Upconversion (UC) luminescence refers to the conversion of electromagnetic waves from long to short wavelengths through multi-photon processes where the absorption of infrared (IR) photons leads to visible emission, which has attracted a lot of attention on the bioimaging, 3-D color display, printing ink, state-of-the-art lighting, solar cell, fingerprint acquisition, anti-counterfeiting, and so on. 1-7 Particularly, based on the measurement of temperature-dependent UC luminescence intensity of two thermally coupled energy levels of trivalent rare earth (RE 3+) ions, the non-contact optical temperature sensor by using the fluorescence intensity ratio (FIR) technique still keeps a research hotspot in recent years owing to its advantages of fast response, high sensitivity and resolution. 8-13 Under consideration of UC luminescence and temperature sensing properties, the Er 3+ ion with a pair of thermally coupled energy levels (2 H 11/2 and 4 S 3/2) is often regarded as the one of the most important activator ions to obtain strong UC luminescence in visible

Simple and efficient preparation high-performance magnetic carbon-based nanocomposites as electromagnetic wave-absorbing materials is a research hotspot. Here, employing a straightforward, ecologically friendly, and effective solid-state technique, FeCo/graphene nanocomposites with good electromagnetic wave absorption capabilities were successfully fabricated without the use of any external carbon sources. m-NaCl powder is combined with Co(acac)2 and Fe(acac)3 and then annealed at a particular temperature. During the annealing process, FeCo nanoparticles were synthesized and supported on graphene nanocomposites. Following annealing at 700 °C, the material showed an ideal reflection loss of −71.63 dB at 10.8 GHz, an effective bandwidth of 4.24 GHz, and a thickness of 2.68 mm. The radar cross section (RCS) of FeCo/C-700 is less than −10 dB m2, which provides evidence that the samples have good radar wave attenuation capabilities when the scattering angle is between 0 and 60°. The approach for creating graphene composites with FeCo nanoparticles suggested in this study serves as a crucial source of inspiration for the later development of new magnetic carbon nanocomposite systems.

No abstract

Er3+ with different concentrations doped K2Yb(PO4)(MoO4) phosphors were prepared by a solid-state reaction method, and the layered orthorhombic crystal structure of the samples was confirmed by X-ray diffraction (XRD). Under...

No abstract