The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray d...The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.展开更多
Oil-gas reservoir space types involving spherulite in pyromeride rocks are common in the Lower Cretaceous Shangkuli Formation, the Hailar Basin, China. The main types include interspherulite fissures, interlayer fissu...Oil-gas reservoir space types involving spherulite in pyromeride rocks are common in the Lower Cretaceous Shangkuli Formation, the Hailar Basin, China. The main types include interspherulite fissures, interlayer fissures, intraspherulite concentric rings and net microcracks, cavity pores, dissolution pores, and devitrification pores. The first two were found to restrict the effective plane porosity of interspherulite. Devitrification microporosities, microcracks, cavity pores, and spherulite diameter influence the effective plane porosity of intraspherulite. The degree of dissolution is determined by the degree of development and the type of intraspherulite microcracks. Another important role of ring and net microcracks is to connect devitrification pores to form a pore and fissure network. Finally, chilling contraction plays an important role in the form and development of interspherulite fissures, microcracks, and cavity pores. The diameter of spherulite restricts chilling contraction, especially when the diameter is between the common spherulites and lithophysae, thus benefiting microcrack and cavity pore formation. To summarize, devitrification microporosities represent excellent oil reservoir space, while offering micro-channels for the movement of formation water and organic fluids. However, the inclusion of microcracks improves this capacity.展开更多
文摘The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.
基金supported by National Basic Research Program of China (Grant No. 2009CB219305)
文摘Oil-gas reservoir space types involving spherulite in pyromeride rocks are common in the Lower Cretaceous Shangkuli Formation, the Hailar Basin, China. The main types include interspherulite fissures, interlayer fissures, intraspherulite concentric rings and net microcracks, cavity pores, dissolution pores, and devitrification pores. The first two were found to restrict the effective plane porosity of interspherulite. Devitrification microporosities, microcracks, cavity pores, and spherulite diameter influence the effective plane porosity of intraspherulite. The degree of dissolution is determined by the degree of development and the type of intraspherulite microcracks. Another important role of ring and net microcracks is to connect devitrification pores to form a pore and fissure network. Finally, chilling contraction plays an important role in the form and development of interspherulite fissures, microcracks, and cavity pores. The diameter of spherulite restricts chilling contraction, especially when the diameter is between the common spherulites and lithophysae, thus benefiting microcrack and cavity pore formation. To summarize, devitrification microporosities represent excellent oil reservoir space, while offering micro-channels for the movement of formation water and organic fluids. However, the inclusion of microcracks improves this capacity.
