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Yamanaka, Takamitsu*; Hattori, Takanori
Physics and Chemistry of Minerals, 53(3), p.21_1 - 21_11, 2026/09
Times Cited Count：0Bulk modulus and electron density distribution of high-pressure polymorphs of Fe-Ti-O minerals (Fe
O
magnetite, Fe
TiO ulv
spinel, FeTiO ilmenite, FeTiO
pseudobrokite) are investigated by X-ray and neutron diffraction. The vacant sites in the unit cell have much larger volumes than cation sites in the all structures. Cation site partly occupied by Ti atom shows a smaller 
than that of only Fe atom and the compressibility of unit cell increases with increasing Ti content. The compressibility of the vacant sites is close to that of unit cells, but are much smaller than that of the cation site. The structure changes such as high-low electron spin transition, Jahn-Teller effect and 
hybridization in the Fe-O bonds are elucidated by present high-pressure experiments. The hybridization in the octahedral cation site was observed by molecular orbital calculation and it brings the deformation of the octahedral cation site, which triggers structure changes in the high-pressure polymorphs.
Kobayashi, Hiroki*; Komatsu, Kazuki*; Ito, Hayate*; Machida, Shinichi*; Hattori, Takanori; Kagi, Hiroyuki*
Journal of Physical Chemistry C, 130(25), p.8795 - 8805, 2026/06
Times Cited Count：0Ice IV, a metastable high-pressure phase of ice, rarely crystallizes from water and has therefore been called by a nickname, "will-o'-the-wisp," a tentative, ghostly form of ice. Here we report by experiments using water-in-oil emulsions that liquid water reproducibly and selectively crystallizes into ice IV at the homogeneous nucleation temperature (
) at pressures between 0.45 and 1.1 GPa. By tracking pressure-induced melting of ice Ih and immediate recrystallization, we show that liquid water preferentially crystallizes into ice IV even below . Thanks to high hydrostaticity and suppressed crystal growth in emulsified ice samples, reliable structure analyses for both ice IV and its potentially hydrogen-ordered state were achieved by neutron diffraction. The achievable degree of ordering in experiments was extremely low and nearly independent of the crystallization methods.
Xue, J.*; Huang, D.*; Hattori, Takanori; Li, L.*; Feng, Y.*; Wang, H.*; Fan, X.*; Yao, J.*; Wang, Y.*; Liu, Z.*; et al.
Applied Physics Letters, 128(20), p.201903_1 - 201903_8, 2026/05
Times Cited Count：0 Percentile：0.00(Physics, Applied)The cycling fatigue and barocaloric response of NHI is directly assessed under loading--unloading cycles with stress up to 100,MPa, with the adiabatic temperature change (
) decaying from 15,K to approximately 0.8,K after 100 cycles. 
X-ray diffraction, Raman spectroscopy, and neutron diffraction concertedly reveal the existence of the residual high-pressure phase even after the first unloading, whose fraction is rapidly increased to 90% at the 100th cycle. A phenomenological model is developed to elucidate this fatigue behavior, and an excellent agreement with experimental data has been achieved. To relieve the intergranular stress and enhance the mobility of grains, we encapsulate the composite of NHI particles and silicone oil into a 3D-printed polymer shell. Such an architectural tailoring has markedly improved the cyclic stability of the barocaloric effect with rising to c.a. 4.6,K after 100 cycles. Our results establish a fundamental understanding of the barocaloric fatigue behavior and pave a feasible route to applicable barocaloric cooling technology.
-iron at high pressures determined using 
neutron diffractionAoki, Katsutoshi*; Takano, Masahiro*; Fukuyama, Ko*; Kagi, Hiroyuki*; Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*
Physical Review B, 113(18), p.184440_1 - 184440_6, 2026/05
Times Cited Count：1 Percentile：86.01(Materials Science, Multidisciplinary)The temperature dependence of the magnetic moment of bcc -iron was investigated over the range 300-950 K at pressures of approximately 2 and 6 GPa by neutron powder diffraction. The 
Fe isotope, whose neutron scattering length is approximately half that of naturally abundant Fe, was employed to enhance the relative contribution of magnetic scattering. Curie temperatures (
) were determined to be 946(30) K, 838(50) K and 740(40) K at 2.1, 6.0 and 6.7 GPa, respectively, defining a magnetic phase boundary described by (K) = 1043 - 49(7)
+ 1.3(1.2)
. Upon heating at 6.7 GPa, the 
structural transition was observed to follow the magnetic transition. This transition sequence indicates that the magnetic phase boundary lies on the low-temperature side of the phase boundary. Accordingly, the transition corresponds to a structural transformation from paramagnetic bcc to paramagnetic fcc iron.
Takahashi, Naoki*; Sakamaki, Tatsuya*; Hattori, Takanori; Funakoshi, Kenichi*; Arima-Osonoi, Hiroshi*; Sano, Asami; Abe, Jun*; Suzuki, Akio*
Scientific Reports (Internet), 16, p.14162_1 - 14162_13, 2026/05
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)We performed high-pressure and high-temperature neutron diffraction and imaging experiments in situ to determine the hydrogen content in liquid iron. We observed that liquid iron contains 0.17(3) wt.% H at 3.4 GPa and 1400 K, indicating that liquid iron is hydrogenated in the magma ocean during core formation. For the hydrogen content in the liquid iron at the base of the magma ocean, we estimated that the outer and inner cores contain 0.60-0.72 and 0.30-0.44 wt.% H, corresponding to 70-85 and 1.9-2.7 times the mass of hydrogen in the ocean, respectively. This suggests that hydrogen can contribute more than half of the density deficit in the outer core. For the magma ocean equilibrating with the hydrogen-rich primary atmosphere, the study findings show that liquid iron plays a crucial role in transporting a large amount of hydrogen into the core.
Glazyrin, K.*; Spektor, K.*; Bykov, M.*; Carvalho, P. H. B.*; Dong, W.*; K
rmann, F.*; Sano, Asami; Hattori, Takanori; Beyer, D. C.*; Sahlberg, M.*; et al.
Nature Communications (Internet), 17, p.2622_1 - 2622_10, 2026/03
Times Cited Count：2 Percentile：83.76(Multidisciplinary Sciences)Studies of high entropy materials contribute to various fields of science and reveal ever more exciting properties of applied interest. Here, we perform a study of the resistance of a Cantor alloy (CoCrFeNiMn) to hydrogen through high-pressure experiments at elevated temperatures by X-ray and neutron time-of-flight experiments and ab initio calculations. We report formation of an fcc hydride based on the Cantor alloy composition. We also provide its characterization, including an estimate of hydrogen content. These findings contribute to the growing body of knowledge on the complex chemistry of high-entropy alloys and high-entropy-hydrides.
Fei, Y.*; Wang, Y.*; Zhang, J.*; Liu, J.*; Zhao, Z.*; Hattori, Takanori; Abe, Jun*; Dong, X.*; Mao, H.-K.*; Zheng, H.*; et al.
Chemistry; A European Journal, p.e71096_1 - e71096_11, 2026/00
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)We systematically investigated the high-pressure polymerization of naphthalene, the simplest polycyclic aromatic hydrocarbons (PAHs), using multiple cutting-edge methods. Naphthalene molecules were stacked in herringbone style, and underwent [4+2] cycloaddition reactions along the a-b direction above 20 GPa, yielding one-dimensional Carbon nanothreads (CNThs). In contrast to the formation of many CNThs, the nucleation of the CNThs occurs during compression while their growth proceeds during decompression, which is likely prevalent among herringbone-stacked aromatics. The unit cell of the obtained CNTh crystal is determined and the possible structure of the CNTh product is also proposed. Our research reveals the polymerization characteristics of naphthalene under high pressure, highlighting the fact that the slip-angle plays an important role in governing the polymerization pathway.
Jing, Z.*; Yamaguchi, Toshio*; Machida, Shinichi*; Hattori, Takanori; Zhou, Y.*
Journal of Chemical Physics, 163(19), p.194505_1 - 194505_12, 2025/11
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Ion solvation in a range of gigapascal pressure is of great significance for high-pressure chemical synthesis and the circulation of matter within the Earth's interior. We perform neutron scattering (NS) experiments and molecular dynamics simulations of deuterated aqueous solutions of MCl (M = Li, Na, K, Rb, and Cs) at 0.1 MPa and 0.7 GPa/298 K. An empirical potential structure refinement method analyzes the NS data. Upon compression to 0.7 GPa, the outer-shell water molecules enter the nearest neighbor of ions, and the solvated ion clusters become denser. The hydration factor 
and static hydration number 
based on the orientation distribution of the water dipole in the first solvation shell, show that the compression weakens the hydration ability of the ions. Compression suppresses the diffusion of ions, particularly of the structure-breaking ions. The ionic diffusion coefficient 
residence time of water molecules 
and dynamic hydration number 
indicate that Rb
and Cs exhibit characteristics of structure-making ions under compression. The dynamic properties are more pressure-sensitive than the static structure.
Saito, Hiroyukki*; Machida, Akihiko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*
Physica B; Condensed Matter, 714, p.417234_1 - 417234_3, 2025/10
Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)Corrigendum to "Neutron diffraction study on the deuterium composition of nickel deuteride at high temperatures and high pressures" [Phys. B Condens. Matter. 587 (2020) 412153] was reported.
Che, G.*; Tang, X.*; Liu, J.*; Lang, P.*; Fei, Y.*; Yang, X.*; Wang, Y.*; Gao, D.*; Wang, X.*; Ju, J.*; et al.
Nano Letters, 25(39), p.14467 - 14472, 2025/09
Times Cited Count：1 Percentile：31.65(Chemistry, Multidisciplinary)Mechanochemical radical polymerization has unique advantages in the synthesis of polymer due to its reduced solvent consumption and adaptability of insoluble monomers. However, it suffers from the uncontrollable degradation of the formed polymers during reaction and new synthetic strategy with precise controllability needs to be developed. Here, by employing high static pressure up to 30 GPa, we found 1,3,5-trifluorobenzene undergoes radical polymerization by breaking the conjugated 
-bonds, and forms a carbon nanothread with high selectivity (Polymer-I polymorph). Based on the crystal structure at the threshold pressure and the calculated energy barriers for the bonding pathway, we concluded that the benzene-rings react via a 1-2 radical polymerization pathway. Our work highlights high pressure is a robust method to initiate the solid-state radical polymerization, even for very stable aromatics, and offers fresh insights for the synthesis of polymeric carbon-based materials with high selectivity.
Yamaguchi, Toshio*; Machida, Shinichi*; Hattori, Takanori
Molecules (Internet), 30(16), p.3417_1 - 3417_18, 2025/08
Times Cited Count：1 Percentile：32.42(Biochemistry & Molecular Biology)1
(mol/kg) ScCl aqueous solution in DO was investigated under the thermodynamic conditions from 0.1 MPa/298 K to 4 GPa/523 K by in-situ neutron diffraction coupled with the empirical potential structure refinement (EPSR) method. A predominant Sc(III) species is [Sc(OH)
]
with a distorted pentagonal bipyramidal geometry together with appreciable amounts of contact ion pair species [ScCl
(OH)
]
(n=1-3) and [Sc(OH)
] with mean Sc-Cl and Sc-OH distances of 2.42 and 2.11
O distance of 3.10 
at 0.1 MPa/298 K and 4 GPa/523 K, respectively. Applying GPa pressure transforms the tetrahedral network structure of water under ambient conditions to a dense, randomly packed structure with a mean coordination number of 12.6, resulting in an increase in the first-neighbor distance from 2.77 to 2.89 AA. The hydrogen bonds between water molecules remain linear but are largely distorted at high temperatures and high pressures.
Zhao, X.*; Zhang, Z.*; Hattori, Takanori; Wang, J.*; Li, L.*; Jia, Y.*; Li, W.*; Xue, J.*; Fan, X.*; Song, R.*; et al.
Nature Communications (Internet), 16, p.7713_1 - 7713_8, 2025/08
Times Cited Count：6 Percentile：81.24(Multidisciplinary Sciences)Caloric effects usually occur in the vicinity of solid-state phase transitions with a limited refrigeration temperature span. Here, we introduce and realize an unprecedented concept -all temperature barocaloric effect, i.e., a remarkable barocaloric effect in KPF
across an exceptionally wide temperature span, from 77.5 to 300 K and potentially down to 4 K, covering typical room temperature, liquid nitrogen, liquid hydrogen, and liquid helium refrigeration regions. The directly measured barocaloric adiabatic temperature change reaches 12 K at room temperature and 2.5 K at 77.5 K upon the release of a 250 MPa pressure. This effect is attributed to a persistent phase transition to a rhombohedral high pressure phases. We depict the thermodynamic energy landscape to account for the structural instability. This unique all-temperature barocaloric effect presents a novel approach to highly applicable solid-state refrigeration technology, transcending the conventional multi-stage scenario.
Ohashi, Tomonori*; Sakamaki, Tatsuya*; Funakoshi, Kenichi*; Steinle-Neumann, G.*; Hattori, Takanori; Yuan, L.*; Suzuki, Akio*
Journal of Mineralogical and Petrological Sciences (Internet), 120(1), p.240926a_1 - 240926a_13, 2025/06
Times Cited Count：1 Percentile：40.06(Mineralogy)We explore the structures of dry and hydrated (HO and DO) NaSiO
melt at 0-6 GPa and 1000-1300 K and glasses recovered from high pressure and temperatures by in-situ neutron and X-ray diffraction. The structures of the melts at 0-10 GPa and 3000 K are also investigated by ab-initio molecular dynamics simulation. In-situ neutron experiments revealed that the D-O distance increases with compression due to the formation of -O-D-O- bridging species, which is reproduced by the molecular dynamics simulations. The pressure-induced -O-D-O- formation reflects a more rigid incorporation of hydrogen, which acts as a mechanism for the experimentally observed higher solubility of water in silicate melts. Together with shrinking modifier domains, this process dominates the compression behavior of hydrous NaSiO melt, whereas the compression of dry NaSiO at 0-10 GPa and 3000 K is governed largely by bending of the Si-O-Si angle. The molecular dynamics simulations on hydrous NaSiO melts further suggest that the sodium ions are scavenged from its network-modifying role via 2(![$$^{[4]}$$](/search/images/ERPHWWZULV4SI.gif)
Si-O
+ Na) 
Si-(O-![$$^{[5]}$$](/search/images/ERPHWWZVLV4SI.gif)
Si-O)
+ 2Na and Si-O + Na + Si-OH Si-(O-H-O-Si) + Na with increasing pressure.
Machida, Akihiko*; Saito, Hiroyuki*; Aoki, Katsutoshi*; Komatsu, Kazuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Machida, Shinichi*; Sato, Toyoto*; Orimo, Shinichi*
Physical Review B, 111(22), p.224413_1 - 224413_6, 2025/06
Times Cited Count：1 Percentile：31.65(Materials Science, Multidisciplinary)The crystal and magnetic structures of antiferromagnetic Mn deuterides formed by hydrogenating Mn metal at high temperature and high pressure, fcc 
-MnDx and hcp 
-MnDx, were investigated by in-situ neutron powder diffraction. Deuterium atoms partially occupied the octahedral interstitial positions of the fcc and hcp metal lattices. The site occupancies increased rapidly with decreasing temperature from 
700 to 450 K and remained down to 300 K. N
el temperature of 543(10) K was determined for -MnD
. For -MnD
, saturation magnetic moment and Nel temperature were determined to be 0.82(1) 
and 347(3) K, respectively. The Nel temperatures determined for -MnD and -MnD are consistent with those predicted by the respective Slater-Pauling curves proposed in previous studies. The updated Nel temperatures provide insights into the development of more accurate Slater-Pauling curves based on electronic band structure calculations.
hydridosilicate at high pressures; A Bridge to BaSiH polyhydrideBeyer, D. C.*; Spektor, K.*; Vekilova, O. Y.*; Grins, J.*; Barros Brant Carvalho, P. H.*; Leinbach, L. J.*; Sannemo-Targama, M.*; Bhat, S.*; Baran, V.*; Etter, M.*; et al.
ACS Omega (Internet), 10(15), p.15029 - 15035, 2025/04
Times Cited Count：3 Percentile：47.58(Chemistry, Multidisciplinary)Hydridosilicates featuring SiH octahedral moieties represent a rather new class of compounds with potential properties relating to hydrogen storage and hydride ion conductivity. Here, we report on the new representative BaSiH obtained from reacting the Zintl phase hydride BaSiH
with H fluid at pressures above 4 GPa and subsequent decompression to ambient pressure. It consists of complex SiH
ions, which are octahedrally coordinated by Ba
counterions. The arrangement of Ba and Si atoms deviates only slightly from an ideal fcc NaCl structure. IR and Raman spectroscopy showed SiH bending and stretching modes in the ranges 800-1200 and 1400-1800 cm
, respectively. BaSiH is thermally stable up to 95
C above which decomposition into BaH and Si takes place. DFT calculations indicated a direct band gap of 2.5 eV. The discovery of BaSiH consolidates the compound class of hydridosilicates, accessible from hydrogenations of silicides at gigapascal pressures (
10 GPa). The structural properties of BaSiH suggest that it presents an intermediate (or precursor) for further hydrogenation at considerably higher pressures to the predicted superconducting polyhydride BaSiH.
Li, F.*; Tang, X.*; Fei, Y.*; Zhang, J.*; Liu, J.*; Lang, P.*; Che, G.*; Zhao, Z.*; Zheng, Y.*; Fang, Y.*; et al.
Journal of the American Chemical Society, 147(17), p.14054 - 14059, 2025/04
Times Cited Count：1 Percentile：27.91(Chemistry, Multidisciplinary)We synthesized a crystalline graphane nanoribbon (GANR) via pressure-induced polymerization of 2,2'-bipyrazine (BPZ). By performing Rietveld refinement of in situ neutron diffraction data, nuclear magnetic resonance spectroscopy, infrared spectra, and theoretical calculation, we found that BPZ experienced Diels-Alder polymerization between the 
stacked aromatic rings, and formed extended boat-GANR structures with exceptional long-range order. The unreacted -C=N- groups bridge the two ends of the boat, and ready for further functionalization. The GANR has a bandgap of 2.25 eV, with booming photoelectric response (
/
=18.8). Our work highlights that the high-pressure topochemical polymerization is a promising method for the precise synthesis of graphane with specific structure and desired properties.
under hydrostatic pressure; A Combined neutron, X-ray, Raman, and first-principles calculation studyEfthimiopoulos, I.*; Klotz, S.*; Kunc, K.*; Baptiste, B.*; Chauvigne, P.*; Hattori, Takanori
Physical Review B, 111(13), p.134103_1 - 134103_13, 2025/04
Times Cited Count：1 Percentile：31.65(Materials Science, Multidisciplinary)We present a comprehensive study of the high pressure behaviour of ReO using X-ray and neutron diffraction, Raman scattering and first-principles calculations to 15 GPa. We show that the ambient pressure 
structure converts at 0.7 GPa in a continuous phase transition directly to a cubic phase with space group 
and rhombohedral 
structures in this pressure range are an artifact due to an alteration of the sample by high-flux synchrotron X-ray radiation. The structural pressure dependence of the 
O samples are presented. The data shed light onto the unusual transition and densification mechanism due to progressive tilting of essentially rigid ReO octahedra.
GeTe to hydrostatic pressureWang, Y.*; Zeng, X.-T.*; Li, B.*; Su, C.*; Hattori, Takanori; Sheng, X.-L.*; Jin, W.*
Chinese Physics B, 34(4), p.046203_1 - 046203_6, 2025/03
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Two-dimensional van der Waals ferromagnet FeGeTe (FGT) holds a great potential for applications in spintronic devices, due to its high Curie temperature, easy tunability, and excellent structural stability in air. In this study, we have performed high-pressure neutron powder diffraction (NPD) up to 5 GPa, to investigate the evolution of its structural and magnetic properties with hydrostatic pressure. The NPD data clearly reveal the robustness of the ferromagnetism in FGT, despite of an apparent suppression by hydrostatic pressure. As the pressure increases from 0 to 5 GPa, the Curie temperature is found to decrease monotonically from 225(5) K to 175(5) K, together with a dramatically suppressed ordered moment of Fe, which is well supported by the first-principles calculations. Although no pressure-driven structural phase transition is observed up to 5 GPa, quantitative analysis on the changes of bond lengths and bond angles indicate a significant modification of the exchange interactions, which accounts for the pressure-induced suppression of the ferromagnetism in FGT.
Xu, J.*; Lang, P.*; Liang, S.*; Zhang, J.*; Fei, Y.*; Wang, Y.*; Gao, D.*; Hattori, Takanori; Abe, Jun*; Dong, X.*; et al.
Journal of Physical Chemistry Letters (Internet), 16(10), p.2445 - 2451, 2025/03
Times Cited Count：3 Percentile：76.32(Chemistry, Physical)The Alder-ene reaction is a chemical reaction between an alkene with an allylic hydrogen, and it provides an efficient method to construct the C-C bond. Traditionally, this reaction requires catalysts, high temperatures, or photocatalysis. In this study, we reported a high-pressure-induced solid-state Alder-ene reaction of 1-hexene at room temperature without a catalyst. 1-Hexene crystallizes at 4.3 GPa and polymerizes at 18 GPa, forming olefins. By exploring gas chromatography-mass spectrometry, we discovered that 1-hexene generates dimeric products through the Alder-ene reaction under high pressures. The in situ neutron diffraction shows that the reaction process did not obey the topochemical rule. A six-membered ring transition state including one C-H 
bond and two alkene bonds was evidenced by the theoretical calculation, whose energy obviously decreased when compressed to 20 GPa. Our work offers a novel and promising method to realize the Alder-ene reaction at room temperature without a catalyst, expanding the application of this important reaction.
Aoki, Katsutoshi*; Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 35(1), p.4 - 11, 2025/03
Iron reacts with hydrogen to form solid solutions with body-centered cubic, face-centered cubic, hexagonal close packed, and double hexagonal close packed structures at high temperatures and high pressures. Neutron diffraction is the most powerful tool for determining the occupation sites and occupancies of hydrogen atoms dissolved in a metal lattice. Structural parameters, including hydrogen occupation sites and occupancies, are refined via Rietveld analysis for neutron diffraction data. We present our expertise in Rietveld refinement of iron hydrides accumulated over 10 years.
