Synthesis and Characterization of New Nickel Phosphates, ANi4(PO4)3(A=K, Rb)

Abstract

for 72 h. The tube was cooled to room temperature at the rate of 12 K/h. In both cases, the excess halide was removed with distilled water and yellow needle-shaped crystals were obtained. The role of chalcogens in the reactions is not clear but it is helpful to obtain the product as single crystals. The crystals are stable in air and water. A qualitative X-ray fluorescence analysis of the crystals indicated the presence of K or Rb, Ni, and P. The compositions of the compounds were determined by single-crystal X-ray diffraction. Crystallographic Studies. The structures of ANi4(PO4)3 (A=K, Rb) were determined by single crystal X-ray diffraction methods. Preliminary examination and data collection were performed with Mo Kα1 radiation (λ = 0.71073 A) on a RIGAKU R-ASXIS RAPID diffractometer. The cell constants and an orientation matrix were determined from leastsquares, using the setting angles in the range 3.0 o < θ < 27.5 o . The crystallographic details are described in Table 1. Intensity data were collected with the ω scan technique. The intensity statistics and systematic absences are consistent with the orthorhombic space group, Pnnm. The initial positions for all atoms were obtained by using direct methods