X-ray diffraction under specular reflection conditions on bicrystal and the determination of mismatch of lattice parameter

The potentiality of determination of lattice parameter small variations (Δa/a < or approx. 10-5-10-6) in thin surface layers of crystals by X-ray diffraction under specular reflection conditions has been theoretically studied. It has been shown that the small variations of lattice parameters in layers as small as ∼ 10-100 A display explicity in the shape of diffraction curves taken depending on the take-off angle of departure of the diffracted waves from the crystal surface and cause small angle scattering in the direction of a specularly reflected beam