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1.
Xian Feng Setsuhisa Tanabe Teiichi Hanada 《Journal of the American Ceramic Society》2001,84(1):165-171
The thermal stability and spectroscopic properties of Er2 O3 -doped TeO2 –GeO2 –ZnO–Na2 O–Y2 O3 glasses for 1.5 μm fiber amplifiers were investigated. The thermal stability of the 75TeO2 ·20ZnO· 5Na2 O glass was improved by introducing GeO2 and Y2 O3 . The radiative transition and the nonradiative transition have a dominant influence on the 4 I13/2 level lifetime of Er3+ in high- and low-GeO2 regions, respectively. Adding Y2 O3 increases the 4 I13/2 level lifetime of Er3+ significantly. The Judd–Ofelt (J-O) parameter Ω6 shows a strong correlation with the 1.5 μm emission bandwidth; and the larger the Ω6 , the wider the bandwidth. 相似文献
2.
The Rayleigh scattering of the mixed-alkali glass system K2 O–Na2 O–MgO–SiO2 (KNMS) was investigated, both experimentally and theoretically. The lowest Rayleigh scattering coefficient (38% of that for pure SiO2 glass) was obtained when the glass composition was 22K2 O–8Na2 O–10MgO–60SiO2 (in mol%). These values are equal to or less than the minimum values reported for the ternary sodium silicate glass Na2 O–MgO–SiO2 . The Rayleigh scattering caused by concentration fluctuation was believed to have been reduced greatly in this KNMS glass, because the mobility of the alkali-metal ions was reduced by the mixed-alkali effect. 相似文献
3.
Noriyuki Wada Takashi Tsuneoka Kazuo Kojima 《Journal of the American Ceramic Society》2002,85(6):1396-1402
Chloride glasses of the ZnCl2 and 20KCl-20BaCl2 -60ZnCl2 -0.5ErCl3 systems were prepared using NH4 Cl as a dehydrating and chlorinating agent, under the melt-quenching method. Water- and ammonium-chloride-related residues in ZnCl2 glasses were investigated by infrared and near-infrared absorption spectra. Water, Zn—OH, ClO, ClO2 − , Zn2+ -coordinated water, free NH3 , NH4 + , and Zn2+ -coordinated NH3 were identified in ZnCl2 glasses. 20KCl-20BaCl2 -60ZnCl2 -0.5ErCl3 glasses prepared by melting at 500°C for 20 min, under reduced pressure, contained the smallest amounts of water, Zn—OH, and Zn2+ -coordinated NH3 and showed strong Er3+ upconversion fluorescence. 相似文献
4.
Maria Teresa Buscaglia Massimo Viviani Vincenzo Buscaglia Carlo Bottino Paolo Nanni 《Journal of the American Ceramic Society》2002,85(6):1569-1575
The incorporation of Er3+ into BaTiO3 ceramics was investigated on samples containing 0.25, 0.5, 1, 2, 8, and 10 at.% of dopant, after sintering at 1350–1550°C in air. For Er3+ concentrations ≤1 at.%, dense and large-grained ceramics with low room-temperature resistivity (102 –103 Ω·cm) were obtained. The observed properties are largely independent of stoichiometry. Simultaneous substitution of Er3+ at both cation sites, with higher preference for the Ba site, is proposed. The behavior of heavily doped ceramics depends on stoichiometry. When Ba/Ti < 1, the electrical properties change from slightly semiconducting to insulating as Er concentration increases from 2 to 8 at.%. The ceramics have tetragonal perovskite structure and contain a large amount of Er2 Ti2 O7 pyrochlore phase. On the other hand, when Ba/Ti > 1, the ceramics are insulating, fine-grained, and single phase. In this case, incorporation of Er3+ predominantly occurs at the Ti site, with oxygen vacancy compensation. Incorporation is accompanied by a significant reduction of tetragonality and by expansion of the unit cell. The different results indicate that Er3+ solubility at the Ba site does not exceed 1 at.%, whereas solubility at the Ti site is at least 10 at.%. However, the incorporation of Er3+ and the resulting properties are also strongly affected by sintering conditions. 相似文献
5.
Yong Su Lee Won Ho Kang Byeoung Il Kim Sun Dal Song 《Journal of the American Ceramic Society》2001,84(10):2433-2435
A 355-nm neodymium:yttrium aluminum garnet laser, produced by a harmonic generator, was used for the nucleation process in photosensitive glass containing Ag+ and Ce3+ ions. The pulse width and frequency of the laser were 8 ns and 10 Hz, respectively. Heat treatment was conducted at 570°C for 1 h, following laser irradiation, to produce crystalline growth, after which a LiAlSi3 O8 crystal phase appeared in the laser-irradiated Li2 O–Al2 O3 –SiO2 glass. The present study compares the effect of laser-induced nucleation on glass crystallization with that of spontaneous nucleation by heat treatment. 相似文献
6.
Riham Michelle Morcos Jean Tangeman Sergey Ushakov Alexandra Navrotsky 《Journal of the American Ceramic Society》2008,91(4):1088-1094
A series of La2 O3 –HfO2 –SiO2 glasses, approximately along the join 0.73SiO2 –0.27( x HfO2 –(1− x )La2 O3 ), 0< x <0.3), was prepared using containerless processing techniques (aerodynamic levitation combined with laser heating in oxygen). The enthalpy of formation and enthalpy of vitrification at 25°C were obtained from drop solution calorimetry of these glasses and appropriate crystalline compounds in a molten lead borate (2PbO–B2 O3 ) solvent at 702°C. The enthalpy of formation from crystalline oxides was exothermic and became less exothermic with increasing HfO2 content. Heat contents were measured by transposed temperature drop calorimetry and depended linearly on the HfO2 content. Differential scanning calorimetry showed that both the onset glass transition and the onset crystallization temperature of these glasses increased with increasing HfO2 content. Upon slow cooling in air, the glasses crystallized to a mixture of baddeleyite, cristobalite, lanthanum disilicate, and hafnon. 相似文献
7.
The effect of niobia on the dielectric properties of glasses in the system Nb2 O5 –Na2 O–SiO2 has been studied from 100 to 1010 cps. The dielectric constant is high even at frequencies up to 1010 cps. The Nb5+ ion, with its small ionic radius and high charge, reinforces the network and raises the dielectric constant. 相似文献
8.
Wioletta Kuncewicz-Kupczyk Dietmar Kobertz Miroslaw Miller Christian Chatillon Lorenz Singheiser Klaus Hilpert 《Journal of the American Ceramic Society》2002,85(9):2299-2305
The vaporization of the samples of the compositions Ga2 O3 + LaGaO3 , LaGaO3 + La4 Ga2 O9 , and La4 Ga2 O9 + La2 O3 was investigated using Knudsen effusion mass spectrometry in the temperature range 1494–1937 K. The partial pressures of the gaseous species O2 , Ga, GaO, Ga2 O, and LaO were determined over the samples investigated. The equilibrium partial pressures were used for the calculation of the thermodynamic activities of the components at 1700 K. Gibbs energies of formation of LaGaO3 ( s ) and La4 Ga2 O9 ( s ) at 1700 K from the component oxides were derived from the thermodynamic activities as −46.4 ± 4.7 and −99.2 ± 7.9 kJ·mol−1 , respectively. The results were compared with the literature data obtained using other methods. 相似文献
9.
Cristina Siligardi Luca Lusvarghi Monia Montorsi Cecilia Vernia 《Journal of the American Ceramic Society》2008,91(3):990-995
In this work several complementary techniques have been employed to carefully characterize the sintering and crystallization behavior of CaO–Al2 O3 –ZrO2 –SiO2 glass powder compacts after different heat treatments. The research started from a new base glass 33.69 CaO–1.00 Al2 O3 –7.68 ZrO2 –55.43SiO2 (mol%) to which 5 and 10 mol% Al2 O3 were added. The glasses with higher amounts of alumina sintered at higher temperatures (953°C [lower amount] vs. 987°C [higher amount]). A combination of the linear shrinkage and viscosity data allowed to easily find the viscosity values corresponding to the beginning and the end of the sintering process. Anorthite and wollastonite crystals formed in the sintered samples, especially at lower temperatures. At higher temperatures, a new crystalline phase containing ZrO2 (2CaO·4SiO2 ·ZrO2 ) appeared in all studied specimens. 相似文献
10.
Ana M. Espino Luis A. Díaz Adolfo Fernández Ramón Torrecillas José S. Moya 《Journal of the American Ceramic Society》2005,88(4):1000-1003
The wettability of binary and ternary glasses belonging to SiO2 –Al2 O3 –ZrO2 diagram has been studied using the sessile drop technique at 1750° and 1800°C. The ternary SiO2 –Al2 O3 –ZrO2 (90–5–5 wt%) glass has proved to be well appropriated as a molybdenum oxidation barrier coating. The addition of 5 wt% of MoO2 slightly improves its wettablity at higher temperatures without affecting its oxidation barrier properties. The Mo comes into the glass network as a mixture of Mo5+ , Mo4+ , and Mo6+ . After oxidation at 1000°C in oxygen atmosphere, the molybdenum remains in the glass network as Mo6+ . 相似文献
11.
Matthew J. Dejneka Benjamin Z. Hanson Steve G. Crigler Luis A. Zenteno John D. Minelly Douglas C. Allan William J. Miller Dmitri Kuksenkov 《Journal of the American Ceramic Society》2002,85(5):1100-1106
Single-mode semiconductor pumps have failed to keep pace with the increasing power requirements of Er-doped fiber amplifiers (EDFAs), so there is a need for high-powered 980-nm sources. Yb3+ -doped tapered fiber lasers can provide high-power output by conversion of a low-brightness, high-powered, 920-nm, multimode broad stripe laser diode to a high-brightness, 980-nm, single-mode output. The tapered fiber laser requires a fiber with high numerical aperture (NA) (>0.4), a rectangular core, and good Yb3+ spectroscopy for efficient operation. CVD-based fiber fabrication methods are incapable of delivering fibers with an NA > ∼0.3 or with good efficiency at 980 nm so a new method of high-NA fiber fabrication was developed. The core glass composition is critical for maintaining a high-NA fiber with good power extraction while avoiding phase separation, loss, and clustering. The SiO2 level controlled the NA and interdiffusion between core and clad, while the Al2 O3 /La2 O3 ratio controlled phase separation. A La2 O3 -Al2 O3 -SiO2 glass was developed that is compatible with a pure SiO2 cladding glass and has a laser slope efficiency of 70% at 980 nm. The optimized fiber composition yielded 450 mW of 980-nm power in a single-mode fiber. 相似文献
12.
The compositional range for glass formation below 1600°C in the Sm2 O3 ─Al2 O3 ─SiO2 system is (9–25)Sm2 O3 ─(10–35)Al2 O3 ─(40–75)SiO2 (mol%). Selected properties of the Sm2 O3 ─Al2 O3 ─SiO2 (SmAS) glasses were evaluated as a function of composition. The density, refractive index, microhardness, and thermal expansion coefficient increased as the Sm2 O3 content increased from 9 to 25 mol%, the values exceeding those for fused silica. The dissolution rate in 1 N HCl and in deionized water increased with increasing Sm2 O3 content and with increasing temperature to 70°C. The transformation temperature ( T g ) and dilatometric softening temperature ( T d ) of the SmAS glasses exceeded 800° and 850°C, respectively. 相似文献
13.
Daniel Caurant Odile Majérus Edward Fadel Marion Lenoir Christel Gervais Olivier Pinet 《Journal of the American Ceramic Society》2007,90(3):774-783
Crystallization of the poorly durable Na2 MoO4 phase able to incorporate radioactive cesium must be avoided in SiO2 –Al2 O3 –B2 O3 –Na2 O–CaO glasses developed for the immobilization of Mo-rich nuclear wastes. Increasing amounts of B2 O3 and MoO3 were added to a SiO2 –Na2 O–CaO glass, and crystallization tendency was studied. Na2 MoO4 crystallization tendency decreased with the increase of B2 O3 concentration whereas the tendency of CaMoO4 to crystallize increased due to preferential charge compensation of BO4 − entities by Na+ ions. 29 Si MAS NMR showed that molybdenum acts as a reticulating agent in glass structure. Trivalent actinides surrogate (Nd3+ ) were shown to enter into CaMoO4 crystals formed in glasses. 相似文献
14.
Luisa Barbieri Anna Maria Ferrari Isabella Lancellotti Cristina Leonelli Jesus Maria Rincòn Maximina Romero 《Journal of the American Ceramic Society》2000,83(10):2515-2520
Aluminosilicate and silicate glass-ceramics were obtained from controlled devitrification of CaO–Al2 O3 –SiO2 glassy systems starting from Spanish and Italian coal fly ash or Italian municipal incinerator slag mixed with other byproducts, such as glass cullet and dolomite. The nucleation mechanism and the crystallization kinetics were investigated by thermal, diffractometric, and microstructural measurements. Moreover, the experimentally observed devitrification and the identification of the crystalline phases formed were compared with the indications derived from Ginsberg, Raschin-Tschetveritkov, and Lebedeva diagrams used for petrological glass-ceramics. All the glasses showed a good crystallization tendency with the formation of dendritic pyroxene and acicular wollastonite together with feldspar and iron spinels starting from the surface. The activation energy values for crystallization ranging from 472 to 832 kJ ·mol−1 were found to be close to those typical for aluminosilicate glasses; moreover, the possibility to vitrify and devitrify up to 100 wt% of slag and up to 40–50 wt% of ash mixed with glass cullet and dolomite makes the vitrification treatment a suitable disposal procedure. 相似文献
15.
Masayuki Nogami Yoichi Goto Toshihiro Kasuga 《Journal of the American Ceramic Society》2003,86(9):1504-1507
The effect of zirconium ions on glass structure and proton conductivity was investigated for sol-gel-derived P2 O5 –SiO2 glasses. Porous glasses were prepared through hydrolysis of PO(OCH3 )3 , Zr(OC4 H9 )4 , and Si(OC2 H5 )4 . Chemical bonding of the P5+ ions was characterized using 31 P-NMR spectra. The phosphorous ions, occurring as PO(OH)3 in the ZrO2 -free glass, were polymerized with one or two bridging oxygen ions per PO4 unit with increased ZrO2 content. The chemical stability of these glasses was increased significantly on the addition of ZrO2 , but the conductivity gradually decreased from 26 to 12 mS/cm at room temperature for 10P2 O5 ·7ZrO2 ·83SiO2 glass. A fuel cell was constructed using 10P2 O5 ·5ZrO2 ·85SiO2 glass as the electrolyte; a power of ∼4.5 mW/cm2 was attained. 相似文献
16.
Mark I. Pownceby Keri K. Constanti-Carey Michael J. Fisher-White 《Journal of the American Ceramic Society》2003,86(6):975-980
Subsolidus phase equilibria in the system Fe2 O3 –Al2 O3 –TiO2 were investigated between 1000° and 1300°C. Quenched samples were examined using powder X-ray diffraction and electron probe microanalytical methods. The main features of the phase relations were: (a) the presence of an M3 O5 solid solution series between end members Fe2 TiO5 and Al2 TiO5 , (b) a miscibility gap along the Fe2 O3 –Al2 O3 binary, (c) an α-M2 O3 ( ss ) ternary solid-solution region based on mutual solubility between Fe2 O3 , Al2 O3 , and TiO2 , and (d) an extensive three-phase region characterized by the assemblage M3 O5 +α-M2 O3 ( ss ) + Cor( ss ). A comparison of results with previously established phase relations for the Fe2 O3 –Al2 O3 –TiO2 system shows considerable discrepancy. 相似文献
17.
Chii-Shyang Hwang Shi-Dong Ji Sin-Lung Lin 《Journal of the American Ceramic Society》1996,79(8):2212-2214
Properties of 15–30 mol% CeO2 /23 mol% Al2 O3 /62–47 mol% SiO2 glasses prepared in air have been investigated in this study. Experimental results show that the glass transformation temperature, the dilatometric softening temperature, and the transmittance in the visible region decrease with increasing ceria content; but the thermal expansion coefficient, the bulk density, and the microhardness increase with increasing ceria content. 相似文献
18.
Peter Majewski Lars Epple Fritz Aldinger 《Journal of the American Ceramic Society》2000,83(6):1513-1517
The phase equilibria of the La2 O3 –SrO–CaO–Mn3 O4 system in air at 1200°C has been studied. Under these conditions, eight univariant four-phase equilbria were observed. Quaternary phases, as well as liquid phases, were not observed. Perovskite-structure phases LaMnO3 , SrMnO3 , and CaMnO3 did not form complete solid solutions within the system. 相似文献
19.
Sander Arnout Dirk Durinck Muxing Guo Bart Blanpain Patrick Wollants 《Journal of the American Ceramic Society》2008,91(4):1237-1243
In this work, the liquidus of synthetic CaO–SiO2 –MgO–Al2 O3 –CrO x slags is evaluated in the industrially relevant compositional domain. Equilibrium experiments are carried out at 1500°C and partial oxygen pressure ( p O2 ) 10−11.04 atm, and at 1600°C and p O2 =10−10.16 and 10−9.36 atm. The studied basicities (CaO/SiO2 ) are 1.2 and 0.5. Al2 O3 levels range from 0 to 30 wt%. Oversaturated liquid is sampled and phase relations are measured with quantitative electron probe microanalysis–wavelength dispersive spectroscopy (EPMA–WDS). The results are compared with the commercially available FactSage thermodynamic databases. Qualitative agreement is always obtained. Also a good quantitative agreement is found at the higher basicity, especially for the spinel liquidus. A minor but systematic deviation can be observed for the eskolaite liquidus. At the lower basicity, the calculated phase diagram deviates strongly from the experimental results, probably due to missing ternary interactions in the database. 相似文献
20.
Yaping Zhang Yunxia Yang Yuwen Ou Wei Hua Jiahua Zheng Guorong Chen 《Journal of the American Ceramic Society》2009,92(8):1881-1883
Glasses with compositions 50Bi2 O3 – x Sb2 O3 –10B2 O3 –(40– x ) SiO2 ( x =0, 1, 3, 5, 8, 10) have been prepared by conventional melt quench technique. Substitution of Sb2 O3 for SiO2 exerted an obvious effect on properties of glasses, especially, increased glass transition temperature ( T g ) and crystalline temperature ( T c ) greatly. Results of infrared transmission spectra attributed the effect to the formation of new bridging bonds of Sb–O–B and Sb–O–Si in glass network. 相似文献