5min:

IGOR VERTEGEL, EUGENE CHESNOKOV AND ALEKSANDR OVCHARENKO, Institute of Physics National Academy of Sciences of Ukraine 46, Prospect Nauki, 03680 Kiev, Ukraine.

In this work the results of the investigation of the ¹²⁷I NQR spectra at 77K for mixed layered semiconductor crystals (PbI₂)_(1-x) (BiI₃)_(x) in a wide range of value (0 \textless x \textless 0.50) are presented. It is shown that in the range 0.05 \textless x \textless 0.20 of admixture PbI₂ the observed behavior of parameters of the ¹²⁷I NQR spectra testify about entrance of admixture atoms PbI₂ into the crystal layers. It is shown, that at 0.05 \textless  x \textless 0.20 clusters from groups of atoms PbI₂ insular type can be formed, which lay within the limits of the layers of crystal (PbI₂)_(1-x) (BiI₃)_(x). Upon further increasing of the containing of admixture PbI₂ in crystal BiI₃ the “new” ¹²⁷I NQR line is appearing. The observed at x _\textasciitilde 0.20 the new line in spectrum ¹²⁷I NQR can testify that the mixed crystal (PbI₂)_(1-x) (BiI₃)_(x) undergoes structural phase transition. It is concluded that at x\textgreater 0.20 a new crystal presents a solid mixture glassy crystal of substitution type in which of PbI₂ atoms are fully or partially are ordering and lay between crystal .