جستجوی مقالات مرتبط با کلیدواژه « انتقال فاز » در نشریات گروه « زمین شناسی »

In this research, pyrophyllite phase transfer to tobermorite group and sodic to calcic zeolites was investigated in presence of NaOH and CaCl2 solutions. The experiments were carried out in three separate stages under constant hydrothermal conditions (temperature 150 °C, time 72 h) in the Teflon-lined autoclaves. The chemical composition of the initial sample was determined by XRF. Morphology and mineralogy of samples were characterized by SEM and XRD, respectively. The results showed that leucite and sodic zeolites (analcime, sodalite) were formed at variable concentration of NaOH (1–8 mol/l). The calcic zeolite was not synthesized in the presence of Na+ (1.5–2.5 mol/l) and Ca+2 (0.25-1 mol/l), but riversideite, hibschite, halite, hydroxycancrinite and trikalsilite were detected. Riversideite (a member of tobermorite group) and hibschite (a type of hydrogrossular) were formed at highest concentration of Ca+2 (1 mol/l), and halite was produced as a main product at lowest concentration of Ca+2 (0.25 mol/l). The concentration of Ca+2 and Na/Ca ratio are the main factors in the synthesis of these products.

A nickel complex with pyridine-2,6-dicarboxylic acid formulated as [Ni(pydcH)2].3H2O was synthesized and its crystal structure determined with single-crystal X-ray at diffraction temperatures (296 K and 120 K). Pyridine-2,6-dicarboxyli acid deprotonated on one group of COOH and two pydcH- anion is coordinated to Ni(II) atom as a tridentate ligand forming a distorted octahedral environment. The phase transition in crystal system is obtained with differ in temperature. The title compound is crystallized in monoclinic system with P21/c space group at 296 K, while it is crystallized in triclinic system with CAWT IMAGE space group at 120 K.