Papers by Keyword: Ion-Exchange

Abstract: Under the high electric field, discharge sometimes occurs along the surface of solid in vacuum, gas or liquid dielectrics, which is called surface flashover.SiO2-B2O3-K2O-Li2O-Al2O3-ZnO-MgO-F system glass ceramics has great machinability and excellent dielectronic property.This paper tries to study different time of ion-exchanged samples and their microstructures，which affect surface flashover performance of this novel material under the systerm of high voltage in vacuum. Compared to traditional coating method on alumina ceramic, the ion exchange treatment on glass ceramic can produce a tremendous improvement of flashover characteristics. The results show that the 10 hours ion-exchanged glass ceramic enjoys the most prominent insulation strength.Based on the theory of SEEA (Secondary Electron Emission Avalanche), these phenomena can be reasonably explained by the charge carrier injection and transport behaviors.

Abstract: The effect of Cs⁺ ion and Rb⁺ ion in the molten salt of different proportion on the single panel fire-resistant glass is discussed in this paper. The single panel fire-resistant glass was prepared by the method of ion-exchange, with proper amount of additives and adding KNO₃ and CsNO₃ , KNO₃ and RbNO₃ as the main part of molten salt. The proportion of the molten salt was changed separately, a contrast test was performed to measure the flexure strength. The results indicated that the flexure strength of the single panel fire-resistant glass increased firstly and then stabilized as the ratios of w(CsNO₃)/w(KNO₃) and w(CsNO₃)/w(RbNO₃) increased respectively. With the ratio of w(CsNO₃)/w(KNO₃) =1.5%, the mechanical property of the single panel fire-resistant glass was proper and the maximum flexure strength was 274 MPa. In the case of RbNO₃, the flexure strength of single panel fire-resistant was 244 MPa with the ratio of w(CsNO₃)/w(KNO₃) = 0.3%. According to the research, it is found that the method of ion-exchange of Cs+ and Rb+ into plain glass to prepare single panel fire-resistant glass is feasible, the sample melted under the condition of 1 hour and 780 without any trace of thermal explosion.

Abstract: Based on X-ray diffraction results, the gallery height of modified Mg3Al-LDH was expanded to 9.6Å from the original 4.8Å, indicating that the H3PW12O40 was indeed inserted into the hydroxide layers. Moreover, the results of FT-IR spectra proved the Keggin structure of PW11O397- species. The resulting material showed a high activity of degradation of methyl orange in the presence of H2O2 and UV light irradiation.

Abstract: Two kinds of Er-doped lithium phosphate glass have been chemically strengthened by ion exchange in a mixed binary melt of KNO3 and NaNO3 at temperature far below glass Tg. Ion depth profile has been determined with WDS technique. The effect of acid wash on surface morphology, hardness and fracture temperature of glass was investigated. It was found that acid wash following ion exchange could improve the surface morphology and strength of glass. Nevertheless, WDS analysis showed that the acid wash could cause the ion diffusion from glass surface to acid wash liquid, i.e. the back diffusion of K+ and Na+. The results revealed that the back diffusion of K+ was severer than that of Na+ during acid wash and the bond of K+ to glass network was weak.

Abstract: The SiO2 aerogels of low density was fabricated by ion exchange and sol-gel method on the basis of sodium silicate. The effect of pH, aging，addition of DCCA and annealed temperature on the gel time, aerogel density, porosity and the micro-structure was systemly studied. The results showed that when the pH is 5, aging was 30%Vol .of TEOS/ethanol solution ,the addition of DCCA was 1.5ml, the gel system was annealed at 50 for 84 h, 60 for 72h, the best quality of silica aerogels with low density (0.14g/cm3), higher specific surface(610.643 m2/g) and pore size of 20~40 nm can be obtained.

Abstract: The layer structured niobate Cs4Nb6O17•3H2O has been prepared in a solid state reaction using Cs2CO3 and Nb2O5 at 1073 K. Ion exchange reactions of Cs+ in the interlayer space were studied in aqueous solutions. The single phases of lithium, sodium and hydrogen ion exchange products were obtained and they also contained interlayer water. The interlayer water of the lithium ion exchange product was removed by heating at 453 K in a vacuum. The resulting niobate Cs0.26Li3.01H0.73Nb6O17 was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 120 and 110 mAhg-1 for the first cycle in the voltage range of 1.5 – 4.2 V. The amount of Li+ intercalated and deintercalated were 4.0 and 3.6 of the formula unit, respectively.

Abstract: The layer structured titanoniobate CsTiNbO5 has been prepared in a solid state reaction using Cs2CO3, anatase type TiO2 and Nb2O5 at 1073 K. Ion exchange reactions of Cs+ in the interlayer space were studied in aqueous solutions. The host layers of the titanoniobate were maintained on the ion exchange reactions and the resulting products were found to contain interlayer water. The interlayer water in the lithium ion exchange product was removed by heating at 453 K in a vacuum. The resulting titanoniobate Cs0.10Li0.60H0.30TiNbO5 was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 130 and 99 mAhg-1 for the first cycle in the voltage range of 1.5 - 4.2 V. The amounts of Li+ intercalated and deintercalated were 1.16 and 0.88 of the formula unit, respectively.

Abstract: A field-assisted solid state ion exchange (FASSIE) approach is used to dope silicate glasses with mono- and/or multivalent ions, in which the diffusion of ions coming from a film deposited onto the glass surface is driven by an external electric field. Metal precipitation to form nanoparticles may take place during the ion exchange, depending on the process parameters, or it can be induced by irradiation with high power laser beams. Characterization of silicate glass samples doped with either gold or silver is performed by optical absorption and transmission electron microscopy.

Abstract: It has been shown that titanium metal subjected to NaOH and heat treatments spontaneously forms a bonelike apatite on its surface in the living body and bonds to living bone. However, its apatite-forming ability was liable to decrease when the treated titanium metal was stored in humid environment. In the present study, the NaOH-treated titanium metal was soaked in a CaCl2 solution at 40°C for 24h, heat-treated at 600°C for 1h, and then soaked in ultrapure water at 80°C for 24h. Calcium titanate was formed on the surface of the titanium metal 1µm in thickness by these treatments. The resultant titanium metal showed high scratch resistance and high apatite-forming ability in a simulated body fluid. This high apatite-forming ability was maintained even after the titanium metal was kept in 95% relative humidity at 80°C for 1 week.

Abstract: The layer structured titanate KxTi2-xFexO4 (x = 0.80) with the lepidocrocite (-FeOOH) type structure has been prepared in a solid state reaction using K2CO3, anatase type TiO2 and -Fe2O3 at 1373 K. Ion exchange reactions of K+ in the interlayer space were studied in aqueouse solutions. The host layers of the titanate were maintained on the ion exchange reactions and the resulting products were found to contain interlayer water. The interlayer water in the hydrogen ion exchange product was removed by heating at 383 K in a vacuum. The resulting titanate H0.79K0.01Ti1.20Fe0.80O4 was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 107 and 69 mAh/g for the first cycle in the voltage range of 1.5 - 4.2 V.