This study selects yellow, red and orange phosphors used in high color rendering white packages, analyzes their luminescence and thermal properties, crystal structures and micro morphologies during both the high temperature and high moisture ageing test and the water immersion test, and finally figures out the degradation mechanisms of different phosphors. The results show that: 1) the hydrolysis reaction of phosphors under hygrothermal environment produces OH^- and increases the environment's pH value, which can lower the crystallinity of phosphor hosts, increase the lattice vibration and light-induced heat, and enhance the thermal quenching effect of phosphors. Meanwhile, the surface roughening of phosphor particles can increase the blue light scattering and lower its absorption and conversion efficiency; 2) the degradation trends of both luminescence and thermal properties of phosphors under the water immersion test are similar to those under high temperature and high moisture ageing test. So it is an effective method to assess the reliability of LED phosphors under hygrothermal environment.

@en

In order to determine the source of the light hydrocarbons in the Kuqa Depression of the Tarim Basin, Northwest China, their geochemical characteristics are documented, and possible influencing factors are discussed in a broad context on the basis of geochemical analyses of natural gas samples from 19 wells in combination with previously reported natural gas components and carbon isotope values from the same depression. The biomarker analytical results show that (a) methyl cyclohexane (37.5–60.3%) of natural gas predominates the C₇ light hydrocarbon series (methyl cyclohexane, heptanes, and dimethyl cyclopentane), and (b) the heptane content (25.0–54.8%) is also relatively high. The C_6–7 light hydrocarbon series (aromatics, normal alkanes, and cycloalkanes) have abnormally high aromatics (benzene and toluene) content (26.2–83.8%). Heptane value (13.31–37.77%) and isoheptane value (2.10–7.64%) indicate that the Kuqa natural gases are of high maturity and typical of coal-derived gas (gas generated by sapropelic source rock). Their light hydrocarbons, however, appear to have some characteristics of mixed-source organic matter. Specifically, the light hydrocarbons in the Dina 2 gas field show characteristics of the coal-derived gas; those in the Dabei gas field show some features of the oil-associated gas (gas generated by humic source rock), whereas those in the Kela 2 and Keshen 2 gas fields and Well Yangtake-101 display characteristics of the mixed source organic matter. The abnormally high content of the aromatics in the Kuqa Depression may have resulted mainly from their high productivity during the thermal maturity of humic type organic matters and the gases accumulation of late stage. The different relative contents of the aromatics in various oil and gas fields may have been accounted by different organic matter types, maturity, and distribution patterns of source rocks.

@en

As a widespread application of high power phosphor-converted white light emitting diodes (pc-WLEDs) with long lifetime and color-consistence, the highly reliable phosphor/silicone composite, one of core materials used for light-conversion, working under severe operation conditions has become increasingly necessary. This paper selects three widely used monochromatic phosphors (Aluminates, Silicates and Nitrides based) as well as a pristine silicone to determine the potential interaction effects in their phosphor/silicone composites operated under different environments. Firstly, the transient thermal quenching and long-term high temperature ageing tests are used to investigate the thermal stabilities of both monochromatic phosphor powders and phosphor/silicone composites. Furthermore, the degradation mechanisms of phosphor/silicone composites aged under the high temperature & blue light exposure and high temperature & high humidity conditions are studied by considering the interaction effect. The results show that: (1) the thermal stabilities of different phosphors are different and the phosphor/silicone composites have more severe thermal quenching effects than those of their corresponding phosphor powders, but with the similar degradation trends; (2) the blue light irradiation can deteriorate silicone which is related to the photolysis effect; (3) the moisture can accelerate the degradation of phosphor/silicone composites because the change of pH condition, owing to the dissolution of phosphor powders in moisture, can degrade both phosphors and silicone.@en