共查询到20条相似文献,搜索用时 62 毫秒
1.
Borik M. A. Volkova T. V. Kuritzyna I. E. Larina N. A. Lomonova E. E. Myzina V. A. Ryabochkina P. A. Tabachkova N. Yu. 《Optics and Spectroscopy》2018,125(6):898-902
Optics and Spectroscopy - The specific features of the local structure of ZrO2–Sc2O3–Y2O3 and ZrO2–Sc2O3–Yb2O3 crystals are revealed by optical spectroscopy using the Eu3+... 相似文献
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Optically clear glasses in the ZnO–Bi2O3–B2O3 (ZBBO) system were fabricated via the conventional melt-quenching technique. Dielectric constant and loss measurements carried out on ZBBO glasses unraveled nearly frequency (1 kHz–10 MHz)-independent dielectric characteristics associated with significantly low loss (D?=?0.004). However, weak temperature response was found with temperature coefficient of dielectric constant 18?±?4 ppm °C?1 in the 35–250 °C temperature range. The conduction and relaxation phenomena were rationalized using universal AC conductivity power law and modulus formalism respectively. The activation energy for relaxation determined using imaginary parts of modulus peaks was 2.54 eV which was close to that of the DC conduction implying the involvement of similar energy barriers in both the processes. Stretched and power exponents were temperature dependent. The relaxation and conduction in these glasses were attributed to the hoping and migration of Bi3+ cations in their own and different local environment. 相似文献
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Influence of different Fe2O3 content on crystallization of MgO–Al2O3–SiO2–TiO2 system glass-ceramics
The crystallization behaviors of MgO–Al2O3–SiO2–TiO2 system glasses doping with different content Fe2O3 were investigated by means of differential thermal analysis and X-ray diffraction. The kinetic parameter of activation energy for crystallization (E) was obtained by the Owaza Johnson–Mehl–Avrami method. The results show that during the heat treatment, the intermediate phase of µ-cordierite initially precipitated from the glass matrix, and with the increasing temperature, it transformed to α-cordierite. The more the Fe2O3 content, the lower the crystallization peak temperature (T p).But the lowering of T p value did not mean that the value of E decreases correspondingly. The experimental results suggest that only with appropriate content (about 4.2 wt%), Fe2O3 can promote the crystallization of this glass effectively. 相似文献
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We investigate the spectroscopic properties of the 1.5-μm emission from the 4I13/2 → 4I15/2 transition of Er3+ ions in PbO–Bi2O3–Ga2O3–GeO2 glasses for applications in broadband fiber amplifiers. The measured emission peak locates at 1,532 nm with a full width
at half-maximum of ∼45 nm. The glasses exhibit a large stimulated emission cross-section of 0.89 × 10−20 cm2 and a large product of 40.0. Infrared-to-green upconversion occurs simultaneously upon excitation of the 1.5-μm emission with a commercially
available 980 nm laser diode. The green-upconversion intensity has a quadratic dependence on incident pump laser power, indicating
a two-photon process. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of
the 2H11/2 of Er3+. The results indicate the possibility towards the development of lead–bismuth–gallate–germanate based glasses as photonics
devices. 相似文献
6.
S.Y. El-Zaiat M.B. El-Den S.U. El-Kameesy Y.A. El-Gammam 《Optics & Laser Technology》2012,44(5):1270-1276
Glasses having composition (B2O3)25 (PbO)70 (Al2O3)5 (Sm2O3)x ,where x=0, 0.5, 1, 2, 3 and 5 g were prepared using the normal melt quench technique. Spectral reflectance and transmittance at normal incidence of the glass samples are recorded with a spectrophotometer in the spectral range 220–2200 nm. These measured values are introduced into analytical expressions to calculate the real and imaginary parts of the refractive indices. Wemple–DiDomenico single oscillator model and one-term Sellmeier dispersion relations are used to model the real refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, lattice oscillating strength, average oscillator wavelength, average oscillator strength and Abbe's number are deduced and compared. Absorption dispersion parameters such as: Fermi energy, optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter are calculated. Effects of doping Sm2O3 on these linear optical parameters are investigated and interpreted. 相似文献
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High Erbium-doped glass showing the wider 1.5-μm emission band is reported in the Bi2O3–B2O3–Ga2O3 system and its thermal stability and optical properties such as absorption, emission spectra, absorption and stimulated emission cross-sections and fluorescence lifetime are investigated. Compared with other glass hosts, the gain bandwidth properties of high Er3+ content in BBG glass are better than those of tellurite, germanate, silicate and phosphate glasses. The broad and flat 4I13/2→4I15/2 emission and the larger stimulated emission cross-section of Er3+ ions around 1.5 μm enable it to be used as a host material for potential broadband optical amplifiers at C and L bands in the microchip configuration. 相似文献
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Al2O3 was added to a 2CaO–La2O3–5P2O5 metaphosphate, to replace 10% of the Ca2+ ions by Al3+, forming a phosphate with the nominal composition 1.8CaO–0.1Al2O3–La2O3–5P2O5. The effect of Al2O3 addition and heat treatment on the microstructure and conductivity of the resulting glass–ceramics was investigated by XRD, SEM, TEM, and AC impedance spectroscopy. Upon transformation from glass to glass–ceramic, conductivities increased significantly. The glasses were isochronally transformed at 700 and at 800 °C for 1 h or 5 h, in air, following heating at 3 or 10 °C/min. With Al2O3 addition, after a heat treatment at 700 °C, 100–300 nm nano-domains of LaP3O9 crystallized from the glass matrix. Annealing at 800 °C produced a further order of magnitude conductivity increase for the Al-free glass, but less so for the Al-containing glass. 相似文献
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A. Maheswaran G. Hirankumar Nithya Heller S. Karthickprabhu Junichi Kawamura 《Applied Physics A: Materials Science & Processing》2014,117(3):1323-1327
Bioactive phosphate glasses have been widely investigated for bone repair. Phosphate glass system of 47P2O5–30.5CaO–(22.5?x)Na2O–xB2O3 has been prepared by melt quenching technique. From the Raman analysis, it is confirmed that phosphate network form metaphosphate structure. Bioactivity of the glass is studied by immersing the prepared glass in simulated body fluid (SBF). All the glasses exhibited bioactivity after soaking in SBF. Addition of B2O3 to the glass by replacing the Na2O produces considerable effect on the dielectric and bioactivity of the glass. Ion dynamics are also analyzed through imaginary modulus and imaginary dielectric permittivity. 相似文献
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Bi2O3 doped 65SiO2–20Al2O3–15La2O3 (in mole%) glasses were prepared by the traditional melting–quenching method. The spectroscopic properties and mechanism of NIR broadband emission in these glasses were investigated in this work. Three excitation wavelengths of 500, 700 and 800 nm were used to test emission spectra. The emission band under 500 nm excitation can be regarded as combination of emission bands under 700 and 800 nm excitation. 2.0 mole% is found to be the optimal Bi2O3 doping level in this glass. Under 500 nm excitation its emission peak, FWHM and lifetime of emission band are 1160 nm, 300 nm and 569 μs, respectively. The longest fluorescent lifetime reaches 620 μs under 700 nm excitation. The valence state of Bi in these glasses is suggested to be lower than +3 by X-ray photoelectron spectroscopy. With the help of energy matching, we infer that both Bi0 and Bi+ centers are responsible for the NIR fluorescence of Bi2O3 doped 65SiO2–20Al2O3–15La2O3 glass. 相似文献
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N. Ch. Ramesh Babu Ch. Srinivasa Rao M. G. Brik G. Naga Raju I. V. Kityk N. Veeraiah 《Applied physics. B, Lasers and optics》2013,110(3):335-344
In this study, we have investigated the principal role of Y2O3 on the emission features of Tm3+ ion and up-conversion phenomenon in Tm3+ and Yb3+ co-doped Li2O–Y2O3–SiO2 glass system. The concentration of Y2O3 is varied from 0 to 5 mol% while that of Yb3+ and Tm3+ is fixed. When the glasses are doped with Tm3+ ions, the intense blue and red emissions were observed, whereas Yb3+ doped glasses exhibited NIR emission at about 980 nm. When the glasses are co-doped with Tm3+ and Yb3+ ions and excited at 900 nm, the blue and red emission lines were observed to be reinforced and strengthened with increase in the concentration of Y2O3. The IR emission band detected at about 1.8 μm due to 3F4 → 3H6 transition of Tm3+ ions is also observed to be strengthened due to co-doping. The reasons for enhancement in the intensity of various emission bands due to co-doping have been identified and discussed with the help of rate equations for various emission transitions. 相似文献
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Glasses xLi2O–(50-x)(MoO3)2–50P2O5 with x = 10, 20, 30, and 40 mol% were prepared and their optical and electrical properties were investigated. Analysis of the IR
spectra revealed that the Li+ ions act as a glass modifier that enter the glass network by breaking up other linkages and creating non-bridging oxygens
in the network. The optical absorption edge of the glasses was measured for specimens in the form of thin blown films and
the optical absorption spectra of those were recorded in the range 200–800 nm. From the optical absorption edges studies,
the optical band gap (E
opt) and the Urbach energy (E
e) values have been evaluated by following the available semi-empirical theories. The linear variation of (αhν)1/2 with hν, is taken as evidence of indirect interband transitions. The E
opt values were found to decrease with increasing Li2O content by causing increase in the number of non-bridging oxygens in network. The Urbach tail analysis gives the width of
localized states between 0.48 and 0.74 eV. 相似文献
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Noelio O. Dantas Valdeir A. Silva Omar. O. D. Neto Marcio L. F. Nascimento 《Brazilian Journal of Physics》2012,42(5-6):347-354
A glass matrix with nominal composition 50Li2O·45B2O3·5Al2O3 (mol%) was synthesized, and its physical properties were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and atomic force microscopy (AFM). The glass transition temperature T g, the crystallization-onset temperature T x,, the crystallization peak temperatures T c1 and T c2, and the fusion peak temperatures T m1 and T m2 were determined from at least two glass matrix phases to be approximately 382, 457, 486, 574, 761, and 787?°C, respectively, at 5?°C/min heating rate. Heat treatments at 450?°C for an increasing sequence of time intervals allowed control over the amount of crystallization. Additional information on the crystallization kinetics for the LBA glass matrix was gathered from AFM images, DTA thermograms, and XRD diffractograms. The latter technique showed that LiBO2 (ICDD-16568) and Li3AlB2O6 (ICDD-51754) phases are formed in the glass?Cceramic system. Debye?CScherrer analysis of the XRD peaks revealed a competition between the evolutions of crystal phases during heat treatment. Activation energies for crystallization, obtained from theoretical models applied to the DTA data showed that the crystallization is heterogeneous. The AFM images demonstrated that this heterogeneous crystallization starts at the surface of the LBA glass matrix and identified crystal sizes in agreement with the results of the Debye?CScherrer analysis. Our study shows that thermal and structural characterization techniques can be combined with theoretical results drawn from well-tested models to offer a unified view of crystallization in a glass?Cceramics system. 相似文献
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A. Padmanabham V. Ravi Kumar T. Satyanarayana N. Veeraiah 《Journal of Physics and Chemistry of Solids》2009,70(3-4):669-679
PbO–Sb2O3–As2O3 glasses mixed with different concentrations of MoO3 (ranging from 0 to 1.0 mol%) were crystallized. The samples were characterized by X-ray diffraction, scanning electron microscopy and differential thermal analysis techniques. The X-ray diffraction and the scanning electron microscopic studies have revealed the presence of Pb5Sb2O8, PbSb2O6, SbAsO4, Sb2MoO6, Sb4Mo10O31, As4Mo3O15, Pb5Sb4O11 crystalline phases in these samples. The differential thermal analysis indicated that the surface crystallization prevails over the bulk crystallization as the concentration of the crystallizing agent is increased. The infrared (IR) spectral studies exhibit bands due to MoO4 structural units in addition to the conventional bands due to various antimonate and arsenate structural groups. The studies on PbO–Sb2O3–As2O3: MoO3 glass-ceramics with respect to various physical properties viz., dielectric properties over a range of frequency and temperature, optical absorption, electron spin resonance (ESR) and magnetic susceptibility at room temperature have also been reported. The optical absorption, ESR and magnetic susceptibility studies indicated that the molybdenum ions exist in Mo5+ state in addition to Mo6+ state in these samples. The redox ratio found to increase as the concentration of the MoO3 is increased. The variations observed in all these properties with the concentration of the crystallizing agent have been analyzed in the light of different oxidation states and environment of molybdenum ions in the glass ceramic network. 相似文献
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《Current Applied Physics》2020,20(11):1207-1216
A series of Dy3+ doped zinc-aluminoborosilicate glasses with chemical composition 30SiO2-(30-x) B2O3–10Al2O3–15NaF–15ZnF2-xDy2O3 (x = 0, 0.5, 0.7, 1.0 and 1.5 mol %) were prepared by conventional melt-quenching method. Structural and optical properties of the glasses were analyzed through XRD, FTIR, UV–Visible–NIR and luminescence studies. Gamma radiation shielding parameters were obtained using PSD software. Nephelauxetic ratio (β) and bonding parameters (δ) calculated using absorption spectrum shows the decreasing ionic nature of the Dy ions. Judd-Oflet parameters (Ω2, Ω4 and Ω6) obtained shows the covalency and asymmetric nature of dysprosium ions. The luminescence properties shows that Dy3+ doped glasses have two strong intense emission at blue (482 nm) and yellow (575 nm) region. Branching ratio and stimulated emission cross section calculated suggests the glasses suitability to act as lasing material. CIE colour coordinates and its colour correlated temperature (CCT) for the glasses were estimated and found that these prepared glasses lie in the warm white light region. 相似文献
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The Er3+/Yb3+ co-doped TeO2–TiO2–K2O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence
of luminescence intensity on the ratio of Yb3+/Er3+ was studied, and the relationship between green upconversion luminescence intensity and Er3+ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses
either when the Yb3+/Er3+ ratio is 25/1 and Er3+ concentration is 0.1 mol%, or when the Yb3+/Er3+ ratio is 10/1 and Er3+ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers. 相似文献
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Glasses in the 90Bi2O3–(10?x)Er2O3?xPbO (x = 3, 5, 7, 9 and 10 mol%) system have been prepared by the melt-quenching technique. Elastic properties and FT-IR spectroscopic studies have been employed to study the role of PbO in the structure of the investigated system. Elastic properties and Debye temperature were recorded using sound wave velocity measurements at 4 MHz at room temperature. The results showed that density increased and molar volume decreased, while both sound velocities increased with an increase in x. Infrared spectra of the glasses revealed that the bismuthate network is affected by an increase in PbO content. The results are interpreted in terms of the conversion of [BiO6] into [BiO3] structural units, indicating that Pb ions have been substituted for erbium ions as tetrahedral network formers. The elastic moduli increased with increasing PbO content due to the increased average bond strength and degree of connectivity, as a direct effect of the increase in [BiO3] structural units. 相似文献