共查询到19条相似文献,搜索用时 421 毫秒
1.
二氧化碲(TeO2)晶体的Raman光谱研究 总被引:5,自引:0,他引:5
利用激光显微高温Raman光谱仪 ,测定了TeO2 晶体的常温Raman光谱及高温熔体法生长TeO2 晶体固 液边界层的高温Raman光谱。通过分析 ,指认了TeO2 晶体的常温Raman谱图 2 0 0~ 80 0cm- 1 谱峰的振动模式 ,解析了高温Raman谱图各谱峰的展宽、频移 ,提出了熔体可能的结构基团 ,从而为研究功能性晶体材料生长机理提供了一定依据。 相似文献
2.
3.
BSO晶体生长固/液边界层结构的实时观测研究 总被引:3,自引:0,他引:3
实时测量BSO晶体水平区熔法生长过程中,研究固/液边界层以及边界层两侧的晶体和熔体的显微拉曼光谱,晶体生长固/液边界层以及边界层两侧的熔体和晶体的结构特征, 生长基元结构从熔体结构经边界层过渡到晶体结构的变化过程。结果显示, BSO熔体中存在Bi3O4和[SiO4]的键合结构; Bi3O4分子基团在固/液边界层聚合形成[BiO7]八面体单体、多聚体,与[SiO4]结构基团联结,在通过固/液边界层时进入格位。 相似文献
4.
测量并研究了不同温度(室温—1573 K)范围内KTN晶体的拉曼光谱及其熔体的高温拉曼光谱,分析了KTN晶体结构随温度变化的规律及其熔体的结构特征.随着温度的升高,KTN晶体的拉曼光谱谱峰都不同程度地向低波数方向移动,同时存在不同程度的展宽,并伴随强度的减弱.观察并解释了温度353 K附近KTN晶体样品的四方—立方转相现象.研究了KTN晶体拉曼光谱中538cm-1,585cm-1,835cm-1和877cm-1谱峰及其
关键词:
高温拉曼光谱
熔体
KTN晶体 相似文献
5.
6.
研究了BGO晶体在不同温度下(在300—1323 K的温度范围)的拉曼光谱及其熔体的高温拉曼光谱,分析了BGO晶体结构随温度变化的规律及BGO熔体的结构特征.随着温度的升高,BGO晶体的拉曼光谱谱峰都不同程度地向低波数方向移动,也存在不同程度的展宽,同时强度减弱.另外,在BGO熔体中存在[GeO4]和[BiO6]的结构基团;但两种结构之间的联键消失,即在熔体中二者是相互独立的生长基元.
关键词:
高温拉曼光谱
熔体
BGO晶体 相似文献
7.
本文利用高温拉曼光谱技术和从头计算的方法, 研究了LiB3O5和CsB3O5晶体高温熔融体的结构, 分析了碱金属阳离子对熔体结构的影响, 以及熔体结构的差异与LiB3O5和CsB3O5晶体结晶习性的联系. 结果表明: LiB3O5和CsB3O5晶体高温熔融体中的结构基团 主要为B3Ø7和B3Ø6两种不同类型的硼氧六元环; 环内BØ4 四面体的数量影响了六元环呼吸振动峰的拉曼频率, 随BØ4四面体数量的增加六元环呼吸振动峰向低频移动; LiB3O5晶体高温熔融体中, BØ4四面体含量相对较多; 然而, 离子半径相对较大的Cs+离子却阻碍了熔体中BØ4四面体的形成, 造成CsB3O5晶体高温熔融体中BØ4/BØ3比值的降低. 结合LiB3O5和CsB3O5晶体生长动力学过程的分析 (Wang D, Wan S M et al. 2011 Cryst. Eng. Comm. 13 5239), 阳离子的不同导致高温熔体中BØ4四面体数量的差异, 被认为是影响LiB3O5和CsB3O5晶体结晶习性的重要因素, 有效降低高温熔体中BØ4四面体的数量, 将是实现LiB3O5晶体生长的关键条件.
关键词:
硼酸盐晶体
熔体结构
拉曼光谱
结晶习性 相似文献
8.
为了研究CNGS晶体的结构,构造了Ca3NbGa2SiO12和Ca3NbGaSi2O12两个团簇模型,对其构型进行优化并计算了振动频率.利用Raman光谱技术测量了该晶体的Raman光谱,依据理论计算结果对测得的Raman光谱进行了指认,讨论了CNGS晶体的层状结构和压电性能. 相似文献
9.
10.
11.
The excitation and emission spectra of CsCdCl3 crystal grown by the Bridgman growth technique, are observed. Its dominant excitation spectra correspond to the transitions between the electronic energy levels of the face-shared [CdCl6]4− octahedron complexes with C3v symmetry. With the help of the molecular orbital diagram of the [CdCl6]4− molecule complex, an approximate electronic energy level diagram of this crystal is constructed using one-electron approximation. 相似文献
12.
Effects of A-site non-stoichiometry on the structural and electrical properties of 0.96K0.5Na0.5NbO3- 0.04LiSbO3 lead-free piezoelectric ceramics
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Effects of A-site non-stoichiometry on the structural and electrical properties of 0.96K0.5+xNa0.5+xNbO3- 0.04LiSbO3 lead-free piezoelectric ceramics were examined for 0 ≤ x ≤ 0.02. The piezoelectric coefficients exhibited a maximum, d33 = 187 pC/N at x = 0.0075, coinciding with the maximum of the grain size and the apparent density at x = 0.0075. The apparent density and the piezoelectric coefficients decreased with increasing x at higher x which was likely due to the crystal geometrical distortion of 0.96K0.5+xNa0.5+xNbO3-0.04LiSbO3. In addition, super-large grains were found and this may be due to liquid phase sintering. Excess (K++Na+) attracted a sum of space charges to keep the charge neutral, resulting in charge leakage during the course of ceramic polarization, influencing the piezoelectric and ferroelectric properties. These findings are of importance for guiding the design of K0.5Na0.5NbO3-based lead-free ceramics with enhanced electrical properties. 相似文献
13.
Akinori Kan Hirotaka OgawaYuki Inami Tohru Moriyama 《Physica B: Condensed Matter》2011,406(17):3170-3174
Bismuth layer-structured (Bi7−xSrx)(Fe3−xTi3+x)O21 (BSFT) ceramics were synthesized and the ferroelectric properties and crystal structure were investigated. X-ray powder diffraction profiles and refinement of the lattice parameters indicated single phase BSFT was obtained in the composition range 0-1.5. The lattice parameter b of BSFT remained almost constant, while a slight decrease in the lattice parameter a was observed by the Sr and Ti substitution for Bi and Fe, respectively, which indicated an increase in the orthorhombicity. The dependence of the BSFT lattice parameter on temperature implied a phase transition from the orthorhombic to the tetragonal phase, which was in good agreement with the Curie temperature. The remnant polarization Pr, of BSFT was significantly improved by the Sr and Ti substitution for Bi and Fe, and ranged from 9 to 16 μC/cm2, although no remarkable variation in the coercive field Ec was observed. As a result, a well-saturated P-E hysteresis loop of BSFT ceramic was obtained at x=0.5 with a Pr of 30 μC/cm at an applied voltage of 280 kV/cm. 相似文献
14.
采用化学共沉淀法制备了不同Ba2+掺杂浓度、 不同煅烧温度的Sr0.8-xBaxEu0.2WO4红色荧光粉. 研究了样品的晶体取向和晶格 畸变对发光性质的影响, 实验结果表明: 合成的Sr0.8-xBaxEu0.2WO4红色荧光粉为四方相, 样品中Eu3+的5D0–7F2跃迁的红光能被近紫外光和蓝光有效激发. 适量的Ba2+离子取代部分的Sr2+提高了Sr0.8Eu0.2WO4荧光粉的发光强度, Ba2+掺杂浓度的改变对基质的晶格参数、晶体对称性和发光性能影响较大, Ba2+的最佳掺杂量为30%. 相似文献
15.
Optical transmittance measurements near the absorption edge of [Kx(NH4)1−x]2ZnCl4 mixed crystals, where x=0.00, 0.232, 0.522, 0.644, 0.859 and 1.00, are reported over 276–350 K range. Analysis reveals that the type of transition is the indirect allowed one. The absorption edge shifted towards lower energy with increasing temperature. It is shown that [Kx(NH4)1−x]2ZnCl4 mixed crystals with x0.644 reveal a phase transition at 319 K, this phase disappeared at high concentrations of K+ ions. The steepness parameter is given, its value is used to estimate the temperature dependence of the indirect energy gap. In the region of the absorption edge, the absorption coefficient obeys Urbach's rule. Urbach parameters are investigated as a function of temperature. 相似文献
16.
Zheng Ke-yu Wei Nian Yang Feng-xia Zhang Duan-ming Qi Ya-jun 《Frontiers of Physics in China》2007,2(4):436-439
Potassium tantalate niobate (KTa0.4Nb0.6O3, KTN) nanoparticles of perovskite structure were successsfully synthesized by a solvothermal method. The KTN nanoparticles
synthesized at 250 °C for 8 h with 1 to 4 M KOH concentration using isopropyl alcohol [(CH3)2 CHOH] as the solvent was composed of a single phase of cubic perovskite structure. Futhermore, the KTN powers synthesized
at the same conditions besides of using (CH3)2CHOH/H2O as a solvent compose of a single phase of tetragonal perovskite structure. The nanoparticles exhibit a mixture of cubic
and prism-like shapes with lengths of 100 nm to 500 nm and average cross sections of 200×200 nm2. The solvent dependence of the powder formation is discussed. X-ray diffraction and electron diffraction results show that
the powders have the needed tetragonal perovskite structure. The band gap of KTN nanoparticles is determined to be 3.26 eV
from the optical absorption spectra.
相似文献
17.
18.
采用溶胶凝胶法制备了Ti1-xCrxO2±δ体系系列样品.利用扫描电子显微镜(SEM),X射线光电子能谱(XPS),粉末X射线衍射分析(XRD)方法研究了Ti1-xCrxO2±δ系列样品的颗粒尺寸、形貌、组分化学态、相关系和固溶区范围;并利用超导量子干涉磁强计对样品的磁性能进行了研究.采用Rietveld结构精修的方法研究了Cr的不同掺杂量对TiO2晶体结构的影响,研究表明,1000℃烧结的样品的固溶区范围是x=0—0.03,为金红石单相;随着Cr掺杂量的增加,金红石相晶胞参数规律性地减小;当x>0.03,为金红石相和CrO2相两相共存.综合XRD和磁性测量结果,500℃烧结的样品的固溶区范围是x=0—0.02,为锐钛矿单相;随着Cr掺杂量的增加,锐钛矿相晶胞参数规律性地减小;当x≥0.04,为锐钛矿相和绿铬矿相(Cr2O3)两相共存.XPS实验结果表明,500℃和1000℃退火的样品中Cr都是以Cr+3和Cr+6两种化学态存在,1000℃烧结的样品中可能有更多的Cr3+转化为Cr6+.根据M-H和M-T曲线的测试结果发现,本文500℃烧结的Ti1-xCrxO2±δ体系样品当x=0—0.02时,为室温铁磁性.当x≥0.04时,由铁磁相和顺磁相所组成,在低温下有较强的铁磁性;室温下主要是顺磁相,铁磁相只占据很小的体积分数.
关键词:
1-xCrxO2±δ体系')" href="#">Ti1-xCrxO2±δ体系
相关系
固溶区
磁性能 相似文献
19.
Raman scattering has been used to study the influence of cobalt, an effective dopant to obtain SrTiO3 magnetic oxide, on the lattice dynamics of SrTiO3. It is found that Co doping increases the lattice defects and induces a Raman vibration mode of 690 cm−1. On the other hand, the ferromagnetism dependence on the x and annealing temperature was clearly and coherently observed in SrTi1−xCoxO3 (x = 0, 0.01, 0.03 and 0.05) nanoparticles. It is found that the ferromagnetism of SrTi1−xCoxO3 nanoparticles is weakly related to crystal deformation and oxygen vacancies in SrTiO3. So, F-center model can explain the origin of the ferromagnetism in the prepared Co-doped SrTiO3 samples. At the same time, the finding of large room-temperature ferromagnetism (1.6 emu/g) in this system would stimulate further interest in the area of more complicated ternary oxides. 相似文献