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Search Results: Records 1-20 displayed on this page of 32

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Journal Articles

Polarized neutrons observed nanometer-thick crystalline ice plates in frozen glucose solution

Kumada, Takayuki; Nakagawa, Hiroshi; Miura, Daisuke; Sekine, Yurina; Motokawa, Ryuhei; Hiroi, Kosuke; Inamura, Yasuhiro; Oku, Takayuki; Oishi, Kazuki*; Morikawa, Toshiaki*; et al.

Journal of Physical Chemistry Letters (Internet), 14(34), p.7638 - 7643, 2023/08

https://doi.org/10.1021/acs.jpclett.3c01448

Times Cited Count：0 Percentile：0.01(Chemistry, Physical)

The structure of nano-ice crystals in rapidly frozen glucose solution was elucidated by using spin-contrast-variation small-angle neutron scattering, which distinguishes the nano-ice crystal signal from the frozen amorphous solution signal by the polarization-dependent neutron scattering. The analysis revealed that the nano-ice crystals form a planar structure with a diameter exceeding tens of nanometers and a thickness of 1 nm, which is close to the critical nucleation size. This result suggests that the glucose molecules are preferentially bound to a specific face of nano-ice crystals, and then block the crystal growth perpendicular to that face.

Journal Articles

Crystallinity in periodic nanostructure surface on Si substrates induced by near- and mid-infrared femtosecond laser irradiation

Miyagawa, Reina*; Kamibayashi, Daisuke*; Nakamura, Hirotaka*; Hashida, Masaki*; Zen, H.*; Somekawa, Toshihiro*; Matsuoka, Takeshi*; Ogura, Hiroyuki*; Sagae, Daisuke*; Seto, Yusuke*; et al.

Scientific Reports (Internet), 12, p.20955_1 - 20955_8, 2022/12

https://doi.org/10.1038/s41598-022-25365-1

Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)

We evaluated Laser-Induced Periodic Surface Structure (LIPSS) crystal structures using the stress imaging station at BL22XU of JAEA-BL on SPring-8. Crystallization of LIPPS was used different two types laser these are Ti:Sapphire laser (wavelength: 800 nm) and MIR-FEL (mid-infrared free electron laser, wavelength 11.4 m). These lasers are different in the laser pulse structure and the wavelength. We investigated on the effects of formed LIPSS crystallization using different kind of laser. Measured synchrotron X-ray energy is 30 keV and beam size is 20 m. Detector of diffracted X-ray is two-dimensional detector (PILATUS300K, DECTRIS). LIPSS formed using Ti:Sapphire laser has deformed structure with good crystallinity. LIPSS formed using MIR-FEL has dislocation or fault without structural stress. These results show depending on select of laser forming LIPPS structure. These information becomes important a point of the functional application of LIPSS.

Journal Articles

Crystallization processes of quartz in a granitic magma; Cathodoluminescence zonation pattern controlled by temperature and titanium diffusivity

Yuguchi, Takashi*; Ogita, Yasuhiro; Kato, Takenori*; Yokota, Rintaro*; Sasao, Eiji; Nishiyama, Tadao*

Journal of Asian Earth Sciences, 192, p.104289_1 - 104289_16, 2020/05

https://doi.org/10.1016/j.jseaes.2020.104289

Times Cited Count：5 Percentile：30.80(Geosciences, Multidisciplinary)

Quartz from a granitic pluton is found to have formed through sequential growth events under different mechanisms and crystallization temperatures, which can provide new insights into magmatic processes of granitic magmas that were eventually consolidified into plutons. The events were identified using (1) the description of crystal shape and occurrence, (2) the study of the internal structure with cathodoluminescence (CL), and (3) derivation of the crystallization temperatures based on TitaniQ thermometry. The magmatic quartz crystals from the Toki granite, central Japan, are characterized as having the following internal structures: oscillatory zonation, no-oscillatory zonation with luminescence graduation (gradational zonation), and heterogeneous CL. The quartz crystals with oscillatory zonation were formed in the temperature range of about 800 $^{circ}$ C to below 700 $^{circ}$ C, which is referred to as oscillatory zoning temperature (OZT) conditions. The CL zonation pattern was controlled by the temperature conditions and titanium diffusivity in the melt (magma). The crystallization process of quartz within the Toki granite reveals the cooling processes of the granitic pluton; the lithofacies with a high frequency of oscillatory-zoned quartz underwent slower cooling under the OZT conditions than those in other lithofacies.

Journal Articles

In-situ observation of strain and stress evolution during thin film growth on H-terminated Si

Asaoka, Hidehito; Yamazaki, Tatsuya*; Shamoto, Shinichi

Nihon Kessho Seicho Gakkai-Shi, 32(3), P. 160, 2005/08

no abstracts in English

Journal Articles

Size of small Si and Ge clusters on Si(111) and Ge(111) surfaces

Asaoka, Hidehito; Cherepanov, V.*; Voigtlnder, B.*

Surface Science, 588(1-3), p.19 - 25, 2005/08

https://doi.org/10.1016/j.susc.2005.05.022

Times Cited Count：24 Percentile：66.97(Chemistry, Physical)

We determined the average size of small Si and Ge clusters conned to one half of a (77) or (55) unit cell of a Si or Ge(111) surface. The size of Si and Ge clusters conned to a Si(111)-(77) half unit cell was determined to be 8.31 atoms and 7.51 atoms, respectively for a growth temperature of 400 K. This is the same value within the error and shows, that the material of the clusters is less important for the cluster size. On the Ge surface it was found that the reconstruction unit cell is important for the cluster size. On the (55) reconstructed Ge(111) surface the Si clusters have a smaller size of 4.71 atoms compared to 8.21 atoms for Si clusters on the Ge(111)-(77) surface.

Journal Articles

Interrelation between speckle images in X-ray diffraction spots of YBa $_{2}$ Cu $_{3}$ O $_{7-x}$ and its superconductive phase transition

Suzuki, Takuya*; Takano, Hidekazu*; Takeuchi, Akihisa*; Uesugi, Kentaro*; Asaoka, Hidehito; Suzuki, Yoshio*

Advances in X-Ray Chemical Analysis, Japan, 36, p.249 - 257, 2005/03

no abstracts in English

Journal Articles

Effects of ultrastrong gravitational field on the crystalline state of a Bi-Sb alloy

Huang, X.*; Mashimo, Tsutomu; Ono, Masao; Tomita, Takeshi; Sawai, Tomotsugu; Osakabe, Toyotaka; Mori, Nobuo*

Journal of Applied Physics, 96(3), p.1336 - 1340, 2004/08

https://doi.org/10.1063/1.1763236

Times Cited Count：11 Percentile：42.70(Physics, Applied)

Mega-gravity field experiments were performed on the Bi $_{70}$ Sb $_{30}$ (atomic percent) alloy and pure Bi below their melting points, to investigate the change in crystalline state. For the alloy centrifuged at 191-205 $^{circ}$ C, no change in composition was observed, and the grain sizes of the crystals decreased from several mm to tens of m, while no distinct change in grain size was observed for the centrifuged pure Bi. The alloy centrifuged at 220-240 $^{circ}$ C consisted of two regions with different morphologies-fine-grained crystals with grain sizes around tens of m in the low gravity region, and large crystals with grain sizes several mm long and hundreds of m wide along the direction of gravity in the high gravity region, where sedimentation of atoms was confirmed. The large crystals with hexagonal structures were formed by preferential crystal growth roughly along the c axes, and a large strain that increased as the gravitational field increased existed inside these crystals. Formation of this anomalous crystal state might be correlated with the sedimentation of atoms.

Journal Articles

Growth and characterization of thin films on hydrogen layers

Asaoka, Hidehito

KEK Proceedings 2004-5, p.52 - 53, 2004/08

no abstracts in English

Journal Articles

Comparison between surfactant-mediated Bi/Ge/Si(111) epitaxy and Ge/Si(111) epitaxy

Paul, N.*; Asaoka, Hidehito; Voigtlnder, B.*

Surface Science, 564(1-3), p.187 - 200, 2004/08

https://doi.org/10.1016/j.susc.2004.06.194

Times Cited Count：7 Percentile：37.58(Chemistry, Physical)

Using scanning tunneling microscopy (STM) the Ge epitaxy on a Bi terminated Si(111) surface is compared to the growth without surfactant. As soon as the 2 bilayer high wetting layer is completed with surfactant, Ge islands with a flat top and an underlying dislocation network occur. Elastic distortions due to the dislocation network result in periodic sub-Angstrom height undulations measured by the STM. In this case the Ge islands have the form of a mesa. With increasing Ge coverage, these mesas spread laterally. Beyond a Ge coverage of 10 bilayers, the Ge mesas have coalesced and further Ge deposition leads to a 2D layer-by-layer growth of Ge on Si(111). In epitaxy without the use of a surfactant as well, the formation of Ge islands with an underlying dislocation network is observed. However, in this case the Ge islands are much higher and show no tendency to coalesce. The partially relaxed islands coexist with another type of tall islands.

Journal Articles

Growth mechanisms in Ge/Si(111) heteroepitaxy with and without Bi as a surfactant

Paul, N.*; Asaoka, Hidehito; Mysliveek, J.*; Voigtlnder, B.*

Physical Review B, 69(19), p.193402_1 - 193402_4, 2004/05

A2003-0489.pdf:0.64MB

https://doi.org/10.1103/PhysRevB.69.193402

Times Cited Count：21 Percentile：67.04(Materials Science, Multidisciplinary)

We compare the initial stages of growth of Ge on Si(111) with Bi as a surfactant and without surfactant. At the beginning of growth, 3D islands with a strain relieving dislocation network at their base are formed in both growth systems. These islands can be regarded as seeds of a flat relaxed Ge layer on Si(111). However, such Ge layer forms at later stages of growth only in the growth with Bi surfactant, while the growing Ge layer without surfactant remains rough. What makes the dierence and the success of Bi surfactant mediated epitaxy is the lateral growth and coalescence of the seed islands that cover the entire surface within first 15 bilayers of Ge deposition. This happens due to a kinetic limitation of the incorporation of Ge into the growing layer in the presence of surfactant.

Journal Articles