Open AccessAnalytic dependence of the Madelung constant on lattice parameters for 2D and 3D metal diiodides (MI2) with CdI2 (2H polytype) layered structure
Author(s) -
Valeri S. Harutyunyan
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
ISSN - 2053-1591
DOI - 10.1088/2053-1591/ab6fa9
Subject(s) - lattice constant , madelung constant , metal , lattice (music) , crystal structure , materials science , constant (computer programming) , lattice energy , work (physics) , crystallography , thermodynamics , chemistry , physics , quantum mechanics , computer science , programming language , diffraction , acoustics , metallurgy
In this theoretical study, the Madelung constant ( A M ) both for a 2D layer and parent 3D bulk crystal of metal diiodides MI 2 (M = Mg, Ca, Mn, Fe, Cd, Pb) with CdI 2 (2 H polytype) structure is calculated on the basis of the lattice summation method proposed in author’s earlier work. This method enabled, both for a 2D layer and 3D bulk crystal of these compounds, to obtain an analytic dependence of the Madelung constant, A M ( a, c, u ), on the main crystallographic parameters a , c , and u . The dependence A M ( a, c, u ) reproduces with a high accuracy the value of the constant A M not only for metal diiodides MI 2 with CdI 2 (2 H polytype) structure, but also for metal dihalides (MX 2 ) and metal dihydroxides [M(OH) 2 ] with the same structure. With the use of the high-pressure experimental results available in literature particularly for FeI 2 , it is demonstrated that the above analytic dependence A M ( a, c, u ) is also valid for direct and precise analysis of the pressure-dependent variation of the Madelung constant.