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Sanghi S Pal I Agarwal A Aggarwal MP 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,83(1):94-99
Glasses with composition 20CdO·xBi(2)O(3)·(79.5-x)B(2)O(3) (15≤x≤35, x in mol%) containing 0.5 mol% of Er(3+) ions were prepared by melt-quench technique (1150°C in air). The amorphous nature of the glasses was confirmed by X-ray diffraction. The spectroscopic properties of the glasses were investigated using optical absorption spectra and fluorescence spectra. The phenomenological Judd-Ofelt intensity parameters Ω(λ) (λ=2, 4, 6) were determined from the spectral intensities of absorption bands in order to calculate the radiative transition probability (A(R)), radiative life time (τ(R)), branching ratios (β(R)) for various excited luminescent states. Using the near infrared emission spectra, full width at half maxima (FWHM), stimulated emission cross-section (σ(e)) and figure of merit (FOM) were evaluated and compared with other hosts. Especially, the numerical values of these parameters indicate that the emission transition (4)I(13/2)→(4)I(15/2) at 1.506 μm in Er(3+)-doped cadmium bismuth borate glasses may be useful in optical communication. 相似文献
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Gowtham S Deshpande M Costales A Pandey R 《The journal of physical chemistry. B》2005,109(31):14836-14844
The results of density functional theory based calculations on Ga3O, Ga3O2, Ga3O3, Ga2O3, and GaO3 clusters are reported here. A preference for planar arrangement of the constituent atoms maximizing the ionic interactions is found in the ground state of the clusters considered. The sequential oxidation of the metal-excess clusters increases the binding energy, but the sequential removal of a metal atom from the oxygen-excess clusters decreases the binding energy. The increase in the oxygen to metal ratio in these clusters is accompanied by increase in both electron affinity and ionization potential. The ionization induced structural distortions in the neutral clusters are relatively small, except those for Ga3O2. In anionic (cationic) clusters, the added (ionized) electron is shared by the Ga atoms, except in the case of GaO3. The vibrational frequencies and charge density analysis reveal the importance of the ionic Ga-O bond in stabilizing the gallium oxide clusters considered in this study. 相似文献
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The adsorption of CO(2) over a set of gallium (III) oxide polymorphs with different crystallographic phases (alpha, beta, and gamma) and surface areas (12-105 m(2) g(-1)) was studied by in situ infrared spectroscopy. On the bare surface of the activated gallias (i.e., partially dehydroxylated under O(2) and D(2) (H(2)) at 723 K), several IR signals of the O-D (O-H) stretching mode were assigned to mono-, di- and tricoordinated OD (OH) groups bonded to gallium cations in tetrahedral and/or octahedral positions. After exposing the surface of the polymorphs to CO(2) at 323 K, a variety of (bi)carbonate species emerged. The more basic hydroxyl groups were able to react with CO(2), to yield two types of bicarbonate species: mono- (m-) and bidentate (b-) [nu(as)(CO(3)) = 1630 cm(-1); nu(s)(CO(3)) = 1431 or 1455 cm(-1) (for m- or b-); delta(OH) = 1225 cm(-1)]. Together with the bicarbonate groups, IR bands assigned to carboxylate [nu(as)(CO(2)) = 1750 cm(-1); nu(s)(CO(2)) = 1170 cm(-1)], bridge carbonate [nu(as)(CO(3)) = 1680 cm(-1); nu(s)(CO(3)) = 1280 cm(-1)], bidentate carbonate [nu(as)(CO(3)) = 1587 cm(-1); nu(s)(CO(3)) = 1325 cm(-1)], and polydentate carbonate [nu(as)(CO(3)) = 1460 cm(-1); nu(s)(CO(3)) = 1406 cm(-1)] species developed, up to approximately 600 Torr of CO(2). However, only the bi- and polydentate carbonate groups still remained on the surface upon outgassing the samples at 323 K. The total amount of adsorbed CO(2), measured by volumetric adsorption (323 K), was approximately 2.0 micromol m(-2) over any of the polymorphs, congruent with an integrated absorbance of (bi)carbonate species proportional to the surface area of the materials. Upon heating under flowing CO(2) (760 Torr), most of the (bi)carbonate species vanished a T > 550 K, but polydentate groups remained on the surface up to the highest temperature used (723 K). A thorough discussion of the more probable surface sites involved in the adsorption of CO(2) is made. 相似文献
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Nie QH Gao Y Xu TF Shen X 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(8):1939-1943
The new Er3+/Yb3+ co-doped 70TeO2-5Li2O-(25-x)B2O3-xGeO2 (x = 0, 5, 10, 15 fand 20 mol.%) glasses were prepared. The thermal stability, absorption spectra, emission spectra and lifetime of the 4I(13/2) level of Er3+ ions were measured and studied. The FT-IR spectra were carried out in order to investigate the structure of local arrangements in glasses. It is found that the thermal stability, absorption cross-section of Yb3+, emission intensity and lifetime of the 4I(13/2) level of Er3+ increase with increasing GeO2 content in the glass composition, while the fluorescence width at half maximum (FWHM) at 1.5 um of Er3+ is about 70 nm. The obtained data suggest that this system glass can be used as a candidate host material for potential broadband optical amplifiers. 相似文献
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Huang Y Yue S Wang Z Wang Q Shi C Xu Z Bai XD Tang C Gu C 《The journal of physical chemistry. B》2006,110(2):796-800
Uniform and well-crystallized beta-Ga2O3 nanowires are prepared by reacting metal Ga with water vapor based on the vapor-liquid-solid (VLS) mechanism. Electron microscopy studies show that the nanowires have diameters ranging from 10 to 40 nm and lengths up to tens of micrometers. The contact properties of individual Ga2O3 nanowires with Pt or Au/Ti electrodes are studied, respectively, finding that Pt can form Schottky-barrier junctions and Au/Ti is advantageous to fabricate ohmic contacts with individual Ga2O3 nanowires. In ambient air, the conductivity of the Ga2O3 nanowires is about 1 (Omega.m)-1, while with adsorption of NH3 (or NO2) molecules, the conductivity can increase (or decrease) dramatically at room temperature. The as-grown Ga2O3 nanowires have the properties of an n-type semiconductor. 相似文献
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Goj Paweł Ciecińska Małgorzata Szumera Magdalena Stoch Paweł 《Journal of Thermal Analysis and Calorimetry》2020,142(1):203-209
Journal of Thermal Analysis and Calorimetry - Iron phosphate glasses are materials that can have many applications like durable matrixes in waste immobilization techniques, biomaterials,... 相似文献
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Several Ti-incorporated Ga-oxide (Ga2O3) thin films with different amounts of Ti contents have been prepared by vacuum evaporation method on glass and silicon substrates. The Ti incorporation level was measured with energy dispersion X-ray spectroscopy (EDX) method. The crystalline structure of the prepared films was determined with X-ray diffraction method. Experimental data indicate that Ti4+ ions doped in host Ga2O3 form solid solutions (SS) even with so large Ti% content ∼10.4% wt. All the prepared solid solutions have the known orthorhombic (ɛ-phase) phase of Ga2O3. The doping controls the optical and electrical properties of the host Ga2O3. It was found that the bandgap of the prepared undoped Ga oxide is 5.23 eV, which was decreased monotonically with increasing of Ti doping level so that it is possible to engineer the bandgap. Furthermore, the electrical measurements show that with Ti doping, it is possible to turn the high-k Ga oxide into low-k dielectric material. The optical sensitivity of the capacitance, dissipation factor, and ac-conductance of the Ga2O3:Ti films grown on Si was studied as a function of Ti-doping level. It was observed that the prepared Ga2O3:Ti film with 6–10% doping level has the highest photosensitivity among the other samples. 相似文献
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Chao-Nan Wang Yong Li Wei-Ping Zhang Min Yin 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):8-13
Y2O3:Eu3+ nano-powders were synthesized by homogeneous precipitation and the influence of solution acidity was investigated. IR and TG–DTA analysis showed that in different acidic solutions different kinds of sediments were generated. TEM images revealed distinct morphologies of obtained powders. The resultant powders were sintered into ceramics in vacuum and then in N2 atmosphere without any additives. SEM images indicated that the morphologies of powders have significant impact on the microstructures of sintering-derived ceramics. Low-agglomerated and uniform powders were in favor of production of ceramics with homogeneous microstructures. Excitation and emission spectra of both powders and ceramics were measured and some changes were observed. 相似文献
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Shen X Nie Q Xu T Dai S Wang X 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(2):389-393
The B2O3 was introduced into the Er3+ doped TeO2-ZnO-Na2O glass to increase the phonon energy of the host. The effect of B2O3 on the non-radiative rate of the 4I11/2-->4I13/2 transition of Er3+, the lifetime of the 4I11/2 and 4I13/2 levels, the green and red upconversion emissions intensity, and the 4I13/2-->4I15/2 emission intensity was discussed. The results show that the phonon energy of boro-tellurite glass is close to that of germanate glass and is quite smaller than that of borate glass. The lifetime of 4I11/2 level and the upconversion emissions decrease with increasing B2O3 concentration. The higher OH group concentration presented in the boro-tellurite glass may shorten the lifetime of 4I13/2 level and also reduce the quantum efficiency of 4I13/2-->4I15/2 emission. The future dehydrating procedures are suggested to enhance the efficiency of amplification at 1.5 microm band. 相似文献
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《Radiation Physics and Chemistry》2006,75(9):959-966
Optical and structural properties of xPbO·2xBi2O3(1−3x)B2O3 glasses of different composition have been studied using UV-VIS and FTIR spectroscopic techniques. Effects of gamma radiations on glass network and structural units have been studied by irradiating glass samples with a 60Co radioisotope to the overall dose of 2.5 kGy. It is shown that irradiation causes compaction of the borate network by breaking the bonds between trigonal elements, which leads to a decrease in the optical band gap energy. Changes in the atomic structure before and after the irradiation are observed and explained. 相似文献
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Qian Q Zhao C Yang GF Yang ZM Zhang QY Jiang ZH 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):280-285
This paper reports on the optical spectroscopic properties and thermal stability of Er(3+)-doped antimony-borosilicate glasses for developing 1.5mum optical amplifiers. Upon excitation at 980nm laser diode, an intense 1.5mum infrared fluorescence has been observed with the maximum full width at half maximum (FWHM) of 90nm for Er(3+)-doped antimony-borosilicate glasses. The emission cross-section and the lifetime of the (4)I(13/2) level of Er(3+) ions are 6.3x10(-21)cm(2) and 0.30ms, respectively. It is noted that the product of the emission cross-section and FWHM of the glass studied is as great as 567x10(-21)cm(2)nm, which is comparable or higher than that of bismuthate and tellurite glasses. 相似文献
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We report on the realization of novel 3-D hierarchical heterostructures with 6-and 4-fold symmetries by a transport and condensation technique. It was found that the major core nanowires or nanobelts are single-crystalline In2O3, and the secondary nanorods are single-crystalline monoclinic beta-Ga2O3 and grow either perpendicular on or slanted to all the facets of the core In2O3 nanobelts. Depending on the diameter of the core In2O3 nanostructures, the secondary Ga2O3 nanorods grow either as a single row or multiple rows. The one-step growth of the unique Ga2O3/In2O3 heteronanostructures is a spontaneous and self-organized process. The simultaneous control of nanocrystal size and shape together with the possibility of growing heterostructures on certain nanocrystal facets opens up novel routes to the synthesis of more sophisticated heterostructures as building blocks for opto- and nanoelectronics. 相似文献
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Iordanova R. Lefterova E. Uzunov I. Dimitriev Y. Klissurski D. 《Journal of Thermal Analysis and Calorimetry》2002,70(2):393-404
Characteristic temperatures, such as T
g (glass transition), T
x (crystallization temperature) and T
l (liquidus temperature) of glasses from the V2O5-MoO3-Bi2O3 system were determined by means of differential thermal analysis (DTA). The higher content of MoO3 improved the thermal stability of the glasses as well as the glass forming ability. The non-isothermal crystallization was
investigated and following energies of the crystal growth were obtained: glass #1 (80V2O5·20Bi2O3) E
G=280 kJ mol-1, glass #2 (40V2O5·30MoO3·30Bi2O3) E
G=422 kJ mol-1 and glass #3 (80MoO3·10V2O5·10Bi2O3) E
G=305 kJ mol-1. The crystallization mechanism of glass #1 (n=3) is bulk, of glass #3 (n=1) is surface. Bulk and surface crystallization was supposed in glass #2. The presence of high content of a vanadium oxide
acts as a nucleation agent and facilitates bulk crystallization.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Guo H Tao H Zhai Y Mao S Zhao X 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(5):1351-1356
The structures of pseudo-binary GeS2-PbI2, Ga2S3(GaS)-PbI2 and pseudo-ternary GeS2-Ga2S3-PbI2 chalcohalide systems were investigated by Raman scattering spectroscopy. By evolving the vibrational bands as a function of PbI2 content, it was verified that the effect of addition of PbI2 to the glass network is threefold, namely: (i) the conversion of GeS4 tetrahedra to GeS3I and GeS2I2 structural units, (ii) the destruction of ethane-like S3Ga(Ge)-(Ge)GaS3 structural units and formation of GaS3I and GeS3I ones and (iii) formation of short S-S chains and [PbIn] structural units when the concentration of PbI2 is high. 相似文献
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Glasses with composition 15Li(2)O-15K(2)O-xBi(2)O(3)-(65 - x)-B(2)O(3)/5V(2)O(5) (3 ≤ x ≤ 15) have been prepared by the conventional melt quench technique. The electron paramagnetic resonance spectra of VO(2+) in these glasses have been recorded in the X-band frequency (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters and covalency rates were evaluated. It was found that the V(4+) ions exist as vanadyl (VO(2+)) ions and are in an octahedral coordination with a tetragonal compression. The covalency rates (1 - α(2)) and (1 - γ(2)) indicate moderate covalency for the σ- and π-bonds. It was observed that the spin-Hamiltonian parameters depend slightly on the relative concentration of Bi(2)O(3). The optical properties of this glass system are studied from the optical absorption spectra recorded in the wavelength range 200-800 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap for indirect allowed transitions have been determined using available theories. The direct current electrical conductivity, σ, has been measured in the temperature range 373-573 K. The conductivity decreases with the increase in Bi(2)O(3) concentration. This has been discussed in terms of the decrease in the number of mobile ions and their mobility. An attempt is made to correlate the EPR, optical, and electrical results and to find the effect of Bi(2)O(3) content on these parameters. 相似文献