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991.
(Na0.5K0.5)0.975Li0.025Nb0.82−xSbxTa0.18O3 lead-free piezoceramics were prepared by the conventional solid-state sintering method. All samples possess a pure perovskite phase, and no secondary phase could be certified. The crystal structure changes from tetragonal to pseudo-cubic with increasing amount of Sb. The ferroelectric Curie temperature (Tc) shifts to lower temperature while the tetragonal to orthorhombic phase transition temperature (To-t) shows no obvious change with increasing Sb5+. Enhanced piezoelectric and electromechanical properties are obtained with x=0.06: d33=352 pC/N, kp=47% and kt=38%, showing that they could be promising candidates as lead-free piezoelectric materials. 相似文献
992.
Jianguo Lv Kai Huang Xuemei Chen Jianbo Zhu Lijun Wang Xueping Song Zhaoqi Sun 《Superlattices and Microstructures》2011
The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band. 相似文献
993.
Youyi Sun Guizheng GuoBinhua Yang Wei CaiYe Tian Minghong HeYaqing Liu 《Physica B: Condensed Matter》2011,406(4):1013-1016
A new synthesis method of α-Fe2O3 nanoparticles was developed, in which the ferrous and ferric salts as well as polyaniline acted as the precursor and dispersant, respectively. From the investigation of X-ray diffraction and FT-IR spectra, the α-Fe2O3 nanoparticles can be directly prepared by the co-precipitation method without high-temperature calcining. Transmission electron microscope (TEM) and scanning electron microscope (SEM) observation revealed that the α-Fe2O3 nanoparticles had average diameters ranging from 30.0 to 75.0 nm. Compared with previous methods, this present method shows an easy processing and can be applied on the large-scale produce of α-Fe2O3 nanoparticles in one step. 相似文献
994.
Kwang-Hua W. Chu 《Physica B: Condensed Matter》2011,406(1):80-83
We study the electric-field-driven transport of electrons in superconductors (CuxBi2Se3) by using the borrowed approach which has been successfully adopted to study the critical transport of other superconductors as well as supersolid helium in very low temperature environment. The critical temperatures related to the nearly frictionless transport of electrons were found to be directly relevant to the superconducting temperature of superconductors (CuxBi2Se3) after selecting specific activation energies. 相似文献
995.
Zhiyun Zhang Chonggao Bao Wenjing YaoShengqiang Ma Lili ZhangShuzeng Hou 《Superlattices and Microstructures》2011
Al-doped ZnO (AZO) transparent conducting films were successfully prepared on glass substrates by RF magnetron sputtering method under different substrate temperatures. The microstructural, electrical and optical properties of AZO films were investigated in a wide temperature range from room temperature up to 350 °C by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM), Hall measurement, and UV–visible meter. The nature of AZO films is polycrystalline thin films with hexagonal wurtzite structure and a preferred orientation along c-axis. The crystallinity and surface morphologies of the films are strongly dependent on the growth temperature, which in turn exerts a great effect on microstructural, electrical and optical properties of the AZO films. The atomic arrangement of AZO film having an wurtzite structure was indeed identified by the HRTEM as well as the Selected Area Electron Diffraction (SAED). The defect density of AZO film was investigated by HRTEM. The film deposited at 100 °C exhibited the relatively well crystallinity and the lowest resistivity of 3.6 × 10−4 Ω cm. The average transmission of AZO films in the visible range is all over 85%. More importantly, the low-resistance and high-transmittance AZO film was also prepared at a low temperature of 100 °C. 相似文献
996.
997.
本文报道了利用混合物理化学气相沉积方法(HPCVD)在SiC衬底上制备出约150 nm厚,结构均匀的MgB2薄膜.由R~T曲线知道样品TC(0)高达40.1K.由M~T曲线知道其TC=40.4K,且曲线转变十分陡峭.X射线衍射分析表明薄膜具有较好的C轴取向,没有氧污染,却存在Mg的杂峰.由M~H曲线,利用毕恩模型计算得到了5 K零场条件下JC(0T,5K)=2.7×106A/cm2,Hc2=19.5 T.这些结果表明过量的Mg对MgB2薄膜的转变温度以及有些性质有较大的影响. 相似文献
998.
YBa2Fe3O8(YBFO)是具有三方钙钛矿结构的反铁磁(AFM)体,研究它的结构和磁性质对于我们认识三方钙钛矿结构具有重要作用.目前,关于固相法制备YBFO中退火温度方面的研究并不多,而控制退火温度是这种工艺中的重要环节.为制备高含量的YBa2Fe3O8,本文分别在760℃、950℃和1100℃退火温度下,采用固相... 相似文献
999.
本文基于OH自由基所固有的分子结构特征,通过分子光谱理论系统地分析和计算了OH自由基A2Σ + →X2Πr 电子带系发射光谱的谱线跃迁频率、能级分布以及爱因斯坦自发发射跃迁概率等重要参数.同时结合实际的光谱实验,分析了谱线的自然展宽、碰撞展宽、多普勒展宽以及仪器展宽等各种展宽因素对谱线线型的影响,从理论上计算了任意转动温度、振动温度以及谱线展宽条件下OH自由基A2Σ 关键词:
发射光谱
转动温度
振动温度
自发发射爱因斯坦跃迁概率 相似文献
1000.
Ce0.8Gd0.05Y0.15O1.9 (GYDC) electrolyte was prepared by a carbonate co-precipitation method. Lithium nitrate at 1, 1.5, 2 and 3 mol% was added to GYDC as sintering additive. 96% relative density was achieved for GYDC at sintering temperature of 800 °C with addition of 1.5 mol% LiNO3. The conductivities of GYDC with sintering aids LiNO3 were measured by a.c. impedance spectroscopy and showed comparable values to that of pure GYDC sample sintered at 1400 °C. A single cell with 1.5 mol% LiNO3 infiltrated GYDC electrolyte was fabricated by sintering at 800 °C for only 2 h. Lithiated NiO was synthesized by the glycine-nitrate combustion method and employed as cathode material. The cell was tested at temperatures from 500 to 575 °C and a maximum power density of 73 mW cm− 2 was obtained at 575 °C. These preliminary results indicate that LiNO3 is a very effective sintering additive for intermediate temperature solid oxide fuel cell fabrication. 相似文献