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1.
The present paper reports the influence of silver oxide addition on the local structure of 2P2O5 · CaO · 0.05ZnO glass matrix. The glass samples were investigated through several methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), infrared absorption (FT-IR) and Raman scattering. The X-ray diffraction patterns confirm the vitreous character of these samples over the explored compositional range and the SEM pictures confirm this information. The phosphate structural units of the network former are assessed from FT-IR and Raman spectra as ultra-, meta-, pyro- and orthophosphate units. A slight structural depolymerization process of these phosphate-based glasses was evidenced for higher silver oxide content. In vitro behavior of the bulk glass sample with the highest silver oxide content was tested by immersion in simulated body fluid (SBF). X-ray diffraction and SEM measurements made on the SBF treated sample revealed growth of a crystalline phase on the surface sample. 相似文献
2.
CuBr nanocrystallite-dispersed glasses were prepared by incorporation of copper into bromide ion-containing borosilicate glass using the technique of copper staining. The copper ion incorporation process was mainly controlled by ionic diffusion from the surface to the interior of the glass. The depth profiles of Cu and CuBr concentration were examined by energy dispersive X-ray analysis and by reference to the change in absorption intensity assigned to the CuBr exciton band along the depth. While the Cu concentration was found to decrease monotonically, the CuBr concentration profile showed a maximum at a distance of 10-50 μm from the glass surface. Although the depth reached by the copper ions became greater with increasing heat-treatment time, the depth at which CuBr was precipitated was found to be saturated. This means that regions were found in the glasses in which no CuBr crystallites precipitated, although migration of Cu ions to these regions had taken place. 相似文献
3.
Glasses of the system: xBi2O3-(100−x)B2O3 (x = 20 to 66 mol%) were prepared and characterized by density, DSC, UV-visible absorption and 11B MAS-NMR spectroscopy. Glass molar volume increases while the glass transition temperature decreases with Bi2O3 concentration. Densities of some bismuth borate glasses are found to be greater or very close to those of single crystal phases with equal composition. B11 MAS-NMR studies determined that the fraction of tetrahedrally coordinated borons (N4) is maximum at 42 mol% of Bi2O3 and that there is a local maxima in N4 at Bi2O3 concentration of 50 mol%. Glasses containing Bi2O3 concentration of 33 mol% and higher show an unusual, intense absorption band just below the optical band gap. Two crystalline phases: Bi3B5O12 and Bi4B2O9 were prepared by devitrification of glasses and characterized by X-ray diffraction, FTIR and 11B MAS-NMR studies. Both crystalline phases contained significantly lower N4 than glasses with equal composition. 相似文献
4.
Robert Carl 《Journal of Non》2007,353(3):244-249
Glasses with the compositions xNa2O · 10MgO · (90 − x)SiO2, 10Na2O · xMgO · (90 − x)SiO2, 5Na2O · 15MgO · xAl2O3 · (80 − x)SiO2, xNa2O · 10MgO · 10Al2O3 · (80 − x)SiO2, 10Na2O · 10MgO · xAl2O3 · (80 − x)SiO2, 10Na2O · 5MgO · 10Al2O3 · (80 − x)SiO2 were melted and studied using UV-vis-NIR spectroscopy in the wavenumber range from 5000 to 30 000 cm−1. At [Al2O3] > [Na2O], the UV-cut off is strongly shifted to smaller wavenumbers and the NIR peak at around 10 000 cm−1 attributed to Fe2+ in sixfold coordination gets narrower. Furthermore, the intensity of the NIR peak at 5500 cm−1 increases. This is explained by the incorporation of iron in the respective glass structures. 相似文献
5.
Sintering of a ZnS–SnO2 mixture under argon flow leads to the growth of columnar nanoplate arrays as well as arrays of nanowires, nanorods and nanoplates with six-fold symmetry. The six-fold nanoplate structures correspond to a more advanced stage of growth than the nanowire structures. Cathodoluminescence (CL) in the scanning electron microscope (SEM) shows that the structures contain Sn, but the amount of this element is normally under the detection limit of X-ray energy-dispersive spectroscopy (EDS). The formation of branches in the hierarchical structures depends on the presence of Sn and on defects in the mixture powder. 相似文献
6.
Preparation and characterization of new fluorotellurite glasses for photonics application 总被引:1,自引:0,他引:1
Guihua Liao Jianjun Xing Hrvoje Gebavi Daniel Milanese Michael Fokine Monica Ferraris 《Journal of Non》2009,355(7):447-503
Glasses based on (85 − x)TeO2-xZnF2-12PbO-3Nb2O5 (x = 0-40) system have been studied for the first time for fabricating mid-infrared optical fiber lasers. The thermal and optical properties including UV-Vis, Raman as well as FTIR spectra are reported. It is demonstrated that increasing the ZnF2 concentration to 30 mol% significantly increased the thermal stability of the glass. Adding ZnF2 also reduced the hydroxyl (OH) content of the glass resulting in lower optical absorption in the mid-infrared region, which is crucial for infrared laser applications. The glass absorption cut-off edge near 400 nm blue-shifts with increasing ZnF2 addition. Raman spectra show a depolymerization of the glass network with increasing transformation of TeO3+1 to TeO3 structures. 相似文献
7.
High purity nanorods of vanadium doped zinc oxide with five different concentrations are prepared by a well known ceramic double sintering method. XRD patterns of the samples reveal a wurtzite phase formation. SEM micrographs confirm the nanorods in the samples. Purity of the samples is characterised using EDX analysis. UV–Vis–NIR study of the samples shows a red shift in bandgap for the substitution of V in ZnO matrix. FTIR study confirms the presence of defect states and enhancement of covalent bonding over ionic bond due to the incorporation of the V ions into ZnO lattice. An ultimate find we report in the present work is that the addition of V in ZnO could smoothly tailor the optical bandgap energy due to formation of the exciton states. An enhancement of covalent bonding in V doped ZnO will provide a platform for the third order susceptibility or photonic applications. 相似文献
8.
H. Tambo S. KimuraY. Yamauchi Y. HiromuraY.K. Zhou S. EmuraS. Hasegawa H. Asahi 《Journal of Crystal Growth》2009,311(10):2962-2965
GaCrN nanorods were grown on GaN nanorods by RF-plasma-assisted molecular beam epitaxy. GaN nanorods were grown on Si (0 0 1) substrates with native SiO2. Cr doping into GaCrN nanorods was conducted at substrate temperatures of 800 and 550 °C. Cross-sectional transmission electron microscopy images revealed that the diameter of GaCrN nanorod gradually increases with growth proceeding at 550 °C, while the growth at 800 °C does not change the nanorod diameter. Low-temperature growth enhances the growth perpendicular to the c-axis and decreases the growth along the c-axis. It was found that the solubility limit of Cr atoms in GaCrN is much higher for the low-temperature growth than for the high-temperature growth. It was also found that the highest saturation magnetization is obtained at some optimum Cr cell temperature. 相似文献
9.
10.
Co2+-doped MgAl2O4 nanocrystalline powders were prepared by co-precipitation method. The gels and/or calcined samples were characterized by means of thermogravimetry and differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectrum and near-infrared absorption spectrum. MgAl2O4 nanocrystals were produced by calcining the gel above 800 °C, with the crystallite size of 10-30 nm in the temperature range of 800-1100 °C. The influence of pH value of precipitant solution on the dispersing of powders was studied and the result showed that Co:MgAl2O4 nanocrystalline powders exhibited good dispersion when pH = 11. The absorption spectrum of Co2+-doped MgAl2O4 exhibited a broad absorption band in the wavelength range of 1200-1600 nm, which indicated that Co2+ ions substituted for the tetrahedrally coordinated Mg2+ ions in the MgAl2O4 lattice. 相似文献
11.
Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses 总被引:1,自引:0,他引:1
As part of ongoing studies to evaluate relationships between structure and rates of dissolution of silicate glasses in aqueous media, sodium borosilicate glasses of composition Na2O·xB2O3·(3 − x)SiO2, with x ≤ 1 (Na2O/B2O3 ratio ≥ 1), were analyzed using deep-UV Raman spectroscopy. Results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. The Q3 fraction was found to increase with increasing Na2O content, in agreement with studies on related glasses, and, as long as the value of x was not too high, this contributed to higher rates of dissolution in single pass flow-through testing. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity, and appeared to grow larger upon further reduction of the Q3 fraction. Results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference. 相似文献
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13.
xTiO2-(60 − x)SiO2-40Na2O glasses have proven an interesting linear and non-linear optical properties [M. Abdel-Baki, F. Abdel Wahab, F. El-Diasty, Mater. Chem. Phys. 96 (2006) 201]. The investigated glasses show one order of magnitude enhancement for the second-order index of refraction and third-order optical susceptibility over some TiO2 silicate glasses. In this work, we continue studying these glasses using three different techniques to analyze the glass structures seeking to provide a deep insight for the relation between structure, compositions and the optical characteristics of these glasses. Radial Distribution Function analysis (RDF) combined Raman spectroscopy are used to study these glasses. Positron annihilation lifetime spectroscopy and Doppler broadening measurements are carried out to investigate the change in the glass structure as the incorporation of TiO2 concentration into glass. The origin of the non-bridging oxygen (NBO) bonds has been traced to correlate their existence with the measured non-linear optical properties of the investigated glasses. 相似文献
14.
Crystallization of amorphous Al-based alloys (Al-Y-Gd-Ni-Fe) was investigated by applying differential scanning calorimetry (DSC), X-ray diffraction (XRD) and high resolution electron microscopy (HREM). It was shown that the crystallization in the examined alloys proceeds in three stages (DSC maxima). The two first stages are attributed to formation of solid solution of fcc Al(RE) nanograins in amorphous matrix. In the third stage the precipitation of ternary compound Al19Ni5RE3 of the orthorhombic Al19Ni5Gd3-type structure was observed. A partial substitution of Ni by Fe causes a change of stoichiometry and crystal structure of the ternary compounds: Al8TM4RE (TM = Fe, Ni; RE = Y, Gd) of the tetragonal ThMn12 (Al8Mn4Ce)-type structure. A partial replacing of Y atoms by Gd in the Al87Y5Ni8 based alloy shifts the Al(RE) nanocrystallization to lower temperatures. In contrast to this a partial replacing of Ni by Fe shifts the nanocrystallization to higher temperatures. 相似文献
15.
N doped TiO2 with anatase and rutile mixed crystal were prepared by using tetrabutyl titanate as the precursor via a modified hydrothermal process and calcination at 320 °C. The microstructure and morphology of samples were characterized by XRD, UV-vis-DRS, FTIR and XPS. The results showed that N-TiO2 particles were crystallized to anatase and rutile mixed crystal structure; they were presented narrow particle size distribution, and the average particle size was ca. 13.5 nm calculated from XRD results. It was found that the N-doped TiO2 particles showed strong visible-light absorption and high photocatalytic activity for the mineralization of Rhodamine B under irradiation by visible light (400-500 nm). The high visible-light photocatalytic activity of the obtained N-doped TiO2 might result from the synergetic effect of nitrogen doping and the mixed lattice structure of N-TiO2. Possible mechanism of N-TiO2 mixed crystal formed under hydrothermal conditions was discussed. 相似文献
16.
Raman spectroscopy has been used to measure the fraction of tetrahedral silicate units connected at three corners into the network (Q3) in binary lithium silicate glasses and also in the more complex borosilicate glasses used for waste immobilization. Agreement within experimental error was obtained with 29Si MAS NMR measurements of the same samples. Raman provides an alternative method of structural determination for silicon-containing glasses with a high content of paramagnetic species where NMR loses resolution. Analysis was performed on borosilicate glasses containing up to 11.98 mol% Fe2O3 and the Q3 values obtained by Raman spectroscopy agree within error with the published 29Si NMR results from borosilicate glasses containing the equivalent quantity of Al2O3. 相似文献
17.
The presence of sulfur in radioactive waste to be incorporated in borosilicate glasses entails difficulties mainly due to the relatively low solubility of sulfates in the vitreous phase. In this work a study is presented on the effects of the ratio R = [Na2O]/[B2O3], the type of sulfate added and the addition of V2O5 on the incorporation of sulfates in borosilicate glasses. Glass samples were prepared at the laboratory scale (up to 50-100 g) by melting oxide and sulfate powders under air in Pt/Au crucibles. XRF and ICP/AES chemical analysis, SEM/EDS, microprobe WDS and Raman spectroscopy were employed to characterize the fabricated samples. The main experimental results confirm that the incorporation of sulfates in borosilicate glasses is favored by the network depolymerization, which evolves with the ratio R. The addition of V2O5 seems to accelerate the kinetics of sulfur incorporation in the glass and, probably, increase the sulfate solubility by modifying the borate network and fostering the formation of voids of shape and size compatible with the sulfur coordination polyhedron in the glassy network. The kinetics of X2SO4 incorporation in the glass seems to be slower when X = Cs. 相似文献
18.
Structure and lattice dynamics of binary lead silicate glasses investigated by infrared spectroscopy
The polar lattices dynamics of seven binary lead silicate glasses have been studied by infrared spectroscopy. The analysis of the reflectivity spectra with a dielectric function model, based on a modified Gaussian profile, allows a quantitative evaluation of the presence of lead cations within different structural sites. From the role of the lead cations versus the degree of polymerization of the silicate network and the comparison with literature results, we may to give a scenario for explaining the observed structural evolution of the glass matrix and more particularly the drastic change occurring around 45% of lead content. Below this threshold, lead cations act only as modifiers of the silicate network. Above, the glass structure is deeply modified; a lead network involving around 10% of the lead content appears in glasses whose composition is just above the threshold and progressively grows at the expense of the silicate network with the increase of lead content. For high lead content, lead cations can act as modifiers of the silicate network or as network formers. Results also show that the analysis of far infrared measurements combined with the knowledge of the UV edge optical response is very promising to characterize the local disorder around cations in glasses. 相似文献
19.
Hrvoje Gebavi Daniel Milanese Qiuping Chen Mile Ivanda Stefano Taccheo 《Journal of Non》2009,355(9):548-26274
In this paper, optical properties of 75TeO2-20ZnO-5Na2O host glass doped with concentration of Tm3+ up to 10 %mol were studied in order to assess the most suitable rare earth content for short cavity fiber lasers. Raman spectroscopy revealed a change in the glass structure while increasing Tm3+ content, similar to the well known addition of alkali ions in a glass. Influence of the fabrication process on the OH− content was determined by FTIR measurements. Refractive index of Tm3+ doped tellurite glasses was measured at five different wavelengths ranging from 533 nm to 1533 nm. Lifetime and emission spectra measurements of the Tm3+ doped tellurite glasses are reported. 相似文献
20.
The structure and elastic properties of a series of xNa2O · MgO · 4SiO2 glasses have been studied using both Raman and Brillouin spectroscopy. Relative to Na2O-SiO2 glasses, the maximum abundance for phyllosilicate structural units in the present glasses shows a lag of 0.5 units in the number of non-bridging oxygen per silicon atom (NBO/Si). This phenomenon has been attributed to the decrease in the average coordination number of modifying cations due to the presence of Mg2+. It has also been found that the decomposition of both metasilicate and disilicate (dimerized SiO4) anionic structural units in Na2O-SiO2 glasses are enhanced by the addition of MgO. However, the presence of Mg2+ does not cause a considerable effect on the decomposition of phyllosilicate structural unit. The acoustic data have revealed that both shear and Young’s moduli of the present glasses decrease with increasing NBO/Si (the variation in bulk modulus is reversed, however). The resistance to shear deformation for the anionic structural units in silicate glasses has been found to decrease in the following order: tectosilicate > phyllosilicate > metasilicate > disilicate > orthosilicate. The relative contribution of the various anionic structural units to the bulk modulus of a glass remains to be determined. The ideal mixing model using Makishima-Mackenzie’s relationship for predicting Young’s modulus is not applicable to the present glasses. 相似文献