Oxynitride glasses are glasses where threefold coordinated nitrogen atoms substitute for twofold oxygen ones, hence resulting in a larger interatomic crosslinking degree. Such glasses were first observed at the grain boundary in silicon nitride ceramics, where they govern the high-temperature behavior. Later, they were prepared as bulk materials and motivated numerous researches, thanks to their large viscosity, glass transition range, elastic moduli, hardness, and fracture toughness among inorganic and non-metallic glasses. In different chemical systems that were investigated, the synthesis routes and the sources for these exceptional mechanical properties are reviewed. Oxynitride glasses are not easy to process and suffer from the loss of transparency as nitrogen is incorporated over some critical content. Nevertheless, they are attractive "specialty" glasses in various niche areas, thanks to their large refractive index and dielectric constant, improved chemical durability, high softening point, etc., and majorly to their exceptional mechanical properties.

Mechanoluminescence is observed in oxynitride glass-ceramics from the BaO-SiO2-Si3N4 chemical system, doped with Eu and Ho. Light emission was investigated by means of uniaxial compression experiments on disks and parallelepipedic bars with constant loading rates ranging from 0.3 to 300 MPa s−1 up to about 500 MPa. In agreement with previous reports on SrAl2O4-based materials [Dubernet et al., Appl. Phys. Lett. 107, 151906 (2015) and Dubernet et al., Sci. Rep. 10, 19495 (2020)], the mechanoluminescence intensity is found proportional to the mechanical power. Nevertheless, in contrast with SrAl2O4, no gain in the intensity is observed at the onset of the unloading stage, but a drop of the photoluminescence intensity during unloading. This stems from different electron trapping populations and associated energy levels for the Ba4Si6O16 phase (the dominant crystallized phase in the present glass-ceramics), which are discussed in light of density functional theory calculations.

Gas networks are interconnected and strategically linked to multiple sources. Because of this, the quality of gas can change rapidly at a given location when switching from one source to another. When this occurs, these rapid changes can result in flashback or flame extinction. To overcome combustion issues and instabilities of gas fired gas turbines due to the variability of gas incoming gas quality, a new sensor called NIRIS NG has been designed which analyzes the natural gas composition at the inlet of the turbine burners. The design of the NIRIS NG sensor boasts a short response time (less than one second), easy installation, simple maintenance, and low cost. This is primarily because unlike other gas quality sensors, the NIRIS NG sensor is based on spectrometry technology and the sensor has been specifically engineered for installation on turbine applications. By employing spectrometry, the NIRIS NG sensor is performing a technological breakthrough by using low cost optical components and proprietary signal treatment software within robust packaging that can sustain the vibration and heat over extended periods. The gas-pipe-plugged sensor provides fast response times and transmits the data to the turbine controller using CAN protocol. This paper will describe in detail the sensor hardware and software technologies, validation testing that has been completed to date, and the expected advantages on industrial gas fired gas turbines.

No abstract