LAUSR

Abstract Nonstoichiometric ceria, CeO 2- δ , has emerged as a promising redox material for thermochemically splitting H 2 O and CO 2 using concentrated solar energy. Knowledge of its radiative properties is crucial for the design of efficient solar reactors. Samples of various nonstoichiometries (0≤ δ ≤0.0377) were prepared by thermal reduction in a thermogravimetric analyzer at high temperatures ( T ≥1473 K) and under low oxygen partial pressures ( p O2 ≤2.5·10 −4  atm). The spectral hemispherical reflectivity was measured using a spectroscopic goniometry system in the spectral range 300–2800 nm. A porous ceria sample with interconnected µm-sized pores showed comparable selectivity because of its high optical thickness. The total hemispherical reflectivity was computed for emission temperatures in the range 900–6000 K relevant to solar reactors.