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Ordered mesoporous carbon (OMC) has been regarded as a promising carbonaceous material for microwave absorption (MA) owing to its high specific surface area, sufficient ordered mesoporous nanostructures and easy decoration. However, its development in MA performance is seriously hampered by its shortcomings of lacking magnetic loss and poor impedance matching. Herein, a series of multi-dimensional ternary OMC/SiO2@Ni composites with hierarchical nanostructure (zero-dimensional (0D) Ni nanoparticles and three-dimensional (3D) OMC/SiO2 framework) is successfully prepared via a self-assembly method, an in situ synthesis, and followed by a calcination treatment. By adjusting the calcination temperature and Ni nanoparticle content, OMC/SiO2@Ni composites with different graphitization degree, Ni nanoparticle size and magnetic properties can be easily obtained. Remarkably, OMC/SiO2@Ni0.5-700 composite exhibits an exceedingly strong reflection loss (RL) value of −62.2 dB and a broad effective absorption bandwidth (RL ≤ −10 dB) of 8 GHz (almost covers X and Ku bands) with a layer thickness of only 2.5 mm. Such fabulous MA performance comes from a synergy between the well-designed hierarchical ternary nanostructure and improved impedance matching. This work provides an insight for rational structure design and multi-component loss mechanism of lightweight MA material, which shows great potential in practical applications.

Near-infrared (NIR) luminescent materials have unparalleled advantages in certain fields, such as anti-counterfeiting. Nd3+ ion doped Gd2O3 near-infrared phosphor was successfully prepared by co-precipitation method and high-temperature solid-phase reaction. The structure and morphology of Gd2O3:Nd3+ cubic phase phosphors were studied in detail. The prepared phosphor was optically analyzed by fluorescence spectrometer. The research results show that with the increase of the Nd3+ doping concentration, the luminous intensity of the near-infrared phosphor in the near-infrared region shows a trend of first increasing and then decreasing. When the Nd3+ ion doping concentration is 1.0 mol%, the obtained phosphors have the best luminous intensity in the near-infrared region under the excitation of 808 nm laser. Gd2O3:Nd3+ phosphor emits near-infrared light due to the intra-4f transitions of Nd3+ ions. The concentration quenching theory is used to prove that the concentration quenching of Gd2O3:Nd3+ belongs to the cross relaxation caused by electric multipole. Due to the unique optical properties of this near-infrared phosphor, it is expected to be further developed in the field of fluorescent materials.

Eu3+-activated BaLaMgNbO6 red-emitting phosphors were synthesized by a high-temperature solid-state reaction method. Phase analysis and luminescence were characterized by X-ray diffraction (XRD) and photoluminescence excitation and emission spectra. The XRD patterns showed that BaLaMgNbO6 had a monoclinic structure with space group P21/n. The excitation spectra consisted of a broad charge-transfer band and some sharp f-f absorption peaks characteristic of Eu3+. The intensity ratio of I615/I590 was used to detect the chemical environment of Eu3+. The chromaticity coordinates of BaLa0.7Eu0.3MgNbO6 were (0.67, 0.33), indicating that the BaLaMgNbO6:Eu3+ phosphors were excellent red-emitting phosphors. Under excitation by near-ultraviolet (UV) and blue light, the phosphor not only exhibited intense red emission but also showed high color quality. The Ozawa and Dexter energy-transfer theories were employed to calculate the theoretical quenching concentration and determine the concentration quenching mechanism. In addition, the activation energy of BaLa0.7Eu0.3MgNbO6 was calculated through the Arrhenius equation. A configurational coordinate diagram was used to explain the thermal quenching mechanism.

A series of Eu 3+ ions activated double perovskite CaLaMgSbO 6 phosphors were successfully synthesized. Crystal structure was investigated by XRD and the results showed that this double perovskite exhibited rock-salt ordering of B-site ions. High-resolution transmission electron microscopy was used to prove the existence of B-site ordering. Thereafter, luminescence properties of the as-prepared powders were discussed in detail. The phosphors could be well excited by ultraviolet, near ultraviolet, and blue light. The quenching concentration for the transition of 5 D 0 - 7 F 2 reached up to 50.0 mol%. The theoretical quenching concentration and quenching mechanism were discussed in detail. Excellent thermal stability of this double perovskite phosphor was obtained and the quenching mechanism was investigated based on the configurational coordinate diagram. The CIE coordinates showed that this double perovskite phosphor had great potential in solid state lighting.

Crystal structures of Sr 1- x Ca x LaMgSbO 6 :Eu 3+ phosphors were studied in detail. Both the SrLaMgSbO 6 and the CaLaMgSbO 6 have a monoclinic ( P 2 1 / n ) structure. With increasing the Ca 2+ concentration, the peaks gradually divided and the phase changed from SrLaMgSbO 6 to CaLaMgSbO 6 . The symmetry of La 3+ in SrLaMgSbO 6 is lower than that in CaLaMgSbO 6 . Eu 3+ ions, as the structural probes, were selected to study the structure. Lifetimes and intensity ratio were used to study the symmetry in the structure. Thermal quenching of the phosphors was discussed from 323 K to 473 K. The emission intensities of 5 D 1 → 7 F J and 5 D 0 → 7 F J damped in different ratios while increasing temperature. The configurational coordinate diagram was used to explain this interesting phenomenon.

A series of ferrite/Co/porous carbon materials were prepared by the situ-thermal carbonization of ferrite/ZIF-67 under N 2 atmosphere, and the microwave absorption properties have also been investigated. The magnetoelectric synergistic microwave absorbing material is promising as an efficient microwave absorbing material. The component absorbers with unique porous carbon structure make great contribution to the impedance match, interface polarization, magnetoelectric synergistic effect, and multiple reflection and scattering loss. The carbonization temperature indicates a crucial effect on the porous structure, and too high temperature will result in the collapse of the porous structure. The ferrite/Co/porous carbon fabricated at 500 °C (FC500) exhibits the most enhanced microwave absorbing performance. The maximum reflection loss (RL) of FC500 reaches −31.05 dB at 14.32 GHz, and the effective absorption bandwidth (RL ≤ −10 dB) is 4.8 GHz (12.24 GHz–17.04 GHz) corresponding to a thickness of 1.5 mm. The maximum reflection loss (RL) can reach −47.31 dB at 8.4 GHz, and absorption bandwidth (RL ≤ −10 dB) is 2.72 GHz (6.80 GHz–9.52 GHz) with a thickness of 2.5 mm. Thus, the component absorption materials can significantly decrease the weight of ferrite absorbers, ascribing to the thinner optimum thickness.

Eu 3+ -doped double perovskite (Ba, Sr)LaMgSbO 6 phosphors were synthesized by the traditional solid-state reaction method. Structure evolution was investigated by X-ray diffraction and Rietveld structure refinement. The crystallographic data of powders were given in detail. Also, the photoluminescence properties, including excitation spectra, emission spectra, intensity ratios of I ( 5 D 0 - 7 F 2 )/I ( 5 D 0 - 7 F 1 ), Commission International de L'Eclairage (CIE) chromaticity coordinates, UV–vis diffuse reflectance spectra, lifetimes, and the thermal quenching properties were thoroughly discussed. With the increase of Sr 2+ concentration, the emission intensities increased and the decay times decreased. Band gap was calculated to explain the phenomenon of the increased emission intensity. The phosphors showed temperature-sensitive luminescent properties based on the thermal quenching performance. The configurational coordinate diagram was used to explain the thermal quenching mechanism.

Graphene is a promising lightweight microwave absorption (MA) absorber, but the limited dielectric loss and nonmagnetic characteristic have impeded its further applications. Through the structure modification, porous (1–2.5 μm) graphene was successfully prepared via a simple pyrolysis process, and the minimum reflection loss (RL) value reached −48 dB at 9.8 GHz, which demonstrated that porous graphene (PG) showed outstanding MA performance than the ordinary graphene (OG). In order to strengthen the magnetic loss, and then boost the impedance matching, Fe3O4 nanoparticles (∼10 nm) were deposited uniformly on the surface of PG via in situ precipitation to synthesize porous graphene-Fe3O4 (PG-Fe3O4) composites. It was found that the as-prepared PG-Fe3O4 composites showed especially high MA performance, and the minimum RL of −53.0 dB was achieved at 5.4 GHz with the thickness of 6.1 mm. The absorption bandwidth of RL less than −10 dB was from 12.6 to 18.0 GHz (5.4 GHz) with a thin thickness of 2.7 mm. The excellent MA properties of PG-Fe3O4 composites were the consequence of the perfect impedance matching, porous structure as well as the multi-polarization. These results demonstrated that the PG-Fe3O4 composites with excellent MA properties and lightweight should be promising absorbers for practical applications.

To obtain excellent microwave absorption (MA) performance, elaborately designing dielectric-magnetic hierarchical C@NiCo 2 O 4 @Fe 3 O 4 composites were successfully synthesized by a two-step route. Both the sea urchin-like structure generated by NiCo 2 O 4 and the void space in the core originated from the decomposition of carbon spheres were beneficial structural characteristics for the attenuation of electromagnetic waves. The impedance matching as a result of the addition of uniformly Fe 3 O 4 nanoparticles was a strong contributor to the excellent MA property of C@NiCo 2 O 4 @Fe 3 O 4 composites. The minimum reflection loss (RL) value of it reached −43.0 dB at 13.4 GHz with a thickness of 3.4 mm, which was much higher than that of C@NiCo 2 O 4 or pure NiCo 2 O 4 .

Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.

A series of double perovskite (Gd0.85-xLux)2MgTiO6: 0.3Eu3+ red phosphors were prepared via a typical high temperature solid-state reaction. XRD and HRTEM exhibits that the phosphors well crystallized as a double perovskite with the space group of P21/n symmetry. The luminescent properties of samples were investigated via excitation and emission spectra. The phosphors emit strong red light and weak orange red light under ultraviolet (UV) and near-UV excitation suggesting that Eu3+ ions situated in the sites without inversion symmetry. The UV–vis spectra included a broad host absorption band assigned to O2--Eu3+ and some peaks at 395 nm, 465 nm and 533 nm attributed to the typical f-f transition of Eu3+. The CIE chromaticity coordinates of all samples were near to the standard red light, indicating that the (Gd0.85-xLux)2MgTiO6: 0.3Eu3+ was a potential candidate material for red emitting phosphors. The decay curves matched with the lines fitted by a one exponential decay formula and the decay time increased with increasing Lu3+-dopant concentration within x

Carbonyl iron fibers were fabricated by magnetic-field-induced thermally decomposition of polymetallic carbonyl. Their fibrous morphology and magnetic properties were investigated by scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) at room temperature respectively. The microwave characterizations of carbonyl iron fiber-filled foam composites were evaluated through arch test based on a network analyzer. The diameter and aspect ratio of the fibers have great influence on reflection loss. It was also found that carbonyl iron fiber-filled foam composites with small thinness and lightweight exhibit good microwave absorbing properties in the frequency of 8–18 GHz, 26–40 GHz and 75–110 GHz.