Formation of PbMnI2 alloys: Structural, photoluminescence and nuclear quadrupole resonance studies

The structural, optical and nuclear quadrupole resonance (NQR) measurements of PbMnI2 alloys were carried out. This allows us to study the peculiarities of the formation of such alloys. It was found that pure PbI2 and Pb1-XMnXI2 crystals with X = (0.03–0.05) have the phase of 2H-polytype. It was shown that the investigated alloys can be presented as the crystal regions of Pb1-XMnXI2 solid solutions, embedded in PbI2 crystal matrix. These formations can be considered as platelet-shaped nanoparticles with a surface of several microns and a thickness of several tens of nm. Thus, PbMnI2 alloys are heterogeneous PbI2–PbMnI2 nanocomposites. The results of NQR spectra measurements also show that Mn2+ ions preferably replace Pb2+ ions in the crystalline layers. Here, the local deformations occur because the radii of Pb2+ and Mn2+ ions differ significantly. The broadening of optical and NQR lines is due to the presence of both these deformations and the crystal field fluctuations, which are characteristic of semiconductor solid solutions.