Preparation of Melilite‐Type Ceramics Utilizing Slag and Metal Oxides: Physical, Mechanical, Electrical, and Optical Properties

The current study involves the fabrication of some melilite‐type ceramics, by recycling industrial slag waste with different transition metal‐oxides like ZnO, CuO, CoO, and NiO. These metals were incorporated in the T 1 position of melilite structure (X 2 T 1 T 2 2 A 7 ). The stoichiometric compositions of desired compounds were designed and sintered at 1100°C, 1150°C, and 1200°C. Additionally, comparative studies were performed by evaluating the qualitative phase analysis, microstructure, and the physical, mechanical, optical, and electrical properties of sintered ceramics. The results showed that the desired phases (Ca 2 ZnSi 2 O 7 , Ca 2 CoSi 2 O 7 , Ca 2 NiSi 2 O 7 , and Ca 2 CuSi 2 O 7 ) were successfully prepared, and the optimum firing temperature for phases’ formation was 1150°C. The physical properties were enhanced with temperature elevation, where Ca 2 CuSi 2 O 7 exhibited the highest bulk‐density (4.20 g cm −3 ) and lowest apparent‐porosity (10.06%) after sintering at 1150°C. The compression strength was increased with rising sintering temperature. The Ca 2 CuSi 2 O 7 sample revealed the highest compressive strength (21 MPa), whereas the Ca 2 ZnSi 2 O 7 sample displayed the lowest one (8 MPa). An enhancement in electrical properties was noticed for the sample that contains Cu metal. For the diffuse reflectance spectra ( R ), all samples except CU sample displayed reflectance less than 43% in UV region, which can extend their applications as smart windows, UV shielding, and smart optoelectronic devices.