稀土掺杂钛酸铋铁电薄膜的光电性能研究

发布时间：2018-07-28 17:07

【摘要】：本文选用化学溶液沉积法(chemical solution deposition, CSD)分别在ITO导电玻璃衬底和石英玻璃衬底上制备(Bi,Eu) 4Ti3O12 (BEuT)铁电薄膜,研究了衬底种类、退火温度、掺杂量等对BEuT铁电薄膜结构、铁电性能及光致发光等性能的影响。为了进一步提高薄膜性能,采用复合薄膜制备技术探索了基于BEuT不同形式复合的ZnO/BEuT铁电薄膜的性能,旨在增强材料的发光性能并弄清其机理。研究的主要内容包括：(1) 在ITO导电玻璃衬底上分别制备不同退火温度Bi3.45Eu0.55Ti3O12铁电薄膜。XRD研究结果表明,BEuT薄膜都呈铋层状钙钛矿结构,且没有出现其他杂相。SEM发现,随着退火温度的提高,薄膜的平均晶粒尺寸增加。光学透过率曲线显示,BEuT薄膜在可见光区具有较高的光学透过率；在低于约350 nm的紫外波段,薄膜对光强烈吸收。铁电性能的测试表明,所制备的BEuT薄膜都具有较好的铁电性能。BEuT光致发光谱的研究表明,Eu3+离子将以5D0→7F1发射光(594 nm)和5D0→7F2发射光(617 nm)。而且,采用波长350 nm的光能更有效地激发Eu3+,这是由于Bi3+离子的发射谱覆盖大部分的Eu3+的激发谱。在石英玻璃衬底上制备的BEuT铁电薄膜,具有类似的温度依赖特性。但石英玻璃衬底制备的BEuT薄膜具有更高的光学透过率,以及更好的发光性能。(2) 研究Eu3+掺杂量对Bi4-xEuxTi3O12铁电薄膜光致发光性能和光学透过率的影响。结果发现Eu3+掺杂量对BEuT薄膜发光强度的影响是比较明显的。BEuT薄膜的发光受浓度猝灭效应的影响。两种衬底的浓度猝灭值均为x=0.40。这个Eu3+的浓度猝灭值是比较大的。因而BEuT薄膜可作为高亮度发光薄膜的候选材料。然而,不同掺杂量的BEuT薄膜样品对光学透过率影响很小。(3) 研究不同形式复合的ZnO/BEuT复合薄膜的发光性能。复合的形式包括交替生长ZnO膜层和BEuT膜层的层状复合薄膜材料,以及将纳米ZnO粉末均匀分散在BEuT薄膜中的纳米复合薄膜材料,还有ZnO-BEuT固溶体状的复合薄膜材料。研究证实,采用复合薄膜的方法均能显著提高BEuT薄膜的光致发光性能。而层状复合的方式效果相比其他方式稍差。这主要是因为在层状复合方式中,ZnO与BEuT还不能充分地接触,所以能量传递效率不如其它方式高。而像ZnO纳米粉末,由于具有很高的比表面积,所以很容易将吸收的入射光能量传递给Eu3+离子,最终使其发射出可见光。
[Abstract]:In this paper, (Bi-EU) 4Ti3O12 (BEuT) ferroelectric thin films were prepared on ITO conductive glass substrates and quartz glass substrates by chemical solution deposition (chemical solution deposition, CSD) method. The structure of BEuT ferroelectric thin films was investigated by substrate type, annealing temperature, doping amount, etc. Effects of ferroelectric and photoluminescence properties. In order to further improve the properties of ZnO/BEuT ferroelectric thin films, the properties of ZnO/BEuT ferroelectric thin films based on different forms of BEuT were investigated by using the composite thin film preparation technology, in order to enhance the luminescence properties of the materials and clarify their mechanism. The main contents are as follows: (1) Bi3.45Eu0.55Ti3O12 ferroelectric thin films with different annealing temperatures were prepared on ITO conductive glass substrates. The results showed that all of the Bi3.45Eu0.55Ti3O12 thin films were of bismuth layered perovskite structure, and no other heterophases were found. With the increase of annealing temperature, the average grain size of the films increases. The optical transmittance curves show that the BEuT thin films have high optical transmittance in the visible region and strong absorption in the ultraviolet band below 350 nm. The measurements of ferroelectric properties show that all BEuT films have good ferroelectric properties. BEuT photoluminescence spectra show that the EU 3 ion will emit light from 5D0 7F1 (594nm) and 5D0 7F2 (617 nm). Moreover, the wavelength of 350nm is used to excite Eu3 more effectively, which is because the emission spectrum of Bi3 ions covers most of the excitation spectra of Eu3. The BEuT ferroelectric thin films prepared on quartz glass substrates have similar temperature-dependent properties. However, the BEuT thin films prepared on quartz glass substrates have higher optical transmittance and better luminescence properties. (2) the effect of Eu3 doping on the photoluminescence and optical transmittance of Bi4-xEuxTi3O12 ferroelectric thin films is studied. The results show that the effect of Eu3 doping on the luminescence intensity of BEuT thin films is obvious. The luminescence of. BEuT thin films is affected by the concentration quenching effect. The concentration quenching values of the two substrates are both 0.40. The concentration quenching value of this Eu3 is relatively large. Therefore, BEuT thin films can be used as candidate materials for high brightness luminescent films. However, different doped BEuT films have little effect on optical transmittance. (3) the luminescence properties of ZnO/BEuT composite films with different forms are studied. The composite forms include the layered composite films of ZnO and BEuT films grown alternately, the nano-composite films which disperse nano-ZnO powder uniformly in the BEuT films, and the ZnO-BEuT solid solubily-like composite thin film materials. The results show that the photoluminescence properties of BEuT thin films can be significantly improved by using composite films. However, the effect of layered composite is slightly worse than that of other methods. This is mainly due to the fact that the energy transfer efficiency is not as high as that of other methods due to the insufficient contact between BEuT and BEuT in the laminated composite mode. Because of its high specific surface area, it is easy to transfer the absorbed incident light energy to the Eu3 ion, which eventually emits visible light.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM221

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