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91.
The plane-wave pseudopotentiai method using the generaiized gradient approximation within the framework of density functional theory is applied to anaylse the bulk modulus, thermal expansion coefficient and heat capacity of LaB6. The quasi-harmonic Debye model, using a set of total energy versus volume obtained with the plane-wave pseudopotential method, is applied to the study of the thermal properties and vibrationai effects. We analyse the bulk modulus of LaB6 up to 1500 K. The elastic properties calculations show that our system is mechanically stable. For the heat capacity and the thermal expansion, significant differences in properties are observed above 300K. The calculated zero pressure bulk modulus is in good agreement with the experimental data. Moreover, the Debye temperatures are determined from the non-equilibrium Gibbs functions and compared to available data. 相似文献
92.
93.
南海水合物黏土沉积物力学特性试验模拟研究 总被引:11,自引:5,他引:6
利用自行研制的含水合物沉积物合成、分解与力学性质测量一体化试验设备,以南海水合物区域的海底粉质黏土作为骨架,制备含水合物沉积物样品,并对其进行了三轴压缩试验研究,获得了水合物分解前后的应力应变曲线和抗剪强度特性. 结果表明:在水合物饱和度0%~45% 的范围内,水合物沉积物的应力应变曲线均表现为弹塑性变形,存在明显的应变硬化现象;抗剪强度、内摩擦角和黏聚力随水合物饱和度的增加而增加. 相对而言,内摩擦角随饱和度增加幅度较小,其他参数在水合物饱和度超过25% 时,呈陡然增高趋势;水合物分解后导致抗剪强度最大可降低为初始的1/4,不同初始饱和度条件下水合物完全分解后沉积物的抗剪强度基本相等,并大于同等围压条件下初始不含水合物的沉积物抗剪强度. 相似文献
94.
Pseudo-potential investigations of structural, elastic and thermal properties of tungsten disilicide 下载免费PDF全文
The plane-wave pseudopotential method using the generalized gradient
approximation within the density functional theory is used to
investigate the structure and bulk modulus of WSi2. The
quasi-harmonic Debye model, using a set of total energy versus cell
volume obtained with the plane-wave pseudopotential method, is
applied to the study of the elastic properties and vibrational
effects. We have analysed the bulk modulus of WSi2 up to
1600~K. The major trend shows that the WSi2 crystal becomes
more compressible when the temperature rises and the increase of
compressibility leads to the decrease of Debye temperature. The
predicted temperature and pressure effects on the thermal expansion,
heat capacity and Debye temperatures are determined from the
non-equilibrium Gibbs functions and compared with the data
available. 相似文献
95.
三维有序大孔(3DOM)材料具有高度有序的孔结构和较大的比表面积,这些特点有利于气体在材料表面的传输与扩散,可以作为良好的气敏材料.本文通过聚苯乙烯模板结合煅烧处理的方法制备了3DOM WO3气敏材料,并运用XRD、SEM、BET、XPS等手段对其物相、形貌、比表面积和表面成分等进行了表征.气敏测试结果表明,所制备的3DOM材料对丙酮灵敏度高(在丙酮浓度10 ppm时,S=10),检测限可低至0.2 ppm.此外,3DOM WO3材料对丙酮还具有良好的选择性和长期稳定性.最后,对所制备的3DOM WO3材料进行了气敏机理解释. 相似文献
96.
Considering a quantum model consisting of two effective two-level atoms and a single-mode cavity,this paper investigates the entanglement dynamics between the two atoms,and studies the effect of the Stark shift on the entanglement.The results show that,on the one hand the atom-atom entanglement evolves periodically with time and the periods are affected by the Stark shift;on the other hand,the two atoms are not disentangled at any time when the Stark shift is considered,and for large values of the Stark shift parameter,the two atoms can remain in a stationary entangled state.In addition,for the initially partially entangled atomic state,the atom-atom entanglement can be greatly enhanced due to the presence of Stark shift.These properties show that the Stark shift can be used to control entanglement between two atoms. 相似文献
97.
通过在WO3纳米片表面负载ZnFe2O4纳米颗粒,构建了一系列S型异质结光催化剂ZnFe2O4/WO3,并研究了其光催化CO2还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe2O4/WO3复合材料可对CO2与水蒸汽进行光催化反应。优化后的材料光照5 h后CO2还原产物CO和CH4的产量分别为7.87和4.88 μmol·g-1。相对于单相组分,CO和CH4的产量明显提高。光催化活性的提高,归因于ZnFe2O4和WO3异质结的形成以及光生载流子的S型电荷传输模式。 相似文献
98.
Quantum entanglement in the system of a moving V-type three-level atom interacting with the SU(1,1)-related coherent fields 下载免费PDF全文
In a system with a moving V-type three-level atom interacting with
the SU(1,1)-related coherent fields,
we investigate the entanglement between the moving three-level atom
and the SU(1,1)-related coherent fields by
using the quantum-reduced entropy, and that
between the SU(1,1)-related
coherent fields by using the quantum relative
entropy of entanglement. It is shown that the two kinds of entanglement
are dependent on the atomic motion and
exhibit the periodic evolution with a
period of 2π/p. The maximal atom--field qutrit entanglement
state can be prepared, and the entanglement preservation
of the SU(1,1)-related coherent fields
can be realized in the interacting process
via the appropriate selection of system
parameters and interaction time. 相似文献
99.
A model containing two two-level atoms and a single-mode cavity is considered, and the effect of the time-dependent atom-field couplings on entanglement between the two atoms is studied. The results indicate that both for one-photon processes and for two-photon processes, the disappearance of the initial entanglement is delayed due to the linear modulation of the atom-field coupling coefficients as compared to the constant coupling model. The delayed time of the disappearance of the initial entanglement for the two-photon processes is much longer than that for the one-photon processes in the case of adiabatic variation. 相似文献
100.
本文利用Born-Markov方程计算并分析了两个生物分子间的纠缠演化问题. Born-Markov方程摒弃了传统方程中的久期近似, 并且重新计算了环境算符关联函数的傅里叶变换. 计算表明, 与经典的Lindblad方程相比, Born-Markov方程得到的结果更加符合预期. 考虑两个相互耦合的发色团对(一种吸光分子)与一个多模的马尔可夫环境相互作用, 发现相比于不对称的生物分子, 对称的生物分子能够大大增加量子纠缠的持续时间. 相似文献