Fabrication of colored R2O-MgO-Al2O3-SiO2 glass-ceramics with nano-sized crystals using natural basalt as a multifunctional additive

This study utilizes basalt enriched with transition metal elements (Fe, Cu, Ti) as a hybrid colorant and nucleating agent for R₂O-MgO-Al₂O₃-SiO₂ glass-ceramics. By employing TiO₂ as a crystallization agent and regulating basalt doping levels (1–10 wt.%), dark-gray to black-gray glass-ceramics with smooth surfaces were prepared. Basalt content critically affects crystallization behavior, coloration mechanisms, and physicochemical properties. Differential scanning calorimetry and Fourier transform infrared spectroscopy analyses indicate basalt incorporation lowers the glass transition temperature, moderately weakens the glass network structure, reduces melt viscosity, and enhances ion migration. X-ray diffraction and scanning electron microscopy reveal that basalt content and heat-treatment temperature synergistically regulate microstructure: 1 wt.% doping refines crystallite size (average grain size: 25.52 nm), while 5 wt.% induces agglomeration (particle size d₉₀ = 291 nm). X-ray photoelectron spectroscopy identifies coloration mechanisms driven by transition metal valence transitions, where Fe²⁺/Fe³⁺ redox pairs dominate chromaticity, while Cu⁺/Cu²⁺ equilibrium and stable Ti⁴⁺(d⁰) states enhance color uniformity. Heat-treatment temperature modulates metal ion valence evolution. Increased basalt content and temperature elevate bulk density (2.692–2.713 g/cm³). Microhardness slightly decreases (7.6–8.6 GPa) due to heterogeneous interfaces and grain coarsening, yet higher crystallization temperatures mitigate losses via increased crystalline phase content. All samples exhibit exceptional corrosion resistance (mass loss <0.08 %). The developed colored glass-ceramics integrate superior performance and aesthetic appeal, demonstrating promising applications in architectural curtain walls and corrosion-resistant coatings, while aligning with resource efficiency and environmental sustainability.