No abstract

The structure of binary (PbO) x (P 2 O 5 ) .1−x/ glasses was investigated using Raman scattering and infrared spectroscopy, over the compositional range x = 0.5-0.68. The distribution of the phosphate groups (PO 2 ) − , (PO 3 ) 2− , (P 2 O 7 ) 4− and (PO 4 ) 3− , determined from the simulation of Raman spectra in the 800-1500 cm −1 wavenumber range, indicates a significant disproportionation reaction near the pyrophosphate composition and shows a phosphorus connectivity scheme in the glass structure in agreement with 31 P magic angle spinning NMR results. The low-wavenumber Raman spectra of glasses are discussed in the light of the spectra of crystals. The mode laying in the far-infrared region and due to lead-oxygen vibrations exhibits a composition-dependent wavenumber that correlates with bulk glass properties such as glass transition temperature.

The normal spectral emittance of a partially yttria‐stabilized hafnia (YSH) ceramic has been measured by infrared emittance spectroscopy in a spectral range going from 60 to 17 500 cm−1 (0.075–2.2 eV), and up to 2350 K. Using these experimental data, the temperature dependence of the absorption coefficient and the total emittance have been calculated. The physical mechanisms explaining the spectral features of the whole set of spectra are exposed qualitatively. The spectral weight of each contribution is then discussed for interpreting the influence of temperature on the total normal emittance in the range of temperatures (1200–2500 K) where YSH ceramics can be used for their refractory properties (thermal barrier coating, nuclear reactor, thermal protection systems, etc.).