非晶态软磁薄膜Fe90-xCoxZr10的平面霍耳效应和磁阻效应

本文研究了非易态软磁薄膜Fe_90-xCo_xZr₁₀的平面霍耳电压及磁阻随磁场方向、成分和温度的变化规律。采用通常的六探针法进行了测量。结果表明平面霍耳电压和磁阻分别满足经验公式V_y=pM²Isin2θ和△ρ=cM²cos2θ;并给出了V_y表达式中的常数项p正比于ρ²。此外,样品Co₉₀Zr₁₀和样品Fe₇₀Co₂₀Zr₁₀晶化前后的V_y变化正好相反,即富钴成分的样品晶化后,V_y增加,而富铁成分的样品V_y下降。 关键词：     

富氮官能团活性炭的制备及其吸附CO2性能研究

本研究以煤基活性炭产品为原料，尿素作为氮源，通过浸渍、高温活化的方法进行改性，开发了一款可用于煤制氢/重整制氢中温变换气中CO₂脱除的煤基富氮活性炭，并对其进行结构及性能表征。其中性能最优样品U-80C-N-550，其表面氮含量为9.92%,N/O比1.22，水接触角为137.92°±1.24°。在测试条件为99.99%CO₂气氛，200?C温度，1 MPa压力下，CO₂吸附容量可以达到1.27 mmol/g，且在进行40次吸附解吸循环过程中CO₂吸附量基本保持不变，循环稳定性好。结果表明，不同条件下制备的富氮活性炭样品表面含氮基团含量及种类不同，因此通过改变吸附剂制备工艺条件，可适当调控活性炭表面含氮基团的种类及含量，从而提高其CO₂吸附性能的同时增强其疏水性，得到了适合于含水蒸气富氢气体中脱除CO₂的吸附剂。     

机械合金化Cu1-xSnx系的穆斯堡尔研究

利用机械合金化方法获得了几种铜－锡合金，特别是熔融法不易获得的η-Cu₆Sn₅，Ｘ射线衍射结果显示球磨使各样品纳米化，并形成包含确定合金相的固溶体，穆斯堡尔谱表明，各固溶体中除包含合金相外，还存在富锡相及富铜相，提出在机械合金化过程中，首先铜和锡纳米化，然后两种原子相互扩散形成包含合金相、富α－锡相和富ｆｃｃ铜相的固溶体。 关键词：     

兴凯湖沉积物富里酸荧光特性研究

采集黑龙江省兴凯湖4个点位沉积物样品(样品号HXXD,HXXX,HXDX,HXDB),开展了沉积物富里酸(fulvic acid, FA)荧光特性研究。二维荧光光谱、三维荧光光谱均显示HXXD点位FA的主要荧光峰均出现在较长波长处。FA荧光光谱特征参数分析表明,各点位富里酸腐殖化程度为：HXXD>HXDX>HXDB>HXXX。其中HXXD点位FA以陆源输入为主,而其他点位FA则陆源与水生生物源并存。利用荧光区域积分(FRI)技术,对FA的三维荧光光谱5个区域(Ⅰ-Ⅴ)的荧光响应值比例(percent fluorescence response, P_{i, n})比较证实,所有点位类胡敏酸区域(Ⅴ区)的P_{Ⅴ, n}、类富里酸(Ⅲ区)的P_{Ⅲ, n}均占有较大的比例,同时采用三维荧光区域积分法判断各点位FA腐殖化程度与二维荧光特性结论一致。三维荧光光谱中r_{(A, C)}值与区域积分(FRI)中P_{Ⅴ, n}/P_{Ⅲ, n}及(P_{Ⅴ, n}+P_{Ⅲ, n})/(P_{Ⅰ, n}+P_{Ⅱ, n}+P_{Ⅲ, n})均具有显著的相关性,因此,r_{(A, C)}值是兴凯湖沉积物FA腐殖程度表征的一个方便、快捷的参数。     

高压下Pd-Ni-P过饱和固溶体的形成

本文中研究了Pd₄₀Ni₄₀P₂₀金属玻璃小球(直径在0.1—1.0mm的范围)在4GPa压力下的晶化过程。与常压晶化实验相比,高压下样品的晶化温度以15K/GPa的速率增加。在接近熔点进行高压退火时,获得单相过饱和固溶体。其晶体结构为面心立方。将铸态Pd₄₀Ni₄₀P₂₀合金在高压下进行退火,同样得到了该固溶相,表明该相为一新的高压相。 关键词：     

利用Raman散射光谱研究铜铟镓硒薄膜表面的掺杂调节作用

主要研究了采用溅射后硒化方法制备CIGS(铜铟镓硒)薄膜太阳电池的吸收体材料中的表面层掺杂调节问题。并利用Raman散射谱分析研究了样品表面层特征峰的移用,研究结果表明: CIGS薄膜表面层由富In表面层调节为富CuGa表面层后,Raman特征峰位向高波数移动,表明薄膜表面的Ga含量随之变化,并导致表面能带的相应改变,经计算证实了富CuGa表面层样品较之富In表面层样品具有更高的表面能带,从而改善了以此材料为吸收层的太阳电池器件性能, V_oc提高了74 mV,填充因子上升8％,最终使器件转换效率η相应提高了约2％。提高了V_oc与FF。同时表明Raman散射谱作为一种灵敏的表面表征手段,在研究太阳电池吸收层表面状态时十分有力。     

包含硅量子点的富硅SiNx 薄膜结构与发光特性

采用等离子体增强化学气相沉积法, 以NH₃与SiH₄为反应气体, n型单晶硅为衬底, 低温(220 ℃)沉积了富硅氮化硅(SiN_x)薄膜. 在N₂氛围中, 于500–1100 ℃ 范围内对样品进行了热退火处理. 采用Raman 光谱技术分析了薄膜内硅量子点的结晶情况, 结果表明, 当退火温度低于950 ℃时, 样品的晶化率低于18%, 而当退火温度升为1100 ℃, 晶化率增加至53%, 说明大部分硅量子点都由非晶态转变为晶态. 实验通过Fourier 变换红外吸收(FTIR)光谱检测了样品中各键的键合结构演变, 发现Si–N键和Si–H键随退火温度升高向高波数方向移动, 说明了薄膜内近化学计量比的氮化硅逐渐形成. 实验还通过光致发光(PL)光谱分析了各样品的发光特性, 发现各样品中均有5个发光峰, 讨论了它们的发光来源, 结合Raman光谱与FTIR光谱表明波长位于500–560 nm的绿光来源于硅量子点, 其他峰则来源于薄膜内的缺陷态. 研究了硅量子点的分布和尺寸对发光带移动的影响, 并根据PL峰位计算了硅量子点的尺寸, 其大小为1.6–3 nm, 具有良好的限域效应. 这些结果有助于制备尺寸不同的硅量子点和基于硅量子点光电器件的实现. 关键词： 硅量子点 氮化硅薄膜 光致发光 Fourier 变换红外吸收     

颗粒超导体Ba2YCu3O7-δ的低温电阻特征

本文中研究了单相Ba₂YCU₃O_7-δ样品的低温电阻与外磁场、温度以及测量电流之间的关系。结果表明,外磁场的大小、方向,以及测量电流的大小,显著地改变着样品的低温电阻行为。从样品的颗粒结构特征对结果进行了讨论。 关键词：     

(Bi,Pb)2Sr2Ca2Cu3Oy单相样品的超导电性与载流子浓度

对(Bi,Pb)₂Sr₂Ca₂Cu₃O_y单相样品进行不同条件下的热处理,通过X射线衍射、电阻-温度关系、交流磁化率,以及Hall系数等测量,发现样品均具有较好的单相性,随着热处理条件的变化,其超导转变中点温度(T_c)有规律地分布在100—110K之间,T_c随载流子浓度(n_H)的增加而升高。实验结果表明,热处理条件对样品的相结构、超导 关键词：     

富锌条件下生长氮掺杂氧化锌薄膜的光学和电学性质

报道了采用等离子体辅助分子束外延方法(P-MBE),利用NO作为N源和O源,在c-面蓝宝石(c-Al₂O₃)衬底上外延生长了N掺杂ZnO薄膜。X射线衍射谱(XRD)和吸收谱中都出现了不同于未掺杂样品的特性,X射线光电子谱(XPS)中也发现了N的受主信号。但是在霍尔效应(Hall-effect)测量中,发现该样品并没有出现预期的p型导电特性,而是出现载流子浓度很高(2.15×10²⁰cm^-3)的n型导电特性。结合XPS结果和理论分析,认为在富Zn条件下生长会导致过量的填隙Zn原子,补偿了全部的受主后,又促使其出现了从半导体-金属的Mott转变。     

Preparation and properties of the single 110 K phase Bi(Pb)-Sr-Ca-Cu-O superconductor

The single 110 K phase Bi(Pb)–Sr–Ca–Cu–O superconductor was made by sintering in air. Its zero-resistance temperature is 106 K, and it is an orthorhombic cell witha=5.403 Å,b=5.412 Å andc=37.062 Å. It formed around the low-T _c phase. The forming period of the 110 K phase can be shortened by multiple sintering and grinding. If PbO is mixed into the samples after the 85 K phase has formed, the forming rate of the 110 K phase can be increased significantly. EDAX analysis of grain composition confirms that the Pb atoms enter the unit cell, and probably Pb cations replace some Ca cations.     

Electrical resistivity and magnetoresistance of CeB6

Electrical resistivity and magnetoresistance of CeB₆ single crystal have been measured in the temperature range from 1.3 to 300 K under the magnetic field up to 85 kOe. Three characteristic phases are distinguished consistently with other measurements. The Kondo like behaviour in the resistivity observed in the high temperature phase is fitted by the conventional form for the dilute Kondo state with the Kondo temperature T_K = 5 ～ 10K and the unitarity limit resistivity $\text{?}{}_{\mathrm{u}}\text{? 110 μΩ}$ cm/Ce-atom. The negative magnetoresistance in the middle phase is stronger with increasing magnetic field and with decreasing temperature suggesting rapid destruction of the Kondo state. The magnetoresistance in the low temperature phase exhibits some anomalies suggesting sub-phases corresponding to several kinds of spin ordering.     

Magnetostriction of a single cubic laves phase compound Tb0.27Dy0.73Fe2

The magnetostriction of a single crystal cubic Laves phase compound Tb_0.27Dy_0.73Fe₂ is measured with the applied field (0–25 kOe) in the [111] direction in the temperature range between 80 and 300 K. Evidence is seen of a possible transition to the[uv0] easy axis phase during the spin re-orientation form [100] easy axis direction to the [110] easy axis direction.     

Influence of heat treatment on the superconducting properties of Bi1.6Pb0.3Sb0.1Sr2Ca2Cu3O y

Differently heat-treated samples with the nominal composition Bi_1.6Pb_0.3Sb_0.1Sr₂Ca₂Cu₃O _y were studied by resistance and ac susceptibility measurements in the temperature range 77 K<T<200 K. The X-ray diffraction patterns at room temperature were also investigated. The experimental results show that repeated quenchings can depress the formation of the 80 K phase, and enhance the formation of the 110 K phase.     

含Sb的Bi系超导体的研究

Bi-Sr-Ca-Cu-O系中掺入适量的Sb,其高温相(110K相)含量明显多于不掺Sb样品。Sb具有加速高温相形成的作用。对于各义组分为Bi_2-xSb_xSr₂Ca_2.5Cu_3.7O_y的样品,x=0.1最有利于高温相的形成。用液氮中淬火后低温回火的方法,发现在865℃烧结时样品中首先形成的是低温相(80K相),然后再逐渐转变为高温相。T_c值随烧结时间的延 关键词：     

Quadrupolar susceptibility and magnetic phase diagram of PrNi2Cd20 with non-Kramers doublet ground state

ABSTRACT

In this study, ultrasonic measurements were performed on a single crystal of cubic PrNi₂Cd₂₀, down to a temperature of 0.02?K, to investigate the crystalline electric field ground state and search for possible phase transitions at low temperatures. The elastic constant (C₁₁?C₁₂)/2, which is related to the Γ₃-symmetry quadrupolar response, exhibits the Curie-type softening at temperatures below ～30?K, which indicates that the present system has a Γ₃ non-Kramers doublet ground state. A leveling-off of the elastic response appears below ～0.1?K toward the lowest temperatures, which implies the presence of level splitting owing to a long-range order in a finite-volume fraction associated with Γ₃-symmetry multipoles. A magnetic field–temperature phase diagram of the present compound is constructed up to 28?T for H || [110]. A clear acoustic de Haas–van Alphen signal and a possible magnetic-field-induced phase transition at H ～26?T are also detected by high-magnetic-field measurements.     

脉冲激光沉积温度及氧压对Bi2Sr2Co2Oy热电薄膜晶体结构与电输运性能的影响

利用脉冲激光沉积技术在c-Al₂O₃单晶基片上制备了Bi₂Sr₂Co₂O_y热电薄膜并研究了沉积温度和氧压对薄膜晶体结构及电输运性能的影响.在最佳沉积条件下制备的单相、c轴取向的Bi₂Sr₂Co₂O_y薄膜的室温电阻率ρ和塞贝克系数S分别为2.9mΩ/cm和110μupV/K,其功率因子S²/ρ好于在单晶样品上得到的值.此外,该薄膜在低温下表现出较强的负磁阻效应,在2K,9T时达到了40%.     

Structural phase transitions in Fe3+ -doped ferroelectric TlGaSe2 crystal

This paper presents the results of dielectric constant and Electron Paramagnetic Resonance (EPR) investigations of Fe³⁺-doped TlGaSe₂ single crystals in the temperature range of 15–300 K. The influence of Fe impurities on dielectric properties and phase transitions of TlGaSe₂ crystal has been studied. The results were considered in comparison with earlier observed results from pure TlGaSe₂ compounds. We observed the considerable decrease of the dielectric constant as well as the change of the shape of the temperature dependence of the dielectric constant in doped crystals. Some certain significant changes of EPR spectra, which are associated with a strong splitting and appearance of additional resonance lines, were observed at the temperatures below 110 K. Such transformations are considered as the result of non-equivalent displacements of different groups of Tl atoms during the structural phase transitions.     

A STUDY ON THE ULTRASONIC VELOCITY AND ATTENU-ATION IN NdFeB MAGNET WITHIN THE TEMPERATURE RANGE OF 80-300K(Ⅰ)

The ultrasonic velocity V and attenuation A of both longitudinal and shear waves in an anisotropic NdFeB magnet were measured over the temperature range from 80K to 300K by the pulse echo method. The anisotropy of the ultrasonic wave propagating in a NdFeB magnet was observed. Anomalous changes in both V-T and A-T curves in the temperature range of 110-160K were found, which might be due to the spin reorientation phase transition of Nd₂Fe₁₄B.     

Crystallization process of Bi(Pb)-Sr-Ca-Cu-O glass

A crystallization study has been carried out for rapidly solidified Bi₂Pb_0.5Sr₂Ca₄Cu₅O_x glass. Glass transition temperature T _g, crystallized superconducting phases and microstructural changes were measured and analysed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The crystallization mechanism of the three superconducting phases — (2201) 20 K phase, (2212) 80 K phase, and (2223) 110 K phase — has been discussed, and a time-temperature-transformation diagram for the glass has been constructed.