Synthesis and Growing up a New Coloured Crystal from An Isomorphous Substances by Using The Overgrothes Phenomenon and Studied Its Pysical , Mecanical and Crystallographic Properties

Abstract

Three crystals of sulfate salt were prepared under lab environments , these are
: KAl(SO4)2.12H2O , Cr2(SO4)3 and KAlCr(SO4)2.12H2O . The physical and
mechanical properties for the KAl(SO4)2.12H2O and KAlCr(SO4)2.12H2O crystals
were studied . We deal with the latter crystal which called overgrowths and prepared
from the isomorphous substances ( aluminum sulfate and chromium sulfate ) .We
prepared this crystal by insertion few Cr atoms in the same places of Al atoms in the
KAl(SO4)2.12H2O cubic lattic crystal . The crystallographic properties of an
overgrothes crystal were studied. The new crystal crystallizes in the cubic system ,
space grope pa-3 . The cell dimentions are : a = b = c = 12.135 AO, α = β =γ =90o ,
volume of Al cell = 1786.98 *106 pm3 , volume of Al – Cr cell = 1800.26 *106 pm3
and Z=4 . The volume of cell indicates that the chemical composition of the two
layers of crystal are different as it shown in formula data obtained from X – Ray
analysis . the retsults obtained from FT-IR and UV. Visib. Spectrum are also support
this conclusion .