X-ray diffraction (XRD) analysis is a fundamental means of characterizing the structure of materials and is indispensable in the research of disciplines such as materials science, physics, and chemistry. Compared with polycrystals, single crystals have more important research and application value in frontier fields such as semiconductors, nonlinear optics, superconductivity, and topological insulators. However, at present, most universities and research institutions are equipped with general-purpose X-ray diffractometers, and the testing steps for single crystal samples are relatively complex. This paper uses a Bruker D8 Advance diffractometer to conduct X-ray diffraction experiments on Si(001) single crystals and elaborates on the experimental steps and results, providing a reference for teaching and research work involving X-ray diffraction experiments.

Radiative cooling (RC) represents a crucial heat dissipation method for spacecraft and electronic devices. In these applications, broader infrared radiation contributes to more efficient cooling. Inorganic materials are extensively employed due to their exceptional resistance to photothermal degradation. However, the narrow infrared intrinsic absorption peaks of these materials present a significant challenge in broadening their radiation bands. This study introduces an innovative square-column metamaterial (SCMM) developed through the integration of a metasurface with an inorganic multilayer film, specifically Si₃N₄/Al₂O₃/SiO₂/Si₃N₄/Ag/(etched Si substrate), using optical etching technology. The incorporation of the metasurface structure extends and regulates the radiation band of the inorganic multilayer film from 8–13 μm to 8–20 μm. Through size adjustment of the square column, the emissivity in the 8–20 μm wavelength range increases from 80.3% to 92.1%. The achievement of broad and high infrared radiation is attributed to localized surface plasmon resonance and metal–insulator–metal cavities in the micrometer array. Moreover, the SCMM demonstrates excellent cooling characteristics in actual temperature measurements. This research offers an innovative approach for RC materials to address spectral requirements in specific applications.

Infrared emissivity is an important parameter to characterize the optical properties of materials in the fields of radiative cooling, photothermal conversion and infrared stealth. In this paper, the infrared emissivity and reflectivity in visible and near infrared bands of SiO₂/TiO₂ composite coating system with different phase volume fraction and thickness are calculated by combining optical matrix method and equivalent medium theory. The results indicated that this method could well predict the optical performance parameters such as infrared emissivity and reflectivity of optical composite coatings, effectively improve the optimization efficiency of process parameters such as phase volume fraction and film thickness of composite coatings, and reduce the experimental workload. It is of great significance to realize the spectral selective regulation of composite coatings.