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The luminescence properties of green-yellow emitting (Sr1-xBax)1.95SiO4:0.05Eu2+ (0≤x≤1) phosphors were discussed in this paper. These phosphors were synthesized through the high temperature solid-state reaction technique and characterized by X-ray diffraction. The experimental results indicated that all the major phase of prepared phosphors gradually varied from α-Sr2SiO4 (x=0) phase to Ba2SiO4 (x=1) phase, and an intermediate phase between the two phases was observed at x=0.5. The excitation spectra (λem λem=524 nm) and emission spectra (λex λex=400 nm) showed a broad band character with peak located at 365 nm and range from 579 nm to 508 nm, respectively. With the increase of concentration of barium, the thermal stability of the phosphors increased first when x is less than 0.5, and then it decreased when x surpasses 0.5. In addition, luminescence intensity was enhanced with the barium concentration. Under the 400 nm NUV light excitation the (Sr1-xBax) 1.95SiO4:0.05Eu2+ phosphors have a potential application in white LED.

Crystalline alumina samples with Al2O3 content of 95.23 wt.% were prepared directly from the nepheline ore in Nanjiang county, Sichuan province of China. Four steps were involved in the experiment of alumina preparation, including calcination, dissolution, carbonation and re-calcination. Lime was used in the calcination process with the nepheline concentrates powders to generate soluble aluminates and insoluble silicates. NaOH solution was used as the mother solution in the dissolution process. CO2 was introduced into the solution to precipitate the Al (OH)3 precursor, which was then fired to obtain crystalline alumina. Among the crystalline alumina obtained three phases of crystals existed which were detected by XRD and SEM, including δ-Al2O3 as the major phase, while θ-Al2O3 and κ-Al2O3 as the minor phases. Various crystal phases of alumina could be ascribed to the purity and crystal structure of precursor, as well as the re-calcination temperature and time.

A series of red-emitting phosphors, Eu3+-doped and Eu3+ with Sm3+ co-doped Li2CaSiO4, were prepared by the combustion method. The phase composition was investigated by XRD, and photoluminescent properties were characterized by fluorescent spectrophotometer. The results show that the diffraction peaks of samples all match well with that of Li2CaSiO4 [JCPDS NO. 27-0290]. The excitation spectra consists of the broadband and the sharp lines, which are assigned to the charge transfer band (CTB) of Eu3+→O2– and the typical intra-4f transitions of the Eu3+ ions, respectively. The emission spectrum covers the characteristic f-f transitions of Eu3+, namely, 5D0→7F1 (596 nm), 5D0→7F2 (620 nm), 5D0→7F3 (657 nm) and 5D0→7F4 (705 nm). The concentration quenching occurs when Eu3+ mol fraction equals to 9%. When Eu3+and Sm3+ were co-doped, the luminous intensity of the emission spectrum was superior to the Eu3+ mono-doped, which explains the Sm3+ has a sensitization effect for Eu3+.

A red-emitting phosphor, Eu3+ activated Ca2Li2BiV3O12 was synthesized via combining combustion with solid state method and characterized by X-ray powder diffraction (XRD) and fluorescence spectrophotometer. The influence of synthesis temperature and the concentration of Eu3+ ions, on phase composition and luminescent properties of the synthesized samples was investigated systematically. The results showed that the Ca2Li2BiV3O12:Eu3+ phosphor with high phase purity and good crystallinity can be obtained by this citric acid - assisted sol combustion-solid state route at the synthesis temperature from 600°C to 700°C. The excitation spectrum of Ca2Li2BiV3O12:Eu3+ was composed of a broad band from 200 nm to 385 nm and a number of sharp small peaks extending from 390 nm to 480 nm, and the main peak was at 277 nm. The main emission peak was at 612 nm due to the electric dipole transition of 5D0 → 7F2 of Eu3+, which results in a red emitting. The sample prepared at T=680 °C, Eu3+ mol%=15 mol% has the highest emission intensity in this work.

A novel process was developed to obtain high content of ceria powder directly from bastnasite mineral. The bastnasite was roasted with NaHCO3 at 550 oC for 2 h, washed with water and dilute HCl respectively to remove impurities, and finally calcined in air. TG-DTA, XRD, XRF, SEM was used to characterize the decomposition process of bastnasite, crystalline phase, the chemical composition, and morphology of the product. The results showed that the concentration of HCl solution was the most important factor in the leaching process, and the calcining temperature of bastnasite mineral should be controlled below 600 oC. The optimal technological parameters were suggested as follows: leaching temperature at 45 oC, for 45min in 3 mol/L HCl, with the weight ratio of solid to liquid of 1:5, and the calcining of the leachate at 600 oC for 2 h. And the high content of ceria (TREO > 80wt %, Ceria/TREO > 85wt %) nanosized (20~100 nm) powder was obtained succeffully, which showed potential application in polishing materials.

High purity spherical silica powder was obtained using silica fume as the raw material in this study. The mixture acids of HF and HCl were used in the purification process to remove the impurities contained in the silica fume. The phase of the product was characterized by X-ray diffraction, indicating that the spherical silica powder was amorphous. The chemical composition of the product was investigated by X-ray fluorescence, showing the SiO2 content was 99.9096 wt%. It had been proved that the purification process could improve the dispersion of the product powder via the morphology comparison and the laser particle analyses. The experimental results showed that the parameters of the product spherical silica powder met all the standards of the electronic-grade packaging materials.

The perovskites red phosphors activated by Pr3+were prepared via the combustion method, using citric acid as a fuel and complex agent. The samples were characterized by X-ray powder diffraction and fluorescence spectrophotometry respectively. The effects of calcination temperature and doping Sr2+ion concentration on the phase compositions and luminescence properties were investigated. The CaTiO3: Pr3+can be obtained with high purity and good crystallinity by the combustion method at different calcination temperatures (750 oC, 850 oC, 900 oC, 950 oC and 1000 oC) for 1 h. The sample obtained at 900 oC exhibits the maximum emission intensity. The crystal structure of the obtained Ca1-xSrxTiO3: Pr3+(x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) changes from perovskite to calcium strontium titanate when x ≥ 0.3. The sample exhibits the maximum red emitting when x = 0.4.

In this work, hot compression tests on columniform TC18 titanium alloy specimens were performed with a Gleeble® 3500 thermal and mechanical simulator in the temperature range of 820-875 °C and at constant strain rates of 0.01, 0.1 and 1 s−1. Relationship model of true stress versus true strain as well as peak stress versus deformation temperature were established, and microstructural micrographs of TC18 titanium alloy were analyzed. The results showed that the flow stress decreased as the deformation temperature increased or the strain rate decreased. Besides, the deformation resistance at temperature above Tβ (β transus temperature) was obviously lower than that at below Tβ. In addition, flow stresses kept almost constant when it deformed in β region where hot deformation mechanism is DRV, but significant flow softening occurred in α+β region, where deformation mechanism is mainly dominated by DRX. And in α+β region, DRX is prone to occur at a low strain rate, and it is difficult for DRX to occur at high strain rate.

Ceria (CeO2) nano particles were synthesized by a new technique named "a two-stage precipitation process". The cerium(III) nitrate hexahydrate, hydrogen peroxide and ammonia were used as the raw materials. The Ce 3+ ions were oxidized to Ce 4+ ions by hydrogen peroxide, the Ce 4+ were then precipitated by ammonium hydroxide to form the precursor in the chemical reaction process. The CeO 2 nano particles were obtained by the heat treatment of the precursor for 2 hrs. at 400∼800°C after drying treatment. The phase composition and the crystal structure of the CeO2 nano particles were studied by XRD (X-ray diffraction) patterns measured at room temperature. The crystal structure of CeO 2 is cubic system. It's space group is O 5 h Fm3m. The morphogenesis of CeO2 particles is ball-like particle observed by scanning electron microscopy (SEM). The average grain size of CeO2 nano crystal was identified by transmission electron microscopy (TEM) to be about 10 nm by heating treatment for 2 hrs at 400°C. The result of ultraviolet radiation-visible light photometer measurement shows that the ultraviolet absorption capability of CeO 2 particles depends on the grain size. The CeO 2 nanoparticle prepared by the process has a better ultraviolet absorption property than that of commercial ceria microparticles. The CeO 2 nano particles exhibited photocatalytic activity for the decomposition of methyl orange under UV light irradiation.

The preparation and the photocatalytic degradation NO2 - activity of Fe3+-doped TiO2 nano-sized particles is reported in this paper. The TiO2 nano particles were prepared by sol-gel method. The various influence factors about the synthesis process of the Fe3+-doped TiO2 nano photocatalyst were controlled and investigated by XRD (X-ray diffraction), SEM (scanning electron microscopy), and TEM (transmission electron microscopy) etc.. The results show that the phase compositions, crystalline grain size, crystal structure , and photocatalytic activity of the Fe3+-doped TiO2 particles prepared by the method depend on the synthesis technology parameters such as calcination temperature, holding time, Fe3+ ions concentration etc.. The influence factors of the preparation process has been discussed. The photocatalytic decomposition of NO2 - ion into N2 and O2 using Fe3+ and Ce4+-doped TiO2 photocatalysts were investigated under UV irradiation. It was fund that Fe3+-doped TiO2 photocatalysts shows much higher photocatalytic activity than that of the Ce4+-doped TiO2 . The photocatalytic decomposition effect of NO2 - ion is related to the crystalline grain size, irradiation time, and the Fe3+ ions concentration. The Fe3+-doped TiO2 nano powders exhibited the photocatalytic degradation NO2 - activity under UV light irradiation.