共查询到20条相似文献,搜索用时 15 毫秒
1.
Vinh Q. Nguyen Jas S. Sanghera Brian Cole Pablo Pureza Frederic H. Kung Ishwar D. Aggarwal 《Journal of the American Ceramic Society》2002,85(8):2056-2058
Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl4 ) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m). 相似文献
2.
Woon Jin Chung Bong Je Park Hong Seok Seo Joon Tae Ahn Myung-Hyun Lee Yong Gyu Choi 《Journal of the American Ceramic Society》2005,88(5):1205-1208
Selenide glass optical fibers were fabricated for Ge30 Sb10 Se58 S2 and Ge20 Sb10 Se70 glasses. Their transmission loss has been measured and compared with the theoretical attenuation loss that was calculated taking into account the electronic transition absorption, Rayleigh scattering, and multiphonon absorption. A low attenuation loss of the Ge20 Sb10 Se70 glass composition in 1.2–1.7 μm range has been expected due to its high optical band gap energy compared with the Ge30 Sb10 Se58 S2 glass. However, the measured attenuation loss of the Ge30 Sb10 Se58 S2 glass fiber was ∼13 dB/m at 1.5 μm while Ge20 Sb10 Se70 glass showed ∼82 dB/m. An enhanced weak absorption tail due to the localized states of the Ge20 Sb10 Se70 glass was responsible for this behavior. Structural defects are related to the localized states and discussed for the present glass compositions. 相似文献
3.
Byung-Hae Jung Do-Kyung Lee Sang-Ho Sohn Hyung-Sun Kim 《Journal of the American Ceramic Society》2003,86(7):1202-1204
Because of their thermal, dielectric, and optical properties, new glass compositions and thick-filmed transparent dielectrics containing neodymium oxide (Nd2 O3 ) were studied as a source of purer images in plasma display panels. In the present study, PbO–B2 O3 –SiO2 and PbO–B2 O3 –SiO2 –ZnO–Al2 O3 were used as starting glass compositions, to which up to 25 wt% of Nd2 O3 then was added. Increased amounts of Nd2 O3 increased the glass transition temperature and dielectric constant of the bulk glasses and decreased the coefficient of thermal expansion. The fired thick films (around 30 μm) allowed selectively visible light to penetrate and showed deep absorption properties at 585 nm that were related to an extraneous gas from neon discharge. 相似文献
4.
Vinh Q. Nguyen Jas S. Sanghera Ishwar D. Aggarwal Isabel K. Lloyd 《Journal of the American Ceramic Society》2000,83(4):855-859
The physical properties of glasses in the Ge30 As10 Se(60— x ) Te x system with x = 25, 28, 30, and 35 at.% Te, the Ge30 As10 Se30 Te(30— y ) I y system with y = 5, 10, 20, and 30 at.% I, the Ge30 As10 Se35 Te(25— z ) I z system with z = 2, 6, 10, and 20 at.% I, and the [Ge30 As10 Se30 Te30 ](100— w ) I w system with w = 0, 5, 10, and 20 at.% I have been investigated. The changes in the glass transition temperature, density, coefficient of thermal expansion, hardness, and viscosity are attributed to the delocalized metallic bonding character of Te in the substitution of Te for Se in the Ge-As-Se-Te glass system and the network-terminating role of iodine in the substitution of I for Te in the Ge-As-Se-Te-I glass system, respectively. 相似文献
5.
Guorong Chen ¶ Stefania Baccaro Martin Nikl Angelica Cecilia Yunxia Yang Du Eva Mihokova 《Journal of the American Ceramic Society》2004,87(7):1378-1380
The ultraviolet absorption and emission spectra of Ce3+ doped phosphate glasses based on gadolinium and sodium phosphates are studied in the present work. Compared with the cerium-free phosphate glass matrixes, CePO4 doping shifts the ultraviolet absorption edge of glasses into the longer wavelength because of the 4f–5d absorption transition of Ce3+ . The emission spectra correlate such red-shift with glass compositions. Explanations are based on variation in the optical basicity of glasses, which corresponds not only to the alkali content but also to the O/P ratio. The latter is proportional to the number of nonbridging oxygen in the oxyanion unit (PO4 ), and most likely plays an overwhelming role in the overall optical basicity of glasses. 相似文献
6.
Tellurite Glasses for Broadband Amplifiers and Integrated Optics 总被引:1,自引:0,他引:1
Shaoxiong Shen Animesh Jha Xiaobo Liu Mira Naftaly Kushvinder Bindra Henry J. Bookey Ajoy K. Kar 《Journal of the American Ceramic Society》2002,85(6):1391-1395
The present investigation discusses the advantage of using RE-ion-doped (Nd3+ , Tm3+ , and Er3+ ) TeO2 glasses for developing fiber and planar broadband amplifiers and lasers. The spectroscopy of RE-ion-doped fibers and glasses is discussed along with the thermal properties of glass hosts. The results of emission from the 3 H4 level in single-mode Tm3+ -doped tellurite fiber show that the emission band overlaps with Er3+ emission from the 4 I13/2 level and Nd3+ emission from the 4 F3/2 level in silicate and tellurite glasses, thereby enabling the development of amplifiers and lasers between 1350 and 1650 nm. Recent results using Z-scan measurements of nonlinear refractive index and absorption demonstrate that the third-order nonlinearity in undoped TeO2 glasses is of the order of 2 × 10−15 to 3 × 10−15 cm2 ·W−1 between 1300 and 1550 nm. These results are briefly discussed in view of an amplifier operation combined with ultrafast all-optical switching. 相似文献
7.
Fiber optics for telecommunications applications require very high purity glass. Light loss in glass results primarily from absorption and scattering. Transition metal ions and OH ions cause most of the absorption, whereas scattering is caused by microheterogeneity. Scattering losses vary from 1 to 4 dB/km at 850 nm; absorption losses are high near 630 nm, because of Cr3+ and Ni2+ impurities, but are lower near 850 nm, making this a preferred wavelength region. Flint glass with a total loss of 50 dB/km at 850 nm, prepared using pure material and special techniques, was used as the core of thin-clad optical fibers 70 μm in diameter; these fibers had an internal loss at 850 nm of ∼450 dB/km. 相似文献
8.
Christina Scheu Gerhard Dehm Wayne D. Kaplan 《Journal of the American Ceramic Society》2001,84(3):623-630
The microstructure of copper–alumina (Cu-Al2 O3 ) composites that have been prepared via the melt infiltration of liquid copper into porous alumina preforms was studied in detail, using various transmission electron microscopy (TEM) techniques. Two different samples—with open pore diameters of 0.2 and 0.8 μm—were investigated. For both specimens, a single crystalline copper network that extended throughout the open porosity of the alumina preform was observed. An amorphous glass phase that contained silicon and calcium was observed at the Al2 O3 /Cu/Al2 O3 triple junctions. The diameters of these amorphous pockets, which were strongly faceted along the Al2 O3 grains, were up to 20 and 100 nm for the initial pore sizes of 0.2 and 0.8 μm, respectively. A glass phase that contained silicon and calcium also was present at the Cu/Al2 O3 interfaces, whereas the Al2 O3 boundaries remained dry. Detailed high-resolution transmission electron microscopy investigations have shown that the interfacial glass phase at the Cu/Al2 O3 interfaces exhibited a uniform equilibrium film thickness along the interface region. However, the interfacial film thickness was dependent on the orientation of the Al2 O3 grain, and its value varied from 0.4 nm for Al2 O3 rhombohedral-plane termination ((1¯012)) up to 1 nm for Al2 O3 basal-plane termination ((0001)). 相似文献
9.
Susan R. Loehr Ki-Ho Chung Cornelius T. Moynihan 《Journal of the American Ceramic Society》1988,71(1):46-C-
A comparative study of infrared absorption due to H2 O and D2 O impurities in a fluorozirconate glass (53ZrF4 ·20BaF2 ·4LaF3 ·3AlF3 ·20NaF) was carried out. The H2 O and D2 O were introduced into the glass by reaction of the surface at 260°C with H2 O and D2 O vapor entrained in a stream of N2 . Reaction with H2 O produced IR absorption bands at 2.9 μm (O–H stretch) and 6.1 μm (H2 O bend). Reaction with D2 O produced bands at 3.9 μm (O–D stretch) and 8.3 μm (D2 O bend). The ratios of the corresponding D2 O/H2 O peak frequencies are 0.74 for both the stretching and bending vibrations, in good agreement with the value of 0.727 predicted from the difference in the OH and OD reduced masses. 相似文献
10.
Detlev F. K. Hennings B. Seriyati Schreinemacher Herbert Schreinemacher 《Journal of the American Ceramic Society》2001,84(12):2777-2782
BaTiO3 and Ba(Ti,Zr)O3 dielectric powders have been prepared from submicrometer BaCO3 , TiO2 , and ZrO2 . By use of submicrometer BaCO3 the intermediate formation of Ba2 TiO4 second phase can be widely suppressed. Monophase perovskites of BaTiO3 were already formed at 900°C and Ba(Ti,Zr)O3 at 1050°C. Aggregates of very small subgrains could be easily disintegrated to particle sizes <0.5 μm. 相似文献
11.
Jau-Ho Jean Chia-Ruey Chang Cheng-Dao Lei 《Journal of the American Ceramic Society》2004,87(7):1244-1249
Effects of Ag addition on sintering of a crystallizable CaO-B2 O3 -SiO2 glass have been investigated at 700°–900°C in different atmospheres. With Ag content increasing in the range of 1–10 vol%, the softening point, the densification, the onset crystallization temperature, and the total amount of crystalline phase formed of the crystallizable glass are reduced when fired in air. A bloating phenomenon is observed when the crystallizable CaO-B2 O3 -SiO2 glass doped with 1–10 vol% Ag is fired at 700°–900°C for 1–4 h. Fired in N2 or N2 + 1% H2 , however, the above phenomena disappear completely. It is thus believed that the diffusion of Ag into the crystallizable glass, which is caused by the oxidation of Ag in air, is the root cause for the above results observed. 相似文献
12.
Nextel™ 720 fibers were coated with LaPO4 and CePO4 monazite. The coatings were applied using washed and unwashed rhabdophane sols derived from La(NO3 )3 /(NH4 )2 HPO4 and a washed sol derived from Ce(NO3 )3 /H3 PO4 . The coatings were cured in-line at 900°–1300°C. Multiple coatings were also applied. Fiber strength was retained after coating with washed sols, but not with unwashed sols. These results are consistent with earlier work on LaPO4 monazite fiber coatings derived from La(NO3 )3 /H3 PO4 . 相似文献
13.
Hassan M. M. Moawad Himanshu Jain Raouf El-Mallawany Tawfik Ramadan Mohamed El-Sharbiny 《Journal of the American Ceramic Society》2002,85(11):2655-2659
We have investigated mixed electronic-ionic conduction in 0.5[ x Ag2 O·(1 − x )V2 O5 ]–0.5TeO2 glasses, where the Ag2 O amount varies over a range of 5–40 mol%. The glass samples have been prepared by quenching the melt. The ac conductivity has been measured at frequencies from 10 Hz to 100 kHz and temperatures of 300–425 K. The data indicate that the conduction mechanism changed from being predominantly electronic to ionic for Ag2 O contents of >27.5 mol%. This transition is due to the change in glass structure, which affects both electronic- and ionic-transport properties. The electronic dc conductivity results have been analyzed in terms of a small polaron-hopping model. 相似文献
14.
Ji-Guang Li Takayasu Ikegami Toshiyuki Mori Yoshiyuki Yajima 《Journal of the American Ceramic Society》2003,86(9):1493-1499
Two wet-chemical routes have been used to synthesize Sc2 O3 nanopowders from nitrate solutions employing ammonia water (AW) and ammonium hydrogen carbonate (AHC) as the precipitants. The precursors and the resultant oxides are characterized by elemental analysis, X-ray diffractometry, differential thermal analysis/thermogravimetry, high-resolution scanning electron microscopy, and Brunauer-Emmett-Teller analysis. Crystalline γ-ScOOH· n H2 O ( n ≈ 0.5) is the only phase obtained by the AW method. This phase dehydrates to Sc2 O3 at ∼400°C, yielding hard aggregated nanocrystalline Sc2 O3 powders. Three types of precursors have been synthesized by the AHC method, depending on the AHC/Sc3+ molar ratio ( R ): amorphous basic carbonate [Sc(OH)CO3 ·H2 O] at R ≤ 3, crystalline double carbonate [(NH4 )Sc(CO3 )2 ·H2 O] at R ≥ 4, and a mixture of the two phases at 3 < R < 4. Among these precursors, only the basic carbonate shows spherical particle morphology, ultrafine particle size (∼50 nm), and weak agglomeration. Sc2 O3 nanopowders (∼28 nm) with high surface area (∼49 m2 /g) have been prepared by calcining the basic carbonate at 700°C for 2 h. 相似文献
15.
Yoshihiko Takano Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》2001,84(10):2445-2447
Intermetallic CoAl powder has been prepared via self-propagating high-temperature synthesis (SHS). Dense CoAl materials (99.6% of theoretical) with the combined additions of ZrO2 (3Y) and Al2 O3 have been fabricated via spark plasma sintering (SPS) for 10 min at 1300°C and 30 MPa. The microstructures are such that tetragonal ZrO2 (0.3 μm) and Al2 O3 (0.5 μm) particles are located at the grain boundaries of the CoAl (8.5 μm) matrix. Improved mechanical properties are obtained; especially the fracture toughness and the bending strength of the materials with ZrO2 (3Y)/Al2 O3 = 16/4 mol% are 3.87 MPa·m1/2 and 1080 MPa, respectively, and high strength (>600 MPa) can be retained up to 1000°C. 相似文献
16.
Yarong Wang Toshiyuki Mori Ji-Guang Li Takayasu Ikegami 《Journal of the American Ceramic Society》2002,85(12):3105-3107
Praseodymium-doped ceria (CeO2 ) nanopowders have been synthesized via a simple but effective carbonate-coprecipitation method, using nitrates as the starting salts and ammonium carbonate as the precipitant. The precursors produced in this work are ammonium rare-earth double carbonates, with a general formula of (NH4 )0.16 Ce1− x Pr x (CO3 )1.58 ·H2 O (0 < x ≤ 0.20), which directly yield oxide solid solutions on thermal decomposition at a very low temperature of ∼400°C. Praseodymium doping causes a gradual contraction of the CeO2 lattice, because of the oxidation of Pr3+ to smaller Pr4+ , and suppresses crystallite coarsening of the oxides during calcination. Dense ceramics have been fabricated from the thus-prepared nanopowders via pressureless sintering for 4 h at a low temperature of 1200°C. 相似文献
17.
Nonradiative Energy Losses and Radiation Trapping in Neodymium-Doped Phosphate Laser Glasses 总被引:4,自引:0,他引:4
Fluorescence radiation trapping and nonradiative energy losses from the Nd3+ 4 F3/2 state are reported for two widely used commercial phosphate laser glasses (LHG-8 and LG-770). The effects of hydroxyl-group, transition-metal (Cu, Fe, V, Co, Ni, Cr, Mn, and Pt), and rare-earth (Dy, Pr, Sm, and Ce) impurities on the 4 F3/2 nonradiative decay rate in these glasses are quantified. Nd concentration quenching effects are reported for doping levels ranging from about 0.5 × 1020 to 8.0 × 1020 ions/cm3 . The results are analyzed using the Förster–Dexter theory for dipolar energy transfer. Quenching rates for transition-metal ions correlate with the magnitude of spectral overlap for Nd emission (donor) and the metal ion absorption (acceptor). The nonradiative decay rates due to hydroxyl groups follow Förster–Dexter theory except at low Nd-doping levels (≲2 × 1020 ions/cm3 ) where the quenching rate becomes independent of the Nd concentration. The data suggest a possible correlation of OH sites with Nd ions in this doping region. The effects of radiation trapping on the fluorescence decay are reported as a function of sample size, shape, and doping level. The results agree well with the theory except for samples with small doping-length products; in these cases, multiple internal reflections from the sample surfaces enhance the trapping effect. 相似文献
18.
Masaru Yamashita Hiroshi Yamanaka Ken-ichi Sasage 《Journal of the American Ceramic Society》2004,87(5):967-969
The behavior of ruthenium oxide (RuO2 ) in aluminoborosilicate glass used for the stabilization of nuclear waste was investigated. It was found that 0.025 mass% RuO2 dissolved as Ru4+ in the glass at 1400°C, which caused the glass to turn yellow. When the RuO2 amount was 0.05 mass%, needle-shaped crystals formed in the glass during slow cooling. If the added amount exceeded 0.1 mass% and the cooling rate was slow, it separated rapidly and the glass became pale after cooling. No dissolution of ruthenium was detectable after melting at 1200°C. 相似文献
19.
A single-phase material (HfMg)(WO4 )3 with an orthorhombic structure, A2 (WO4 )3 -type tungstate, has been successfully prepared for the first time by the calcination of HfO2 , MgO, and WO3 , substituting Hf4+ and Mg2+ for A3+ cations in A2 (WO4 )3 . The new material shows a negative thermal expansion coefficient of approximately −2 ppm/°C from room temperature to 800°C. The mechanism of negative thermal expansion is assumed to be the same as that of Sc2 (WO4 )3 . 相似文献
20.
JACKSON S. STROUD 《Journal of the American Ceramic Society》1971,54(8):401-406
The effect of impurities on the color of dense flint glass was investigated by comparing the optical absorption caused by cations in Na2 O·3SiO2 ·2PbO glass, in Na2 O·3SiO2 ·2PbO:1 wt% Sb2 O3 glass, and in Na2 O·3SiO2 glass; all three are colorless when of high purity. Of 11 colorants, only vanadium colored both lead glasses less intensely than the Na2 O·3SiO2 glass. Factors that make the lead glass more susceptible to coloration are higher oxidation states of polyvalent cations, larger absorption cross sections of polyvalent cations, and the tendency of prominent absorption bands to be closer to the wavelength at which eye sensitivity is a maximum. 相似文献