The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the ...The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale（<100 nm） at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 3050 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.展开更多
The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffract...The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffraction. The complex belongs to a triclinic system, space group P?with a = 6.645(1), b = 9.870(2), c = 13.263(3) ? a = 70.68(3), b = 76.27(3), g = 71.66(3), V = 770.5(3) 3, Mr = 808.58, Dc = 1.743 g/cm3, Z = 1, m = 0.968 mm-1, l(MoKa) = 0.71073 and F(000) = 416. The final R = 0.0465 and wR = 0.1091 for 2974 observed diffractions with I ≥ 2s(I). In the complex, the V atom is octahedrally coordinated to the oxo ligand, two N and three O atoms of the triethylenetetraaminehexaacetic (TTHA) ligand. All of the ten chelating sites are coordinated to the two vanadium atoms, and the coordination octahedron is distorted. Each [V2O2(ttha)]2- ion is further connected by the K+ ions through carboxyl groups of TTHA6- ion, forming a two dimensional network structure.展开更多
基金the Foundation of the Ministry of Science and Technology of China(No.G19990 2 2 4 0 8and0 0 1CB10 890 6 )
文摘The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale（<100 nm） at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 3050 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.
基金the National Natural Science Foundation of China (20173046)
文摘The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffraction. The complex belongs to a triclinic system, space group P?with a = 6.645(1), b = 9.870(2), c = 13.263(3) ? a = 70.68(3), b = 76.27(3), g = 71.66(3), V = 770.5(3) 3, Mr = 808.58, Dc = 1.743 g/cm3, Z = 1, m = 0.968 mm-1, l(MoKa) = 0.71073 and F(000) = 416. The final R = 0.0465 and wR = 0.1091 for 2974 observed diffractions with I ≥ 2s(I). In the complex, the V atom is octahedrally coordinated to the oxo ligand, two N and three O atoms of the triethylenetetraaminehexaacetic (TTHA) ligand. All of the ten chelating sites are coordinated to the two vanadium atoms, and the coordination octahedron is distorted. Each [V2O2(ttha)]2- ion is further connected by the K+ ions through carboxyl groups of TTHA6- ion, forming a two dimensional network structure.
