Lattice variation and thermal parameters of NixMg1-xSO4 center dot 7H(2)O single crystals

Ni(x)Mg(1-x)SO(4)(.)7H(2)O single crystals were grown by the slow evaporati on method from aqueous solutions. Density was measured by the floatation me thod. X-ray diffraction data were collected for powder samples and used for the estimation of lattice variation and thermal parameters like Debye-Wall er factor, mean-square amplitude of vibration and Debye temperature. Lattic e volumes approximately obey a relation similar to Retger's rule. Values of thermal parameters do not follow any particular order with composition. Th e results obtained are reported.