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1.
The optical properties of GeO(2) glass were investigated to clarify its potentiality as an optical fiber material. Glass samples were prepared by the flame hydrolysis and the melting techniques, and their Rayleigh scattering and infrared absorption properties were examined. Optical fibers composed of a pure GeO(2) core and an F-doped GeO(2) cladding were drawn to clarify the scattering loss characteristics. The Rayleigh-scattering intensity obtained from spectral loss measurements on the fibers agreed with that measured in bulk samples, and the intensity relative to that of SiO(2) glass was found to be approximately 3. These results suggest that a minimum loss of 0.15 dB/km is expected at a wavelength of 2 mum. 相似文献
2.
Electron spin resonance measurements show a reduction in the spin density associated with unpaired electron dangling bonds of a mixed complex of co-evaporated GeO2/SiO
x
films compared with that of SiO
x
films investigated under similar conditions. Unlike the behaviour of BaO/GeO2 complex films, these samples show a decrease in the optical gap as the thickness increases for films of fixed compositions. However, it increases as the SiO percentage increases in films of the same thickness. D.C. measurements at low applied fields below 105 V cm–1 agree well with the spin density results. 相似文献
3.
Dielectric constant , loss tan and ac conductivity of ZnF2-Bi2O3-TeO2 glasses with varying concentrations of Bi2O3 (from 5 to 20%) are studied as a function of frequency and temperature over moderately wide ranges. The dielectric breakdown strength for these glasses is also determined in air medium. From the analysis of these studies along with the IR spectra & DTA recordings of these glasses, the structural changes in ZnF2-Bi2O3-TeO2 glass system with change in the concentration of Bi2O3, are discussed. 相似文献
4.
5.
The variation of some physical properties of equimolar copper-phosphate glasses has been reported in the literature. The present work studied a 60 mol% P2O5-40 mol % CuO glass system using electrical conductivity, infrared absorption, optical absorption spectroscopy and differential scanning calorimetry. The results revealed an increase in the activation energy and the optical energy gap compared with that for equimolar P2O5-CuO, which could be attributed to the variation of reduced valence states of the copper ion in the process of glass formation. The relation between the a.c. electrical conductivity with frequency was found to be almost temperature-independent. Infrared measurement revealed similar trends to those reported for the same glass composition. DSC measurements showed endothermal peaks at 360, 520, 560 and 580 °C for this glass composition. 相似文献
6.
The GeO2 nanocrystals (α-quartz type structure) with β-phase are synthesized at relatively lower temperature by hydrothermal route using autoclave. All samples are characterized by XRD, FESEM, EDS, TEM, photoluminescence (PL) and UV–vis absorption spectroscopy techniques. Synthesized nanocrystals have uniform shape and uniform size distribution for a particular synthesis condition, which is about 30–300 nm depending on synthesis conditions. The XRD results indicate that grown GeO2 crystals only shows peak related to α-quartz structure with lattice parameters a = 4.985 Å and c = 5.648 Å. UV–vis absorption spectroscopy measurements reveal the bandgap energies corresponding to the GeO2 α-quartz structure. Synthesized nanocrystals are capable to emit strong blue light around 425–435 nm under excitation of 300 nm and 325 nm and consequently the as synthesized material can be used in integrated optical devices. 相似文献
7.
The a.c. dielectric breakdown and electrical resistivity of glass ceramics in the system MgO-Al2O3-SiO2-TiO2 have been studied using three sets of samples having different crystallinity contents. Standard a.c. (50 Hz) breakdown tests were performed at room temperature (18 °C) using planar disc specimens and hemispherically-ended brass contact electrodes. The breakdown process caused the formation of a breakdown channel which terminated at the specimen surface in a crater. The breakdown strength was independent of the rate of voltage rise, but decreased exponentially (60 to 10 kV mm–1) with increasing specimen thickness. A high crystallinity content, good surface finish and a homogeneous microstructure yielded high breakdown strengths whilst poor microstructural development caused a reduction in breakdown strength. The breakdown mechanism is believed to be a combination of electronic, thermal and electromechanical processes. 相似文献
8.
The results of an investigation of some properties of CuO-TeO2 glasses are reported. X-ray diffraction, differential scanning calorimetry and optical absorption measurements are discussed with respect to the compositions. D.c. conductivity is measured in the temperature range 293 to 453 K and discussed in terms of small polaron theory. 相似文献
9.
The phase diagram has been determined using a combination of high temperature powder diffraction and quench furnace equilibration. Na2GeO3 forms a range of solid solutions which covers over half of the diagram at solidus temperatures (900 C) but whose extent is much more restricted at lower temperatures. Na2GeO3 solid solutions may undergo a variety of reactions on cooling, which include phase transformation and coherent precipitation. 相似文献
10.
Takeshi Kikuchi Yoshizo Kitami Masato Yokoyama Hiroshi Sakai 《Journal of Materials Science》1989,24(12):4275-4278
The phase equilibria in the pseudo-binary system Bi2O3-TeO2 at 600° 950° C in air were examined by solid-state reaction techniques and X-ray powder diffraction method. Four pseudo-binary compounds appeared, i.e., -Bi2O3 type solid solution having a compositional range of (1-x)Bi2O3·xTeO2 wherex=0 0.4 a new compound Bi6Te2O15 which has an orthorhombic cell of a=2.27(4) nm, b=1.06(1) nm and c = 0.539(8) nm, 2Bi2O3 · 3TeO2, and an unidentified phase Bi2O3·2TeO2. The formation of the phase Bi6Te2O15, in which all the Te ions are hexavalent, was confirmed by the thermogravimetry and by the Mössbauer spectra. The liquidus curves for whole system were determined by DTA method. 相似文献
11.
S. Kawasaki 《Journal of Materials Science Letters》1996,15(21):1860-1862
12.
Two series of glass and thin film specimens of BaO-TeO2 were prepared. The optical absorption edges and infrared absorption spectra were investigated. It was found that the fundamental absorption edge is a function of BaO content in both kinds of films and that the absorption is due to indirect electronic transitions. The values of optical gap for blown films were greater than those of thin evaporated films, but the widths of the band tails were greater for the evaporated thin films, which were expected to be more disordered than the thin blown glass films. 相似文献
13.
14.
The d.c. electrical conductivity of Na2O-ZnO-B2O3 glass system has been measured as a function of temperature in the range of 350–600°K. The conductivity data show that the
activation energy of Na+ ions is dependent on ZnO concentration. The results have been discussed in the light of the cluster model of glasses. 相似文献
15.
Stanislaw Komornicki Marta Radecka Mieczyslaw Rekas 《Journal of Materials Science: Materials in Electronics》2001,12(1):11-16
The a.c. impedance response of polycrystalline ceramics SnxTi-x1O2 was studied in the air in the temperature range 298–1073 K. The impedance spectra were analyzed in terms of two proposed equivalent circuits involving both resistor and non-Debye constant phase element (CPE). The presence of CPE elements may be interpreted by diffusion phenomena. The results indicate a negligible contribution of grain boundary resistance to the total resistivity of the studied materials. The determined activation energy of the bulk conductivity of TiO2 was compared with literature data. © 2001 Kluwer Academic Publishers 相似文献
16.
P. Kantha N. Pisitpipathsin K. Pengpat S. Eitssayeam G. Rujijanagul R. Gua Amar S. Bhalla 《Materials Research Bulletin》2012,47(10):2867-2870
This paper presents the effect of GeO2 glass former on the physical and electrical properties of BaFe0.5Nb0.5O3 (BFN) perovskite ceramics. The BFN powder was prepared by a conventional mixed-oxide method and the GeO2 contents, ranging from 1 to 5 wt.%, were subsequently added to the calcined BFN powder. The mixtures were pressed and sintered to form dense ceramics. We showed that, with the addition of GeO2, the maximum density was achieved at lower sintering temperature, approximately 200–225 °C lower than those required by the pure BFN ceramic. However, the densities of these GeO2 doped BFN ceramics were slightly lower than those of pure BFN due to the occurrence of pores. We also found that the addition of GeO2 reduces the dielectric loss at room temperature from 4.29 to 0.39–0.79 but the dielectric constant at room temperature decreased with the increased GeO2 concentrations. With small amount of added GeO2, ferroelectric property of BFN ceramics was also obtained, as confirmed by their hysteresis loops. 相似文献
17.
Tien-Chai Lin Wen-Chang Huang Wei-Che Lan 《Journal of Materials Science: Materials in Electronics》2014,25(7):3077-3084
The electrical and optical properties of InGaZnO (IGZO) thin films were studied in the research. It was found that all the films deposited at room temperature exhibit amorphous structures. A better film quality was obtained at a lower pressure with sputtering ambiance. The RF power toward the IZO target was constant at 125 W; the RF power toward the Ga2O3 target varied from 0 to 70 W. A best IGZO film with corresponding resistivity, carrier concentration, and mobility is 7.94 × 10?4 Ω-cm, 1.68 × 1020 cm?3, and 47 cm2/V-s, respectively. Due to the doping of gallium in the IGZO film, it led to a lower resistivity than that of the IZO film. A blue shift effect of the film was also observed in the doping of gallium to the IGZO film. The H2 plasma effects toward the IGZO were also observed. 相似文献
18.
P.C. Lansåker K. GunnarssonA. Roos G.A. NiklassonC.G. Granqvist 《Thin solid films》2011,519(6):1930-1933
We report on a detailed study on the optical and electrical properties of Au films made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films had thicknesses up to 10.7 nm and hence spanned the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less “holey” film. Scanning electron microscopy and atomic force microscopy demonstrated that the SnO2:In films were considerably rougher than the glass itself, and this roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and reflectance and of electrical resistance gave a fully consistent picture that could be reconciled with impeded Au film formation on the SnO2:In layer; this led to pronounced “plateaus” in the near infrared optical spectra for Au films on SnO2:In and a concomitant change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses. Our work highlights the importance of the substrate roughness for transparent conductors comprising coinage metal films backed by wide band gap transparent conducting oxides. 相似文献
19.
The electrical and optical properties of BiSiO2 cermet films were studied. Using the temperature dependence of the resistivity of the cermet films and the dependence of the amount of oxidation of the fine bismuth particles on the volume percentage of bismuth, the three-dimensional percolation threshold composition was determined to be approximately 18 vol. % Bi. 相似文献
20.
The effect of film thickness on the optical and electrical properties of Cu-30 wt % GeO2-70 wt % thin cermet films prepared by electron-beam deposition at about 10–3 Pa and at a substrate temperature of 300 K is reported. The ultraviolet, visible and direct current (d.c.) conductivity results are analysed with the aim of determining the optical band gap,E
opt, the width of the band tails,E
e, and the d.c. thermal activation energy,E
a. It was found that the optical energy gap increases with increasing thickness and that the absorption was due to indirect transitions ink-space. The general feature of the absorption edge remains similar for both unannealed and annealed films, but annealing has the effect of decreasingE
opt. The d.c. conductivity results show thatE
a decreases with increasing thickness. From a knowledge ofE
opt andE
a, a probable model of the electronic band structure in Cu-GeO2 thin films has been suggested. 相似文献