Abstract:We report on the evidenced orbital mediated electron -phonon coupling and band gap tuning in HoFe 1-x Cr x O 3 (0 ≤ x ≤ 1) compounds. From the room temperature Raman scattering, it is apparent that the electron-phonon coupling is sensitive to the presence of both the Fe and Cr at the B-site. Essentially, an A g like local oxygen breathing mode is activated due to the charge transfer between Fe 3+ -Cr 3+ at around 670 cm -1 , this observation is explained on the basis of Franck-Condon (FC) mechanism. Optical absorption studies infer that there exists a direct band gap in the HoFe 1-x Cr x O 3 (0 ≤ x ≤ 1) compounds. Decrease in band gap until x = 0.5 is ascribed to the broadening of the oxygen p -orbitals as a result of the induced spin disorder due to Fe 3+ and Cr 3+ at B-site. In contrast, the increase in band gap above x = 0.5 is explained on the basis of the reduction in the available unoccupied d -orbitals of Fe 3+ at the conduction band. We believe that above results would be helpful for the development of the optoelectronic devices based on the ortho-ferrites.

Low-temperature, symbiotic synthesis of nanocomposites, with heat of formation of phase1 crystallizing phase2, and phase2 preventing grain growth of phase1.

No abstract

No abstract

No abstract