New online beam intensity synchronous monitoring system in scanning transmission X-ray microscopy

The scanning transmission X-ray microscopy (STXM) platform based on synchrotron radiation has achieved nanoscale imaging with chemical sensitivity using spectro-microscopy techniques. However, the quality of STXM imaging is affected by the stability of the beam intensity. The top-up operation mode of synchrotrons to maintain a constant electron beam intensity introduces periodic fluctuations in the X-ray beam intensity, leading to notable imaging noise that decreases both contrast and precision. To address this issue, a high-speed real-time beam intensity monitoring system was designed and implemented at the BL08U1A beamline of the Shanghai Synchrotron Radiation Facility. This system utilizes an yttrium-aluminium-garnet crystal along with dual detectors having an acquisition frequency of up to 1 MHz and a synchronization error of less than 20 ns between them. This system can precisely and synchronously monitor the X-ray beam intensity variations which are used to remove noise due to electron injection from STXM images, thereby markedly improving the quality of STXM imaging.

Dual precipitating reagents-assisted deep blue-emitting borate and near-white oxide-based luminescent materials

We explored dual precipitating reagents-assisted Ce-based deep blue-emitting borate and near-white oxide-based luminescent materials. The first precipitating reagent (aqueous sodium borohydride) was used until gelation. The second precipitating reagent (ammonia solution) was employed to prepare as-synthesized powders. XRD analysis, FTIR spectroscopy, and Raman spectroscopy of calcined powders ranging from 1000 °C to 1400 °C confirmed the development of a primary borate phase (i.e., nearly polyhedral-shaped YBO3) with secondary phases of (Y,Al)BO3 and oxide. However, the preliminary oxide phase (i.e., elongated/rod-like YAG) and secondary phases of YBO3, Al2O3, and CeO2 were developed at 1500 °C with different holding times. The emission behavior and CIE coordinates confirmed that the borate (i.e., YBO3-based) sample was deep blue. However, the oxide (i.e., YAG-based) sample showed tunable color emissions from light blue to near white with increased holding time. The average lifetime of prepared samples varied between 788 ns and 891 ns, which indicated a long decay time. The quantum yield of the sample calcined at 1400-1500 °C varied between ∼61% and ∼77%. Based on the emission behavior, CIE diagram, CCT, powder color, average lifetime, and quantum yield, the developed deep blue-emitting borate and light blue/near white oxide-based luminescent materials could be used in lighting industries.