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The increasing use of electronic devices has led to an increase in electromagnetic interference (EMI) pollution, which not only adversely affects the performance of electronic devices, but also poses potential risks to human health. Traditional EMI shielding methods work by reflecting incoming electromagnetic waves, but this approach can cause secondary EMI pollution. Absorption-based shielding effectively absorbs incoming EMI and offers an environmentally friendly solution. Since bare carbon-based materials exhibit minimal magnetic losses and limited microwave absorption capabilities, in contrast to higher electrical losses, we, in this study, focused on functional coatings on carbon materials and modification of dielectric and magnetic materials and designed hierarchical Ni-Zn alloy and Fe3O4/epoxy on carbon fiber fabrics (CFF). The X-band (8–12 GHz) electromagnetic interference (EMI) shielding properties and microwave properties of this design were investigated. The structural integrity and elemental composition of the design were verified using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). Electromagnetic evaluation performed with a vector network analyzer (VNA) showed that, in particular, the CFF/Ni-Zn/Fe3O4-epoxy composite (CFF/NZ/F50E50) with a weight ratio of 50:50 exhibited the strongest reflection coefficient performance, reaching up to − 31.96 dB at 8.73 GHz. This sample also exhibited a wide reflection loss range exceeding − 20 dB from 8.41 to 9.08 GHz. The study revealed that the incorporation of Fe3O4 nanoparticles significantly improved the dielectric and magnetic loss properties of the composite coatings. The CFF/Ni-Zn/Fe3O4-epoxy composites exhibited a remarkable absorption contribution with an average of 43 dB. The SEA value of CFF/NZ/F50E50 sample reaches 45.75 dB at 8.24 GHz and constitutes 99% of SET. The results showed that CFF/Ni-Zn/Fe3O4-epoxy composites are low-reflection and absorption-dominant EMI shielding materials. CFF/Ni-Zn/Fe3O4-epoxy has the potential to find applications in technological areas. [ABSTRACT FROM AUTHOR]

CaAl12O19:Mn4+ phosphor (CAO:Mn), which has advanced color rendering and high productivity for white light-emitting diodes (wLEDs), is an important candidate for red-emitting materials due to its large absorption band from the visible region to the deep-red region based on the d-d transitions of manganese ions. For this reason, it is widely used especially in wLEDs, and in recent years, many researchers have aimed to improve the optical properties of the aforementioned red phosphor material with the use of different dopants and additives. In this study, the observed enhancements in the photoluminescence based optical properties of sol-gel synthesized CAO:Mn phosphor were described in detail in the presence and absence of pristine zinc oxide nanowires grown on carbon fibers (ZnO NWs/CFs), Al-doped ZnO NWs/CFs (Al-ZnO NWs/CFs) and K-doped ZnO NWs/CFs (K-ZnO NWs/CFs) additives. The addition of pristine ZnO NWs/CFs and Al- and K-doped ZnO NWs/CFs to CAO:Mn phosphor in the ethyl cellulose (EC) matrix resulted in an increase in emission intensity of 74%, 81%, and 84%, respectively. Additionally, the features of the synthesized phosphor’s emission/excitation spectra and decay times were examined on both the nano- and microsecond time scales. The presented material can be shown as a new candidate for improving the properties of red phosphors related to brightness, stability, and degradation times. [ABSTRACT FROM AUTHOR]

Over the last decades, a considerable attention has been drawn on the cerium dioxide (ceria, CeO2) due to promising changes in physical and chemical properties in nanoscale. The researches on CeO2 and its structural and morphological modifications have brought about remarkable applications as optical devices, sensors, medical equipments and luminescent materials. For instance, rare earth (RE) ion-doped cerium oxides have exhibited enhanced peculiar optical, catalytic and magnetic properties with respect to the dopant-free CeO2 nanoparticles. Herein we aimed to compare characteristics of undoped (CeO2) and europium (Eu3+) doped ceria (CeO2:Eu3+) nanoparticles synthesized by sol–gel (SG) and one-step flame spray pyrolysis (FSP) methods. In this work, fabricated nanoparticles were evaluated in terms of the structural, morphological, chemical and optical properties by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron (XPS) and photoluminescence spectroscopy (PL), respectively. Nanoparticles in the intended crystalline CeO2 structure were obtained for both methods. Spherical particles in nanoscale (particle size < 100 nm) and sharp edged blocky particles in sub-micron size (particles size range 200–1000 nm) were produced through FSP and SG, respectively. Nevertheless, no significant difference due to the difference in particle size was observed in optical properties. On the other hand, Eu3+ doped particles of both methods exhibited longer decay time than the undoped particles. [ABSTRACT FROM AUTHOR]