Cadmium telluride nanofilms application in carbon monoxide detection
The research is centered on CdTe nanofilms. The article is aimed at developing innovative primary transducer nanoscale material for semi-conductor sensors, investigating their surface physicochemical properties and evaluation their applicability in carbon monoxide diagnostics. Cadmium telluride nanofilms were obtained by discrete thermal evaporation in vacuum. CdTe nanofilms applicability in gas analysis was investigated. Adsorption properties of the given material for carbon oxide (II) and oxygen were studied by the piezoquartz microweighing. The principles of adsorption, depending on the process conditions and the test sample habitus, were established. Based on the obtained experimental data, CO micro-impurities sensors were developed, the laboratory tests passed successfully.
MoS2 hybrid heterostructure thin film decorated with CdTe quantum dots for room temperature NO2 gas sensor
Abstract Molybdenum disulfide (MoS2) is a very promising candidate for room temperature (RT) gas sensing applications. However, the limitation of synthesis techniques, incomplete recovery, and selectivity at RT are prime drawbacks. In this report, MoS2 nanoworms (NWs) thin film and CdTe quantum dots (QDs) decorated MoS2 NWs hybrid heterostructure thin film (CdTe QDs/MoS2 NWs) have been fabricated by scalable sputtering technique on the p-Si substrate and tested for RT NO2 gas sensing applications. The proposed CdTe QDs/MoS2 NWs hybrid heterostructure thin film sensor manifests an excellent sensor response (∼40 %), fast response time = 16 s, complete recovery (recovery time = 114 s) and highly selective towards 10 ppm NO2 at room temperature in comparison to pristine MoS2 NWs thin film sensor (response ∼26 %, response/recovery time ∼23 s/incomplete recovery). This superior gas sensing performance may be attributed to the combined effect of factors such as hybrid heteronanostructure with unique morphology, catalytic activity, synergistic effects, and p-n heterojunctions. The approach employed here may lead to the development of RT operable MoS2-based heterojunction gas sensors.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.