CO and C 3

ZnSb2O6 has been synthesized by a microwave-assisted solution method in order to test its possible application as a gas sensor. Zinc nitrate, antimony trichloride, and ethylenediamine were used as precursors and deionized water as solvent. Microwave radiation, with a power of ~350 W, was applied for solvent evaporation. The thermal decomposition of the precursors leads to the formation of ZnSb2O6 at 600°C. This oxide crystallized in a tetragonal structure with cell parameters a=4.66 Å, c=9.26 Å and space group P42/mnm. Microwires and microrods formed by nanocrystals were observed by means of scanning and transmission electron microscopies (SEM and TEM, resp.). Pellets of the oxide were tested as gas sensors in flowing atmospheres of carbon monoxide (CO) and propane (C3H8). Sensitivity increased with the gas concentration (0–300 ppm) and working temperatures (ambient, 150 and 250°C) increase. The results indicate high sensitivity of ZnSb2O6 in both gases at different concentrations and operating temperatures

Sensitivity of Mesoporous CoSb 2

Mesoporous CoSb2O6 nanoparticles, synthesized through a nonaqueous method (using cobalt nitrate, antimony trichloride, ethylenediamine, and ethanol as a solvent), were tested to establish their sensitivity to CO and C3H8 atmospheres at relatively low temperatures. The precursor material was dried at 200°C and calcined at 600°C. X-ray diffraction and scanning electron microscopy were employed to verify the existence of crystal phases (P42/mnm) and the morphology of this trirutile-type CoSb2O6 oxide. Pyramidal and cubic shaped crystals (average size: 41.1 nm), embedded in the material’s surface, were identified. Mesopores (average size: 6.5 nm) on the nanoparticles’ surface were observed by means of transmission electron microscopy. The best sensitivity of the CoSb2O6 in a CO atmosphere was at the relatively low temperatures of 250 and 350°C, whereas, in a C3H8 atmosphere, the sensitivity increased uniformly with temperature. These results encourage using the CoSb2O6 nanoparticles as gas sensors

A Gas Sensor for Application as a Propane Leak Detector

A propane gas detector was built based on the semiconductor nickel antimonate oxide (NiSb2O6) by means of an analog electronic circuit. The gas detector was designed for monitoring atmospheres where the leakage of propane gas could possibly occur. The prototype’s construction methodology is presented in 5 stages: (1) synthesis of NiSb2O6 oxide powders, (2) characterization of the powders by XRD and TEM, (3) manufacture and electrical characterization of the chemical gas sensor, (4) design of the analog circuit based on the electrical response of the gas sensor, and (5) functionality tests. The gas detector was built at low cost and showed excellent functionality. The operating conditions were as follows: 200°C, gas concentration of 5 ppm, electronic circuit gain of 5, and sensor sensitivity of 0.41

A simple route for the preparation of nanostructured GdCoO3 via the solution method, as well as its characterization and its response to certain gases

This work presents the synthesis of perovskite GdCoO3 by a microwave-assisted solution method in order to test its possible application as a gas sensor. The crystal evolution, structure, composition, texture, morphology, and particle size were analyzed by X-ray diffraction, scanning and transmission electron microscopies, and nitrogen physisorption. Our synthesis route allowed to obtain GdCoO3 at lower temperatures and shorter reaction times than conventional methods. Measurements confirmed the formation of porous GdCoO3 microbases with a thickness of 7–13 μm. The GdCoO3 microbases were constituted by nanoparticles of size 10–20 nm. Additionally, crystallites of size 85–130 nm were observed distributed on the surface of the microbases, covering a surface area of around 19 m2/g. Pellets elaborated from GdCoO3 powders were tested as sensors in carbon monoxide and propane gaseous atmospheres at different temperatures and gas concentrations. The GdCoO3 showed a good performance as a gas sensor compared to other similar oxides. The oxide was clearly sensitive to the studied gases even at concentrations as low as 5 ppm at a temperature of 100 °C. The response of the material was homogeneous and increased with both the increase in temperature and gas concentration. Keywords: GdCoO3, Perovskites, Nanoparticles, Gas sensor

Mentors as Female Role Models in STEM Disciplines and Their Benefits

Several studies have addressed the benefits of mentoring from the mentor’s perspective, especially those related to soft skills. However, to the best of our knowledge, there are no studies that either relate the mentoring in STEM areas with female role models or that analyze them from a data-mining perspective. In this work, a questionnaire was elaborated to address the mentor’s benefits related to soft skills and technical knowledge; afterward, a data-mining methodology was used to analyze the mentor’s perceptions related to female role models and STEM reinforcement. In addition, sentiment analysis was performed in order to determine the emotional polarity in the text used by the mentors to describe their mentoring experience. The results show that soft and technical skills are acquired by the mentors, and participating in mentoring programs allows them to perceive themselves as female role models. Additionally, by using decision trees, it was possible to determine the mentors’ characteristics that perceive a STEM reinforcement or that produce attraction. In addition, the results show that the general perception of the mentors’ experience was positive. Finally, the use of machine learning techniques, specifically data mining and sentiment analysis, allowed us to both confirm the results obtained in a qualitative way and to obtain new interesting results

Mentors as Female Role Models in STEM Disciplines and Their Benefits

Several studies have addressed the benefits of mentoring from the mentor’s perspective, especially those related to soft skills. However, to the best of our knowledge, there are no studies that either relate the mentoring in STEM areas with female role models or that analyze them from a data-mining perspective. In this work, a questionnaire was elaborated to address the mentor’s benefits related to soft skills and technical knowledge; afterward, a data-mining methodology was used to analyze the mentor’s perceptions related to female role models and STEM reinforcement. In addition, sentiment analysis was performed in order to determine the emotional polarity in the text used by the mentors to describe their mentoring experience. The results show that soft and technical skills are acquired by the mentors, and participating in mentoring programs allows them to perceive themselves as female role models. Additionally, by using decision trees, it was possible to determine the mentors’ characteristics that perceive a STEM reinforcement or that produce attraction. In addition, the results show that the general perception of the mentors’ experience was positive. Finally, the use of machine learning techniques, specifically data mining and sentiment analysis, allowed us to both confirm the results obtained in a qualitative way and to obtain new interesting results

Sensitivity Tests of Pellets Made from Manganese Antimonate Nanoparticles in Carbon Monoxide and Propane Atmospheres

Nanoparticles of manganese antimonate (MnSb2O6) were prepared using the microwave-assisted colloidal method for its potential application as a gas sensor. For the synthesis of the oxide, manganese nitrate, antimony chloride, ethylenediamine and ethyl alcohol (as a solvent) were used. The precursor material was calcined at 800 °C in air and analyzed by X-ray diffraction. The oxide crystallized into a hexagonal structure with spatial group P321 and cell parameters a = b = 8.8054 Å and c = 4.7229 Å. The microstructure of the material was analyzed by scanning electron microscopy (SEM), finding the growth of microrods with a size of around ~10.27 μm and some other particles with an average size of ~1.3 μm. Photoacoustic spectroscopy (PAS) studies showed that the optical energy band (Eg) of the oxide was of ~1.79 eV. Transmission electron microscopy (TEM) analyses indicated that the size of the nanoparticles was of ~29.5 nm on average. The surface area of the powders was estimated at 14.6 m2/g by the Brunauer–Emmett–Teller (BET) method. Pellets prepared from the nanoparticles were tested in carbon monoxide (CO) and propane (C3H8) atmospheres at different concentrations (0–500 ppm) and operating temperatures (100, 200 and 300 °C). The pellets were very sensitive to changes in gas concentration and temperature: the response of the material rose as the concentration and temperature increased. The results showed that the MnSb2O6 nanoparticles can be a good candidate to be used as a novel gas sensor

Gas Sensing Properties of NiSb 2

Micro- and nanoparticles of NiSb2O6 were synthesized by the microwave-assisted colloidal method. Nickel nitrate, antimony chloride, ethylenediamine, and ethyl alcohol were used. The oxide was obtained at 600°C and was analyzed by X-ray diffraction (XRD) and Raman spectroscopy, showing a trirutile-type structure with cell parameters a = 4.641 Å, c = 9.223 Å, and a space group P42/mnm (136). Average crystal size was estimated at ~31.19 nm, according to the XRD-peaks. The microstructure was scrutinized by scanning electron microscopy (SEM), observing microrods measuring ~3.32 μm long and ~2.71 μm wide, and microspheres with an average diameter of ~8 μm; the size of the particles shaping the microspheres was measured in the range of ~0.22 to 1.8 μm. Transmission electron microscopy (TEM) revealed that nanoparticles were obtained with sizes in the range of 2 to 20 nm (~10.7 nm on average). Pellets made of oxide’s powders were tested in propane (C3H8) and carbon monoxide (CO) atmospheres at different concentrations and temperatures. The response of the material increased significantly as the temperature and the concentration of the test gases rose. These results show that NiSb2O6 may be a good candidate for gas sensing applications

Facile Synthesis, Microstructure, and Gas Sensing Properties of NdCoO3 Nanoparticles

NdCoO3 nanoparticles were successfully synthesized by a simple, inexpensive, and reproducible solution method for gas sensing applications. Cobalt nitrate, neodymium nitrate, and ethylenediamine were used as precursors and distilled water as solvent. The solvent was evaporated later by means of noncontinuous microwave radiation at 290 W. The obtained precursor powders were calcined at 200, 500, 600, and 700°C in a standard atmosphere. The oxide crystallized in an orthorhombic crystal system with space group Pnma (62) and cell parameters a=5.33 Å, b=7.52 Å, and c=5.34 Å. The nanoparticles showed a diffusional growth to form a network-like structure and porous adsorption configuration. Pellets prepared from NdCoO3 were tested as gas sensors in atmospheres of carbon monoxide and propane at different temperatures. The oxide nanoparticles were clearly sensitive to changes in gas concentrations (0–300 ppm). The sensitivity increased with increasing concentration of the gases and operating temperatures (25, 100, 200, and 300°C)