Tuning of structural and optical properties by sintering of multiferroic GdMnO3 precursor

Multiferroic GdMnO3 was synthesized by the modified sol-gel route. The GdMnO3 precursor were sintered for 2hours at different temperatures ranging from 300 (GMO300) to 800 degrees C (GMO800). X-ray diffraction pattern shows that the crystallinity improves with sintering temperatures. The Raman data and Fourier transform infrared analysis also support the X-ray diffraction data. UV-Visible spectrum of the sample GMO300 shows absorption peak at 2.39eV whereas the completely crystallized sample sintered at 800 degrees C (GMO800) shows two absorption bands at 2.25 and 2.56eV. These bands are attributed to the Mn (d-d) transitions. Higher energy bands at (3.27 and 4.94 eV) of GMO700 and (3.26, 4.40, 4.74 and 5.08 eV) of GMO800 are attributed to the charge transfer transitions from O(2p) to Mn(3d) state. Moreover, the completely crystallized sample (GMO800) exhibits the signature of magneto-dielectric coupling.