Study of optical constants and dielectric properties of nanocrystalline α-cordierite ceramic

Abstract

The nanocrystalline 2 Mg.2Al2O3.5SiO2 as amorphous-type α-cordierite was prepared by the modified sol-gel (or Pechini) technique. After calcination at 800ºC, the pressed powder as disk pellets was sintered at 1150ºC, 1250ºC, and 1350ºC. The structural information of α-cordierite was obtained by X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman scattering spectra, and Fourier transform infrared (FTIR) spectra. The XRD and Raman spectra showed that the nanocrystalline α-cordierite phases from pellets of glass-ceramic powders appeared when the temperature increased. The SEM results confirmed the rounded shape of the nanocrystalline α-cordierite. Using Kramers–Kronig (KK) method, the FTIR spectroscopy was evaluated. The increasing synthesized temperature increased the size of nanocrystalline. Furthermore, by increasing the synthesized temperatures the optical constants of nanocrystalline, both real and imaginary parts of the refractive index and dielectric function decreased. Consequently, the transversal optical (TO) and longitudinal optical (LO) phonon frequencies shifted to red frequencies by increasing reaction temperature.

Keywords

• cordierite
• kramers-kronig
• dielectric coefficient
• optical properties