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通过简单的水热法控制性合成了两种不同形貌的锰氧化物(层状OL和隧道状OMS),并考察了这两种材料对几种重金属离子Pb2+,Cu2+,Ni2+,Hg2+的吸附。通过原子吸收光谱(AAS)和原子荧光光谱(AFS)测定吸附前后离子浓度,比较两种材料的吸附性能,以及对不同离子的选择性吸附。实验表明OMS形貌的锰氧化物是一种良好吸附剂,对铅离子具有很好的选择性吸附,两分钟内吸附率达98%。由此可建立一种简单、绿色、高效地去除污水中重金属离子的方法。 相似文献
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Improvement in electroluminescence performance of n-ZnO/Ga_2O_3 /p-GaN heterojunction light-emitting diodes 下载免费PDF全文
n-ZnO/p-GaN heterojunction light-emitting diodes with and without a Ga2O3 interlayer are fabricated. The electroluminescence (EL) spectrum of the n-ZnO/p-GaN displays a single blue emission at 430 nm originating from GaN, while the n-ZnO/Ga2O3/p-GaN exhibits a broad emission peak from ultraviolet to visible. The broadened EL spectra of n-ZnO/Ga2O3/p-GaN are probably ascribed to the radiative recombination in both the p-GaN and n-ZnO, due to the larger electron barrier (ΔEC=1.85 eV) at n-ZnO/Ga2O3 interface and the much smaller hole barrier (ΔEV=0.20 eV) at Ga2O3/p-GaN interface. 相似文献
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2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography 下载免费PDF全文
We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm~2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature. 相似文献
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The test-QD in-situ annealing method could surmount the critical nucleation condition of InAs/GaAs single quantum dots(SQDs) to raise the growth repeatability.Here,through many growth tests on rotating substrates,we develop a proper In deposition amount(θ) for SQD growth,according to the measured critical θ for test QD nucleation(θ_c).The proper ratio θ/θ_c,with a large tolerance of the variation of the real substrate temperature(T_(sub)),is 0.964-0.971 at the edge and 0.989 but 0.996 in the center of a 1/4-piece semi-insulating wafer,and around 0.9709 but 0.9714 in the center of a 1/4-piece N~+ wafer as shown in the evolution of QD size and density as θ/θ_c varies.Bright SQDs with spectral lines at 905 nm-935 nm nucleate at the edge and correlate with individual 7 nm-8 nm-height QDs in atomic force microscopy,among dense 1 nm-5 nm-height small QDs with a strong spectral profile around 860 nm-880 nm.The higher T_(sub) in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θ_c:only one 7-nm-height SQD in25 μm~2.On a 2-inch(1 inch = 2.54 cm) semi-insulating wafer,by using θ/θ_c = 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-T_(sub) region in the center by using a proper θ/θ_c. 相似文献
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Study of white light emission from ZnS/PS composite system 总被引:1,自引:0,他引:1
ZnS films were deposited by pulsed laser deposition(PLD)on porous silicon(PS)substrates formed by electrochemical anodization of p-type(100)silicon wafer.The photoluminescence(PL)spectra of ZnS/PS composites were measured at room temperature.Under different excitation wavelengths,the relative integrated intensities of the red light emission from PS layers and the blue-green emission from ZnS films had different values.After samples were annealed in vacuum at different temperatures(200,300,and 400℃)for 30 min respectively,a new green emission located at around 550 nm appeared in the PL spectra of all ZnS/PS samples,and all of the ZnS/PS composites had a broad PL band(450-700 nm)in the visible region,exhibiting intensively white light emission. 相似文献
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利用脉冲激光沉积(PLD)法在Si(111)衬底上分别生长了ZnO薄膜和Cu薄膜, 用Cu薄膜作电极,研究了ZnO薄膜与Cu薄膜的接触特性。分别用X射线衍射仪、扫描电子显微镜和I-V测试的方法对样品的晶体质量、结构和电学性质进行了测试。结果表明:样品中ZnO薄膜和Cu薄膜均具有高度的择优取向;当Cu和 ZnO直接接触时,样品的I-V特性是非线性的;当Cu和 ZnO之间通过ZnO:Cu层间接接触时形成良好的欧姆接触,而且退火后欧姆接触性能明显提高,电阻率降低约2/3。本研究为价格低廉的Cu电极成为ZnO基器件的欧姆电极提供了一定的依据。 相似文献
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Structure and frustrated magnetism of the two-dimensional triangular lattice antiferromagnet Na2BaNi(PO4)2 下载免费PDF全文
A new frustrated triangular lattice antiferromagnet Na2BaNi(PO4)2 was synthesized by high temperature flux method. The two-dimensional triangular lattice is formed by the Ni2+ ions with S =1. Its magnetism is highly anisotropic with the Weiss constants θCW =-6.615 K (H⊥c) and -43.979 K (H||c). However, no magnetic ordering is present down to 0.3 K, reflecting strong geometric spin frustration. Our heat capacity measurements show substantial residual magnetic entropy existing below 0.3 K at zero field, implying the presence of low energy spin excitations. These results indicate that Na2BaNi(PO4)2 is a potential spin liquid candidate with spin-1. 相似文献