Browsing by Author "Wang, C."
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Item LA-ICP-MS U–Pb zircon, columbite-tantalite and 40Ar–39Ar muscovite age constraints for the rare-element pegmatite dykes in the Altai orogenic belt, NW China(Geological Magazine, 2018-01) Zhou, Q.; Qin, K.; Tang, D.; Wang, C.; Sakyi, P.A.The Chinese Altai is renowned for its rich rare-element resources. Nine representative rare-element (REL) pegmatites were dated using LA-ICP-MS and ⁴⁰ Ar– ³⁹ Ar methods. The columbite grains yield a weighted mean ²⁰⁶ Pb/ ²³⁸ U age of 239.6±3.8 Ma for the Dakalasu (Be-Nb-Ta) pegmatite and concordia U–Pb ages of 258.1±3.1 Ma and 262.3±2.5 Ma for the Xiaokalasu (Li-Nb-Ta) pegmatite. The zircons display a weighted mean ²⁰⁶ Pb/ ²³⁸ U age of 198.5±2.5 Ma for the Husite (Be) pegmatite and concordia U–Pb ages of 194.3±1.6 Ma and 248.2±2.2 Ma for the Qunkuer (Be) and Taerlang (barren) pegmatites. The muscovite ⁴⁰ Ar– ³⁹ Ar dating gives plateau ages of 286.4±1.6 Ma, 297.0±2.6 Ma, 265.2±1.5 Ma, 178.8±1.0 Ma, 162.2±0.9 Ma, 237.7±1.3 Ma, 237.4±1.2 Ma and 231.9±1.2 Ma for the Talate (Li-Be-Nb-Ta), Baicheng (Nb-Ta), Kangmunagong (barren), Husite (Be), Qunkuer (Be-Nb-Ta), Xiaokalasu (Li-Nb-Ta), Weizigou (Be) and Taerlang (barren) pegmatites, respectively. These new ages coupled with previous geochronological work suggest that the REL pegmatites in the Chinese Altai formed during early Permain – Late Jurassic time. The REL pegmatites located in the Central Altaishan terrane are younger than those in the Qiongkuer–Abagong terrane, showing a correlation with the coeval and adjacent granites. The formation of the REL pegmatites and these granites indicates frequent and strong magmatic activity in the post-orogenic and anorogenic setting. The spatial and temporal distribution of pegmatites and granites reveals a magmatism path from the SE (of age early–middle Permian), to the NW (middle Permian – Middle Triassic) and finally to the central part (Middle Triassic – Jurassic) of the Chinese Altai.Item Non-Metallic Particles in Solar Grade Silicon (SoG-Si)(IEEE, 2010) Damoah, L.N.W.; Dong, A.; Zhang, L.; Zhu, H.; Wang, C.This study investigated the non-metallic inclusions in Solar 2rade Silicon (SoG-Si), especially the distribution of inclusions in the top 15mm layer of multicrystalline silicon ingot. The SoG-Si ingot produced from directional solidification process usually pushes the impurities to the top and finally cut off and discarded, which leads to material loss. The hard inclusions lead to wire breakages during the cutting of the ingot into wafers. The main kinds of inclusions found in top-cut silicon scraps from two manufacturers have been investigated using acid extraction, automated feature analysis techniques and SEM-EDS and optical Microscope: they are needle-like Si3N4 and lumpy SiC inclusions. Surface observations of the scraps before polishing revealed that, Si3N4 inclusions are usually bigger and in some cases can be about a few millimeters. SiC inclusions are usually smaller, ∼200μm but can be ∼500μm in some cases. F or the directional solidified silicon ingot, it was determined that an approximate distance of ∼10mm is a good enough cutoff thickness.Item Removal of inclusions from solar grade silicon using electromagnetic field(John Wiley & Sons, Inc., 2011) Dong, A.; Damoah, L.N.W.; Zhu, H.; Zhang, L.; Wang, C.The characteristics of the top-cut solar grade silicon (SoG-Si) scraps produced from SoG-Si ingots were investigated using optical microscope observation, SEM-EDS analysis and automatic inclusion scanning (ASPEX). Particles of SiC and Si3N4 are the main non-metallic inclusions in the SoG silicon top-cut scrap. The deeper into the scrap from the surface, the less and smaller inclusions are found. A laboratory-scale electromagnetic purification unit was used to melt the silicon scraps and remove inclusions from the melt. The experimental results indicated that the electromagnetic (EM) field efficiently pushed the non-metallic particles and less-conductive metallic impurity elements to the boundary layer.