Electronic structure and optical properties of Cs2HgI4: Experimental study and band-structure DFT calculations

Single crystal growth, electronic structure and optical properties of Cs2HgBr4

“…In the present work, results of calculations of the optical properties using the theoretically obtained E g value for Cs 2 HgBr 4 are reported. It should be mentioned that, similar DFT band-structure calculations of Cs 2 HgI 4 gave the theoretical E g = 2.177 eV, which is in fair agreement with the experimental E g = 2.34 eV for this iodide at room temperature [35]. In the latter work, it has been established that there is no need to make scissors corrections when calculating the mentioned optical characteristics of Cs 2 HgI 4 .…”

“…single crystal surface before and after its Ar + ion-bombardment. Binding energies of cesium and mercury atoms of the relative iodide, Cs 2 HgI 4 , that were measured recently using the same apparatus and experimental conditions [35], are also listed in Table 1 was observed recently in the top surface layers of the Cs 2 HgI 4 single crystal [35]. Interestingly, as can be seen from data listed in Table 1 However, the LDA+U model [26,27] in known to overcome this problem.…”

“…In our APW+lo calculations, the value U = 9 eV was used. Furthermore, due to the fact that Cs and Hg are considered to be heavy elements [35], in our band-structure calculations spin-orbit coupling (SOC) [37][38][39] has been taken into account. Application of SOC in band-structure calculations of compounds based on heavy elements (e.g., U, Np, Pu, Am, Th, etc.)…”

Facile sonochemical method for preparation of Cs2HgI4 nanostructures as a promising visible-light photocatalyst

“…Cesium mercury tetraiodide, Cs 2 HgI 4 belongs to an attractive group of M 2 NX 4 syntheses (N = Hg, Cd, Zn, Mn, Co; X = Cl, Br, I) comprising isolated tetrahedral NX 4 2- ions [11] . Two groups exist at room temperature in the A 2 BX 4 compounds either in a monoclinic Sr 2 GeS 4 -type structure with a space group P2 1 /m [12] , [13] or an orthorhombic β-K 2 SO 4 -type structure with a space group Pnma [14] . Due to the A 2 BX 4 compounds containing Cs, practically all of them are crystallized in the orthorhombic β-K 2 SO 4 -type structure [15] , [16] ; nevertheless, just two syntheses, namely Cs 2 HgI 4 and Cs 2 CdI 4 , form in the monoclinic structure of Sr 2 GeS 4 -type [17] , [18] .…”

“…However, upon heating, Cs 2 HgI 4 and Cs 2 CdI 4 convert from the monoclinic structure of Sr 2 GeS 4 -type (α-phase) to the orthorhombic structure of β-K 2 SO 4 -type (β-phase), and this transmutation is identified as α → β phase transition [19] . For Cs 2 HgI 4 , the α → β phase transition transpires at around 520 K [20] or 523 K [12] . Shimizu et al [20] showed that α → β transformation in Cs 2 HgI 4 is a first-order phase transition using Differential Thermal Analysis (DTA).…”