Abstract

Photopyroelectric spectroscopy is used to investigate the optical absorption behaviour of the ceramic composite (ZnO + 1 MnO + y Dy₂O₃), where y = 0 - 2 mol%. Ceramics were sintered at 1200 and 1300°C for 1 and 5 h. PPE spectrum with reference to the doping level and sintering time is discussed. Optical energy band-gap (E_g) is determined from the plot (ρhυ)² vs hυ. It is found that the the value of E_g is reduced from 3.2 (pure ZnO) to 2.15 eV at the 0 mol% of Dy₂O₃ and is further reduced to 2.04 eV at the 2 mol% of Dy₂O₃ for 5 h sintering time at the 1300°C sintering temperature.  Steepness factor σ_A and σ_B which characterizes the slope of exponential optical absorption is discussed with reference to the variation in the value of E_g. The phase constitution is determined by XRD analysis. Microstructure and compositional analysis are analyzed using SEM and EDAX. The maximum grain size and density of the ceramic were found to be 14 µm, 89%, respectively.

Key words: Photopyroelectric spectroscopy, ZnO, optical energy band-gap, Dy₂O₃.