共查询到20条相似文献,搜索用时 15 毫秒
1.
I. A. Boiaryntseva A. V. Gektin G. B. Stryganyuk V. N. Baumer A. N. Belsky 《Journal of Applied Spectroscopy》2012,79(4):589-594
Luminescence spectra of Ca0.65Pr0.35F2.35 solid solutions are studied. It is found that, depending on the excitation energy, different kinds of emission centers appear
in these spectra. An interconfigurational 4f 15d1 →4f2 luminescence is typical for single Pr3+ ions in tetragonal sites. Data on the structure of the solid solutions show that the emission centers involved in 1S0 → 4f2 transitions can be attributed to Pr3+ ions contained in clusters. 相似文献
2.
S. V. Grigoriev V. A. Dyadkin S. V. Maleyev D. Menzel J. Schoenes D. Lamago E. V. Moskvin H. Eckerlebe 《Physics of the Solid State》2010,52(5):907-913
Two systems of noncentrosymmetric cubic helical magnets Mn1 − y
Fe
y
Si (y = 0.06, 0.08, 0.10) and Fe1 − x
Co
x
Si (x = 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.50) have been compared. The concentration dependences of the critical temperature
and magnetic field have been obtained using small-angle polarized-neutron scattering and analyzed in the framework of the
Bak-Jensen model. It has been established that, among the two interactions that play the main role in these systems, i.e.,
the isotropic symmetric ferromagnetic exchange and the Dzyaloshinskii-Moriya isotropic antisymmetric interaction, the former
interaction determines the critical temperature in the Mn1 − y
Fe
y
Si system and the latter interaction determines this temperature in the Fe1 − x
Co
x
Si system. 相似文献
3.
Guo-Yu Lan Yang-Wei Lin Zong-Hong Lin Huan-Tsung Chang 《Journal of nanoparticle research》2010,12(4):1377-1388
This article describes the synthesis of highly water-soluble Zn
x
Hg1−x
Se
y
S1−y
quantum dots (QDs) in aqueous solution through a simple photo-assisted reaction between ZnSe QDs and mercury(I) nitrate dihydrate
[Hg2(NO3)2·2H2O]. In order to deduce the optimal synthesis conditions, we varied several parameters, including the concentrations of mercaptosuccinic
acid (MSA) and Hg2(NO3)2·2H2O, the illumination time, and the reaction temperature. When irradiated at temperatures below 80 °C, the ZnSe QDs reacted
with the S2− ions formed rapidly from MSA and the Hg2+ ions formed from Hg2
2+ ions to form Zn
x
Hg1−x
Se
y
S1−y
QDs through a process of photo-etching and surface combination. Under different conditions, we prepared a series of Zn
x
Hg1−x
Se
y
S1−y
QDs that emit fluorescence at the maximum wavelengths ranging from 405 to 760 nm. Inductively coupled plasma-mass spectrometry
and transmission electron microscopy/energy dispersive spectrometry revealed that the content of Hg in the Zn
x
Hg1−x
Se
y
S1−y
QDs was greater when the synthesis was conducted at higher temperature. The Zn0.88Hg0.12Se0.44S0.56 QDs exhibit improved photostability than crude ZnSe QDs and possess long lifetimes (τ1 ~ 38 ns and τ2 ~ 158 ns). 相似文献
4.
P. A. Popov P. P. Fedorov V. M. Reiterov E. A. Garibin A. A. Demidenko I. A. Mironov V. V. Osiko 《Doklady Physics》2012,57(3):97-99
The thermal conductivity of single crystals of Ca1 − x
Er
x
F2 + x
(x = 0.01, 0.05, 0.07, and 0.10) and Ca1 − x
Tm
x
F2 + x
(x = 0.02, 0.04, and 0.06) solid solutions is studied in the temperature ranges 50–300 and 298–673 K. With increasing content
of rare-earth elements, the behavior of thermal conductivity in these solid solutions changes from the characteristic of defect
single crystals to glasslike. The concentration dependences of thermal conductivity for the two systems differ insignificantly. 相似文献
5.
介绍了一种基于新型非线性晶体Ba1-xB2-y-zO4SixAlyGaz 的可调谐深紫外飞秒激光光源. 从理论上分析了基频光和倍频光在通过非线性晶体时所造成的空间走离和群速度失配, 为了补偿空间走离以及波长调谐过程中晶体折射造成的光束偏离现象, 将两块相同的倍频晶体成镜像放置来产生二次谐波. 并调节延迟线的长度来补偿基频光和倍频光之间的群速度失配, 从而提高和频转换效率. 然后通过和频方式进行三倍频和四倍频来突破晶体相位匹配条件的限制, 产生了波长低于200 nm的深紫外飞秒激光. 利用钛宝石激光器提供基频光光源, 最终在250–300 nm, 192.5–210 nm 范围内获得了高重频、可调谐超短脉冲紫外和深紫外激光. 并在基频光波长为800 nm时, 得到的二倍频、三倍频和四倍频的功率分别为1.28 W, 194 mW和5.8 mW, 相对于前一级的转换效率依次为46.14%, 15.16%和3%. 采用互相关法测量得到266.7 nm紫外激光的脉冲宽度约为640.4 fs. 相似文献
6.
I. A. Starkov A. S. Kozhemyachenko S. F. Bychkov A. P. Nemudry N. Z. Lyakhov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1059-1061
The oxygen permeability of ceramic SrCo0.8 − y
Fe0.2Nb
y
O3 − z
(0 ≤ y ≤ 0.2) and La0.3Sr0.7Co0.6Fe0.2Nb0.2O3 − z
disc membranes as a function of temperature and oxygen partial pressure was studied. Kinetic analysis was performed based
on the experimental data on oxygen permeability as a function of oxygen partial pressure. 相似文献
7.
A. A. Lotin O. A. Novodvorsky V. Ya. Panchenko L. S. Parshina E. V. Khaydukov D. A. Zuev V. V. Rocheva O. D. Khramova K. D. Chtcherbachev 《Physics of the Solid State》2011,53(3):467-471
Thin films of Cd
y
Zn1 − y
O and Mg
x
Zn1 − x
O (y = 0−0.35, x = 0−0.45) ternary alloys have been grown by pulsed laser deposition onto sapphire substrates. The record solubility limits
of Cd (y = 0.3) and Mg (x = 0.35) have been achieved in hexagonal zinc oxide. The mismatch of the lattice parameters a of Cd0.2Zn0.8O and Mg0.35Zn0.65O does not exceed 1%; in this case, the band gap discontinuity is 1.3 eV. The surface roughness of the films does not exceed
2.5 nm at x = 0−0.27 and y = 0−0.20. 相似文献
8.
9.
结合机械合金化与放电等离子烧结工艺制备了Ni和Se共掺的细晶方钴矿化合物Co1-xNixSb3-ySey,研究了晶界和点缺陷的耦合散射效应对CoSb3热电输运特性的影响.通过Ni掺杂优化载流子浓度提高功率因子.在x=0.1时,功率因子达到最大值1750μWm-1K-2(450℃),是没有掺Ni试样的两倍.晶界和点缺陷的耦合散射机理使晶格热导率急剧下降,其中Co0.9Ni0.1Sb2.85Se0.15的室温晶格热导率降低至1.67Wm-1K-1,接近目前单填充效应所能达到的最低值1.6Wm-1K-1,其热电优值ZT在450℃时达到最大值0.53.将Callaway-Von Baeyer点缺陷散射模型嵌入到Nan-Birringer有效介质理论模型,对晶界散射和点缺陷散射的耦合效应对热导率的影响进行了定量分析,模型计算与实验结果符合.理论模型计算表明,当晶粒尺寸下降到50nm同时掺杂引入点缺陷散射后,Co0.9Ni0.1Sb2.85Se0.15的晶格热导率下降到0.8Wm-1K-1.
关键词:
3')" href="#">CoSb3
Ni和Se掺杂
热电性能
耦合散射效应 相似文献
10.
采用脉冲激光沉积技术,在Si(111)衬底上成功制备出不同含量Na,Co共掺的ZnO薄膜.利用X射线衍射仪、原子力显微镜、荧光光谱仪以及四探针电阻率测试台对薄膜的结构、表面形貌和光电性质进行了表征.重点讨论了不同掺杂浓度对薄膜光电性质的影响.结果表明:Na,Co共掺没有改变ZnO的六角纤锌矿结构且掺杂导致薄膜仅有的的紫外发光峰出现红移.当Na,Co掺杂浓度分别为10%时,峰值最强且红移最明显,发光峰波长为397 nm,薄膜的电阻率最低,达到了8.34×10-1 Ω ·cm.深入讨论了
关键词:
脉冲激光沉积
1-x-yNaxCoyO薄膜')" href="#">Zn1-x-yNaxCoyO薄膜
光电性质
红移 相似文献
11.
12.
A. I. Galyas O. F. Demidenko G. I. Makovetski? K. I. Yanushkevich L. I. Ryabinkina O. B. Romanova 《Physics of the Solid State》2010,52(4):687-690
Regions of the existence of sulfide Gd
x
Mn1 − x
S and selenide Ti
x
Mn1 − x
Se solid solutions have been identified. Their electrical and thermoelectric properties have been studied in the temperature
range 80–900 K. It has been established that the substitution of Gd2+ and Ti2+ ions for Mn2+ cations initiates reversal of the type of charge carrier with respect to the starting compounds MnS and MnSe. The cation
substitution in solid solutions brings about a change from the hole conduction (α > 0) characteristic of the manganese monosulfide
and monoselenide to the electronic conduction (α < 0). 相似文献
13.
We have investigated the structure, optical and magnetic properties of ferroelectric KNb1-xFexO3-δ (X=0, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25) synthesized by a traditional solid-state reaction method. According to the X-ray diffraction and the results of Rietveld refinement, all the samples maintain orthorhombic distorted perovskite structures with Amm2 space group without any secondary phase, suggesting the well incorporation of Fe ions into the KNbO3 matrix. With the increase of Fe concentration, the band gap of each sample is decreased gradually, which is much smaller than the 3.18 eV band gap of pure KNbO3. Through X-ray photoelectron spectrum analysis, the increased density of oxygen vacancy and Fe ions may be responsible for the observed decrease in band gap. Compared with the pure KNbO3, Fe doped samples exhibit room-temperature weak ferromagnetism. The ferromagnetism in KNb1-xFexO3-δ with low-concentration dopants (X=0.01-0.10) can be attributed to the bound magnetic polaron mediated exchange. The enhancement of magnetism for the high-concentration (X=0.10-0.20) doped samples may arise from the further increase of magnetic Fe ions. 相似文献
14.
A. V. Voitsekhovskii S. N. Nesmelov S. M. Dzyadukh V. S. Varavin S. A. Dvoretskii N. N. Mikhailov Yu. G. Sidorov 《Russian Physics Journal》2011,54(3):263-270
The effect of regions with periodic sharp 48–54 nm thick inhomogeneities in composition on the electrophysical characteristics
of MIS structures based on graded-gap n-Hg1–x
Cd
x
Te (x = 0.29–0.31) grown by molecular-beam epitaxy is studied. It is found that major electro-physical and photo-electrical
characteristics are qualitatively similar for MIS structures based on n-Hg1–x
Cd
x
Te with sharp inhomogeneities in composition (barriers) and without “barriers”. It is shown that the electrical characteristics
are mostly affected by the “barrier regions” located close to the insulator – semiconductor interface. This effect is manifested
in an increase of the effective dielectric thickness, which can be due to the fact that the regions of enhanced composition
form potential barriers for electrons, and in a decrease in the relaxation time of non-equilibrium carriers due to recombination
at the boundaries of the regions with sharp changes in composition. 相似文献
15.
基于k·p微扰理论, 通过引入应变哈密顿量作为微扰, 建立了双轴应变Ge/Si1-xGex价带色散关系模型. 模型适于任意晶向弛豫Si1-xGex虚衬底上的应变Ge价带结构, 通过该模型可获得任意k方向应变Ge的价带结构和空穴有效质量. 模型的Matlab模拟结果显示, 应变Ge/Si1-xGex价带带边空穴有效质量随Ge组分的增加而减小, 其各向异性比弛豫Ge更加显著. 本文研究成果对Si基应变Ge MOS器件及集成电路的沟道应力与晶向的设计有参考价值. 相似文献
16.
采用分子束外延的方法在BaF2(111)衬底上制备出了高质量的Pb1-xMnxSe(0≤x≤0.0681)薄膜.X射线衍射结果表明,Pb1-xMnxSe薄膜为立方相NaCl型结构,没有观察到MnSe相分离现象,薄膜的取向为平行于衬底(111)晶面.晶格常数随着Mn含量的增加逐渐减小,Mn含量由Vegard公式得到.通
关键词:
1-xMnxSe外延薄膜')" href="#">Pb1-xMnxSe外延薄膜
透射光谱
带隙
折射率 相似文献
17.
利用X射线衍射(XRD)和X射线吸收近边结构(XANES)方法研究了在Si(100)衬底上及600℃温度条件下用分子束外延(MBE)共蒸发方法生长的MnxSi1-x磁性薄膜的结构.由XRD结果表明,只有在高Mn含量(8%和17%)样品中存在着Mn4Si7化合物物相.而XANES结果则显示,对于Mn浓度在0.7%到17%之间的MnxSi1-x样品,其Mn原子的XANES谱表现出了一致的谱线特征.基于多重散射的XANES理论计算进一步表明,只有根据Mn4Si7模型计算出的理论XANES谱才能够很好的重构出MnxSi1-x样品的实验XANES谱.这些研究结果说明在MnxSi1-x样品中,Mn原子主要是以镶嵌式的Mn4Si7化合物纳米晶颗粒存在于Si薄膜介质中,几乎不存在间隙位和替代位的Mn原子.
关键词:
xSi1-x磁性薄膜')" href="#">MnxSi1-x磁性薄膜
分子束外延
XRD
XANES 相似文献
18.
M. D. Durruthy-Rodríguez J. Costa-Marrero M. Hernández-Garcia F. Calderón-Pi?ar Célia Malfatti J. M. Yá?ez-Limón 《Applied Physics A: Materials Science & Processing》2011,103(2):467-476
In this work, visible photoluminescence was observed at room temperature in a sintered Pb(Zr1-xTix)1-y NbyO3\mathrm{Pb}(\mathrm{Zr}_{1-x}\mathrm{Ti}_{x})_{1-y} \mathrm{Nb}_{y}\mathrm{O}_{3} perovskite-type structure system, doped with Nb using the next excitation bands 325, 373 and 457 nm. The intensity and energy
of such emissions have been studied by changing the Nb concentration (0<y<0.01) and the Ti content (x), with x=0.20,0.40,0.53,0.60 and 0.80, on both sides of the morphotropic phase boundary (MPB) zone. The principal bands become visible
at energies of 1.73, 2.56 and 3.35 eV. The results reveal the role of the Nb5+ ion substitutions by Zr4+ or Ti4+ ions and the symmetry presented in the rhombohedral or tetragonal side of the MPB. Raman spectra which are similar for compositions:
20/80, 40/60 and 53/47 (tetragonal phases) show nine bands, centered around 137, 194, 269, 331, 434, 550, 612, 712 and 750
cm−1. The spectra for samples 60/40 and 80/20, rhombohedral phase, show significant differences, only six bands appear, centered
around 124, 209, 234, 330, 549 and 682 cm−1. In addition, optical absorption spectroscopy, structural and micro-structural measurements were carried out by using Uv-vis
spectroscopy, X-ray diffraction and scanning electron microscopy techniques, respectively. The experimental results of band
gap energy, e.g., in our samples are in accordance with the findings by J. Baedi et al. in the calculations of band structure,
energy gap and density of states for different phases of Pb(Zr1−x
Ti
x
)O3 using density functional theory (DFT). 相似文献
19.
In the EPR of (La1––x
Gd
y
Ce
x
)Al2 a bottleneck in the relaxation of the conduction electrons to the lattice is present at sufficiently high Gd-concentrations. The bottleneck can be broken by decreasing the Gd-concentration or by adding Cerium as a spin-flip-scatterer.g-factor and line broadening are measured for (La1–y
Gd
y
)Al2 and (La1––x
Gd
y
Ce
x
)Al2 as a function of temperature and Gd- and Ce-concentrations. The Cerium induced relaxationsrate
eL
(Ce) increases linearly with Ce-concentration up tox0.025. This corresponds to the fact, well known by measurements of the Kondo anomalies, that Cerium impurities show no significant interaction up to rather high concentrations. 相似文献