Raman spectroscopic studies of CuFeO2 at high pressures

Comparative study of the structural and optical properties of epitaxial CuFeO2 and CuFe1−xGaxO2 delafossite thin films grown by pulsed laser deposition methods

“…The Ga content was estimated at 25% taking into account the onset of strain resulting from the increased lattice mismatch between CuGaO 2 and the Al 2 O 3 substrate. Figure 3 shows the spectral region corresponding to expected delafossite peak Raman shift(s); these results show good agreement with expected Raman shift positions as reported by [23]. The CuFeO 2 samples showed a typical delafossite spectrum with three main peaks at 350, 511 and 689 cm -1 .…”

“…The CuFeO 2 samples showed a typical delafossite spectrum with three main peaks at 350, 511 and 689 cm -1 . The peak located at 350 cm -1 was attributed to the E g vibrational mode along the c-axis of the octahedral structure, the peak at 689 cm -1 was attributed to the A1g vibrational mode along a plane perpendicular to the c-axis; the peak at 511 cm -1 was attributed to non-zero wave vector phonons typical of crystalline defects, as described in [23]. [24], therefore the Ga content must explain the shifting observed in our results.…”

Copper Delafossites under High Pressure—A Brief Review of XRD and Raman Spectroscopic Studies

“…While both the Raman modes harden under pressures up to 18 GPa, the first transition around 18 GPa to the reported monoclinic C2/c phase is indicated by splitting of the E g mode. This is accompanied by softening of A g mode thereafter [76]. Figure 12b shows the pressure dependence of mode frequencies.…”

Optical and structural properties of CuCrO 2 thin films on c-face sapphire substrate deposited by reactive RF magnetron sputtering

“…Primitive unit cell of CuCrO 2 (space group Rm) consists of 4 atoms resulting in 12 normal modes of vibration which are written in terms of irreducible representation as Γ=A 1g +E g +3A 2u +3E u . The E modes represent the triangular lattice vibration perpendicular to the c-axis, and the A modes represent the O-Cu-O bonds vibration along the c-axis [15,16]. CuCrO 2 thin film exhibited Raman shifts at 203 (A g ), 450 (E g ), and 705 cm −1 (A 1g ) [17].…”

“…CuCrO 2 thin film exhibited Raman shifts at 203 (A g ), 450 (E g ), and 705 cm −1 (A 1g ) [17]. CuCrO 2 should only have E g and A 1g active modes [15,18], but the spectra showed A g peak relating to non-zero wavevector phonon which is normally forbidden by Raman selection rules. It is considered that the selection rules were relaxed by the tilted orientation and intrinsic defects, for example Cu vacancies, O interstitials, or tetrahedrally coordinated Cr 3+ ions at the Cu site [17,18].…”