Some peculiarities of EPR spectra of E′-centers in ion-implanted silica glasses

Богомолова, Л.Д.; Teplyakov, Yu.G.; Deshkovskaya, A.A.; Caccavale, F.

doi:10.1016/0022-3093(96)00173-1

Cited by 14 publications

(7 citation statements)

References 18 publications

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“…A number of experimental investigations have been performed in order to clarify the properties of Al and P impurities in both crystalline and amorphous silica, [1][2][3][4][5][6][7][8][9][10][11] but the experimental techniques employed usually only yield indirect information about the geometry and electronic structure of the impurities and their local environments. Thus there is a need to complement the experimental investigations by theoretical studies that may provide a link between the ''fundamental'' impurity properties and the experimentally accessible quantities ͑e.g., results from optical or magnetic resonance spectroscopies͒.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Lægsgaard

Stokbro

2002

Phys. Rev. B

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Section: Introductionmentioning

confidence: 99%

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Lægsgaard

Stokbro

2002

Phys. Rev. B

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“…A number of experimental investigations have been performed in order to clarify the properties of Al and P impurities in both crystalline and amorphous silica, [1][2][3][4][5][6][7][8][9][10][11] but most of the results obtained are of a qualitative nature. The purpose of the present paper is to complement the experimental information by a theoretical study of the local chemistry governing the behavior of dilute Al or P impurities in a silica environment.…”

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confidence: 99%

Local chemistry of Al and P impurities in silica

Lægsgaard

Stokbro

2000

Phys. Rev. B

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“…5b) is known as a powder pattern, characteristic of different Lande factors g x , g y , g z at different directions. This phenomenon occurs when the chemical surrounding of the unpaired electron is asymmetric [13]. It is suggested that this peak is related to dangling bonds at the W/SiO 2 interfaces.…”

Section: Discussionmentioning

confidence: 99%

Dielectric Properties of W‐SiO ₂ Nanocomposites

Berger

Tepper

2000

Interface Controlled Materials

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The dielectric properties of nanocomposite materials composed of nano-sized amorphous silica powder and micron-sized tungsten powder were studied as a function of composition and heat treatment temperature. The dielectric constant of the nanocomposites, at all compositions, is higher than that of a pure silica powder. The percolation threshold of this system is at about 20% vol. W. Above this composition a sharp increase in the dielectric constant occurs, which becomes even sharper after a heat treatment at 950°C for 1 hour. The dielectric constant of pure silica specimens, on the other hand, decreases after the heat treatments. ESR measurements show peaks associated with dangling bonds at the surfaces of the particles. The change of the intensity and location of the ESR peaks is correlated with the change of the dielectric constant of the powders due to the heat treatments. IntroductionThe electrical properties of composite materials made of a mixture of conducting and insulating phases have been extensively studied, both theoretically [1-2] and experimentally [3][4][5][6][7][8][9][10][11] as a function of composition, frequency and temperature. The electrical properties of such materials can be altered by few orders of magnitude by changing the composition. At the percolation threshold a conducting path is formed throughout the material's volume [1] due to either physical contacts or short distances between neighboring conducting particles. Experimental data show that the percolation threshold can not be predicted theoretically in composite materials having particles with different sizes and shapes. Preliminary estimations of the effect of the size ratio between the SiO 2 and W particles predict a substantial increase in the dielectric constant of the composite material compared to pure SiO 2 powder. Our study was therefore focused on nanocomposite specimens, which consist of two constituents that differ in size, by a factor of 50. The goal of the study is to understand the enhancement of the dielectric constant of the W-SiO 2 nanocomposites. For this purpose, specimens were prepared with different compositions and exposed to various heat treatment temperatures. The dielectric constant was determined by capacitance measurements. The type and density of chargeable energy states were determined from ESR measurements. The SiO 2 /W materials system was chosen for their high stability against interdiffusion and interaction up to at least 1500°C, for their low thermal expansion coefficient, and for their relatively low price.Interface Controlled Materials. Edited by M. Rühle and H. GleiterThe raw materials of the studied specimens are SiO 2 and W powders. The pure SiO 2 powder, purchased from Aldrich Chemical Company, Inc., consists of amorphous particles with an average size of about 20nm. The pure tungsten powder (99.99%), purchased from ISKAR ltd., has an average grain size of about 1µm. The powders with various compositions were mixed for 12 hours in a Fritsch planetary ball milling system operated at 2300 rpm. G...

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Some peculiarities of EPR spectra of E′-centers in ion-implanted silica glasses

Cited by 14 publications

References 18 publications

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Local chemistry of Al and P impurities in silica

Dielectric Properties of W‐SiO ₂ Nanocomposites

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Some peculiarities of EPR spectra of E′-centers in ion-implanted silica glasses

Cited by 14 publications

References 18 publications

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

Local chemistry of Al and P impurities in silica

Dielectric Properties of W‐SiO 2 Nanocomposites

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Product

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About

Dielectric Properties of W‐SiO ₂ Nanocomposites