Effect of nitrogen content on optical properties of transparent γ-AlON polycrystalline ceramics. Issue 7 (July 2021) - Zheng, Kaiping
Abstract: A series of transparent ceramics with the composition of Al(8+ x )/3 O4− x N x ( x = 0.299–0.575) were prepared without any sintering additives by presintering combined with hot isostatic pressing (HIP). The composition of the samples was accurately determined to investigate the effect of nitrogen content on optical properties in γ-AlON. The samples with x = 0.299–0.510 possessed excellent in-line transmittance (>80 %) from the visible light to middle-infrared wavelengths, which was attributed to rare pores and high density in these ceramics. As the increasing nitrogen content, the refractive index increased, the UV absorption edge presented a red-shift, and the transmittance at about 5.5 μm decreased. The Sellmeier optical coefficients E o, λo, S o, and E d were obtained on the basis of the single-term oscillator equation, which associates directly with the electronic energy band structure. The origin of the high refractive index is ascribed to the large electronic polarizability of nitrogen ions.