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MgAlON transparent ceramic was prepared via pressureless sintering and post hot isostatic pressing. The in-line transmittance of MgAlON ceramic exceeds 80% in the range 0.39–4.67 μm, and the ceramic was fully dense with average grain sizes ∼55 μm. The mechanical properties at the grain boundary (GB) and the center of the grain (CG) of MgAlON ceramic was investigated by nanoindentation at forces of 1 × 102–3 × 105 μN. The results indicated that the hardness values of MgAlON ceramic were sensitive to the testing forces and measurements position. The hardness at GB zone was lower than that at CG zone, which was probably ascribed to weaker interatomic bonding force in GB area. The Meyer's index of the hardness in GB and CG regions is 1.87 and 1.82, respectively. There is a weaker ISE in GB area of MgAlON as a result of larger plasticity and smaller elasticity. The hardness values of GB and CG regions are ∼13.36 GPa and ∼13.58 GPa, respectively.

Magnetic polariton resonance, standing wave, and their coupling have provided interesting and exotic characteristics for infrared metamaterial. In this paper, the metal-insulator-metal metamaterial absorbers consisting of either single layer dielectric or bilayer dielectrics are discussed to reveal the geometric and dielectric thin film control of resonance absorption modes. These absorption modes can be independently manipulated by specific geometrical parameters, and thus provide a multi-peak characteristic for the metamaterial absorber. Comparing to the single dielectric structure, a new freedom of modes control is introduced to the bilayer dielectric structure by the addition of low epsilon MgF2, and then results in a quasi-continuous broadband absorption in the range of 5-8 μm. Experimental result further demonstrates the broadband effect, consistent with the numerical simulation.

Atmospheric windows play an important role in the field of infrared detection and radiative cooling. In this paper, the development of VO

Ball mill of thermal power plant has high energy consumption and the grinding capability is usually used for representing the efficiency of ball mill. This paper proposes a density clustering analysis method of fuzzy neural network initialization for grinding capability prediction of power plant ball mill. The proposed method integrates the density clustering algorithm and the fuzzy neural network to predict grinding capability, where the density clustering algorithm is used to initialize the rules base of the fuzzy neural network. Furthermore, two parameters of the density clustering analysis can be determined by calculation formula, and the structure of the proposed model could be optimized by the training capability of neural network. The experiments are performed on two datasets obtained from the thermal power plant under the stable conditions. The experiments results verify that the proposed model has higher effectiveness. In addition, the proposed model has been put into practice and the field operation curve proves that the grinding capability could be predicted correctly.

In natural or artificial Epsilon-near-zero (ENZ) materials, excitation of the absorption at ENZ point requires large incident-angle or polarization dependence, and thus become limited in practical applications. In this paper, the magnetic dipole resonance in a metal-ENZ-insulator–metal structure breaks such restrictions on ENZ absorption, by providing a critical longitudinal electric field to the embedded ENZ material. In numerical and corresponding experimental realizations, a thin SiO2 film in the metal-ENZ-insulator–metal structure serves as the ENZ layer at mid-infrared and holds the ENZ absorption at both TE and TM polarizations under normal incidence. The cooperation of ENZ absorption, magnetic dipole mode and the loss of SiO 2 film further results in infrared absorption enhancement and band-width broadening.

With the rapid development in near / far field thermal radiation and micro- / nano- fabrication, passive radiative cooling has become an intriguing topic in both fundamental scientific research and practical energy engineering. In this paper, we use Amorphous Alumina Nanotubes (AANs) to prepare a flexible material for high-efficient daytime radiative cooling. Instead of applying parallel nanotube array or total randomly distributed nanotubes, we experimentally fabricated a porous membrane by introducing hexagonal lattice roots at the bottom and random agglomeration at the top for AANs. Near-unity emissivity originated from alumina absorption and complex scattering inside the membrane covers the 8-13 µm atmosphere window. Under direct sunlight, the flexible AANs membrane achieves a theoretical net cooling power of 71.0 W/m2, leading to an experimental maximum temperature reduction of 6.7 °C to the ambient air. Our material paves herein a way for producing low-cost and efficient flexible daytime radiative coolers.

Metal nanoparticles (NPs) are widely applied in many fields, such as optics, electronics, and sensor platforms. The size and density of the NPs play important roles in device performance and nanostructure distribution. In this paper, the periodically distributed Au NPs are obtained by dewetting the Au film or Au–Ge film on a patterned SiO2 substrate. The influence of the substrate morphology and the Ge film on the dewetting process is investigated. The former modifies the crucial dewetting parameters periodically, i.e., the surface curvature, while the latter provides energy for Au atoms' surface diffusion. The extinction spectrum shows a prominent enhancement in local surface plasmon resonance, over 5 times in the visible region, which is due to the periodicity and high-density in NP distribution. This study provides a simple and regulable method to prepare periodically distributed metal NPs.

Atmospheric windows play an important role in the field of infrared detection and radiative cooling. In this paper, the development of VO2-based metamaterial emitter brings broadband thermal-switching light to mid-infrared atmospheric windows. At room temperature, the emitter radiates light in both 3-5μm and 8-14μm atmospheric windows. At high temperature, the radiation peaks move out of the atmospheric windows and result a strong radiation at 5-8μm. The underlying mechanism relies on the relationship between VO2 metal-insulator transition (MIT) and resonant absorption modes coupling. Corresponding thermal imaging experiment exhibits two distinct phenomena. One is the observation of unchanged thermal radiation around MIT temperature. The other phenomenon regards the concealment of the emitter from Al background at specific temperatures. These two phenomena show potential application in infrared anti-detection.