A high-pressure Raman study of FeTiO3 ilmenite: Fermi resonance as a manifestation of Fe-Ti charge transfer
A high-pressure Raman study of FeTiO3 ilmenite: Fermi resonance as a manifestation of Fe-Ti charge transfer
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FeTiO3 钛铁矿的高压拉曼研究：费米共振作为 Fe-Ti 电荷转移的表现
DOI：
10.1007/s00269-021-01151-9
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发表时间：
2021
影响因子：
1.4
通讯作者：
Williams, Quentin
中科院分区：
文献类型：
--
作者：
Vennari, Cara E.;Williams, Quentin
利用拉曼光谱研究了钛铁矿在300 K高压下的行为。压缩后，我们观察到的费米共振之间的最低频率Ag对称峰（ν 4和ν5）之间的~ 10和~ 30 GPa：带，涉及的主要成分的Ti-O和Fe-O相关的位移，分别。峰的相对强度在~ 18 GPa处发生切换，并且它们在~ 20 GPa处也达到它们的最小间隔，这表明它们的最大共振发生在18和20 GPa之间。在压缩条件下，与Ti-O相关的ν 4振动的负位移与Ti在压缩条件下从4 +到3 +的价态位移完全一致。异常小的模式转变的其他，更本地化的振动也符合从铁到钛的压缩下的电荷转移。在更高的压力下，我们还没有发现在300 K下转变为钙钛矿结构的确切证据，这在高压和高温下已经得到了很好的表征。在40 GPa下，我们观察到一种明显的可逆无序，这种无序一直持续到我们的最高压力。FeTiO 3中的拉曼激活模在压力下的300 K模位移与其它ABO 3化合物（A = Mg，Mn，B = Ti，Si）明显不同;在其它钛铁矿结构的化合物中，峰位移速率更快，没有观察到费米共振。因此，铁的复杂的电子结构，其与钛的电荷转移，似乎在FeTiO 3钛铁矿中的声子的行为中发挥主要作用。
We investigated the 300 K high-pressure behavior of ilmenite using Raman spectroscopy to 54 GPa. Upon compression, we observe a Fermi resonance between the lowest frequency Agsymmetry peaks (ν4and ν5) between ~ 10 and ~ 30 GPa: bands that involve major components of Ti–O and Fe–O-related displacements, respectively. The peaks’ relative intensities switch at ~ 18 GPa and they also reach their minimum separation at ~ 20 GPa, indicating that their maximum resonance occurs between 18 and 20 GPa. The negative shift of the Ti–O-associated ν4vibration under compression is fully consistent with a shift in valence of Ti from 4 + to 3 + under compression. Anomalously small mode shifts of other, more localized vibrations are also consistent with a charge transfer from Fe to Ti under compression. At higher pressures, we have not found definitive evidence for a transition to the perovskite-structure at 300 K, which has been well characterized at high pressures and temperatures. At 40 GPa, we observe an apparent reversible disordering that persists up to our highest pressure. The 300 K mode shifts of the Raman active modes in FeTiO3under pressure are notably different from those of other ABO3compounds (where A = Mg, Mn and B = Ti, Si); in other ilmenite-structured compounds, the peaks shift at a faster rate and there has not been any observation of Fermi resonance. Thus, iron’s complex electronic structure, and its charge transfer with titanium, appears to play a primary role in the behavior of phonons in FeTiO3ilmenite.
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Quentin Williams、Raymond Jeanloz 和 Paul McMillan 对“MgSiO3 钙钛矿的振动光谱：零压拉曼和 27 GPa 的中红外光谱”的修正
影响因子：
--
作者：
Q. Williams;R. Jeanloz;P. McMillan
通讯作者：
P. McMillan
CH 中振动子和力子之间的压力调谐共振
DOI：
10.1103/physrevb.32.4120
发表时间：
1985
期刊：
Physical review. B, Condensed matter
影响因子：
--
作者：
Shimizu
通讯作者：
Shimizu
影响因子：
1.4
作者：
H. Yusa;M. Akaogi;N. Sata;H. Kojitani;R. Yamamoto;Y. Ohishi
通讯作者：
H. Yusa;M. Akaogi;N. Sata;H. Kojitani;R. Yamamoto;Y. Ohishi
影响因子：
1.4
作者：
Knittle, E;Phillips, W;Williams, Q
通讯作者：
Williams, Q
高压高温下角闪石透闪石压缩和亚稳定性的拉曼光谱约束
影响因子：
1.4
作者：
J. Ott;Q. Williams
通讯作者：
Q. Williams