Ultrasensitive detection of low-ppm HS gases based on palladium-doped porous silicon sensors.

In this study, the sensing properties of palladium-doped porous silicon (Pd/p-Si) substrates for low-ppm level detection of toxic HS gas are investigated. A Si substrate with dead-end pores ranging from nano- to macroscale was generated by a combined process of metal-assisted chemical etching (MacE) and electrochemical etching with tuned reaction time, in which nano-Pd catalysts were decorated by E-beam sputtering deposition. The sensing properties of the Pd/p-Si were enhanced as the thickness of the substrate layer increased; along with the resulting variation in surface area, this resulted in superior HS sensing performances in the low-ppm range (less than 3 ppm), with a detection limit of 300 ppb (sensitivity 30%) at room temperature.

Effects of Different Salts on Salt-Assisted Ultrasonic Spray Pyrolysis (SA-USP) Calcination for the Synthesis of Strontium Ferrite.

Strontium ferrite (hexaferrite), SrFe12O19, was successfully fabricated in sizes ranging from hundreds of nanometers to several micrometers by salt-assisted ultrasonic spray pyrolysis-calcination using different salt media. All samples were single phases of SrFe12O19 without the intermediate phase, α-Fe2O3, and their morphology was hexagonal. As calcination temperature increased, the size of as-calcined samples and saturation magnetization, Ms, increased while coercivity decreased.