RT journal article
T1 Nb-Doped VO2-Based Coatings on Glass: Substrate Effects, Thermochromic Performance, and an Effective Transition Temperature for Smart-Glazing Applications
A1 Santos Izquierdo-Bueno, Antonio Jesús
A1 Casas Acuña, Andrea
A1 Mánuel, José M.
A1 Jiménez, Juan  J.
A1 Obrero Pérez, José Manuel
A1 Benedetto, Davide
A1 Martin, Nicolas
A1 Morales Sánchez, Francisco Miguel
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
A2 Física de la Materia Condensada
K1 glancing angle codeposition
K1 Nb-doping
K1 rapid thermal annealing
K1 smart glazing
K1 substrate effect
K1 thermochromic behavior
K1 vanadium dioxide
AB Niobium-doped VO2 thin films were deposited on soda-lime and borosilicate glass substrates to investigate the coupled effects of dopant concentration, substrate chemistry, and thermal processing on microstructure, thermochromic performance, and metal–insulator transition (MIT) kinetics. Coatings with nominal Nb contents of 3, 4.5, and 6 at. % were fabricated using controlled mono- and multilayer codeposition strategies followed by rapid thermal annealing. Structural and morphological analyses confirm VO2(M) as the dominant phase on both substrates, while revealing a strong substrate-dependent stability of secondary phases driven by Na diffusion, especially in soda-lime glass. Advanced scanning-transmission electron microscopy image and spectroscopic-related techniques demonstrate that Nb exhibits a less homogeneous spatial distribution than other dopants (such as W) under comparable processing conditions, leading to compositional modulations and multistep MIT behavior, particularly on soda-lime substrates. In contrast, borosilicate glass enables enhanced grain coalescence, reduced Na-induced phase instability, and a more uniform Nb incorporation. These microstructural differences directly impact the optical response. Borosilicate-supported coatings exhibit a more favorable balance between luminous transmittance (Tlum) and solar modulation efficiency (ΔTsol), while films on soda-lime glass show a progressive degradation of ΔTsol at higher Nb contents. Despite a lower Tc reduction efficiency compared to W, Nb doping preserves or even improves Tlum at elevated concentrations. Finally, an application-oriented effective transition temperature, Teff, is proposed as a more realistic metric for assessing the suitability of VO2-based coatings for smart-glazing applications.
PB American Chemical Society
SN 1944-8252
YR 2026
FD 2026-06-12
LK http://hdl.handle.net/10498/40429
UL http://hdl.handle.net/10498/40429
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 08-nov-2026