Cadmium clusters in CdI₂layered crystals: the influence on the optical properties

Abstract

The influence of overstoichiometric Cd i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI 2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cd i concentration and features in absorption and emission spectra up to concentrations of 10 18 cm −3. At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of (CdI i) n clusters are calculated in the frame of Mie theory and are found to correlate with the optical studies.

Calculations of structural, elastic, electronic, and optical properties of trigonal CdI2

“…3). Our results are better than the previously calculated data (the direct gap 1.6 eV and the indirect gap 1.0 eV) [1], but all of these data are smaller than the experimental data (the indirect bandgap 3.2 eV [35] and the direct gap 3.6 [2,36], 3.8 eV [37]) due to the well-known underestimation of conduction-band state energies in DFT calculations. Figure 4 shows the total and the partial density of states of trigonal CdI 2 .…”

Studies of CdI2-Bi3 microstructures with optical methods, atomic force microscopy and positron annihilation spectroscopy

“…and τ b are almost unchanged, while positron trapping rate in defects, κ d in CdI 2 -BiI 3 decreases to 0.30 ns as compared to CdI 2 (Table 1). It means that existing free volume voids in pure CdI 2 should be converted into a smaller number of larger voids after doping with BiI 3 . In other words, we can argue that doping CdI 2 crystals with BiI 3 causes agglomeration of smaller free-volume entities and formation of complex clusters composed of smaller vacancies.…”

“…Due to peculiarities of the structural arrangement of CdI 2 there are specific ways of the incorporation of impurities or overstoichiometric Cd atoms into the crystal lattice. Therefore, a number of reports were devoted to the studies of doped CdI 2 crystals and crystals with excess of cadmium (see [2][3][4]). In particular, as demonstrated earlier [5], interesting changes in optical absorption are observed when CdI 2 is doped with BiI 3 (which is another layered compound).…”

A Metasurfaces Review: Definitions and Applications

“…It was found that these multiple layers of artificial dielectrics could replicate the reflection coefficient of real materials, frequency selective surfaces, and even complex reflection profiles of arbitrary bespoke materials [54]. In related work, it was found that layered Cadmium iodide crystals of different sizes could be used to control the absorption over optical wavelengths [55].…”