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Yamanaka, Takamitsu*; Hirao, Naohisa*; Nakamoto, Yuki*; Mikouchi, Takashi*; Hattori, Takanori; Komatsu, Kazuki*; Mao, H.-K.*
Physics and Chemistry of Minerals, 49(10), p.41_1 - 41_14, 2022/10
Times Cited Count:3 Percentile:7.21(Materials Science, Multidisciplinary)Magnetic and crystal structure of MnFe
O
solid solutions under high-PT conditions are investigated by neutron diffraction and synchrotron M
ssbauer spectroscopy. The ferrimagnetic-paramagnetic transition and tetragonal-cubic transition of Mn
FeO
spinel occur at 100
C and 180
C, respectively, suggesting both the transitions are not coupled. The structure transition temperature decreases with pressure. M
ssbauer experiments and neutron diffraction revealed that the Fe
occupancy in tetrahedral site increases increase with pressure, suggesting Mn
FeO
phase approaches inverse spinel. Magnetic structure refinement clarified paramagnetic and ferrimagnetic structure of MnFe
O
and Mn
FeO
. These spinels transform into high-pressure orthorhombic phases at 18.4 and 14.0 GPa, respectively, indicating lower transition pressure with increasing Mn content.
Yamanaka, Takamitsu*; Rahman, S.*; Nakamoto, Yuki*; Hattori, Takanori; Jang, B. G.*; Kim, D. Y.*; Mao, H.-K.*
Journal of Physics and Chemistry of Solids, 167, p.110721_1 - 110721_10, 2022/08
Times Cited Count:1 Percentile:6.44(Chemistry, Multidisciplinary)High-pressure neutron diffraction proved that MnFeO
and Mn
FeO
spinels transform into CaMn
O
-type structure above 18 GPa and 14 GPa, respectively. The transition pressure of Mn
Fe
O
solutions decreases with increasing Mn content. Synchrotron X-ray M
ssbauer experiments revealed that Fe
and Fe
distribution at the tetrahedral (A) and octahedral (B) sites in the spinel structure changes with pressure. MnFe
O
and Mn
FeO
spinels are ferrimagnetic and the CaMn
O
-type phase is paramagnetic. The temperature dependence of resistivity indicates that both spinels are semiconductors wherein electrons hop between cations at the A and B sites. A pressure-induced shortening of B-B distance promoted conduction via greater electron mobility between adjacent B cations. The Fe
and Fe
occupancies at the B sites in MnFe
O
are much larger than those in Mn
FeO
. The CaMn
O
-type phase is metallic. Theoretical calculation confirmed the metallic character and Fe d-orbitals strongly renormalized compared to Mn d-orbitals.
Sugiyama, Yasuharu; Tomita, Yoshiaki; Ikezoe, Hiroshi; Yamanouchi, Y.; Ideno, K.; Hamada, S.; Hijiya, M.*; Sugimitsu, Tsuyoshi *; Mukae, T.*; Nakamoto, K.*; et al.
Physical Review C, 49(6), p.3305 - 3308, 1994/06
Times Cited Count:3 Percentile:17.56(Physics, Nuclear)no abstracts in English
Hoshi, T.*; Nakamoto, K.*
PNC TN241 70-48VOL2, 6 Pages, 1970/10
Hoshi, T.*; Nakamoto, K.*; Nakano, H.*; Onishi, K.*; Mizuta, H.*; Kishida, K.*; Saji, G.*
PNC TN241 70-48VOL1, 9 Pages, 1970/10