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Fly ash (FA) and sugarcane bagasse ash (SCBA) are the wastes from lignite power plants and sugar industries, usually disposed of as landfills. In this research, these wastes were effectively utilized as a construction material, namely geopolymer. The effect of the SCBA (0–40 wt.%) addition to the FA geopolymers was investigated. The compressive strength of the FA geopolymers was reduced with the SCBA addition. The reduction was mainly due to the presence of the highly stable and non-reactive quartz (SiO2) phase in SCBA. The SCBA was not dissolved in the alkaline activated solution and hence did not contribute to the geopolymerization process. The unreacted SCBA particles remained in the geopolymer matrix but did not provide strength. However, if the amount of SCBA was about 10 wt.% or less, the impact on the characteristics and properties of FA geopolymers was minimal. Furthermore, this research also studied the dielectric properties of the FA geopolymer/SCBA composites. The relatively large dielectric constant (e’ = 3.6 × 103) was found for the pristine geopolymer. The addition of SCBA decreased the e¢ slightly due to high carbon content in SCBA. Nevertheless, the variation in e’ was mainly controlled by the geopolymerization process to form the aluminosilicate gel structure.

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Here, metasurface magnetic carbon films synthesized via chemical vapour deposition (CVD) by using adamantane as a precursor and electron beam lithography (EBL) exhibited tuneable magnetic properties. The magnetic properties of carbon films were previously reported to occur from dangling bonds[1]. In this study, we observed a significant increase in saturation magnetization compared to the baseline film by controlling the array size of the metasurface film. Magnetic force microscopy (MFM) measurements confirmed the increasing saturation magnetization of the metasurface film. Magnetization originated from surface dangling bonds; smaller film sizes resulted in higher magnetization due to increased surface area. Furthermore, the saturation magnetization of the CVD carbon film could be tuned by controlling the humidity, and its prediction could be achieved through the utilization of the Raman technique. These findings highlight the potential of metasurface magnetic carbon films for developing tuneable magnetic microscale devices in areas, such as data storage, spintronics, and sensing.

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