Abstract
Polyaniline (PANI) as a unique polymer that also has electromagnetic absorption used as the substrate. In this research, SrTiO3 was synthesized as IR absorbent and core and then SrFe12O19 as microwave absorbent was prepared on SrTiO3 via co-precipitation method as the first shell. As the next step, PANI was coated on SrTiO3/SrFe12O19 nanoparticles via in situ polymerization by multi core–shell structures (SrTiO3/SrFe12O19/PANI). Nanometer size and structures of samples were measured by TEM, XRD and FTIR. Morphology of nanocomposite was showed by SEM images. The magnetic and electric properties were also performed by VSM and four probe techniques. Thermal infrared (IR) absorption and microwave reflection loss of nanocomposites were investigated at 10–40 μm and 8–12 GHz, IR and microwave frequencies, respectively. The results showed that the SrTiO3/SrFe12O19/PANI nanocomposites have good compatible electric and magnetic properties and hence the microwave absorbency shows wide bandwidth properties. The infrared thermal image testing showed that the function of infrared thermal imaging was optimized by increasing SrTiO3/SrFe12O19 as core and independent to increasing PANI as the final shell.
1. Introduction
Thermal infrared radiation is much commonly known as kind of radiative heat. The thermal infrared region is the wavelength range of the electromagnetic spectrum which is also a characteristic of the thermal or heat radiation from the Earth’s surface and from the atmosphere. In thermal equilibrium, the emission of radiation in the infrared is governed by Planck’s law, which describes the spectral distribution of the energy emitted by ‘‘black’’ bodies (i.e. having unit emissivity at all wavelengths) as a function of temperature. Both the Earth’s surface and the atmosphere emit in the so-called ‘‘thermal’’ infrared, having spectral distributions described by the Planck function corresponding to the local temperature, (i.e. the surface temperature of the Earth and the temperature as function of altitude.)
4. Conclusion
The SrTiO3/SrFe12O19/PANI nanocomposites were well defined in size and shape and exhibited good electrical conductivity. The light reflectivity times of samples on human body are higher than metallic disks. So, they are suitable for thermal IR absorbers. The light reflectivity times of samples were increased by increasing weight ratio and thickness. Human temperature could not transmit to samples by increasing weight ratio of core. Therefore weight ratio (SrTiO3/SrFe12O19 as core) above 40% and 1 mm diameter are the best result as thermal IR absorber. The SrTiO3/SrFe12O19/PANI enhanced broad band infrared light absorption was observed in the wavelength range of 10–40 lm. A minimum RL of 15 dB was observed at 9.2 GHz for a 1 mm thickness nanocomposite. The application of these samples may improve the IR thermographic detection, catalysis, sensors, magnetic data storage, electromagnetic resonance wave absorption, photonic crystals, and microelectronic devices and military aspects.
