固体热膨胀系数与压强关系的一个近似公式

 假定Anderson-Grüneisen参量δ_T(T, p)=δ_T(T, 0),利用改造的Tait方程,导出了固体热膨胀系数与压强关系的一个近似公式。应用于NaCl晶体,在压强为0～1 GPa、温度为300～800 K范围内,热膨胀系数的计算值与实验值一致。     

碱卤晶体热导率与压强的关系

 本文指出，关于碱卤晶体热导率λ与压强p之间关系的经验方程：λ=A+Bp或λ=A+Bp+Cp²，可以由Bridgman参量的定义g=-(d lnλ/dlnV)_T和Tait方程ΔV/V₀=ln(1+βp)/α导出。     

Fe:LiNbO3全息图热定影及H+浓度的影响

应用光折变效应动力学方程,导出了在Fe:LiN_bO₃中对光折变全息图热定影所需的最小H⁺浓度,以及H⁺浓度与光栅空间频率的关系.应用光谱比较法测量了不同样品的H⁺浓度值.得出了进行有效热定影的H⁺浓度范围.完成了Fe:LiN_bO₃全息存储和热定影实验.获得了100h连续无损读出的良好热定影实验结果.     

压力对TlPbxBaCa3Cu3O超导电性的影响

 在零电阻温度T_c0达到120 K的TlBaCa₃Cu₃O_y超导体中，掺入不同含量的Pb后，超导电性受到抑制，点阵常数减小。加压时，T_c先随压力p的增加而上升，样品1（x_Pb=0.05）的dT_c0/dp=1.7 K/GPa，样品2（x_Pb=0.5）的dT_c0/dp=2.2 K/GPa。T_c的峰值随Pb的增加而减小。加压时，对由于Pb的加入引起的Cu—O层的精细结构变化起到调制作用。     

基于组分Ca2Pr2Cu5O10三元固溶区的范围和晶体结构

 利用X射线衍射分析和Rietveld结构精修方法研究了基于组分Ca₂Pr₂Cu₅O₁₀三元固溶区的范围和晶体结构。根据X射线分析结果和相消失法，为了保持Ca_2+xPr_2-xCu₅O₁₀结构单位晶胞中恒定的氧含量和电价平衡，基于组分Ca₂Pr₂Cu₅O₁₀的三元固溶区的范围可确定为：在Ca_2+xPr_2-xCu₅O₁₀固溶区的富Ca区（Ca/Pr>1），其表达式仍可以表示为一般的化学计量式Ca_2+xPr_2-xCu₅O₁₀（x=0.4, 0.2, 0）；在富Pr区（Ca/Pr<1），其表达式为Ca_1.7Pr_2.2·Cu₅O₁₀、Ca_1.4Pr_2.4Cu₅O₁₀，即：Ca_2+xPr_2-xCu₅O₁₀固溶区范围从Ca_2.4Pr_1.6Cu₅O₁₀至Ca_1.4Pr_2.4·Cu₅O₁₀。研究表明：基于组分Ca₂Pr₂Cu₅O₁₀的三元固溶体晶体结构可以看作是正交晶系NaCuO₂型亚晶胞的无公度相；Ca_2.4Pr_1.6Cu₅O₁₀亚晶胞的点阵常数为a₀=0.282 46(7) nm，b₀=0.636 93(1) nm，c₀=1.067 94(1) nm；其正交超结构的点阵常数为a=5a₀，b=b₀，c=5c₀。Ca_2.4Pr_1.6Cu₅O₁₀的结构也可以用单斜超晶胞来表述，该单斜超晶胞的空间群为P2₁/c，Z=4，a=5a₀，b=b₀，c=c₀/sin β，β=104.79°或136.60°，V=5a₀b₀c₀。在基于组分Ca₂Pr₂Cu₅O₁₀的三元固溶体晶体结构中，Ca和Pr之间在一定范围内是可以相互替代的，而且它们在结构中的占位是无序的。     

液态金属的定容比热随温度变化的理论研究

 Grover根据实验数据给出，液态金属的定容比热随温度近似线性减小：c_V≈3R-ζRT/T_m，式中T为温度，T_m为熔化温度，R为普适气体常数，ζ为经验常数，其值在0.11至0.24之间，就平均来说，ζ≈0.15。利用Lennard-Jones-Devonshire理论对这一经验关系进行了解释。     

重核惯性张量的微观研究

本文在线性响应理论的基础上, 推导得出惯性张量的微观计算表达式; 取尼尔逊单粒子态^[1], 对²³⁶U核裂变的惯性张量进行了数值计算; 观察了惯性张量随核温度T和形坐标δ₂、δ₄的变化; 分析了惯性张量的对效应和壳效应; 对惯性张量在能级交叉处和通过临界温度T_c时出现的特殊现象进行了讨论.     

Na填充型方钴矿化合物CoSb3的高压合成及电输运特性研究

 利用高压合成方法,在压力为2 GPa、温度为900 K的条件下,以NaN₃作为添加剂,成功地合成出了Na填充型的方钴矿化合物CoSb₃。X射线衍射（XRD）研究结果表明,当Na填充量达80%时,合成的Na填充型方钴矿化合物CoSb₃仍为单相方钴矿结构,没有Na和NaN₃等杂质峰。在室温下对不同Na填充量的样品进行了电阻率（ρ）和Seebeck系数（α）的测试,研究了不同Na填充量对样品电阻率、Seebeck系数和功率因子（α²σ）的影响。研究结果表明：室温下,样品的电导率随Na填充量的增加而增大,Seebeck系数的绝对值随Na填充量的增加而减小。当Na填充量为0.4时,样品获得了最高的功率因子（8.72 μW·cm^-1·K^-2）,此值高于He等报道的利用热压法制备的CoSb₃的值。填充量对样品电输运特性的影响规律与Pei等研究的K填充型CoSb₃的研究结果相一致。上述研究结果表明,高压合成技术有利于提高填充型方钴矿化合物的填充量,并有效地提高样品的电输运特性。     

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。     

高温高压下CeTbO3合成过程中电阻的动态测试研究

 在0.5 GPa、4.0 GPa的压力下，从室温到800 ℃的温度范围内测量了氧化物CeTbO₃、单稀土氧化物Tb₄O₇、CeO₂和摩尔比维4∶1配比的混合物CeO₂+Tb₄O₇等的电阻随温度变化关系。对这四种物质均反映出电阻随温度增加而减小的半导体特征。在压力维0.5 GPa，温度高于600 ℃时发现了混合物CeO₂+Tb₄O₇、氧化物Tb₄O₇中电阻变化的起伏。X射线衍射谱表明，对应这一电阻变化，在结构上出现了变化。结果分析表明，这一变化与Tb⁴⁺→Tb³⁺的价态变化密切相联。     

Eccentricity and elliptic flow at fixed centrality in Au+Au collisions at sNN=200 GeV in AMPT model

In this paper, elliptic flow is studied at fixed centrality in Au+Au collision at √s_NN=200 GeV in the AMPT model. It is observed that with the participant increasing, elliptic flow has an increase or a decrease at different fixed impact parameter, but it does not have a trivial fluctuation. It is analyzed that the initial space anisotropy dominates the participant dependence of elliptic flow in near-central collisions(b=5 fm) and mid-central collisions(b=8 fm), while the interaction between particles can mainly answer for the behavior of elliptic flow with participant in peripheral collisions (b=12 fm). To distinguish the pure geometrical effect, elliptic flow scaled by initial eccentricity is studied. It is found that the ratio v₂/ε increases with participant and reaches a saturation when the participant is large enough, indicating that the collision system may reach the local equilibrium.     

以修正WLF方程研究压力作用下丁腈橡胶的阻尼性能

时温等效原理表明固定频率下温度越高,模量越低,而相同温度下频率越低,模量越低,即升高温度与降低频率具有同等效应。根据这一规律,可将聚合物的力学性能随温度的变化转化为这些性能随频率的变化,从而可通过不同温度下的力学性能测试数据,换算成宽频率范围内的材料力学性能表现。为了研究压力作用下橡胶阻尼性能的基本变化规律,通过自由体积理论推导出加压后的修正WLF方程,采用动态热机械分析实验,测试得到丁腈橡胶在不同温度下的损耗因子tanδ对频率ω的曲线,根据计算得到不同压力下的测试温度至室温的平移因子,便可做出加压后的丁腈橡胶的损耗因子-频率谱的主拟合曲线,其曲线的频率跨度达10个数量级以上。结果表明,丁腈橡胶的tanδ测试段在高于参考温度以后出现,而随着压力的增加,玻璃化温度相应升高,峰值往高频移动达1.5个数量级。此结果为研究压力作用下橡胶材料阻尼性能的定量变化提供了理论依据。     

高氧压合成产物La2CuO4+δ的相变研究

 本文采用超高氧压2.3 GPa合成方法，得到超导相含量大于30%的超导化合物La₂CuO_4+δ所采用的压力是目前所见报导中对La₂CuO₄化合物施加的最高氧压。湿化学方法测量给出过量氧含量δ=0.05±0.01，而TGA（氮气中）给出δ=0.143。高氧压合成产物经在空气中、不同温度下加热，然后淬火到室温，结果发现超导体在200~300 ℃的加热处理中存在着一个一级相变。经此相变后，超导体转变成反铁磁半导体。TGA及DSC证实了此相变的存在。该相变前后所联系的氧含量变化恰好为湿化学方法给出的结果，这部分与超导电性存在联系的过量氧，实际上引起了Cu²⁺向Cu^(2+2δ)+的转变。该结果强有力地排除了所谓“超氧化物”引起超导电性的可能性。     

Viscoelastic and Dielectric Behavior of Poly(1‐Butene)/Multiwalled Carbon Nanotube Nanocomposites

Linear viscoelastic properties and dielectric behavior of poly(1‐butene)/multiwalled carbon nanotube (MWCNT) nanocomposites were investigated. Dynamic mechanical analysis showed significant increase in storage modulus in the rubbery regime. The tan δ peak temperature remained constant; however, the peak intensity was lowered for the nanocomposites. In melt rheological studies the nanocomposites showed a shift in crossover frequency to the lower side, suggesting delayed relaxation of the molecular chains in the presence of MWCNT and this shift was found to depend on the content of MWCNT. The dielectric constant increased from 2.2 to 70 for the nanocomposite with 7 wt. % MWCNT. The electrical conductivity increased significantly, from 10^?15 to 10^?3 S/cm. The results of rheology and dielectric studies indicate that a percolation network is formed that is responsible for the observed changes.     

Aggregation Behaviour of Cationic Diblock Copolymer （MTAC）10（BA）16： MesoDyn Simulation Study

The aggregation behaviour of an amphiphilic cationic block copolymer （MTAC）10（BA）16 in aqueous solution is investigated by MesoDyn simulation. Simulation results show that （MTAC）10 （BA）16 can form spherical, irregular and network aggregates with the increasing volume fraction. The time evolution of order parameter shows that the process of aggregate formation can be divided into diffusion control stage and hydrophobic interaction control stage, while the time evolution of energy indicates that the aggregate formation is driven by enthalpy but not entropy. The order parameter of the hydrophobic blocks BA increases with the increasing （MTAC）10（BA）16 concentration, while the time needed for system balance has the contrary trend.     

CO_2膨胀液体的分子动力学模拟

采用分子动力学方法,模拟了CO2膨胀甲醇体系、CO2膨胀乙醇体系的热力学性质和输运性质,以及对氯硝基苯在CO2膨胀甲醇体系、苯甲腈在CO2膨胀乙醇体系中的扩散性质。CO2膨胀甲醇体系的密度模拟值略高于实验值,而CO2膨胀乙醇体系的密度模拟值与实验值非常接近。模拟结果表明:CO2使甲醇和乙醇溶液的膨胀非常明显,当CO2的摩尔分数达到0.5时,溶液膨胀约100%;得到了CO2、甲醇、乙醇、对氯硝基苯以及苯甲腈的扩散系数,其中对氯硝基苯和苯甲腈在两种膨胀液体中的扩散系数与实验结果接近;通过扩散系数关联了两种膨胀液体的粘度,计算结果与修正的Wilke-Chang方程得到的体系粘度规律一致。     

Calculation of B/A for n-alkane liquids using the Tait equation

The B/A parameter of acoustic nonlinearity was calculated for a series of n-alkane liquids using the Tait PVT equation of state supplemented with specific heat data. The calculations of sound speed, sound speed derivatives, the two components of B/A, and the value of B/A itself were compared with experimental data taken from the literature and with earlier calculations using a different equation of state. In addition, a comparison of the results with Ballou's rule (linear relation of B/A and reciprocal sound speed) was made. It is concluded that B/A can be calculated from the Tait equation of state with about the same accuracy as direct measurements of sound speed versus pressure and temperature, though the the temperature derivatives of the sound speed are calculated with much lower accuracy than pressure derivatives. The calculations made using the Tait equation are about the same accuracy as calculations made using our equation of state. Also, Ballou's rule does not hold for these liquids.     

Effect of carbon nanotubes implantation on electrical properties of sisal fibre–epoxy composites

In this paper, the effects of carbon nanotubes (CNT) implantation and sisal fibre size on the electrical properties of sisal fibre-reinforced epoxy composites are reported. For this purpose, the epoxy composites reinforced with CNT-implanted sisal fibre of 5 mm and 10 mm lengths were prepared by hand moulding and samples characterized for their electrical properties, such as dielectric constant (ε′), dielectric dissipation factor (tan δ) and AC conductivity (σ_ac) at different temperatures and frequencies. It was observed that the dielectric constant increases with increase in temperature and decreases with increase in frequency from 500 Hz to 5 KHz. Interestingly, the sample having CNT-implanted sisal fibre of 5 mm length exhibited the highest value of dielectric constant than the one with length 10 mm. This is attributed to the increased surface area of sisal fibre and enhancement of the interfacial polarization. At a constant volume and a length of 5 mm of the fibres, the number of interfaces per unit volume element is high and results in a higher interfacial polarization. The interfaces decrease as the fibre length increases, and therefore, the value of ε′ decreases at 10 mm fibre length. The peak value of the dielectric constant decreases with increasing frequency. A continuous decrease in dissipation factor (tan δ) with increasing frequency for all samples was observed, while at lower temperatures, the values of tan δ remains approximately same. The AC conductivity for 5 mm length sisal epoxy composite and 10 mm length sisal fibre–epoxy composites is higher than that of pure epoxy at all the frequencies.