On possible states of the crystal structure preceding to a phase transition in Zn$_{1-x}$V$_{x}$Se (0.01 $\le x\le$ 0.10) crystals

The systematic new formations observed in the reciprocal lattice of the cubic structural modification of a II–VI compound are characterized using a detailed neutron diffraction study of bulk semiconducting ZnSe crystals with an increased vanadium content. Direct evidence that the additional sites $k$ = (1/3 1/3 1/3) 2$\pi/a$ ($k$ is the wave vector and $a$ is cubic unit cell parameter) observed by neutron scattering in the crystals, in the case when they belong to mutually penetrated rotated sublattices, contain a superstructure contribution formed by short-wave deformation, is obtained for the first time. This structure state is determined as a pretransition to the concentration fcc–hcp phase transformation, and the basis functions that allow one to analyze atomic displacements, the correlation between which create distortion-type superstructures, are indicated for the transition through one-arm channel, considering the transitions by the star of wave vector $k_5$ of the fcc lattice.