权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Pressure-induced delocalization in charge-ordering rare-earth compounds studied bynuclear resonant scattering

通过核共振散射研究电荷排序稀土化合物的压力诱导离域

基本信息

批准号：
17340098
负责人：
KOBAYASHI Hisao
金额：
$ 9.25万
依托单位：
University of Hyogo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340098/
关键词：
High Pressure Phonon Charge-ordered state Nuclear resonant scattering

项目摘要

The pressure versus temperature phase diagram of the mixed-valent Eu4As3 compound was determined by means of x-ray diffraction measurements using synchrotron radiation. The structural phase transition occurs at 343 K under ambient pressure with volume reduction and the transition temperature increases linearly with pressure up to about 5 GPa. The entropy change at this transition is estimated to be 41 J/molK from the Clausius-Clapeyron relation. The value is twice lager than the configuration entropy which is expected from the random arrangement of Eu^<3+> and Eu^<2+> ions in the thermally derived valence fluctuating state of Eu_4As_3.^<151>Eu nuclear resonant inelastic x-ray scattering (NRIXS) experiments have been performed on Eu_4As_3 from 301 to 406 K. We derived the thermodynamic parameters from inelastic components in the observed NRIXS spectra using the sum rules. The mean recoilless fraction shows the softening in the lattice vibration of the Eu ion around the boundary of the B … More rillouin zone in the valence fluctuating state. We present by the temperature dependence of mean force constant that the hybridization between the 4fstates and the conduction or valence bands in Eu_4As_3 plays a role around the charge ordering temperature and in the valence fluctuating state.We have carried out high-pressure x-ray diffraction experiments on Eu_4As_3 at mom temperature, and individual atomic coordinates as well as lattice parameters were derived precisely from the diffraction data. We have confirmed that a trigonal structure with the R3c space group does not change up to 19 GPa. The pressure dependence of the distortion angle changes at 10 GPa although the volume shows no anomaly as a function of pressure. The results show that the volume of the EuAs_6 octahedron and the valence state of the Eu ion are closely correlated, and pure trivalent and divalent Eu ions occupy two nonequivalent Eu sites, respectively, in the charge-ordered state at ambient pressure. We present dear evidence on the basis of the pressure dependence of these volumes at two nonequivalent Eu sites that a melting of the static charge order occurs at 10 GPa and Eu_4As_3 is in a mixed-valence state above 10 GPa. Less

通过同步辐射x射线衍射测量，确定了混合价Eu4As3化合物的压力-温度相图。在环境压力下，在343 K时发生结构相变，体积减小，相变温度随压力线性升高，最高可达5 GPa左右。根据克劳修斯-克拉珀龙关系，估计这一转变的熵变为41 J/molK。该值比Eu_4As_3热推导价态波动态中Eu^<3+>和Eu^<2+>离子随机排列所期望的构型熵大两倍。^<151>Eu核共振非弹性x射线散射（NRIXS）实验在301 ~ 406 K的Eu_4As_3上进行。我们利用求和规则从观测到的NRIXS光谱中的非弹性组分推导出热力学参数。平均无后坐力分数表明，在价态波动状态下，Eu离子在B…More瑞因区边界附近的晶格振动软化。我们通过平均力常数的温度依赖性证明了Eu_4As_3中4f态与导带或价带之间的杂化在电荷有序温度附近和价态波动状态下起作用。本文对Eu_4As_3在室温下进行了高压x射线衍射实验，并根据衍射数据精确地导出了单个原子坐标和晶格参数。我们已经确认，R3c空间群的三角结构在19gpa以下不会发生变化。变形角的压力依赖性在10gpa时发生了变化，而体积随压力的变化没有异常。结果表明，EuAs_6八面体的体积与Eu离子的价态密切相关，在常压下，纯三价Eu离子和纯二价Eu离子在电荷有序态中分别占据两个不相等的Eu位。基于两个非等效Eu位点上这些体积的压力依赖性，我们提出了有力的证据，表明在10 GPa时发生了静态电荷序的熔化，而在10 GPa以上Eu_4As_3处于混合价态。少

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）

Elastic properties of filled-Skutterudite compound probed by Mossbauer nuclei.

通过穆斯堡尔核探测填充方钴矿化合物的弹性特性。

DOI：
发表时间：
2006
期刊：
Hyperfine Interact. 168
影响因子：
0
作者：
S.Tsutsui;H.Kobayahi et al.
通讯作者：
H.Kobayahi et al.

^<149>Sm nuclear forward scattering of Sm_4Bi_3 under high pressure

^<149>高压下Sm_4Bi_3的Sm核前向散射

DOI：
发表时间：
2007
期刊：
J.Magn.Magn.Mater 310
影响因子：
0
作者：
H.Kobayashi;A.Ochiai;et. al.
通讯作者：
et. al.

Low-lying optical modes in filled skutterudites usilg inelastic x-ray scattering techniques.

使用非弹性 X 射线散射技术研究填充方钴矿中的低位光学模式。

DOI：
发表时间：
2007
期刊：
J.Phys.:Conf.Series 92
影响因子：
0
作者：
S.Tsutsui;H.Kobayashi;et. al.
通讯作者：
et. al.

149Sm nuclear resonant inelastic scattering of Sm-based filled-skutterudite compounds

Sm基填充方钴矿化合物的149Sm核共振非弹性散射

DOI：
10.1016/j.physb.2006.03.082
发表时间：
2006
期刊：
Physica B-condensed Matter
影响因子：
2.8
作者：
Satoshi Tsutsui;J. Umemura;H. Kobayashi;Y. Yoda;H. Onodera;H. Sugawara;D. Kikuchi;H. Sato;C. Sekine;I. Shirotani
通讯作者：
I. Shirotani

Electronic states of Eu_4A_s3 under high pressure

高压下Eu_4A_s3的电子态