排序方式: 共有3条查询结果,搜索用时 109 毫秒
1
1.
As a widely used pressure calibrator, the structural phase transitions of bismuth from phase I, to phase II, to phase III,and then to phase V with increasing pressure at 300 K have been widely confirmed. However, there are different structural versions for phase III, most of which are determined by x-ray diffraction(XRD) technology. Using x-ray absorption fine structure(XAFS) measurements combined with ab initio calculations, we show that the proposed incommensurate composite structure of bismuth of the three configurations is the best option. An abnormal continuous increase of the nearest-neighbor distance of phase III with elevated pressure is also observed. The electronic structure transformation from semimetal to metal is responsible for the complex behavior of structure transformation. 相似文献
2.
采用密度泛函理论中的赝势平面波方法研究了高压下超导材料 ErNi2B2C 的弹性性质、电子结构和热力学性质.分析表明, 弹性常数、体弹模量、剪切模量、杨氏模量和弹性各向异性因子的外压力效应明显. 电子态密度(DOS)的计算结果显示, 在费米能级(EF)处的 DOS 峰随外界压强的增大显著降低, 由于 ErNi2B2C 相对较高的超导温度(Tc)起因于EF处的 DOS 峰, 因此推测压强增大可能会降低 ErNi2B2C 的 Tc.类似的现象在超导材料 MgB2和 SrAlSi 中已被发现.此外, 基于准谐德拜模型, 对 ErNi2B2C 在高温高压下的热力学性质的研究表明, 在一定范围内, 温度和压强将对其热膨胀系数和热容产生明显的影响.
关键词:
高压
弹性性质
电子结构
热力学性质 相似文献
3.
Predicted novel insulating electride compound between alkali metals lithium and sodium under high pressure 下载免费PDF全文
The application of high pressure can fundamentally modify the crystalline and electronic structures of elements as well as their chemical reactivity, which could lead to the formation of novel materials. Here, we explore the reactivity of lithium with sodium under high pressure, using a swarm structure searching techniques combined with first-principles calculations, which identify a thermodynamically stable Li–Na compound adopting an orthorhombic oP8 phase at pressure above 355 GPa. The formation of Li–Na may be a consequence of strong concentration of electrons transfering from the lithium and the sodium atoms into the interstitial sites, which also leads to open a relatively wide band gap for Li NaoP8. This is substantially different from atoms sharing or exchanging electrons in common compounds and alloys. In addition, lattice-dynamic calculations indicate that Li Na-oP8 remains dynamically stable when pressure decompresses down to 70 GPa. 相似文献
1