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1.
采用共沉淀法按不同Al掺杂比例x[x=n(Al)∶n(Mn+Al)=0, 0.025, 0.050, 0.100, 0.150, 0.200]制得了Al(OH)3和Mn3O4混合物, 将其与LiNO3按一定比例混合, 在空气中于700 ℃烧结得Li[Mn(Al)]2O4样品. X射线衍射和Raman光谱结果表明, 在0≤x≤0.20范围内均得到了单相的尖晶石型样品, 随着x的增加, 晶胞参数减小, 晶格振动能量增加, Mn(Al)-O的结合增强, 结构稳定性增强. 相似文献
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麝香草的新单萜配糖物的分离与合成 总被引:1,自引:0,他引:1
从麝香草(Thymus vulgaris L)的甲醇萃取物中分离出三个单萜配糖物. 用核磁共振光谱确定了它们的结构为对伞花-9-基-β-D-葡糖苷(1), 5-β-D-葡糖苷百里氢醌(2)和2-β-D-葡糖苷百里氢醌(3). 其中1是新化合物, 用以对伞花-9-醇为原料的对映体选择性合成方法确定了化合物1的8位的立体化学为R型. 相似文献
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In this paper,we use the a-plane InGaN interlayer to improve the property of a-plane GaN.Based on the a-InGaN interlayer,a template exhibits that a regular,porous structure,which acts as a compliant effect,can be obtained to release the strain caused by the lattice and thermal mismatch between a-GaN and r-sapphire.We find that the thickness of InGaN has a great influence on the growth of a-GaN.The surface morphology and crystalline quality both are first improved and then deteriorated with increasing the thickness of the InGaN interlayer.When the InGaN thickness exceeds a critical point,the a-GaN epilayer peels off in the process of cooling down to room temperature.This is an attractive way of lifting off a-GaN films from the sapphire substrate. 相似文献
4.
水热合成了2个以D-樟脑酸(D-H2cam)与1,4-二(咪唑-1-基)丁烷(1,4-bimb)为配体的配位聚合物:[Co(D-cam)(1,4-bimb)]n·4nH2O(1)和[Ni(D-cam)(1,4-bimb)]n(2)。通过X-射线单晶衍射,元素分析,红外光谱,XRD分析,热重,和磁性分析对其结构进行了表征。测定了这两个聚合物的磁性。结构分析表明,1为P2空间群,其链状结构由氢键作用连接形成二维结构;2为Pna21空间群,呈四重穿插的dia网络结构。 相似文献
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Hydrothermal reactions of rare earth oxides with racemic tartaric acid (H2tar) yielded 7 rare earth(III) MOFs with general formulas [R2(tar)3(H2O)2]n (R=Y (1), Sm (4), Eu (5), Tb (6), Dy (7)) and [R2(tar)2(C2O4)(H2O)2]n·4nH2O (R=La (2), Nd (3)). X-ray powder diffraction analysis and single-crystal X-ray diffraction analysis reveal that they present two different structural types. MOFs 1, 4, 5, 6 and 7 are isostructural and crystallize in the orthorhombic non-centrosymmetric space group Iba2, and feature unusual fsc-3,4-Iba2 topology. MOFs 2 and 3 are isostructural and crystallize in monoclinic P21/c space group and display rare fsx-4,5-P21/c topology containing hydrophilic channels bounded by triple helical chains along a axis. MOFs 3, 4, 5, 6 and 7 exhibit intense lanthanide characteristic photoluminescence at room temperature. 相似文献
7.
A unusual electrochromism is observed in amber cubic boron nitride (cBN) single crystals when breakdown possibly related to impurities and defects occurs. The electrochromism induces an abrupt increase in the absorption coefficient of the cBN crystals within the visible and infrared region. The change of the absorption coefficient of cBN crystal can be increased linearly by raising the current after the electrochromism occurs, whereas it is irrelevant to the polarization of the incident light. The absorption related to the electrochromism in the cBN single crystal has potential applications in designing and manufacturing electro-optical modulators, optical switches, and other optoelectric devices. 相似文献
8.
We report low-threshold high-temperature operation of 7.4#m strain-compensated InGaAs/lnAIAs quantum cascade lasers (QCLs). For an uncoated 22-μm-wide and 2-mm-long laser, the low-threshold current densities, i.e. 0.33kA/cm^2 at 81 K in pulsed mode and 0.64kA/cm^2 at 84K in cw mode, are realized. High-temperature operation of uncoated devices, with a high value of 223K, is achieved in cw mode. 相似文献
9.
Ordered InAs Quantum Dots with Controllable Periods Grown on Stripe-Patterned GaAs Substrates 下载免费PDF全文
GaAs (001) substrates are patterned by electron beam lithography and wet chemical etching to control the nucleation of lnAs quantum dots (QDs). InAs dots are grown on the stripe-patterned substrates by solid source molecular beam epitaxy. A thick buffer layer is deposited on the strip pattern before the deposition of InAs. To enhance the surface diffusion length of the In atoms, InAs is deposited with low growth rate and low As pressure. The AFM images show that distinct one-dimensionally ordered InAs QDs with homogeneous size distribution are created, and the QDs preferentiMly nucleate along the trench. With the increasing amount of deposited InAs and the spacing of the trenches, a number of QDs are formed beside the trenches. The distribution of additional QDs is long-range ordered, always along the trenchs rather than across the spacing regions. 相似文献
10.
Wang Jun Liu Xiang-Lin Yang An-Li Zheng Gao-Lin Yang Shao-Yan Wei Hong-Yuan Zhu Qin-Sheng Wang Zhan-Guo 《Applied Physics A: Materials Science & Processing》2011,104(4):1099-1103
Four novel dmit complexes: [(C2H5)4N][Ni (dmit)2], [(C3H7)4N][Ni(dmit)2], [(C2H5)4N][Au(dmit)2] and [(C3H7)4N][Au(dmit)2], abbreviated as EtNi, PrNi, EtAu, and PrAu, were synthesized. The third-order nonlinear optical properties of them in acetonitrile
solutions were investigated by using the Z-scan technique with 20 ps pulses width at 1064 nm. When the on-axis irradiance
at focus I
0 was 5.025 GW/cm2, the nonlinear refraction coefficient n
2, the third-order nonlinear susceptibility χ
(3), the molecular second-order hyperpolarizability γ of the four types of material were obtained with subject to Z-scan curves, and these indexes were with the magnitudes of
10−18 m2/W, 10−13 esu, and 10−31 esu, respectively. The nonlinear absorption coefficient β of Ni samples had the 10−12 m/W scale. The impact of different metals and cations on the third-order nonlinear optical properties of materials was analyzed.
Through the derivation, the result suggests that these dmit complexes are promising candidates for applications to nonlinear
optical devices manufacture in the near-infrared waveband. 相似文献