热压烧结制备KNN基透明陶瓷

发布时间：2018-03-17 08:12

本文选题：铌酸钾钠　切入点：热压烧结　出处：《常州大学》2015年硕士论文　论文类型：学位论文

【摘要】：利用烧结助剂通过热压烧结工艺成功制备了钙钛矿结构的铌酸钾钠(KNN)基透明陶瓷。研究了稀土掺杂后透明陶瓷的光学性能和荧光特性,以及引入Sr2+、Ba2+后对介电及压电性能的影响。具体研究内容包括:(1)采用热压烧结工艺,以Li和Bi作为烧结助剂,制备了铌酸钾钠基上转换透明陶瓷K0.5(1-y)Na0.5(1-y)LiyNb1-yBiy O3-Er0.005Yb0.005x(KNNLB:Er/Yb)。并对其微观结构、光学透光率和上转换效应等进行了研究。结果表明:该透明陶瓷具有正交钙钛矿型结构,晶粒尺寸小于1μm,致密度较高,具有良好的透明性,当y=0.06、x=0时,在可见光范围内透过率可达到45%(样品厚度为0.5 mm),红外光区域透过率达到95%以上。但是随着Yb3+离子掺杂量的增加,产生的杂相量变多,光学透光率因此呈明显的下降趋势。该体系透明陶瓷用氙灯光源激发(900 nm波长)即可以观察到很明显的上转换效应。(2)采用热压工艺制备出未掺杂的以及Eu3+掺杂的铌酸钾钠基下转换透明陶瓷K0.47Na0.47Li0.06Nb0.94Bi0.06O3-Eux(KNN:Eu)。陶瓷的断面扫描电镜表明这些陶瓷具有致密的微观结构,XRD结果显示制得的陶瓷都具有纯相的钙钛矿结构。对该体系透明陶瓷的光学透光度、室温下的光致发光激发谱和发射谱研究表明:这些陶瓷具有良好的光学透光率,在可见光区域最高可以达到60%,而在红外区域能够达到接近100%。高掺杂浓度引起的离子空位和晶体缺陷的增加会导致这些陶瓷在可见光区域的透过率降低。对光致发光谱的分析表明,基于下转换效应,这些陶瓷可以在近紫外和蓝色光的激发下发射出很强的红色荧光,其中与Eu3+的电偶极跃迁5D0-7F2相关的位于613 nm处的发射光尤其强烈。此外在晶体结构的基础上对陶瓷的光致发光特性进行了分析,结果表明陶瓷的晶相转变引起了发射谱线的Stark分裂。研究显示这些透明陶瓷可以作为潜在的红色荧光基底材料。(3)将碱土离子Sr2+、Ba2+引入KNN体系,采用热压工艺制得透明KNN基陶瓷[(K0.5Na0.5)1-2x(Sr0.75Ba0.25)x]0.93Li0.07Nb0.93Bi0.07O3(KNNLB:Sr/Ba)。对陶瓷的晶相结构、压电及介电性能进行了初步的研究。结果表明微量的Sr2+、Ba2+掺杂可以有效的提高此陶瓷材料的电学性能。当掺杂量x=0.025时,此陶瓷拥有最佳的电学性能参数:εr=1679,d33=151 pC/N和tanδ=0.026。然而过多的Sr2+/Ba2+掺杂量会引起杂相的产生,电学性能也会随之迅速下降。
[Abstract]:KNN-based transparent ceramics with perovskite structure were successfully prepared by hot pressing sintering with sintering aids. The optical properties and fluorescence properties of rare-earth doped transparent ceramics were studied. The effect of Sr2 Ba2 on the dielectric and piezoelectric properties was studied. (1) the potassium and sodium niobate based up-conversion transparent ceramics K _ 0.5N _ (1-yn) Na _ (0.5) N _ (1-yBi) O _ (3) er 0.005Yb 0.005x KNLB: Er-YbO _ (1) were prepared by hot-pressing sintering process and Li and Bi as sintering aids. The microstructure of KNLB _ (1) -Y _ (2) O _ (3) O _ (3) O _ (3) er _ (0.005) Yb _ (0.005) Y _ (1) O _ (3) was studied. The optical transmittance and upconversion effect are studied. The results show that the transparent ceramic has orthogonal perovskite structure, grain size is less than 1 渭 m, high density and good transparency, when yr 0.06 X = 0:00, In the visible range, the transmittance can reach 45% (the thickness of the sample is 0. 5 mm ~ (-1), the transmittance of the infrared region is over 95%. However, with the increase of the doping amount of Yb3 ions, the amount of heterogeneity will increase. The optical transmittance of this system is obviously decreasing. The transparent ceramics in this system are excited by xenon lamp light source at 900nm) the obvious upconversion effect can be observed. (2) the undoped and Eu3 doped ceramics are prepared by hot pressing process. K0.47Na0.47Li0.06Nb0.94Bi0.06O3-EuxN = Eu.0.47Na0.47Li0.06Nb0.94Bi0.06O3-EuxN: Eu.The sectional scanning electron microscope of the ceramics shows that all of the ceramics have dense microstructure and the XRD results show that all of the ceramics have pure perovskite structure. The optical transmittance of the transparent ceramics in this system is also studied. The photoluminescence excitation and emission spectra at room temperature show that these ceramics have good optical transmittance. It can reach up to 60 in the visible region and close to 100 in the infrared region. The increase of ion vacancy and crystal defect caused by high doping concentration will reduce the transmittance of these ceramics in the visible region. Spectral analysis shows that, Based on the downconversion effect, these ceramics emit strong red fluorescence under the excitation of near ultraviolet and blue light. The emission at 613nm, which is related to the dipole transition of Eu3 5D0-7F2, is especially strong. The photoluminescence properties of the ceramics are analyzed based on the crystal structure. The results show that the crystal phase transition of the ceramics leads to the Stark splitting of the emission lines. The results show that these transparent ceramics can be used as the potential red fluorescent substrates to introduce alkali earth ion Sr2 Ba-2 into the KNN system. Transparent KNN based ceramics [K0.5Na0.51-2xFSr0.75Ba0.25x] 0.93Li0.07Nb0.93Bi0.07O3KNLBSr-Bax were prepared by hot pressing process. The crystal structure, piezoelectric and dielectric properties of the ceramics were studied. The results show that the electrical properties of the ceramics can be improved effectively by microamount of Sr2 Ba2 doping. This ceramic has the best electrical properties: 蔚 rn 1679 d 33C 151 pC/N and tan 未 O 0.026. However, excessive doping of Sr2 / Ba 2 leads to the generation of heterogenous phase, and the electrical properties decrease rapidly.
【学位授予单位】：常州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.758.23

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