We have conducted x-ray absorption near-edge structure (XANES) experiments on germanium selenide glasses, in search of a structural signature of the intermediate phase (IP). Quantitative analyses of the XANES spectra reveal compositional plateaus that coincide with the IP reversibility window, providing structural evidence for the IP. Molecular dynamic simulations have been performed to understand the atomistic origin of the electronic structure of the glasses. The IP originates from a competition between amorphous ${\text{GeSe}}_2$ and amorphous Se clusters and produces measurable signatures. Our study provides atomistic insight into the structural origin of the IP in Ge–Se glasses.

As the main detector of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor mission (GECAM), the calibration of the energy response and detection efficiency of the gamma-ray detector (GRD) is the main content of the ground-based calibration. This article mainly focuses on the calibration of the energy response and detection efficiency in the 8–160 keV with a refined measurement around the absorption edges of the lanthanum bromide crystal ($\rm {LaBr_3}$). The GRD performances for different crystal types, data acquisition modes, working modes, and incident positions are also analysed in detail. We show that the calibration campaign is comprehensive, the detector performance meets the flight requirements, and the calibration results generally agree with simulations as expected. The detector’s model was corrected by the ground-based calibration, which led to the establishment of the calibration data base.

We have applied x-ray scattering to characterize residual strain in nanostructured glasses. The first sharp diffraction peak (FSDP) and the nanostructures of periodic mesoporous silica were investigated as a function of annealing temperature. It is found that position and width of the FSDP exhibit different temperature dependencies, which correspond to two types of residual strain caused by defects and constrained nanostructures, respectively. The latter appear to be inherent to the periodic mesoporous material as confirmed by the small-angle x-ray scattering analysis. Our study has implications for the structural properties of periodic mesoporous materials.