研究者詳細 - 難波　徳郎

論文 - 難波　徳郎

分割表示 117 件中 41 - 60 件目／全件表示 >>

A theoretical interpretation of 17O NMR spectra in borosilicate glasses

M. Urushihara, T. Nanba, Y. Miura, S. Sakida

Ceramic Transactions 197 189 - 196 2006年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Local structure around oxygen is directly elucidated by 17O nuclear magnetic resonance (NMR). However, the 17O NMR spectra in borosilicate glasses are quite complicated, and hence the assignments of the peaks have been empirically done. In the present study, 17O NMR parameters for the various oxygen sites in the borosilicate system were obtained from the ab-initio molecular orbital calculations using the Gaussian03 programs. As for the oxygen atoms in SiOSi, SiOB[3], and B[3]OB[3] bridging bonds (B[n]: n-fold coordinated boron), the isotropic chemical shift δiO decreased with increasing the bond angle. The oxygen atoms coordinated by B[4] as SiOB[4], B[3]OB[4], and B[4]OB[4] bridges showed weak dependency in δiO against the bond angle, and B[4]OB[4] showed a maximum in δiO at 150°. The quadrupole coupling constant Cq of all the bridging oxygens increased with increasing the bond angle. When the oxygen atoms in SiOB[4], B[3]OB[4] bridges were coordinated by Na ion, δi O decreased by 5 ∼ 10 ppm. The oxygen atoms in trimeric ring clusters showed different δiO from dimeric clusters, indicating that δiO was also influenced by the second neighboring cations. The order of δiO was expected as SiOSi &lt
SiOB[4] &lt
SiOB[3] &lt
B[4]OB[4] &lt
B[3]OB[4] &lt
B[3]OB[3], which was in accordance with the order of bond covalency.

Scopus

researchmap

Consideration on the correlation between basicity of oxide glasses and O1s chemical shift in XPS 招待査読

T Nanba, Y Miura, S Sakida

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 113 ( 1313 ) 44 - 50 2005年1月

担当区分：筆頭著者記述言語：英語出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

O1s binding energy measured by X-ray photoelectron spectroscopy (XPS) is candidate as a new tool to determine a new scale of Lewis basicity of oxide ions in glass. Some mathematical expressions for the basicity or XPS chemical shift, such as charge parameter and optical basicity, were compared with the experimental O1s binding energy in binary alkali oxide glasses. The expressions so far in use needed some modification in parameters. A new empirical expression introduced in this paper gives a new concept and universal scale of basicity.

DOI： 10.2109/jcersj.113.44

Web of Science

Scopus

researchmap

テルライト系ガラスの屈折率の組成依存性

赤嶺宗子, 崎田真一, 難波徳郎, 三浦嘉也

日本セラミックス協会年会・秋季シンポジウム講演予稿集 2005S 468 - 468 2005年

出版者・発行元：公益社団法人日本セラミックス協会

Lorentz-Lorenz式によると、屈折率は分極率に依存し、特に酸化物ガラスにおいてはアニオンである酸化物イオンの分極率に大きく依存する。一般に、XPSによるO1s束縛エネルギーは酸化物イオンの分極率と関連付けることができるとされている。アルカリシリケート系ガラスではアルカリ酸化物の添加に伴い屈折率は増加し、O1s束縛エネルギーは減少する。しかし，アルカリテルライト系ガラスではアルカリ酸化物の添加に伴い屈折率とO1s束縛エネルギーは共に減少する。本研究ではテルライト系ガラスの特異的な屈折率変化について、テルルイオンの分極率などテルライト系ガラスの屈折率に影響を与える因子について検討した。

DOI： 10.14853/pcersj.2005s.0.468.0

CiNii Article

researchmap

Molecular dynamic simulation on the structure of sodium germanate melts 査読

T. Nanba, M. Nakamura, Y. Miura

J. Ceram. Soc. Japan, Suppl. 112 ( 5 ) S1250 - S1253 2004年

An interpretation of 11B and 29Si NMR spectra in alkali borosilicate glasses 査読

T. Nanba, M. Nishimura, Y. Miura

Geochimica et Cosmochimica Acta 68 ( 24 ) 5103 - 5111 2004年

Changes in atomic and electronic structures of amorphous WO3 films due to electrochemical ion insertion 査読

T Nanba, M Ishikawa, Y Sakai, Y Miura

THIN SOLID FILMS 445 ( 2 ) 175 - 181 2003年12月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE SA

The structural changes in amorphous WO3 films were investigated both on the atomic and electronic levels, and the experimental findings were interpreted using molecular orbital calculations. Electrochemical fast intercalation resulted in the splitting of a peak in the valence band region of the X-ray photoelectron spectrum. This splitting could be attributed to the formation of non-bridging oxygen. Decomposition Of WO6 units into WO4 units could also be inferred from the data. This decomposition was, however, not responsible for the split of the photoelectron peak. From the population analyses it was found that the average bond strength decreased due to the intercalation, while select W-O bonds increased in strength. It was expected that these changes in the chemical bonding character lead to localization of electrons and distortion of WO6 units, which was consistent with the theoretical interpretations of electrochromism, the intervalence charge transfer model and the small polaron absorption theory. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)01188-X

Web of Science

researchmap

Alkali distribution in borosilicate glasses 査読

T Nanba, Y Miura

PHYSICS AND CHEMISTRY OF GLASSES 44 ( 3 ) 244 - 248 2003年6月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC GLASS TECHNOLOGY

The alkali distribution in borosilicate glass has been discussed on the basis of the different quantities obtained by various experimental methods. The NBO fraction was chosen as a common quantity for evaluating the alkali distribution models. The NBO fractions in sodium borosilicate glasses were estimated from B-11 and Si-29 NMR as well as XPS. However, the best model was not found among the existing models. The amounts of sodium oxide consumed for the NBO formation in borate and silicate networks and for the formation of BO4 units were separately estimated from the B-11 and Si-29 NMR data. A new trend was found in the alkali distribution suggesting the possibility for a new universal distribution model.

Web of Science

researchmap

Chemical bonding state of sodium silicates 査読

T Nanba, T Hagiwara, Y Miura

ADVANCES IN QUANTUM CHEMISTRY, VOL 42 42 187 - 198 2003年

An interpretation of B-11 and Si-29 NMR spectra in alkali borosilicate glasses

Nanba, T, Nishimura, M, Miura, Y

Geochimica Et Cosmochimica Acta 67 ( 18 ) 2003年

X-ray and neutron scattering study of the structure of lithium bismuth oxide glass 査読

T Watanabe, T Nanba, Y Miura

JOURNAL OF NON-CRYSTALLINE SOLIDS 297 ( 1 ) 73 - 83 2002年1月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

The structure of (100 -lambda)Bi2O3 . xLi(2)O (25less than or equal toxless than or equal to35 mol%) glasses has been investigated by means of X-ray and neutron scattering methods. Comparing the glasses with several bismuthate crystals in total correlation function T(r), it is concluded that a large amount of edge-sharing BiOn polyhedra are present in the glasses and the network structure is similar to the Bi2O4 crystal. In the crystal, BiO6 octahedra form a layer sharing their four corners mutually, and the BiO4+4 distorted polyhedra are placed between the layers sharing all the edges with the neighboring polyhedra. Assuming two different Li sites in the Bi2O4-based structure, structural models were constructed to compare T(r), from which it was suggested that some Li ions substituted for the octahedral Bi site and some occupied an interstitial vacant site, In addition, the glasses have various defects such as excess 0 ions, positive-holes on 0 ions, vacant space to accept atmospheric oxygens, and Bi vacancies. The glass formation is sensitive to the melting conditions, such as temperature and period, suggesting that there exists some optimum quantity in the defect structures. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00921-8

Web of Science

researchmap

X-ray photoelectron spectroscopy of sodium borosilicate glasses 査読

Y Miura, H Kusano, T Nanba, S Matsumoto

JOURNAL OF NON-CRYSTALLINE SOLIDS 290 ( 1 ) 1 - 14 2001年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

X-ray photoelectron spectra of RNa2O . B2O3 . KSiO2 (R = 0.2 to 5.0, K = 0.5 to 6.0) glasses were measured by a monochromatised Al-Ka XPS instrument. Chemical shifts of the core-level photoelectron spectra of the glass constituent ions were investigated. Peaks at the higher and lower energy sides of an Ols signal were ascribed to bridging oxide (BO) and non-bridging oxide (NBO) components, respectively. The BO component could not be separated into the oxide ions with different environment such as Si-O-Si, B-O-Si and B-O-B. Na1s signal could not be separated into two components of Na+ ions associated with [BO4/2](-) tetrahedron and NBO. For the small K values (=0.5 and 1.0), the NBO fractions measured by XPS agreed very well with the structural model proposed by Dell et al. [J. Non-Cryst. Soilds 58 (1983) 1], where NBO did not appear until R = 0.5 regardless of K values. With increasing K, however, the dependence of the NBO fraction upon R gradually came to disagree with the Dell model. At smaller R values than Rv = 0.5 +K/16, the NBO component already appeared to a considerable extent and the discrepancy between the XPS results and the Dell model became more significant with increasing K. This fact meant that additional sodium oxides were shared proportionally between silicate and borate networks even at the small R when K was larger than 2. A new sharing model was proposed on the basis of an acid-base concept. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00720-7

Web of Science

researchmap

Electron paramagnetic resonance study of positive-hole pairs on oxide ions in lithium bismuthate glass 査読

T Watanabe, T Nanba, Y Miura

CHEMISTRY LETTERS ( 2 ) 156 - 157 2001年2月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

The electron paramagnetic resonance signals attributed to the triplet state of the positive-hole pairs on oxide ions are observed in (100-x) Bi2O3. xLi(2)O glass (x = 25, 30, 35 mol%). So far as we know, this is the first experimental observation of the triplet oxygen hole center in oxide glasses.

DOI： 10.1246/cl.2001.156

Web of Science

researchmap

Molecular dynamic simulation on the structure of sodium germanate glasses 査読

Tokuro Nanba, John Kieffer, Yoshinari Miura

Journal of Non-Crystalline Solids 277 ( 2-3 ) 188 - 206 2000年12月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier Science Publishers B.V.

The structure of Na2O-GeO2 glasses has been investigated, using molecular dynamics (MD) simulations based on an empirical three-body interaction model. A multi-body potential function with two energy minima in the angular term for a given three-atom unit was introduced to permit a transformation between different coordination states, such as 4- and 6-fold coordinated Ge sites. Parameters in the potential function were optimized with a non-linear least-squares (NLS) method. The optimal parameter set obtained with a Na4Ge9O20 crystal was employed for the structural models of pure GeO2 and 2Na2O·9GeO2 glasses. In the model for the binary glass, however, a number of 5-fold coordinated Ge, non-bridging O and 3-fold coordinated O formed. Another binary model free from 5-fold Ge was prepared using a simple scheme in which no three-body interaction was applied to the structural units containing 5-fold coordinated Ge. All the structural models produced showed good agreement with the experiments, including vibrational spectra and radial distribution functions (RDFs). No significant difference between the experimental observables of the two binary glass models was revealed, except for the coordination environment of Ge. This is because 5- and 6-fold Ge do not occur in a discrete arrangement through a corner-sharing of GeO4, e.g. GeO5,6-GeO4-GeO5,6, but in a dense configuration, e.g. as edge-sharing GeO5,6-GeO5,6, forming smaller rings than those in pure GeO2 glass.

DOI： 10.1016/S0022-3093(00)00313-6

Web of Science

Scopus

researchmap

X-ray photoelectron spectroscopy of sodium aluminosilicate glasses 査読

Y Miura, S Matsumoto, T Nanba, T Akazawa

Physics and Chemistry of Glasses 41 ( 1 ) 24 - 31 2000年2月

Photoluminescence increase of Er3+ in Na2O-Nb2O5-SiO2 glasses after crystallization 査読

ZD Yao, Y Ding, T Nanba, Y Miura

JOURNAL OF NON-CRYSTALLINE SOLIDS 259 45 - 50 1999年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Photoluminescence (PL) of Er3+ doped in xNaO(0.05)-xNbO(2.5)-(100 - 2x)SiO2 (mol%) (x = 24, 27, 30, 33, 36) glasses was investigated before and after crystallization. After crystallization, Er3+ was determined to be in the glass phase. Following the precipitation of the NaNbO3 crystalline phase in these glasses, PL intensity of S-4(3/2) --> I-4(15/2) transition of Er3+ increased. A maximum of >100-fold increment in the PL intensity was observed after crystallization as compared with that of the uncrystallized glass. The mechanism of augmentation of the PL intensity is discussed in terms of the theory of PL intensity. We assume that the difference in the refractive index between the residual glass and crystallized phases was a dominant factor causing the increase of the PL intensity after crystallization. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(99)00525-6

Web of Science

researchmap

Oriented surface crystallization of lithium niobate on glass and second harmonic generation 査読

Y Ding, Y Miura, S Nakaoka, T Nanba

JOURNAL OF NON-CRYSTALLINE SOLIDS 259 132 - 138 1999年11月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Surface crystallization of LiNbO3 on xK(2)O .(35-x)Li2O . 30Nb(2)O(5). 35SiO(2) (0 less than or equal to x less than or equal to 35) (mol%) glasses was investigated. The c-axis orientation of surface crystallized LiNbO3 was Improved when the glass contained 10 mol% K2O. Furthermore, Li ions in the LiNbO3 crystallites were partially replaced by K ions from the glass. Transparent surface crystallized LiNbO3 films on glasses were prepared by controlled heat treatment, which showed optical second harmonic generation. The estimated second-order non-linear optical susceptibilities were d(33) = 6.40 pm/V and d(31) = d(21) = d(34) = d(15) = 1/3d(33) = 2.14 pm/V for a film 1.33 mu m in thickness prepared after heating at 620 degrees C for 3 h, when the c-axis oriented film was described by a space group C-infinity v. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(99)00502-5

Web of Science

researchmap

Compositional dependences of Judd-Ofelt parameters of Er3+ in borosilicate glasses 査読

Z Yao, Y Ding, T Nanba, Y Miura

PHYSICS AND CHEMISTRY OF GLASSES 40 ( 4 ) 179 - 183 1999年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC GLASS TECHNOLOGY

The compositional dependences of Judd-Ofelt intensity parameters Omega(t) with t=2,4,6 of Er3+ were investigated systematically in xN(n)2O .(40-x)B2O3. 60SiO(2). 0.25Er(2)O(3) (mol%) glasses. The value of Omega(2) reveals a maximum around 10 mol% Na2O, inconsistent with a maximum shown at a Na:B ratio of about I in some physical properties of sodium borosilicate glasses. Whereas those of Omega(4) and Omega(6), decrease monotonically, with increasing Na2O content. The compositional dependences of the intensity, parameters were also compared with those of silicate and borate glasses. It was found that the borosilicate glass compositions can be tailored to obtain those intensity parameter values in both silicate and borate glasses.

Web of Science

researchmap

Chemical Bonding State of Sulfur in Oxysulfide Glasses 査読

T. Asahi, Y. Miura, T. Nanba, H. Yamashita

The Korean Journal of Ceramics 5 ( 2 ) 178 - 182 1999年2月

Local structure of Eu3+ in borosilicate glasses by phonon sideband spectra 査読

ZD Yao, Y Ding, T Nanba, Y Miura

MATERIALS SCIENCE RESEARCH INTERNATIONAL 4 ( 4 ) 239 - 243 1998年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC MATERIALS SCIENCE, JAPAN

InxNa(2)O . (40-x)B2O3 . 60SiO(2) (mol%) (x = 5,10,15,20,25,30) glasses with 0.25mol% Eu2O3 as additive, the local structure around Eu3+ was explored by employing the phonon sideband spectra of Eu3+ associated with the D-5(2) <--F-7(0), transition. It was found that the types and fraction of the structural units around Eu3+ varied with glass composition. Moreover, the B-O- vibrational mode of BO3 unit exists around Eu3+ when x &LE; 15, which is not present in the same composition glasses free of Eu3+. A greatest asymmetry in the surrounding, of Eu3+ occurs at x = 10, inconsistent with a maximum of some physical properties found in sodium. borosilicate glasses at a Na:B ratio of about unity. In addition, various structural units possess different coordination preference to Eu3+. The highest theoretical microscopic optical basicity on the oxygen atoms in these units was advocated as a criterion of the coordination preference, which successfully elucidated a series of coordination preference phenomena occurring in silicate, borate and borosilicate glasses.

Web of Science

researchmap

Photoluminescence enhancement of Er3+ in phase separated borosilicate glasses 査読

ZD Yao, Y Ding, T Nanba, Y Miura

MATERIALS SCIENCE RESEARCH INTERNATIONAL 4 ( 4 ) 244 - 248 1998年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC MATERIALS SCIENCE, JAPAN

Two sodium borosilicate glasses containing Er3+ were isothermally heat treated for phase separation, followed by the formation of the droplet and interconnected textures, respectively. The effects of heat treatment condition and the phase separated texture on photoluminescence (PL) intensity of S-4(3/2) --> I-4(15/2) transition of Er3+ were studied. It was found that the PL intensity increased with phase separation developing in both glasses. Moreover, the maximum PL intensities obtained by the phase separation in both glasses are 8.5 and 4.1 times as high as those in the respective untreated samples, the droplet texture being superior to the interconnected one. The mechanism of augmentation of the PL intensity was discussed in terms of the derived expression of the PL intensity. It was supposed that the induced interface after phase separation, causing notable increase in the radiative decay rate from the S-4(3/2) to I-4(15/2) levels, was responsible for the significant enhancement in the PL intensity.

Web of Science

researchmap

　前のページ - 次のページ　

<難波 徳郎>

論文 - 難波 徳郎

<難波　徳郎>

論文 - 難波　徳郎