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Guest-Host Interaction and High-pressure Phase Transitions in Semiconductor Clathrates Studied by Raman Spectromopy

通过拉曼光谱研究半导体包合物中的客主相互作用和高压相变

基本信息

批准号：
18540315
负责人：
SHIMIZU Hiroyasu
金额：
$ 2.43万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18540315/
关键词：
Raman Scattering Semiconductor Clathrate Nano-Structure Rattling Vibration High Pressure Guest-Host Interaction

项目摘要

1.High-pressure Raman and XRD measurements of a defect clathrate Ba_8Ge_(43) □_3 have been carried out at room temperature up to 40 GPa. Raman spectra show a pressure-induced phase transition at 8 GPa, which is due to the structural distortion through the three-bonded Ge atoms and to the change in the guest-host electronic interaction.Both Raman spectra and XRD patterns present the evidence for the amorphization of Ba_8Ge_(43) around 30-40 GPa. The isostructural phase transition associated with the large volume reduction was not observed for Ba_8Ge_(43) up to 40 GPa. The pressure dependence of the lattice constant (a) normalized by a_0 at 1 bar ( ; a/s_0) shows the continuous decrease with pressure until amorphization. From the good coincidence of these curves between Ba_8Ge_(43) and Ba_sSi_(46) at pressures above 15 GPa, we propose that the isostructural phase transition found for Ba_8Si_(46) at 15 GPa may be originated from a defect-induced transformation to Ba_sSi_(43) □_3 with the … More help of their theoretical EOS by the first-principles calculations.2.High-pressure Raman measurements of type-III germanium clathrate Ba_(24)Ge_(100) has been made up to 26 GPa at room temperature. We observed low-frequency vibrational (rattling) modes associated with guest Ba atoms at 25-50 cm^(-1), and host Ge framework vibrations around 50-250 cm^(-1), which are compared with those of silicon clathrate Ba_(24)Si_(100). High-pressure phase transition was found at 3.2 GPa, which seems to be due to the structural distortion combined with the enhanced guest-host interactions.Ba_(24) Ge_(100) becomes irreversibly amorphous at pressures above 22 GPa. This pressure is less than that of type-I Ba_8Ge_(43) clathrate, indicating that type-III structure is less stable than type-I Ge clathrate under high pressures.The present results throw valuable light on the understanding and the application of semiconductor clathrates, the high pressure phase tuansitions, and the general system of guest-host interactions. Less

1.在室温至40 GPa下对缺陷包合物Ba_8Ge_(43) □_3进行了高压拉曼和X射线衍射测量。拉曼光谱显示出在 8 GPa 下压力诱导的相变，这是由于三键 Ge 原子的结构畸变以及客主电子相互作用的变化所致。拉曼光谱和 XRD 图案都提供了 Ba_8Ge_(43) 在 30-40 GPa 左右非晶化的证据。对于高达 40 GPa 的 Ba_8Ge_(43)，没有观察到与大体积减小相关的同构相变。 1 bar 下由 a_0 归一化的晶格常数 (a) 的压力依赖性 (; a/s_0) 显示随压力持续减小直至非晶化。从压力高于 15 GPa 时 Ba_8Ge_(43) 和 Ba_sSi_(46) 之间的这些曲线的良好重合来看，我们提出，在 15 GPa 压力下发现的 Ba_8Si_(46) 的同构相变可能源于缺陷诱导的向 Ba_sSi_(43) □_3 的转变，借助他们的理论 EOS。第一性原理计算。2.III型锗包合物Ba_(24)Ge_(100)的室温高压拉曼测量达到26 GPa。我们在 25-50 cm^(-1) 处观察到与客体 Ba 原子相关的低频振动（嘎嘎声）模式，并在 50-250 cm^(-1) 附近观察到主 Ge 骨架振动，并将其与硅包合物 Ba_(24)Si_(100) 进行比较。在3.2 GPa下发现高压相变，这似乎是由于结构畸变和客主相互作用增强所致。Ba_(24) Ge_(100)在压力高于22 GPa时变得不可逆非晶态。该压力小于I型Ba_8Ge_(43)包合物，表明在高压下III型结构不如I型Ge包合物稳定。本研究结果为半导体包合物、高压相转变和客主相互作用的一般系统的理解和应用提供了有价值的启示。较少的

项目成果

期刊论文数量（0）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Raman and x-ray diffraction studies of Ba doped germanium clathrate Ba_8 Ge_<43> at high pressures

高压Ba掺杂锗包合物Ba_8 Ge_<43>的拉曼和X射线衍射研究

DOI：
发表时间：
2007
期刊：
J. Appl. Phys. 101・6
影响因子：
0
作者：
H. Shimizu;et. al.;H.Shimizu et al.
通讯作者：
H.Shimizu et al.

High-pressure Raman study on two modifications of BaAl_2Si_2

BaAl_2Si_2两种变体的高压拉曼研究

DOI：
发表时间：
2007
期刊：
Phys. stat. solidi(b) 244
影响因子：
0
作者：
H. Shimizu;et. al.
通讯作者：
et. al.

Semiconductor Clathrates at High Pressure

高压下的半导体包合物

DOI：
发表时间：
2007
期刊：
影响因子：
0
作者：
H. Shimizu;et. al.;H.Shimizu et al.;T.Kume et al.;H.Shimizu et al.;T.Fukushima et al.;清水宏晏;H. Shimizu and T. Kume
通讯作者：
H. Shimizu and T. Kume

High-pressure Raman study of nano-channel materials: BaAl_2Si_2 and BaSi_6

纳米通道材料BaAl_2Si_2和BaSi_6的高压拉曼研究