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Journal Articles

Multi-methodical study of the Ti, Fe$$^{2+}$$ and Fe$$^{3+}$$ distribution in chevkinite-subgroup minerals; X-ray diffraction, neutron diffraction, $$^{57}$$Fe M$"o$ssbauer spectroscopy and electron-microprobe analyses

Nagashima, Mariko*; Armbruster, T.*; Akasaka, Masahide*; Sano, Asami; Nishio-Hamane, Daisuke*; Malsy, A.*; Imaoka, Teruyoshi*; Nakashima, Kazuo*

Physics and Chemistry of Minerals, 47(6), p.29_1 - 29_18, 2020/06

 Times Cited Count:1 Percentile:27.06(Materials Science, Multidisciplinary)

Three non-metamict chevkinite-subgroup minerals, from Cape Ashizuri, Japan, Tangir Valley, Diamar District, Pakistan and Haramosh Mts., Skardu district, Pakistan, were studied by crystal chemical techniques. Powder X-ray diffraction and transmission electron microscopic observations confirmed well crystalline samples. Electron-microprobe analyses indicated the general composition known for chevkinite-(Ce). Site scattering values determined by single-crystal X-ray structure refinements suggested assignment of subordinate Nb to the octahedral M3 and M4 sites, minor Th to M1 for the Ashizuri sample and minor Mg to M1 for both samples from Pakistan. Neutron time-of-flight powder diffraction studies were applied to determine the Ti/Fe distribution among octahedral sites for all samples and Mossbauer spectroscopy served for the Fe valence assignment at the four octahedral sites. The dominant iron valence at M1 of the Haramosh sample is ferric whereas for samples Nos. 1 and 2 iron is ferrous.

Journal Articles

Crystal structure change of katoite, Ca$$_{3}$$Al$$_{2}$$(O$$_{4}$$D$$_{4}$$)$$_{3}$$, with temperature at high pressure

Kyono, Atsushi*; Kato, Masato*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori

Physics and Chemistry of Minerals, 46(5), p.459 - 469, 2019/05

 Times Cited Count:1 Percentile:12.33(Materials Science, Multidisciplinary)

To reveal the decomposition mechanism with temperature under high-pressure, crystal structure of a hydrogrossular, katoite Ca$$_{3}$$Al$$_{2}$$(O$$_{4}$$D$$_{4}$$)$$_{3}$$ has been studied by in-situ neutron diffraction at 8 GPa. Although unusual expansion behavior was discerned at 200-400$$^circ$$C, the unit cell was continuously expanded up to 850$$^circ$$C. At 900$$^circ$$C, katoite was decomposed, indicating that pressure strongly increases dehydration temperature from 300$$^circ$$C to 900$$^circ$$C. On release of pressure, the katoite reappear together with corundum and portlandite. At 8 GPa, CaO$$_{8}$$ and AlO$$_{6}$$ polyhedra expand with temperature up to 850$$^circ$$C by about 8% and 13%, respectively. On the other hand, tetrahedral interstices are isotopically squeezed by about 10%: due to the expansion of above polyhedra. The neighboring D-D distance remains almost unchanged in this temperature range, while the O-D bond distance shrinks drastically just before decomposition. This finding suggests that the shortening of O-D distance caused by the D-D repulsion destabilizes the O-D bond, which induces the thermal decomposition of katoite.

Journal Articles

Hydrogen sites in the dense hydrous magnesian silicate phase E; A Pulsed neutron powder diffraction study

Tomioka, Naotaka*; Okuchi, Takuo*; Purevjav, N.*; Abe, Jun*; Harjo, S.

Physics and Chemistry of Minerals, 43(4), p.267 - 275, 2016/04

 Times Cited Count:6 Percentile:26.06(Materials Science, Multidisciplinary)

Journal Articles

Observation of pressure-induced phase transition of $$delta$$-AlOOH by using single-crystal synchrotron X-ray diffraction method

Kuribayashi, Takahiro*; Sano, Asami; Nagase, Toshiro*

Physics and Chemistry of Minerals, 41(4), p.303 - 312, 2014/04

 Times Cited Count:29 Percentile:78.96(Materials Science, Multidisciplinary)

Pressure-induced phase transition of $$delta$$-AlOOH was confirmed between 6.1 and 8.2 GPa by using a single-crystal synchrotron X-ray diffraction method. The phase transition is reversible and unquenchable. The space group of the post-transition phase should be ${it Pnnm}$ or ${it Pnn}$2 to satisfy the systematic absence rule. Crystal structure refinements of the post-transition phase conducted for the three models (${it Pnnm}$, ${it Pnn}$2, and ${it P}$2$$_{1}$$${it nm}$) indicate that the space group of the post-transition phase is ${it Pnnm}$. The O-O distance of hydrogen bond in the post-transition phase at 8.2 GPa is 2.439(6) ${AA}$ and is significantly longer than the predicted distance (2.366 ${AA}$) of the hydrogen bond symmetrization in $$delta$$-AlOOH. The H distribution in the post-transition phase would display a fully disordered hydrogen bond pattern.

Journal Articles

Compression behaviors of distorted rutile-type hydrous phases, MOOH (M = Ga, In, Cr) and CrOOD

Sano, Asami; Yagi, Takehiko*; Okada, Taku*; Goto, Hirotada*; Kikegawa, Takumi*

Physics and Chemistry of Minerals, 39(5), p.375 - 383, 2012/05

 Times Cited Count:17 Percentile:57.49(Materials Science, Multidisciplinary)

X-ray diffraction measurements of distorted rutile-type oxyhydroxides $$beta$$-GaOOH, InOOH, $$beta$$-CrOOH, and $$beta$$-CrOOD were taken at a maximum pressure of up to 35 GPa under quasi-hydrostatic conditions, at ambient temperature. Anomalies in the evolution of the relative lattice constants and the axial ratios of $$beta$$-GaOOH, InOOH, and $$beta$$-CrOOD suggest anisotropic stiffening along the a- and/or b-axes where the hydrogen bond is formed. The changes were observed at 15 GPa in $$beta$$-GaOOH and InOOH and at 4 GPa in $$beta$$-CrOOD. The pressures were higher in oxyhydroxides that have longer O...O distances of the hydrogen bond at ambient pressure. In contrast, such stiffening behavior was not observed in CrOOH, which has a significant short O...O distance and strong hydrogen bond. The stiffening behaviors observed in the present study can be attributed to the symmetrization of the hydrogen bonds in oxyhydroxides, as was previously found in $$delta$$-AlOOH(D).

Journal Articles

Pressure responses of portlandite and H-D isotope effects on pressure-induced phase transitions

Iizuka, Riko*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Ushijima, Daichi*; Nakano, Satoshi*; Sano, Asami; Nagai, Takaya*; Yagi, Takehiko*

Physics and Chemistry of Minerals, 38(10), p.777 - 785, 2011/12

 Times Cited Count:8 Percentile:31.14(Materials Science, Multidisciplinary)

The pressure responses of portlandite and the isotope effect on the phase transition were investigated at room temperature from single-crystal Raman and IR spectra and from powder X-ray diffraction using diamond anvil cells under quasi-hydrostatic conditions in a helium pressure-transmitting medium. Phase transformation and subsequent peak broadening observed from the Raman and IR spectra of Ca(OH)$$_{2}$$ occurred at lower pressures than those of Ca(OD)$$_{2}$$. In contrast, no isotope effect was found on the volume and axial compressions observed from powder X-ray diffraction patterns. X-ray diffraction lines attributable to the high-pressure phase remained up to 28.5 GPa, suggesting no total amorphization in a helium pressure medium within the examined pressure region. These results suggest that the H-D isotope effect is engendered in the local environment surrounding H(D) atoms.

Journal Articles

Kinetics of the graphite-diamond transformation in aqueous fluid determined by in-situ X-ray diffractions at high pressures and temperatures

Okada, Taku; Utsumi, Wataru; Kaneko, Hiroshi*; Turkevich, V.*; Hamaya, Nozomu; Shimomura, Osamu*

Physics and Chemistry of Minerals, 31(4), p.261 - 268, 2004/05

 Times Cited Count:11 Percentile:42.99(Materials Science, Multidisciplinary)

The graphite-diamond transformation was investigated by in situ time-resolved X-ray diffraction experiments using aqueous fluid containing dissolved MgO as the diamond forming catalyst under conditions of 6.6-8.9 GPa and 1400-1835 $$^{circ}$$C. The transformed volume fractions of diamond as a function of time under various pressure-temperature conditions were obtained and analyzed using the JMAK rate equation. Variations in the nucleation and growth processes during diamond formation as a function of pressure and temperature were clarified.

Journal Articles

In situ X-ray observations of the decomposition of brucite and the graphite-diamond conversion in aqueous fluid at high pressure and temperature

Okada, Taku; Utsumi, Wataru; Kaneko, Hiroshi*; Yamakata, Masaaki*; Shimomura, Osamu

Physics and Chemistry of Minerals, 29(7), p.439 - 445, 2002/08

 Times Cited Count:14 Percentile:49.96(Materials Science, Multidisciplinary)

An experimental technique to make real-time observations at high pressure and temperature of the diamond forming process in candidate material of mantle fluids as a catalyst has been established for the first time. In situ X-ray diffraction experiments using synchrotron radiation have been performed upon a mixture of brucite (Mg(OH)$$_{2}$$) and graphite as starting material. Brucite decomposes into periclase (MgO) and H$$_{2}$$O at 3.6 GPa and 1050$$^{circ}$$C while no periclase is formed after the decomposition of brucite at 6.2 GPa and 1150$$^{circ}$$C, indicating that the solubility of the MgO component in H$$_{2}$$O greatly increases with increasing pressure. The conversion of graphite to diamond in aqueous fluid has been observed at 7.7 GPa and 1835$$^{circ}$$C. Time-dependent X-ray diffraction profiles for this transformation have been successfully obtained.

Journal Articles

Thermoelastic properties of the high-pressure phase of SnO$$_{2}$$ determined by in situ X-ray observations up to 30GPa and 1400K

Ono, Shigeaki*; Ito, Eiji*; Katsura, Tomoo*; Yoneda, Akira*; Walter, M.*; Urakawa, Satoru*; Utsumi, Wataru; Funakoshi, Kenichi*

Physics and Chemistry of Minerals, 27(9), p.618 - 622, 2000/11

 Times Cited Count:42 Percentile:80.3(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Determination of the phase boundary between ilmenite and perovskite in MgSiO$$_{3}$$ by in situ X-ray diffraction and quench experiments

Kuroda, Koji*; Irifune, Tetsuo*; Inoue, Toru*; Nishiyama, Norimasa*; Miyashita, Minoru*; Funakoshi, Kenichi*; Utsumi, Wataru

Physics and Chemistry of Minerals, 27(8), p.523 - 532, 2000/09

 Times Cited Count:35 Percentile:76.06(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Melting of portlandite up to 6GPa

Fukui, Hiroyuki*; Otaka, Osamu*; Nagai, Takaya*; Katsura, Tomoo*; Funakoshi, Kenichi*; Utsumi, Wataru

Physics and Chemistry of Minerals, 27(6), p.367 - 370, 2000/06

 Times Cited Count:4 Percentile:22.42(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Synchrotron radiation study on the high-pressure and high-temperature phase relations of KAlSi$$_{3}$$O$$_{8}$$

Urakawa, Satoru*; Kondo, Tadashi*; Igawa, Naoki; Shimomura, Osamu*; Ono, Hideo

Physics and Chemistry of Minerals, 21, p.387 - 391, 1994/00

no abstracts in English

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