Phonons in silver gallium diselenide

Abstract

The dispersion curves along the directions [100] and [001] of have been measured by inelastic neutron scattering. The results are analysed with different rigid-ion models: Born - von Karman and valence force field models, which give a good agreement with experiments. Additional measurements of the acoustical branches allow us to determine elastic stiffness constants which are () , , , , , . The compressibility calculated from these constants is in accordance with the experimental value.

Adiabatic bond charge model for lattice dynamics of ternary chalcopyrite semiconductors

“…Except for CuGaS 2 and CuGaSe 2 Group I -Group VI interaction parameter is lower than that of Group IIIGroup VI. The ratio of 1 2 / 1/2 φ φ ′′ ′′≈ for AgGa-based systems seems to be common with similar interactions considered in valance-force field models of Fouret et al [17] and Artus et al [25]. Ion-BC central interaction term for Group I-BC interaction is negative for almost all the systems considered here we think this is related to the fact that BC picture is not very applicable for the Group I -Group VI bond.…”

“…[3] are Raman [4][5][6][7][8][9][10][11][12], Infrared [13][14][15][16] and neutron scattering [17,18] results). Theoretical studies of same properties can be divided into two main groups: phenomenological models and ab initio calculations.…”

“…Theoretical studies of same properties can be divided into two main groups: phenomenological models and ab initio calculations. Among phenomenological models for chalcopyrite zone center phonons one can count Born-von Karman [17,18], rigid ion [19][20][21], Urey-Bradley force field model [22], valence force field [17,18], universal force field [23] and Keating models [24][25][26][27]. Ab initio lattice dynamical calculations of several members of this family (AgGaSe 2 [28][29][30], AgGaTe 2 [30], AgGaS 2 [31], CuInSe 2 [32,33], CuInS 2 [34,35] and CuGaS 2 [36]) have been reported.…”

Phonons calculated from first-principles

“…In the past the phonon dispersion curves and phonon density of states have been successfully calculated for T iC [9], ZrC [10], MgO [11], BN [12], GaN [8], HgSe [13], ZnT e [14], F eBO 3 [15], AgGaS 2 [16], AgGaSe 2 [17], AgGaT e 2 , CuI nS 2 [18], CuI nSe 2 [19], ZnSnP 2 [20], AgGaSe 2 [21], CuI nSe 2 [22], CuI nSe 2 [23], Ba 8 Si 46 [24], Ba 24 Si 100 [25], UCoGa 5 [26], P uCoGa 5 [27].…”

Lattice dynamics and related properties of AIBIII and AIIBIV compounds, I. Elastic constants

“…Eimerl et al [60] have used ultrasonic wave velocity measurements on single crystals at temperatures close to room temperature (T ~ 0 -50ºC) to determine the elastic stiffness constants. Inelastic neutron scattering at room temperature and atmospheric pressure [61] has been used as the second experiment to deduce the complete set of elastic stiffness constants from the slope of the acoustic phonon branches measured along the directions [001], [100], [110], [101] and [111]. However, comparing the results of both experiments (Table 4) it is obvious that agreement is far from being satisfactory.…”