由观测无胁强作用下的热膨胀和电阻研究金属玻璃(Fe0.85Ni0.15)84B16的结构弛豫

本文通过长度、电阻和热膨胀系数的测量研究了(Fe_0.85Ni_0.15)₈₄B₁₆金属玻璃结构弛豫和退火温度T_a的关系。基于上述物理量对结构弛豫的关系,对曲线作了分析和讨论。在退火温度为175℃至250℃之间结构弛豫随T_a的变化率最大。 关键词：     

CO2跨临界系统在冷藏车上的应用研究

采用CO₂双缸滚动转子压缩机搭建冷藏车用制冷机组，在焓差室内测试车厢温度(T_a)、压缩机频率(f)与排气压力(P_d)对排气温度(T_d)、制冷量(Q₀)和能效比(COP)的影响，分析机组用于冷藏车的可行性，适用的冷藏车类型及最佳运行方式.结果表明：名义工况下，Q₀=1.47 kW,COP=0.91,满足运输用制冷机组标准.在环境温度T_w=30℃,车厢温度T_a=0℃时，机组最大制冷量为Q₀=2.43 kW,因此机组可适用于车厢容积18m³内的D类冷藏车.用于上述冷藏车时，机组最佳运行方式为：预冷工况下，车厢温度T_a>5℃时，采用f=140 Hz,P_d=10 MPa运行；车厢温度T_a≤5℃时，采用f=140 Hz,P_d=9 MPa运行；运输工况下，采用f=80 Hz,P_d<...     

退火对Co35(SiO2)65颗粒膜巨磁电阻效应的影响

采用多靶离子束溅射镀膜机制备了一系列不同退火温度的Co₃₅(SiO₂)₆₅（体积百分数）颗粒膜样品,发现样品的巨磁电阻效应随着退火温度T_a的升高而单调下降.应用磁力显微镜对样品的磁结构进行了观测,发现随着退火温度的升高,近邻的Co颗粒的磁矩倾向于平行排列,形成磁畴结构,从而导致Co₃₅(SiO₂)₆₅颗粒膜巨磁电阻效应单调下降. 关键词：     

R1-xPrxBa2Cu3O7-δ超导Tc平台的离子尺寸效应

系统地研究了Ｒ_1-xＰｒ_xＢａ₂Ｃｕ₃Ｏ_7-δ的超导Ｔ_c与Ｐｒ替代浓度ｘ的关系。发现在离子半径ｒ_i≤ｒ_i（Ｄｙ）时，在低Ｐｒ浓度范围内存在一个超导Ｔ_c平台，并且平台宽度表明一个Ｒ^３＋离子尺寸效应。我们认为，Ｔ_c平台宽度的离子尺寸效应可能起源于Ｐｒ４ｆ电子局域态的改变。提出一个临界Ｒ^３＋离子半径ｒ_ic，ｒ_i＞ｒ_ic时ＲＢａ₂Ｃｕ₃Ｏ_7-δ的超导电性消失 关键词：     

a-Ge/Ag迭层中的临近效应和互扩散

本文研究了不同厚度Ag膜与2000?非晶Ge膜形成的迭层行为。发现随Ag膜厚度的减小,迭层的室温电阻率愈来愈小于相同厚度单层Ag膜的室温电阻率,实验在室温下得出明显的临近效应。当对这些迭层退火时,实验得到十分不同的电阻R_300K与退火温度T_a的关系以及不同T_a下各种R(T_a)-T的关系。由X射线衍射结构分析电子显微镜观察和电子探针扫描成分分析的结果,本文给这些退火过程中的新现象以物理解释。 关键词：     

AlGaN/GaN异质结Ni/Au肖特基表面处理及退火研究

采用O₂等离子体及HF溶液对AlGaN/GaN异质结材料进行表面处理后，Ni/Au肖特基接触特性比未处理有了明显改善，反向泄漏电流减小3个数量级.对制备的肖特基接触进行200—600℃ 5min的N₂气氛退火，发现退火冷却后肖特基反向泄漏电流随退火温度增大进一步减小.N₂气中600℃退火后肖特基二极管C-V特性曲线在不同频率下一致性变好，这表明退火中Ni向材料表面扩散减小了表面陷阱密度；C-V特性曲线随退火温度增大向右移动，从二维电子气耗尽电压绝对值减小反映了肖特基势垒的提高. 关键词： AlGaN/GaN 肖特基接触 表面处理 退火     

ArCN三原子准分子的研究(Ⅰ)——电子态的量子化学计算

分别采用６－３１Ｇ＊，６－３１Ｇ?＊基组对线性ＡｒＣＮ分子的X²∑⁺，Ａ²∏_i，Ｂ²∑⁺，Ｃ²∏_i，Ｄ²∑⁺和Ｅ²∏_r ６个电子态进行了从头计算法开壳自旋限制Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＲＯＨＦ）计算。计算结果表明线性ＡｒＣＮ分子的电子态具有典型的准分子结构，从而可以肯定ＣＮ与稀有气体原子Ｒｇ（Ａｒ，Ｋｒ，Ｘｅ）能够形成自由基准分子。对Ｘ²∑⁺，Ａ²∏_i的自旋非限制Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＵＨＦ）计算证实较大的自旋污染不影响势能曲线的形状。 关键词：     

非平衡Fe-Pd合金的矫顽力与磁致伸缩

通过测量非平衡Fe_1-xPd_x合金的矫顽力H_c与饱和磁致伸缩系数λ_s,随合金成分的变化,发现H_c随x增加而减小,而λ_s随x增加而增大。认为晶粒尺寸减小引起的平均各向异性的降低可能是H_c减小的原因。退火温度T_a>600K时,由于具有高磁晶各向异性的有序FePd相的分离析出,矫顽力H_c随T_a升 关键词：     

退火加热速度对Fe-Cu-Nb(V)-Si-B纳米晶合金磁性的影响

研究了退火温度为550℃的纳米晶化过程中加热速度对Fe_72.7Cu₁Nb₂V_1.8Si_13.5B₉与Fe_73.5Cu₁Nb₃Si_13.5B₉合金磁性的影响．磁性测量结果表明，退火加热速度对这两种合金软磁性能有明显的影响，快速加热可显著提高合金的初始磁导率μ_{i 关键词：}     

Gd1-xCaxBa2Cu3O7-y高温超导体压力效应的研究

研究了Ｇｄ_1-xＣａ_xＢａ₂Ｃｕ₃Ｏ_7-y（０．０≤Ｘ≤０．２０）高温超导体在常压和高压下的超导电性在１－３００Ｋ温度范围内，利用Ｂｒｉｄｇｍａｎ对顶砧获得压力达９．０ＧＰａ，测量了（Ｘ＝０．１０，０．１５，０．２０）样品的ｄＴ_c／ｄｐ分别为７．６８，７．８和４．４６Ｋ／ＧＰａ。发现Ｔ_c的压力导数随着ｃａ²⁺含量的增加而下降，分析了氧含量对Ｔ_c和ｄＴ_c／ｄＰ的影响．利用常压下晶格参数精修值和阳离子与氧离子间距随压力的改变，说明ＣｕＯ₂面在超导电性上的作用，用ＣｕＯ₂面之间耦合解释Ｔ_c（Ｐ）曲线的非线性关系。 关键词：     

非晶La80Al20晶化相的超导电性

 本文把非晶La₈₀Al₂₀在真空中、不同温度及其时间条件下进行退火，以及在6 GPa不同温度退火40 min，并对退火样品的相结构及超导性进行了研究。发现真空中，250 ℃退火的样品晶化成了T>4.2 K、不超导的单相四方La₄Al；300 ℃及450 ℃退火的样品晶化成La₃Al、α-La、β-La及一些未知杂相，这些多相混合物的T_C<6.0 K。在6 GPa 300 ℃及以下温度退火的样品，晶化成单相六角La₄Al，其晶格常数与六角La₃Al的完全相同，这些样品的T_C>5.1 K；6 GPa、350 ℃及以上温度退火的样品，晶化成La₃Al相及新未知相H，新相H的T_C约为6.3 K。     

Magnetic phase transitions in the Fe1−xMnxSn2 alloys for 0≤x≤1.0: A Mössbauer and magnetization study

⁵⁷Fe Mössbauer study of the pseudo-Binary alloys Fe_1?xMn_xSn₂ for 0≤x≤1.0 reveal the antiferromagnetically ordered state at 79K for all the specimens of the series. The hyperfine field at Fe site decreases with increasing manganese concentration. Magnetic susceptibility measurements performed in the temperature range 80 K≤T≤300 K indicate that the Néel temperature decreases with increasing Mn concentration for the samples withx≤0.4 whereas it increases continuously for the specimens havingx>0.4 of the alloy series.     

Long-wave IR emission in CH3I pumped by a continuously tunable,narrowed-line,CO2 laser

About 150 FIR lines are produced in CH₃I by pumping with a narrowed-line continuously tunable CO₂ laser the 2ν₃ P, Q bands at 9.6 μm. We have obtained in the 330–1560 μm wavelength range, up to 2 μJ pulsed energies by pumping some of the K-sublevels of the P (16≤J≤46) and R (16≤J≤60) absorption lines.     

3.508 μ-HeXe-laser line absorption by CH3COOCH3, CH3, and NO2 and infrared emission at 6.89 μ by CH3COOCH3 and CH3 at elevated temperatures

Shock-tube HeXe-laser absorption data at ω_L=2850.633 cm^-1 for CH₃COOCH₃ at 757≤T, °K≤1344, NO₂at 412≤T, °K≤1859, andCH₃at 1283≤T, °K≤1562 are presented. Approximate models are used for the effective spectral absorption coefficient of vibration-rotation lines for analytical representations of the results around atmospheric pressures. For CH₃COOCH₃, an equivalent Voigt-profile for an isolated line was adopted in order to account for a dependence on total pressure of the laser absorption coefficient. Shock-tube emission data at λ=6.890 μ(Δλ=0.197μ) forCH₃COOCH₃at 814≤T, °K≤1651 and for CH₃at 1377≤T, °K≤1562 in the v₄-fundamental of the H-bond bending mode of the CH₃-group are well described at atmospheric pressures by approximations of just-overlapping-line models for polyatomic molecules. The adopted models are useful for concentration-time history measurements of methyl acetate, nitrogen dioxide, and methyl radicals behind shock waves.     

Preparation and superconductivity of (B1−xCx)(Sr1−yBay)2Ca2Cu3Oz

Preparation of (B_1−xC_x)(Sr_1−yBa_y)₂Ca₂Cu₃O_z has been studied using high-pressure synthesis technique to improve sample quality. Samples were prepared from various starting compositions of 0.2≤x≤0.8 and 0≤y≤1. Nearly single-phased samples were obtained for (B_0.6C_0.4)(Sr_1−yBa_y)₂Ca₂Cu₃O_z (0≤y≤0.75) and (B_1−xC_x)-(Sr_0.25Ba_0.75)₂Ca₂Cu₃O_z (0.3≤x≤0.6). We have found that the partial substitution of Ba is effective to improve the sample quality as well as to enhance the T_c. The C substitution was also demonstrated to affect the sample preparation and the physical properties. Based on the substitution study, a maximum T_c of 120 K was observed for the sample with a starting composition of (B_0.65C_0.35)(Sr_0.3Ba_0.7)₂Ca₂Cu₃O_9+δ. Critical current density (J_c) and irreversibility field (H_irr) were estimated from magnetization measurements. The J_c at 77 K in a field of 1 T was about 1.1×10⁴ A/cm³ and the H_irr at 77 K was about 2.5 T. The H_irr was well-described by H_irr=a(1−T/T_c)ⁿ with a=39.1 and n=2.38.     

Anomalous X-ray transmission through sapphire crystals

The triple-crystal X-ray diffractometry of anomalous X-Ray transmission is used to investigate sapphire single crystals grown in protective gaseous media with the help of the horizontal directional-crystallization method. The dependences between the integral intensities of anomalously transmitted and Bragg-Laue reflected X-ray beams (T _i and R _i , respectively) and the thickness of the samples under study, which enable us to determine regions of thin- and thick-crystal approximation, have been obtained at 2.52 ≤ μt ≤ 18.9. The integral coefficient μ _i of interference absorption and the integral characteristic y _i are calculated in the dynamic thick-crystal approximation. It is demonstrated that dislocations are distributed mainly within the small-angle boundaries of a grown sapphire crystal. It is ascertained that the parameter μ _i is highly sensitive to the dislocation density and the pattern of the dislocation distribution in a crystal.     

LISICON(锗酸锌锂)单晶的Li+离子电导

本文研究了Lisicon(锗酸锌锂)单晶的Li⁺离子电导率。发现各结晶学方向电导率之间的关系为σ_b≤σ_a≤σ_c≤σ_[110],但各向异性不强。晶体中Li含量对电导率有明显的影响,当Li/Zn比率由6.7变到9.2时,300℃a方向电导率由4.3×10^-2Ω^-1·cm^-1增加到1.25×10^-1Ω^-1·cm^-1,logσT对1/T的曲线显示出三个转变点,分别在～80℃,～140℃和～300℃。电导的激活能分别为0.50—0.58eV(25—80℃),0.92eV(～80—140℃),0.64eV(～140—300℃)和0.36eV(>300℃),极化实验表明单晶的电子电导可以忽略。 关键词：     

因瓦合金纳米微粉的恒磁导率及其压力、频率特性和压力相变

 以Fe-30wt%Ni合金片为母合金，用蒸发冷凝法制备了三种粗细不同的纳米微粒。经透射电镜和X光衍射物相分析，微粒成分与母合金一致。5T、5H和3K粉的平均粒度分别为13.6、27和40 mm。在室温和43~28个不同的流体静压力（0.000 1~2.205 GPa）下测量了它们的磁化曲线、磁导率曲线和起始磁化曲线。结果表明：（1）在H＝(20－132)(1000/4π)A/m范围内Fe-30Ni合金三种纳米粉均具有恒磁导率。（2）三种纳米粉恒磁导率随静水压的变化规律如下：μ_r＝3.83+0.253p-0.022 1p²-0.007 22p³（5T粉）；μ_r＝3.93+1.20p-1.97p²+1.52p³-0.510p⁴+0.059 9p⁵（5H粉）；μ_r＝5.96-0.276p+0.107p²-0.045 9p³（3K粉）。前两者随压力增加而升高。后者随压力增加而下降。（3）γ-α马氏体相变明显存在于5T、5H粉中，而3K粉中未见到。（4）Fe-30Ni合金片的μ_i从200kHz至2 MHz已下降一个数量级，而其纳米粉μ_i的频率范围高于300 MHz，增大两个数量级以上。     

Possible oxygen hopping in the YBa2Cu3O7 system observed by Mössbauer spectroscopy

In situ high temperature⁵⁷Fe Mössbauer measurements have been performed on samples of YBa₂ (Cu_1?xFe_x)₃O_7?δ withx=0.005 andx=0.010, in pure oxygen or in air, in the range 295 K≤T≤640 K. TheT-dependence of Fe species, of the Debye-Waller factorf(T) as well as of the hyperfine parameters is analysed.