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A series of Ba3-x ( VO4 )2 : xSm3+ (x = 0.02-0.16) phosphors were synthesized using the molten salt method with KCl as the salt. The effects of synthesis conditions as well as Sm3+ doping concentration on the phase structure and luminescence properties of the sample were investigated in detail. The temperature sensing characteristics of the sample were also studied. The optimum reaction conditions for synthesizing the sample are calcination temperature of 900 °C, calcination time of 1h, and a mass ratio of raw materials to molten salt of 1 : 3. The obtained sample has high phase purity and crystallinity. The micromorphology of the sample is lamellar with a thickness of about 1.53 mm. Upon the ultraviolet excitation of 318 nm, the broad emission from the VO43- groups and characteristic emissions from Sm3+ can be observed simultaneously in the emission spectra of Ba3-x(VO4)2:xSm3+ phosphors, with the emission colors concentrated in the yellow-white light region. With the increase of Sm3+ doping concentration (x) from 0.02 to 0.16, the intensity of the characteristic emission peak of Sm3+ first increases and then decreases, reaching its maximum value when x =0.10. The dominant mechanism for the concentration quenching in Ba3-x(VO4)2 :xSm3+ phosphors is attributed to the dipole-dipole (d-d) interaction. Moreover, for Ba2.9 (VO4 )2 : 0.10Sm3+ phosphors, it is found that the fluorescence intensity ratio of Sm3+ (652 nm) and VO43- groups (504 nm) shows a significant temperature dependence in the temperature range of 298-473 K. Its maximum absolute and relative temperature sensor sensitivities are 0.36/K and 1.99%/K, respectively. The results indicate that Sm3+ doped Ba3(VO4)2 phosphors exhibit excellent temperature sensing performance and potential applications in non-contact optical thermometry. [ABSTRACT FROM AUTHOR]

The Santanghu Basin is a typical low-rank coal-bearing basin in northwest China, with abundant coalbed methane (CBM) resources. However, the understanding of the main controlling factors and reservoir formation models of CBM in low-rank coal is still insufficient, which has restricted the exploration and development of CBM in this region. In this paper, the CBM enrichment controlling factors and enrichment models are analyzed based on the aspects of sedimentary environment, reservoir characteristics, sealing conditions, and hydrogeological conditions after systematically analyzing the geological characteristics of coal measures. The research results indicate that the coal seams of the Xishanyao Formation in the Santanghu Basin are stably developed, with the main macerals being vitrinite and a lower degree of coalification belonging to low-rank coal; the highest content of CBM can reach 7.17 m3/t, and the methane is mainly composed of biogenic gas supplemented by thermogenic gas; the roof lithology of the coal seam is mainly mudstone and siltstone, with good sealing conditions. Finally, two enrichment modes of coalbed methane in slope zones are proposed, namely, the CBM enrichment in the slope zone and the CBM enrichment by fault-hydraulic plugging. The results of this study can serve as a guide for the exploration and development of the deep-buried coalbed methane in the low-rank coal areas. [ABSTRACT FROM AUTHOR]

Organic geochemistry characteristics of carbonate rock and mudstone samples are reported for cores in exploration wells and outcrops in the Carboniferous and Lower Permian, Turpan-Hami Basin. Extensive analyses include organic matter abundance, kerogen type, hydrocarbon generation and thermal evolution. The mudstone is higher in organic content, ranging from 0 – 4.45% TOC, suggesting relatively good source rock potential; whereas, the carbonate rock has a maximum TOC of 0.52% and is basically non-source rock. The matrix types of both carbonate rock and mudstone are grouped into Type III (dominant) and II2 (less). The carbonate rock is a bit better quality than the mudstone in organic types. The source rock from downhole samples can be early mature to highly mature. The maturity of outcrop samples range from mature to over-mature. The lower maturity of well samples is related to the shallower depth of the samples. The higher maturity of outcrop samples may be related to the tectonic movement and high geothermal gradient. Based on characteristics of thermal evolution, more effective Carboniferous-Lower Permian source rocks are distributed in the deeper location of the sag and can generate more natural gas. The igneous/volcanic rocks are better deep reservoirs in which natural gas accumulates. Key words: Organic geochemistry, Carboniferous, Lower Permian, source rock, Turpan-Hami Basin