of 2.5ev. On this basis, the electronic structure and optical properties are calculated respectively. The results show that the absorption effect in the ultraviolet region is very good, and the absorption effect is the best when the incident wavelength is about 400nm in the visible range. According to the visible spectrum range, the incident light is purple. It corresponds to the electron transition from O 2p (upward) state to Fe 3d (downward) state. In chapter 4, the effects of rare earth Co doping on the density of states and optical absorption of ferroelectric BiFeO3 obliquely hexagonal B site are studied. The results show that the range of absorption spectrum changes from visible light to ultraviolet region after doping. It can be seen from the side that the effect of BiFeO3 doping on the optical absorption spectrum is blue shift.
【學(xué)位授予單位】：青島大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ174.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 施科;何泓材;王寧;;多鐵性磁電材料應(yīng)用于存儲技術(shù)的研究現(xiàn)狀[J];硅酸鹽學(xué)報;2011年11期

2 晏伯武;;多鐵性材料及其研究進(jìn)展[J];現(xiàn)代技術(shù)陶瓷;2009年04期

3 晏伯武;;鐵電磁體BiFeO_3及其研究進(jìn)展[J];中國陶瓷;2010年11期

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本文編號：1779519