本文用比热和X射线衍射方法研究了压力对黝铜矿Cu $_{10}$ Zn $_{2}$ Sb $_{4}$ S $_{13\,}$(CZSS)和Ⅰ型包合物Ba $_{8}$ Ga $_{16}$ Sn $_{30\,}$(BGS)振动的影响。通过施加压力$P$,CZSS的拍击能量最初减小,并且对于$P$ $\textgreater$ $1$ GPa急剧增加。相比之下,BGS的能量随着$P$单调增加到6.5 GPa。压力依赖的比热和X射线衍射的分析表明,在CZSS的S $_{3}$三角形的Cu原子的面外的嘎嘎声源于化学压力,不同于在一个超大的笼BGS的偏心位置之间的Ba离子的嘎嘎声。当$P$进一步增加到2 GPa以上时,CZSS中的嘎嘎声停止,这表明铜原子逃离了S $_{3}$三角平面。
英文摘要:
We have studied the pressure effect on the rattling of tetrahedrite Cu$_{10}$Zn$_{2}$Sb$_{4}$S$_{13\,}$(CZSS) and type-I clathrate Ba$_{8}$Ga$_{16}$Sn$_{30\,}$(BGS) by specific heat and x-ray diffraction measurements. By applying pressure $P$, the rattling energy for CZSS initially decreases and steeply increases for $P$ $\textgreater$ $1$ GPa. By contrast, the energy for BGS increases monotonically with $P$ up to 6.5 GPa. An analysis of the pressure dependent specific heat and x-ray diffraction indicates that the out-of-plane rattling of the Cu atoms in the S$_{3}$ triangle of CZSS originates from the chemical pressure, unlike the rattling of the Ba ions among off-center sites in an oversized cage of BGS. The rattling in CZSS ceases upon further increasing $P$ above 2 GPa, suggesting that Cu atoms escape away from the S$_{3}$ triangle plane.
Phonon Scattering Mechanism in Thermoelectric Materials Revised via Resonant X-ray Dynamical Diffraction
热电材料的工程需要理解晶格和电子自由度的热传导。填充方钴矿表示适合于热电应用的材料的大家族,其中减少的晶格热传导归因于结构的大笼内的填料阳离子的局部低频振动(嘎嘎声)。本文提出了一种利用X射线在CeFe $_4$ P $_{12}$单晶中的动态衍射的多波长方法,并将其应用于求解原子振动的振幅。结果表明,整个填充笼系统的振动动力学是热电性能优化背后的实际活动机制。
Neutron and X-ray Diffraction Reveal the Limits of Long-Range Machine Learning Potentials for Medium-Range Order in Silica Glass
Department of Material Design and Innovation, University at Buffalo(材料设计与创新系,布法罗大学);NVIDIA Corp.(NVIDIA公司);X-ray Science Division, Advanced Photon Source, Argonne National Laboratory(先进光子源X射线科学部,阿贡国家实验室)
Pressure-Driven Phase Evolution and Optoelectronic Properties of Lead-free Halide Perovskite Rb$_2$TeBr$_6$
Indian Institute of Science Education and Research Kolkata(印度科学教育研究学院加尔各答分校);National Centre for High Pressure Studies, Indian Institute of Science Education and Research Kolkata(印度科学教育研究学院加尔各答分校高压研究中心);Elettra-Sincrotrone Trieste S.C.p.A.(的里雅斯特电子同步辐射中心)
Constructing a bifunctional platform based on Mn2+-doped Mg2Y8(SiO4)6O2 phosphors for multi-parameter optical thermometry and manometry
School of Physical Science and Technology, Ningbo University(宁波大学物理科学与技术学院);Institute of Low Temperature and Structure Research, Polish Academy of Sciences(波兰科学院低温结构研究所)
Pressure dependence of the structure and electronic properties of Sr3Ir2O7
利用X射线衍射研究了Sr $_3$ Ir $_2$ O $_7$的结构演化与压力的关系。在54 GPa的压力下,在室温下,我们观察到一级结构相变,与从四斜晶系到单斜对称的变化,并伴随着4%的体积塌陷。高压相的Rietveld细化揭示了Ruddlesden-Popper结构的一种新的修改,该结构采用了钙钛矿双层的改变的堆叠顺序。由于氧原子的位置不能从数据中得到可靠的精确,我们使用密度泛函理论(局域密度近似+ $U$ +自旋轨道)来优化晶体结构,并阐明在高压下Sr $_3$ Ir $_2$ O $_7$的电子和磁性。在低压四面体中,我们发现IrO $_6$八面体的面内转动随压力的增加而增加.计算进一步表明,带宽驱动的绝缘体-金属转变发生在$\sim$ 20 GPa,随着淬灭的磁矩。在高压单斜相,结构优化导致复杂的倾斜和旋转的氧八面体,强烈重叠的$t_{2g}$和$e_g$带。$t_{2g}$带宽使得自旋-轨道耦合和电子相关性在打开电子能隙方面无效,导致Sr $_3$ Ir $_2$ O $_7$的高压相的稳健金属态。
Pressure induced structural transitions, coordination crossover, and optoelectronic response in divalent metavanadate CaV$_2$O$_6$
Indian Institute of Science Education and Research Kolkata(印度科学教育研究学院加尔各答分校);National Centre for High-Pressure Studies(高压研究中心);IMPMC, Sorbonne Université(巴黎第六大学地球物理学研究所);Beijing Academy of Quantum Information Sciences(北京量子信息科学研究院);Deutsches Elektronen Synchrotron(德国电子同步辐射中心)