OPTICAL PHONONS IN I-III-VI₂ COMPOUNDS

Abstract

Rhumb.-Les phonons optiques (k-0) de CuInS2, AgInS2 et CuFeS, ont ete analyses par des mesures d'absorption et de reflexion dans la region de 1 000 jusqu'a 50 cm-1. La determination des frequences des phonons optiques transversaux et longitudinaux a et6 effectuk B I'aide dqCquations Kramers-Kronig ainsi que de modtles classiques d'oscillateurs. Les rksultats sont cornparks aux spectres connus de CuAIS,, CuGaS2 et AgGaS2. Une comparaison systematique des frequences des modes montre quc les constantcs de force des differents coniposes 1-111-S2 sont presque egales. Les differences des frequences des modes correspondants paraissent dependre principalement des differentes masses des cations.

Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

“…The B 2 and E modes are also IR active, and they present LO-TO splitting due to their polar character. From all these modes the A 1 symmetry ones are expected to be the strongest lines in the Raman spectra, in agreement with the behaviour observed for the closely related chalcopyrite crystals [9].…”

Optical phonons in AgGaSe2

“…Note that these modes in AgGaSe, have significantly higher energies than the equivalent ZnSe and CdSe energies. This is similar to the situation in the sulphide compounds discussed by Koschel et al [17] and is due to the difference in the bond stretching force constants of the two different bonds in chalcopyrite and the binary compounds. From the increased covalency going from a I-VI to a 111-VI bond [ 181, the force constants are expected to differ in the order, a(Ag-Se) < a(ZnSe) < a(GaSe).…”

“…3 [19,20]. For both CuGaS, and AgGaS, the frequency of the r15(B2 + E) modes are extremely close to that of GaP [17].…”

ELECTRICAL BEHAVIOR OF A Cu2Fe0.4Co0.6SnS4 CERAMIC

“…The DTA, in all of the samples, presented an important endothermic signal, which is consistent with an incongruent melting point that has also reported for the related compounds Cu 2 MnSnSe 4 [16] The Raman spectra ( Figure 4) showed two main peaks; the most intense peak occurred at approximately 320 cm -1 , and a smaller shoulder was found at 290 cm -1 , which can be assigned to the symmetry mode (A1). These vibrations can be interpreted as the "breathing" mode of the MS 4 tetrahedral (M = Fe, Co) and SnS 4 , according to the assignment proposed by Koschel et al [19,20]. , which are characteristic of this type of compounds [21,22].…”