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91.
Bi2Te2.7Se0.3of high performance doped with Gd bulk materials was prepared by a high pressure(6.0 GPa) sintering(HPS) method at 593 K,633 K, 673 K and 693 K. The sample was then annealed for 36 h in a vacuum at 633 K. The phase composition, crystal structure and morphology of the sample were analyzed by X-ray diffraction and scanning electron microscopy. The electric conductivity, Seebeck coefficient, and thermal conductivity aspects of the sample were measured from 298 K to 473 K. The results show that high pressure sintering and the doping with Gd has a great effect on the crystal structure and the thermoelectric properties of the samples. The samples are consisted of nanoparticles before and after annealing, and these nanostructures have good stability at high temperature. HPS together with annealing can improve the TE properties of the sample by decreasing the thermal conductivity of the sample with nanostructures. The maximum ZT value of 0.74 was obtained at 423 K for the sample, which was sintered at 673 K and then annealed at 633 K for 36 h. Compared with the zone melting sample, it was increased by 85% at423 K. Hence the temperature of the maximum of figure of merit was increased. The results can be applied to the field of thermoelectric power generation materials. 相似文献
92.
Single crystalline Fe-doped ZnO nanocantilever arrays have been synthesized by thermal evaporating amorphous Zn-Fe-C-O composite powder. The characterizations of composition, structure and phonon spectrum properties of the nanocantilevers have been performed. Arrays of uniform, perfectly aligned and single-crystal nanowires have been observed by electron microscopy. The results of the X-ray photo-electric spectra and the Raman spectrum provide the evidence that Fe is incorporated into the ZnO lattice at Zn site. Abnormally, the room temperature UV emission band of Fe-doped ZnO nanocantilevers disappears and the green one has a large red-shift, and the intensity of the green emission is strongly quenched because the Fe^3+ enters the ZnO crystal lattice. 相似文献
93.
LiF:Mg,Cu,P和LiF:Mg,Cu样品主峰温度相近,推断形成样品中相应峰的缺陷有相似结构。同剂量LiF:Mg,Cu和LiF:Mg,Cu,P发光曲线相似,但发光谱中心却差别很大,推测LiF:Mg,Cu,P复合中心与P元素有密切关系。 相似文献
94.
制备了DCM掺杂层靠近阴极的双发光层有机发光器件ITO/CuPc/NPB/Alq3(发射绿光)/Alq3:DCM(发射红光)/LiF/Al,并在不同温度下测量了该器件和无DCM掺杂的单发光层参考器件的磁电致发光(Magneto-ElectroLuminescence,MEL)和磁电导(Magneto-Conductance,MC).在注入相同电流密度下,发现双发光层器件MEL的高场(B50mT)效应随温度降低呈现先减小后增大的非单调变化,这与单发光层参考器件的单调递增变化明显不同.同时测量了不同温度下的电致发光光谱,发现双发光层器件的533nm和600nm两个特征峰的强度随温度变化出现了此消彼长的现象,表明激子复合区域随温度变化发生了移动.通过分析工作温度对器件各发光层中的三重态激子对间相互作用及载流子迁移率的影响,对双发光层器件中MEL的高场效应随温度的非单调变化进行了定性解释.实验结果进一步验证了在单发光层器件中得到的有机磁效应高场变化的相关结论. 相似文献
95.
本文通过溶胶-凝胶法,研制了氧化镍一氧化锌复合薄膜/Sn掺杂玻璃光波导(OpticalWaveguide,owe)气体传感器,并调节敏感层(yio—ZnO薄膜1中NiO的最佳含量对挥发性有机物气体进行检测。所研制的(5%)NiO—ZnO复合薄膜/sn掺杂玻璃光波导气体传感器对体积比浓度为1×10—7(v/vo)的二甲苯气体具有一定的选择性响应。该传感器具有灵敏度高、容易制备和重复使用等特点。 相似文献
96.
为了探究掺杂对材料光学性能的影响,采用基于密度泛函理论的第一性原理的平面波赝势方法研究313 K时YB6、La0.125Y0.875B6、La0.250Y0.750B6的电子结构、能带结构和光学性能。结果表明,La替换Y原子掺杂YB6使总态密度和能带结构能量下降,随着YB6中La掺杂量增加至25%时,材料会明显降低对近红外线的反射率和吸收系数,反而增加透过性。 相似文献
97.
模式竞争效应是实现激光器稳定输出的理论基础。由于各纵模的损耗不同,导致起振阈值不同。在测量掺铒光纤Bragg光栅FP腔激光器振荡模式损耗的基础上,对掺铒光纤Bragg光栅FP腔激光器的模式竞争效应进行理论与实验研究。采用衰荡光谱技术测量掺铒光纤Bragg光栅FP腔激光器振荡模式的损耗,确定各振荡模式的阈值条件,讨论激光器中的模式竞争。研究结果表明各振荡纵模损耗直接影响模式竞争结果。所得结果为单波长、双波长及多波长光纤激光器制作提供理论依据。 相似文献
98.
采用溶胶凝胶法制备La掺杂改性纳米TiO_2光催化材料,利用X射线衍射仪与jade软件分析材料的晶相结构与晶格参数,采用三因素正交试验法探索La掺量、热处理温度、热处理时间对材料的光催化性能的影响;并利用SEM对最佳制备工艺条件下的材料进行微观表征。结果表明,在La摩尔掺量为0.5%、热处理温度为550℃、热处理时间为2 h条件下,材料的晶粒大小和畸变程度达到最佳平衡状态;对NO气体的光降解率达到70.26%。La掺杂改性后,材料粒径更加均匀,多分布在18~20 nm区间。 相似文献
99.
100.
Effect of vacuum annealing on the characteristics of composite pellets containing DBSA-doped polyaniline and Fe nanoparticles
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The DBSA-PANI-Fe composite powder with 50wt% of Fe nanoparticles was prepared by mechanically mixing the DBSA-doped polyaniline powder and Fe nanoparticles. The composite powder was compacted to pellets and the pellets were annealed in vacuum at 443,493,543, and 593 K for 60 and 120 min. The conductivity of the pellet increases markedly with increasing the annealing temperature up to 493 K, and then decreases with further increasing the annealing temperature. When the pellet was annealed at 493 K for 60 min, the increment of conductivity reaches a maximum value, and the conductivity is 2.6 times as large as that of the pellet unannealed. The conductivities of the pellets annealed under the conditions of 543 K/120 min, 593 K/60 min, and 593 K/120 min are lower than the conductivity of the pellet unannealed. For all the pellets, the variation in conductivity with temperature reveals that the charge transport mechanism can be considered to be 1-D variable-range-hopping (1-D VRH). The composite pellet shows a magnetic hysteresis loop independent of the annealing condition. The saturation magnetization is about 5.4×104 emu/kg. The saturation field and the coercivity are estimated to be 4.38×105 and 3.06×104 A/m, respectively. The crystalline structure ofFe nanoparticles in the composites does not change with the annealing condition. The annealing condition cannot destroy the polymer backbones. 相似文献