A new packing variant of catena-poly[[aquachlorocopper(II)]-mu-pyrazine-2-carboxylato-O,N:N'].
Single crystals of the title coordination polymer, [CuCl(C5H3N2O2)(H2O)], have been prepared by hydrothermal synthesis. The compound is composed of infinite one-dimensional chains of pseudo-square-pyramidal Cu(II) ions connected via pyrazine-2-carboxylate ligands. A network of O-H...O hydrogen bonding between adjacent chains is responsible for a bilayer structure different from the previously reported polymorph.
Synthesis and structural characterization of 2-pyrazinecarboxylate zinc compound {[Zn2(Pyz)2(H2O)4] · SO4}n (Pyz = 2-pyrazinic acid)
A solvothermal reaction of 2-pyrazinic acid with Zn(SO4)2 · 7H2O yielded the title complex of the formula {[Zn2(Pyz)2(H2O)4] · SO4}n (I). X-ray diffraction study shows that the complex I crystallizes in mono-clinic system, space group P21/c, with lattice parameters a = 11.2687(6), b = 7.3511(4), c = 11.8506(7) Å, β = 95.070(2)°, V = 977.83(9) Å3, Z = 4, and ρcalcd = 2.184 mg m−3.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.