The preparation of thermally stable TiNx/Ag(Mo)/TiNx ultrathin films by magnetron sputtering

• TiNx/Ag(Mo)/TiNx/films were thermally durable until 773 K.
• High visible transmittance was obtained by adopting the amorphous TiNx films.
• Ag(Mo) film was protected until 773 K by partial oxidation of TiNx layers.

Thermally stable optically selective coatings are indispensable for low emissivity (low-e) applications. Low-e coatings effectively reduce energy loss from the building glazing systems by allowing high visible transmittance and reflecting most near-infrared radiation of the solar spectrum. In the present study, we investigated the thermal stability and optical properties of TiNx/Ag(Mo)/TiNx films deposited on glass substrates by using rf and dc magnetron sputtering at room temperature. The deposited multilayer stacks were annealed up to 873 K for 1 h in air ambient and a rigorous analysis was presented on the structure, microstructure, topography, chemical composition, and optical properties by grazing incidence X-ray diffraction, high resolution transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Auger electron spectroscopy, and Ultraviolet–visible–near infrared spectrophotometer, respectively. The results revealed that the proposed structure was thermally stable with dense and smooth microstructure until 773 K; in addition, noteworthy inward/outward diffusion of silver was not observed due to the good diffusion barrier performance of TiNx. An abrupt rise in root mean square roughness and locally isolated islands like structures was observed at 873 K annealing temperature. The deposited films showed high transmittance in the visible region and high reflectance in the infrared region of the solar radiation spectrum.