發(fā)布時(shí)間：2018-05-01 04:46

  本文選題：鐵酸鉍薄膜 + 溶膠-凝膠法　； 參考：《內(nèi)蒙古大學(xué)》2015年碩士論文

【摘要】：鐵酸鉍在室溫下具有多鐵性,即同時(shí)含有鐵電性和反鐵磁性。鐵酸鉍的微觀結(jié)構(gòu)是鈣鈦礦型對(duì)稱三方晶系結(jié)構(gòu),屬于R3c點(diǎn)群。由于鐵酸鉍(BFO)的居里溫度(Tc=1103k)和尼爾溫度(TN=643k)較高,它在未來的鐵電存儲(chǔ)器、傳感器和光全息存儲(chǔ)器等有著廣泛的應(yīng)用前景,因此受國內(nèi)外許多學(xué)者的追捧。本文用化學(xué)方法之一溶膠凝膠方法(sol-gel法),配置了物質(zhì)量濃度為0.2mol/L的純鐵酸鉍(BiFeO3)、Bi0.9Ce0.1FeO3、BiFe0.9Cr0.1O3等前驅(qū)體溶液。然后用勻膠機(jī)在白金襯底上鍍了BiFeO3、 BiFe0.9Cr0.1FeO3、BiFe0.9Cr0.1O3的薄膜,最后經(jīng)掃描電子顯微鏡(SEM)、 X射線衍射(XRD)、拉曼光譜測(cè)試(RAMAN)、光電子能譜測(cè)試(XPS)、鐵電測(cè)試和漏電流等的一系列性能測(cè)試后發(fā)現(xiàn)；(1)摻鈰對(duì)純鐵酸鉍薄膜的性能影響是,通過掃描電子顯微鏡發(fā)現(xiàn),摻鈰之后薄膜的表面形貌更加致密,孔洞明顯減少。XRD結(jié)果表明,鐵酸鉍在32°附近的104峰和110峰,在摻鈰之后合并為一個(gè)峰。這是由于鐵酸鉍原來的對(duì)稱三方晶系相結(jié)構(gòu)變?yōu)樗姆骄�系和斜方晶系相共存結(jié)構(gòu)。拉曼光譜測(cè)試的結(jié)果是,A1-1、A1-2、E-2和A1-3等聲子模都有了紅移,并且在428.25cm-1處的峰也消失。通過XPS測(cè)試發(fā)現(xiàn),摻鈰之后鐵酸鉍的Fe2+離子減少,因而也減少了氧空位。漏電流和鐵電測(cè)試發(fā)現(xiàn),由于鐵二價(jià)離子的減少,使得鐵酸鉍的漏電流降低了約兩個(gè)數(shù)量級(jí),提高了鐵酸鉍的鐵電性,即分別將剩余極化強(qiáng)度和飽和極化強(qiáng)度由原來的6.22μC/cm2提高到25.10μC/cm2和27.07μC/cm2到49.22μC/cm2.(2)摻鉻對(duì)純鐵酸鉍薄膜的性能影響是,通過掃描電子顯微鏡發(fā)現(xiàn),薄膜的表面形貌不同于純相鐵酸鉍,變得顆粒狀不明顯,孔洞也減少,但表面起伏度增加。由XRD晶體結(jié)構(gòu)測(cè)試發(fā)現(xiàn),摻Cr后除了純相鐵酸鉍的主峰,還有在27.9°附近出現(xiàn)了新的峰,這是BiCrO3的(211)晶向主峰,還有在52.9°和57.6°附近出現(xiàn)了兩個(gè)鉻酸鉍的(420)和(422)晶向峰,這表明,摻Cr使BFO原來的三方晶系相結(jié)構(gòu)變?yōu)锽FO和BCO共融體結(jié)構(gòu)。鐵酸鉍的A1-1(cm-1)、A1-2(cm-1)、E-1(cm-1)、 E-2(cm-1)、E-7(cm-1)振動(dòng)模由原來的79.09 cm-1、40.34 cm-1、220.83 cm-1.264、87 cm-1、613.59 cm-1藍(lán)移后變?yōu)?9.62cm-1、140.51cm-1、 222.29cm-1、268.54cm-1、682.61cm-1,而振動(dòng)模A1-3(cm-1)、E-4(cm-1)、 E-6(cm-1)紅移后變?yōu)?70.29 cm-1、342.98 cm-1、506.34 cm-1。振動(dòng)模E-3、E-5摻鈰后消失,有新的模E-8出現(xiàn),這一現(xiàn)象也進(jìn)一步說明了相的變化。摻鉻之后鐵酸鉍的Fe2+離子的減少通過XPS測(cè)試發(fā)現(xiàn),對(duì)純相BFO和BiFe0.9Cr0.1O3的薄膜多鐵性測(cè)試后漏電流降低了,但對(duì)于鐵電性沒有增強(qiáng),反而降低,這是因?yàn)镃r3+離子代替Fe3+離子后,破壞了結(jié)構(gòu)的對(duì)稱性,使BFO薄膜原來的極化機(jī)制變?nèi)跛�致�?br/>[Abstract]:Bismuth ferrate has polyferric properties at room temperature, that is, it contains both ferroelectric and antiferromagnetic properties. The microstructure of bismuth ferrate is a perovskite-type symmetric rhombohedral system and belongs to R3c point group. Because the Curie temperature of bismuth ferrate (BFOO) is higher than that of Nier temperature (TN643k), it will be widely used in ferroelectric memory, sensor and optical holographic memory in the future, so it has been sought after by many scholars at home and abroad. In this paper, the sol-gel method, one of the chemical methods, has been used to prepare the precursor solutions of bismuth ferrate (0.2mol/L) with mass concentration of 0.2mol/L, such as Bi0.9Ce0.1FeO3, BiFe0.9Cr0.1O3 and so on. Then the thin films of BiFeO3, BiFe0.9Cr0.1FeO3and BiFe0.9Cr0.1O3 were deposited on the platinum substrate by a rubber leveling machine. Finally, the effects of cerium on the properties of pure bismuth ferrate thin films were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRDX), Raman spectroscopy (Raman spectroscopy), photoelectron spectroscopy (XPS), ferroelectric measurement and leakage current. Scanning electron microscopy (SEM) showed that the surface morphology of the films was denser after cerium doping. The results of XRD showed that the 104th and 110 peaks of bismuth ferrate near 32 擄were merged into a single peak after cerium doping. The reason is that the phase structure of bismuth ferrate is changed into tetragonal system and oblique crystal system. The Raman spectra show that the phonon modes such as A1-1OA1-2OE-2 and A1-3 have red shifts and the peaks at 428.25cm-1 also disappear. The XPS results show that the Fe2 ion of bismuth ferrate decreases after cerium doping, thus reducing the oxygen vacancy. The leakage current and ferroelectric test show that the leakage current of bismuth ferrate decreases by about two orders of magnitude due to the decrease of iron divalent ions, and the ferroelectric property of bismuth ferrate is improved. That is to say, the residual polarization strength and saturated polarization intensity were increased from 6.22 渭 C/cm2 to 25.10 渭 C/cm2 and 27.07 渭 C/cm2 to 49.22 渭 C / cm ~ (2.2) respectively. The effect of chromium doping on the properties of pure bismuth ferrate thin films was found by scanning electron microscopy. The surface morphology of the films was different from that of pure bismuth ferrate films. It became less granular and the pores decreased, but the surface undulation increased. From the XRD crystal structure test, it is found that in addition to the main peak of pure bismuth ferrate, there is a new peak near 27.9 擄, which is the main peak of the crystal direction of BiCrO3, and there are two peaks of bismuth chromate 420) and calcareous 422) near 52.9 擄and 57.6 擄. Cr-doped BFO changed the original rhombohedral phase structure into BFO and BCO eutectic structure. 閾侀吀閾嬬殑A1-1(cm-1),A1-2(cm-1),E-1(cm-1), E-2(cm-1),E-7(cm-1)鎸�鍔ㄦā鐢卞師鏉ョ�，

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