X-ray powder diffraction studies are performed on solid CD4-Kr solutio
ns from helium to their melting points at Kr concentration 20-35%. The
phase boundaries are specified in the phase equilibrium diagram. A re
gion of two coexists phases is revealed at T > 24 K. The phases have t
he similar fcc-symmetries but differ in molar volumes and apparently i
n the degree of the rotational motion retardation of CD4 molecules in
them. This region corresponds to the krypton concentrations in deutero
methane 28-32% at 24 K, the critical concentration being x(c) congruen
t-to 29% Kr. Unlike other binary cryosolutions, this system is noted f
or the narrowest region of stratification into two isomorphic phases (
approximately (5 +/- 2)%) and the lowest critical temperature (approxi
mately 52 K).