Structural and optical characterization of MgO: X (XÂ =Â Li, Na, and K) by solution combustion technique

Pure MgO and Li, Na and K doped MgO nanocrystallites were synthesized by solution combustion method. XRD analysis reveals that all the MgO doped nanocrystals exhibited cubic structure. Scanning electron microscopy (SEM) studies revealed the spherical crystal structure for MgO:Na with small porous spherical structure for MgO:K. The UV-VIS showed that band gap is blue shifted for as-prepared samples and red shifted for the annealed samples. The result suggests that MgO nanocrystallites were transformed from semi-insulator to semiconductor while doped with alkali metals. FT-IR shows the band at 472 cm−1, associated with the characteristic vibrational mode of symmetric MgO6 octahedral of MgO. FT-Raman spectra show the peaks below 1500 cm−1 associated to D-bands and peak at 1918 cm−1 represents the G-band.