  We have performed high resolution x-ray scattering measurements on single
crystal samples of Ba(Fe(1-x)Cr(x))2As2 (x = 0 to 0.335). These measurements
examine the effect of Cr-doping on the high temperature tetragonal (I4/mmm) to
low temperature orthorhombic (Fmmm) structural phase transition of the parent
compound BaFe2As2. Increasing Cr concentration is found to suppress the
structural transition temperature (Ts), and reduce the magnitude of the
orthorhombic strain (delta). The doping dependence of the orthorhombic strain,
combined with complementary measurements of the high temperature magnetic
susceptibility, suggests the presence of a magnetostructural crossover at x ~
0.05. In particular, this crossover appears to mark a shift from strong to weak
orthorhombicity and from predominantly itinerant to localized magnetic
behavior.
