The structure of triclinic disodium hafnium disilicate, Na2HfSi2O7, has been determined by laboratory powder X-ray diffraction and refined by the Rietveld refinement. The structure is a framework made of alternate layers of HfO6 octa-hedra and SiO4 tetra-hedra linked by common O atoms. Sodium atoms are located in the voids of the framework, aligned into tunnels along the [010] direction. Na2HfS...

The structural characterization of the new iron-zinc hepta-borate bromide with composition Fe(1.59)Zn(1.41)B(7)O(13)Br, prepared by chemical transport is reported. A rigid-body model with constrained generalized coordinates was defined in order to hold the positions of the B atoms at reasonable inter-atomic distances that typically would reach unacceptable values because of the weak scattering ...

With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom...

PdZn catalysts have been proven to be a viable option to replace current Cu catalysts for methanol steam reforming. The change in selectivity to CO2 that makes this a possibility has been attributed to the formation of tetragonal β1-PdZn at treatment temperatures of 500 o C. Through the course of studying the phase evolution of the 1:1 PdZn, it was seen that an intermediate Pd2Zn phase formed a...

Binary oxides of Mg and Ti were prepared by the sol-gel technique in various Mg/Ti atomic ratios, r. Metastable phases, produced between 873 and 973 K from xerogels with Mg/Ti atomic ratios in the range ~1.1 < r ≤ 2, were studied by XRD and ND. XRD analysis showed crystal structures similar to that of Mg2TiO4 (qandilite), an inverse spinel of cubic structure. The composition range where this oc...