Tga dsc 1 sf 1382

Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) images were obtained on a JSM-7500F electron microscope. X-ray diffraction (XRD) patterns were recorded on a Shimadzu XRD-6000 with Cu K_α radiation (λ = 1.5418 Å) operating at 40 kV and 30 mA. Thermo-gravimetric differential scanning calorimetry (TG-DSC) analysis was carried out under an air atmosphere with a METTLER TGA/DSC 1 SF/1382 within a temperature range from room temperature to 800 °C with a heating rate of 10 °C min⁻¹. The BET (Brunauer–Emmett–Teller) surface area and pore size of the catalysts were determined on a QuadraSorb SI instrument. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images were taken on JEM-F200 microscopes at 200 kV. X-ray photoelectron spectroscopy (XPS) was performed using a Shimadzu Axis Supra (600 W) using 200 W monochromated Al K_α radiation. A 500 μm X-ray spot was used for XPS analysis. The base pressure in the analysis chamber was about 3 × 10⁻¹⁰ mbar. Typically, the hydrocarbon C 1s line at 284.8 eV from adventitious carbon is used for energy referencing.

The morphology of the products was observed by transmission electron microscopy (TEM: 1200EX, JEM) and a high-resolution transmission electron microscope (HRTEM: Tecnai G2 F20 S-TWIN, FEI). The structural and elemental characterization of the samples was carried out by powder X-ray diffraction (XRD: D8 Advance, Bruker) using Co Kα radiation, Raman spectroscopy (Renishaw inVia) and Thermogravimetric Analysis (TGA: TGA/DSC 1 SF/1382, METTLER). The magnetic properties were studied by a vibrating-sample magnetometer (ASM: Squid-VSM, Quantum Design). X-ray photoelectron spectra were obtained using an X-ray photoelectron spectrometer (XPS: Thermo ESCALAB 250XI, Thermo Electron Corporation).
The samples for electromagnetic parameter measurement were prepared by mixing paraffin with 40 wt% sample, which was pressed into toroidal shapes of 3 mm in inner diameter, 7 mm in outer diameter, and a thickness of 2 mm. The complex permittivity and complex permeability of the samples was characterized by a HP8722ES vector network analyzer in the frequency range 1–18 GHz. The reflection loss (R_L) is calculated according to the following equations:^{32 (link)} where Z_in is the input impedance, ε_r and μ_r are the relative complex permittivity and permeability respectively, f is the frequency of the microwaves, d is the layer thickness and c is the velocity of microwaves in free space.