本文選題：磷酸鉛 + 拉曼光譜�。� 參考：《新疆大學(xué)》2017年碩士論文

【摘要】：隨著社會(huì)的發(fā)展和能源的消耗,環(huán)境污染問(wèn)題越來(lái)越嚴(yán)重。多鐵性材料的研究在解決該問(wèn)題上能夠提供一個(gè)很有效的解決方法。多鐵性材料是多性能的材料,具有鐵電、鐵磁、鐵彈的特性,同時(shí)具有兩種或者兩種以上鐵性的新型材料。多鐵性材料在現(xiàn)代科學(xué)研究領(lǐng)域與實(shí)際應(yīng)用當(dāng)中吸引了越來(lái)越多的關(guān)注,引發(fā)了大量的研究,發(fā)表了許多科研論文。目前為止依然是研究的熱門(mén)話題之一。盡管如此,由于多鐵性材料的鐵彈性能很難滿足實(shí)際應(yīng)用的需要,因此發(fā)展鐵彈性材料的彈性性能是非常重要的,并在該材料的研究中具有主導(dǎo)作用。磷酸鉛Pb_3(PO_4)_2是一種典型的鐵彈性材料。在材料和地球科學(xué)領(lǐng)域中,其在高壓和室溫下的相變行為采用各種方法已被廣泛研究。本文采用高溫拉曼光譜和高溫布里淵光譜方法來(lái)研究鐵彈性磷酸鉛單晶體,發(fā)現(xiàn)該單晶體具有很強(qiáng)的鐵彈性能力,晶體分別在光路平行極化、垂直極化、無(wú)偏振的情況下的內(nèi)外振動(dòng)模式、居里溫度、生成的模數(shù)都不同而已。論文的主要工作,內(nèi)容布局、得到的結(jié)果如下:(1)本論文的前三章主要是解釋多鐵性材料的研究背景、描述了國(guó)內(nèi)和國(guó)外的研究現(xiàn)狀和研究目的及其研究意義、分類(lèi)、性能、自由能、熱熔、應(yīng)力與應(yīng)變等理論基礎(chǔ),光的散射、晶體的相變以及相變的分類(lèi)這為我們的科學(xué)研究打下一定的基礎(chǔ)。(2)鐵彈性磷酸鉛單晶體在高溫拉曼光譜研究。拉曼光譜中顯示出,單晶體的溫度高達(dá)182℃的顯著變化,然后沒(méi)有顯示出明顯的溫度依賴(lài)性。在VH幾何環(huán)境溫度下41cm~(-1)處的模式顯示輕度軟化至182℃,并且在該溫度以上消失,而在VV幾何形狀中,該最低模式在182℃以上沒(méi)有完全消失。在溫度大概達(dá)到180℃時(shí),140 cm~(-1),159 cm~(-1)和184 cm~(-1)處的三個(gè)模隨著溫度的升高逐漸變寬。在386 cm~(-1)和413 cm~(-1)處的拉曼模式也合并成185℃以上的拉曼模式。表明當(dāng)T_c=182℃時(shí),在三角相中L點(diǎn)的失穩(wěn)引起Pb_3(PO_4)_2的一階鐵彈相變,即從高溫(HT)三角形鐵彈相,空間晶體結(jié)構(gòu)R(?)m-D_(3d)~5,向低溫(LT)單斜相,空間晶體結(jié)構(gòu)C2/C_(2h)~6,轉(zhuǎn)變,從而使晶胞體積加倍。我們的結(jié)果也表明,高溫相變過(guò)程非常復(fù)雜。VV幾何振動(dòng)模式中41 cm~(-1)處,最低拉曼模式的高溫行為表明,盡管相轉(zhuǎn)變發(fā)生在182℃,但是一些單斜晶體微疇仍然存在于T_c以上。在高于T_c的高溫下的中間范圍內(nèi)的拉曼模式的廣泛性質(zhì)表明在三角相中存在無(wú)序的局部結(jié)構(gòu)。(3)鐵彈性磷酸鉛單晶體在高溫布里淵光譜研究。使用布里淵光譜學(xué)研究了高溫下彈性Pb_3(PO_4)_2在后向散射幾何中的彈性特性和相變機(jī)理。在室溫下觀察到一個(gè)縱向聲學(xué)(LA)和兩個(gè)橫向聲學(xué)(TA)模式,與反向散射幾何中單斜對(duì)稱(chēng)的選擇規(guī)則一致。在20℃至300℃的溫度范圍內(nèi)測(cè)量三個(gè)聲學(xué)聲子。隨著溫度的升高,聲子頻率,線寬和強(qiáng)度顯示明顯的變化。在181℃時(shí),兩個(gè)TA模式減少到一個(gè)了。然后我們觀察到只有兩個(gè)聲學(xué)聲子直到300℃,表明從單斜晶系結(jié)構(gòu)到較高對(duì)稱(chēng)相的相變。在180℃以上觀察到的LA和TA聲子與該測(cè)量幾何中的三角對(duì)稱(chēng)性的選擇規(guī)則一致。
[Abstract]:With the development of society and the consumption of energy, the problem of environmental pollution is becoming more and more serious. The study of multi iron materials can provide a very effective solution to this problem. The multi iron material is a multi performance material with the characteristics of ferroelectric, ferromagnetic and iron, with two or more than two kinds of iron. Sexual materials have attracted more and more attention in the field of modern scientific research and practical applications, which have caused a lot of research and published many scientific research papers. So far, it is still one of the hot topics of research. Nevertheless, the development of ferroelastic material is due to the difficulty of the ferroelastic properties of the multi iron material to be full of practical application. The elastic properties of the material are very important and play a leading role in the study of the material. Lead phosphate Pb_3 (PO_4) _2 is a typical kind of iron elastic material. In the field of material and earth science, the phase transition behavior at high pressure and room temperature has been widely studied. The spectral method is used to study the iron elastic lead phosphate single crystal. It is found that the single crystal has a strong iron elastic ability. The internal and external vibration modes of the crystal are in parallel polarization, vertical polarization and no polarization respectively. The Curie temperature and the generated modulus are different. The main work of the paper and the content layout are as follows: (1) this paper (1) this paper The first three chapters mainly explain the background of the research on the multiferroic materials, and describe the status and purpose of research at home and abroad and the significance of research, classification, performance, free energy, thermal melting, stress and strain and other theoretical bases, light scattering, crystal phase transition and phase transition. (2) iron Raman spectra of elastic lead phosphate single crystals show that the temperature of the single crystal is significantly higher than 182 degrees C, and there is no apparent temperature dependence. The mode of 41cm~ (-1) at the temperature of VH shows a mild softening to 182 C, and it disappears above the temperature, but in the geometry of the VV, The minimum mode is not completely disappearing at 182 degrees centigrade. At the temperature of 180 C, the three modes at 140 cm~ (-1), 159 cm~ (-1) and 184 cm~ (-1) gradually widen with the increase of temperature. The Raman modes at 386 cm~ (-1) and 413 cm~ (-1) are also merged into the Raman modes above 185 degrees C. Instability causes the first order iron elastic phase transition of Pb_3 (PO_4) _2, that is, from high temperature (HT) triangular iron projectile phase, space crystal structure R (?) m-D_ (3D) ~5, low temperature (LT) monoclinic phase, and C2/C_ (2H) ~6 of space crystal structure, so that the cell volume doubles. The high temperature behavior in the low Raman mode shows that although the phase transition occurs at 182 C, some monoclonal crystal microdomains still exist above T_c. The extensive properties of Raman modes in the intermediate range above the high temperature of T_c indicate that there is a disordered local structure in the triangle phase. (3) the high temperature Brillouin spectrum of the iron elastic lead phosphate single crystal. Study. The Brillouin spectroscopy was used to study the elastic properties and phase transition mechanism of elastic Pb_3 (PO_4) _2 at high temperature in backscattering geometry. A longitudinal acoustic (LA) and two transverse acoustic (TA) modes were observed at room temperature, consistent with the selection rules of monoclinic symmetry in the backscatter geometry. The measurement of three in the temperature range of 20 to 300 C Acoustic phonons. With the increase of temperature, the phonon frequency, line width and strength show obvious changes. At 181 C, two TA modes are reduced to one. Then we observe only two acoustic phonons until 300 degrees, indicating the phase transition from the monoclinic system to the higher symmetric phase. The LA and TA phonons observed above 180 degrees C and the measurement are also observed. The selection rules of trigonometric symmetry in geometry are consistent.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TQ134.33

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