CONCENTRATION DEPENDENCE OF I-127 NQR SPECTRUM PARAMETERS FOR MIXED LAYERED SEMICONDUCTORS (BiI3)(1-x)(PbI2)(x)

The results of our studies dealing with the NQR spectra of I-127 in mixed layered semiconducting crystals (BiI3)(1-x) (PbI2)(x) measured at a temperature of 77 K and in a wide range of PbI2 contents x (0 < x < 0 : 5) are reported. In the range 0 : 05 < x < 0 : 2; the observed behavior of I-127 NQR spectrum parameters testifies that PbI2 atomic groups are located within the structural layers of a BiI3 crystal. In this x -range, clusters composed of PbI2 groups were demonstrated to form an island structure. A further growth of the PbI2 content results in the appearance of a new I-127 NQR line which testifies that the mixed crystal (BiI3)(1-x) (PbI2)(x) undergoes a structural phase transition at x approximate to 0 : 2. A conclusion is made that, at x approximate to 0 : 2; the synthesized crystal is a glassy substitutional solid solution, in which PbI2 atomic groups, being completely or partially ordered, are intercalated between the BiI3 crystal layers.