Design of metamaterial absorbers with near-perfect absorbing properties in the visible region via self-assembly of core–shell Au@SiO ₂ plasmonic NPs.

A facile self-assembly strategy for the fabrication of tunable coupled plasmonic superlattices composed of unique high-index faceted gold nanocrystal units.

Li₂O–Al₂O₃–SiO₂ (LAS) glass–ceramics are widely used in many fields owing to their ultra-low coefficient of thermal expansion (CTE). The ultrasonic velocity method shows potential as an effective method for the nondestructive measurement of the CTE and CTE homogeneity of large LAS glass–ceramics. To further improve the precision of ultrasonic velocity (c_L) measurements of LAS glass–ceramics and reveal the effect of the temperature (T) on c_L, an improved correlation method to rapidly determine the time of flight (TOF) in LAS glass–ceramics is proposed. The proposed method significantly reduces the calculation time by a factor of 100 for LAS glass–ceramics with a thickness of 50 mm. Furthermore, the TOF results obtained by this method were compared with those obtained by the commonly used peak and zero-crossing methods. The proposed correlation method showed better TOF repeatability precision (0.69 ns). Considering the effect of T on the precision of the c_L measurement, a c_L–T exponential model was developed based on the theoretical c_L–T analytical model. The accuracy of the c_L–T exponential model was experimentally verified. The root-mean-square error was within 0.30 m/s, which shows that the developed exponential model can reliably predict the c_L values of LAS glass–ceramics at different temperatures. The two meaningful findings mentioned above provide methodological and modeling support for high-precision nondestructive CTE testing of large LAS glass–ceramics at specific temperatures.