http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Compressed-exponential relaxations in supercooled liquid trehalose
서정아,권현정,Kunimitsu Kataoka,Ken-ichi Ohshima,신동명,김형국,황윤회 한국물리학회 2012 Current Applied Physics Vol.12 No.6
We investigated the a-relaxations in supercooled liquid trehalose by using photon correlation spectroscopy (PCS) and found an interesting compressed-exponential relaxation at temperatures above 140 ℃. The q-1 dependence of its relaxation time corresponds to an ultraslow ballistic motion due to the local structure rearrangements. In the same temperature range, we found the glycosidic bond structure changes in trehalose molecule from the Raman scattering and the X-ray direction measurements. We concluded that the compressed-exponential relaxation in supercooled liquid trehalose might originate from the intra-molecular (glycosidic bond) structure change.
Dielectric Properties of Amorphous KNbXO5 (X=Ge, Si)
송철호,양용석,최현우,박현욱,Ken-ichi Ohshima,Mac Kim 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
We have investigated the dielectric response of amorphous KNbXO5 (X = Ge, Si) in the glass region. The samples were prepared by a twin-roller quenching method and measurements were carried out in the frequency range from 100 Hz to 15 MHz. The frequency dependence of the electrical data has been analyzed in the framework of the modulus formalism. Similar values of the activation energies between KNbGeO5 (KNGO) and KNbSiO5 (KNSO) indicate that there is no significant difference in the energy barrier for the charge carriers to overcome between KNGO and KNSO. In the temperature dependence of a master curve, the overlap of all the curves for various temperatures on a single master curve indicates that the relaxation mechanism is independent of temperature. The smaller values of the stretched exponent parameter for KNSO than for KNGO are understood, based on the weight difference of nonbridging oxygen between KNGO and KNSO.
Dielectric properties of LiNbO3 glass mixed with strong glass former SiO2
J.E. Kim,Y.S. Yang,최현우,Ken-ichi Ohshima,S.J. Kim 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
We have studied the crystallization process and electrical properties of LiNbO3 glass with strong glass former SiO2. In dierential thermal analysis and X-ray measurements, it has been found that 2LiNbO3-SiO2 glass crystallizes into LiNbO3 and Li6Si2O7. The dielectric response reveals that there is a negative capacitance eect in the glass state. We conclude that this eect originates from the presence of external inductive reactance.
Crystallization and dielectric properties of 2SrTiO3-SiO2 glass
J.E. Kim,Y.S. Yang,Ken-ichi Ohshima,S.J. Kim 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
We have investigated the crystallization process and dielectric properties of 2SrTiO3-SiO2 glass. Dierential thermal analysis (DTA) measurements show two exothermic peaks with heating. Xray measurements identify that the glass crystallizes into cubic SrTiO3 and tetragonal Sr2TiSi2O8. The activation energies, which are calculated by the modied Ozawa equation, for SrTiO3 and Sr2TiSi2O8 crystallization, are 4.99 eV and 5.68 eV, respectively. In electrical measurements, high temperature dielectric behavior is well explained by the conjunction of crystallization processes appearing in DTA results. We have found that oxygen vacancies produce a pronounced dielectric anomaly in the glass state.
Electrical anomaly in 2SrTiO<sub>3</sub>–SiO<sub>2</sub> glass
Kim, J.E.,Choi, H.W.,Kim, S.J.,Ohshima, Ken-ichi,Yang, Y.S. Elsevier 2007 Materials science & engineering. properties, micro Vol.449 No.-
<P><B>Abstract</B></P><P>We report the electrical properties of 2SrTiO<SUB>3</SUB>–SiO<SUB>2</SUB> glass in the frequency range 100≤<I>f</I>≤10<SUP>7</SUP>Hz from 30°C to near 600°C. We have found that the anomalous dielectric constant decreases with the increase of annealing cycle and the heat-treated sample under oxygen atmosphere. The non-Debye behavior in the complex permittivity Cole–Cole formula has been used to interpret the relaxation mechanism of a dielectric anomaly. The activation energy for the relaxation process related to oxygen vacancies is in the range of 0.5–0.6eV. The values of <I>α</I> are 0.76–0.84 for the sample of the various heat-treatment conditions. We have explained that the dielectric relaxation originates from the hopping of ions and local arrangement in this system.</P>