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In this paper, a type of vapor chamber with a gradient pore size wick (VC-G) was developed, and its thermal performance was experimentally tested and compared with two types of VCs with uniform pore size wick (which can be defined as VC-U (200) and VC-U (50) as the powder size of the wick is 50-mesh and 200-mesh, respectively) and a VC without a wick (VC-N). In addition, a VC heat transfer ability experiment platform was built, and the thermal resistance, temperature distribution and thermal response time of the VC with different wick structures were experimentally investigated. The experiment results show that the capillary driving force provided by gradient pore size wick increases gradually from outside, which can not only promote the condensation fluid to gather in the central heat source but also facilitate the vapor to spread around. Therefore, compared with VC-U (200), VC-U (50) and VC-N, VC-G shows the best heat transfer performance, temperature uniform performance and start-up performance. [ABSTRACT FROM AUTHOR]

Abstract: The photoluminescence (PL) properties of Bi3+ in the MSb2O6 (M=Ca, Sr) have been reinvestigated. Our results are essentially different from the reported data. The PL spectra of MSb2O6:Bi consisted of an ultraviolet (UV) band due to 3 P 1–1 S 0 transition of isolated Bi3+ ions and a visible band due to Bi3+ pairs (clusters), which have not been reported with high intensities even at room temperature. In CaSb2O6:Bi the visible emission (443nm) predominated over the UV emission (297nm), while in SrSb2O6:Bi the visible emission (487nm) had similar intensity to the UV emission (319nm). The maximum visible emission intensity was at x =0.0075 (x: the doping Bi concentration per mol of host) in MSb2O6:Bi (M=Ca, Sr), and the value in CaSb2O6:Bi was about six times higher than in SrSb2O6:Bi. The intense blue emission in CaSb2O6:Bi proves that the modified solid state reaction is a better method to synthesize a higher-performance CaSb2O6:Bi phosphor as a potential candidate for white-light-emitting diode pumped by UV chip (w-UVLED) and other display devices. [Copyright &y& Elsevier]

Abstract: A novel visible-light-driven photocatalyst of Sr2Bi2O5 is prepared by solid-state reaction at 780 °C. The optical band gap of Sr2Bi2O5 is determined to be 2.87 eV by UV–Vis diffuse reflectance spectroscopy. Under both UV and visible-light irradiation, the photocatalytic activity for degrading methyl orange (MO) over Sr2Bi2O5 is higher than those over BiVO4, and SrBi2O4. The relationships between the photocatalytic properties of Sr2Bi2O5, SrBi2O4, and BiVO4 and their crystal structures are discussed. Among Sr2Bi2O5, SrBi2O4, and BiVO4, the higher photocatalytic activity of Sr2Bi2O5 is ascribed to its higher level of distortion of the metal–oxygen polyhedra, and the lower packing factor degree. [Copyright &y& Elsevier]

Abstract: Single anatase TiO2 nanocrystals with controllable crystallinity are prepared by a simple and readily available hydrothermal route. The crystallinity has been successfully manipulated via varying the temperature. TiO2-240 prepared at 240°C holds the highest crystallinity, i.e., the largest crystallite size of 14.2nm and the lowest lattice strain of 12.56×10−3, and the highest photocatalytic efficiency. The feasible method is also successfully applied in the synthesis of Eu3+-doped TiO2 (TiO2:Eu3+) nanoparticles. Both the photocatalytic activity of TiO2 and the photoluminescence (PL) properties of the TiO2:Eu3+ intensifies obviously as the crystallinity increases. The photocatalytic activity of nanoTiO2 and PL properties of the TiO2:Eu3+ are discussed in detail from the viewpoints of crystallinity based on various characterizations. This method can be developed for the deliberate synthesis of other functional nanomaterials. [Copyright &y& Elsevier]

Abstract: Sillenite-type Bi25GaO39 as an efficient photocatalyst was studied in the present paper. The compound synthesized by a solid state reaction method has a band gap of 2.95eV. It possesses a fair visible-light-response ability. The UV-light-induced photocatalytic activities for degrading methylene blue follow the decreasing order of anatase TiO2 >Bi25GaO39 >Bi12GeO20 >Bi24Ga2O39, different from Bi12GeO20 >Bi25GaO39 >Bi24Ga2O39 >TiO2 under visible light irradiation. The dispersion of Pt over Bi25GaO39 leads to an obvious increase in photocatalytic performance. The opener structure of Bi25GaO39 is proposed to explain the higher UV-light-induced photocatalytic activity, compared with Bi24Ga2O39 and Bi12GeO20. [Copyright &y& Elsevier]

Abstract: M2Sb2O7 (M=Ca, Sr) photocatalysts were synthesized by a solid state reaction method. The results concerning methyl orange (MO) photodecomposition generally show that the catalytic efficiency of Sr2Sb2O7 is much higher than that of Ca2Sb2O7 under UV light irradiation. The more open structure in Sr2Sb2O7 is suggested to be responsible for its higher photocatalytic activity. In the investigation on pH-dependent photocatalysis over Sr2Sb2O7 catalyst, the pseudo-first reaction rate k was found to be increased by about six times as the pH value decreases from 6.88 to 3.91. We believe that the decolorization of MO in neutral or alkaline conditions is primarily through a photocatalytic process, while the MO photosensitization and photolysis mechanisms play more important roles in acidic conditions. [Copyright &y& Elsevier]