High performance mid-temperature selective absorber based on titanium oxides cermet deposited by direct current reactive sputtering of a single titanium target

This article reports the design and fabrication of a new double cermet-based low-mid temperature solar selective absorber based on TiOx cermet layers, which were deposited with a single Ti target by varying O2 partial pressure in sputtering chamber as reactive gas. High metal volume fraction cermet 1 and low metal volume fraction cermet 2 were deposited with O2 partial pressure of 0.15 mTorr and 0.25 mTorr, respectively, with direct current power density of 6.58 W cm−2. The complex refractive indices from ellipsometry were used to design solar selective absorber. The reflectance, thermal stability, and morphology were studied in absorbers on Cu and stainless steel. The effect of TiO2 and SiO2 as anti-reflective coating layers was investigated. The absorber on Cu substrate has high absorptance of 90.8% and low emittance of 4.9% (100 °C), and changed to 96.0% and 6.6%, respectively, after annealing at 300 °C for 4 days.