Embedded ZnO nanorods and gas-sensing properties

Regular hexagonal embedded ZnO nanorods were successfully prepared by a simple hydrothermal method. The addition of urea as a homogeneous precursor was found to play a vital role in the embedding of secondary nanorods. The nanostructures were characterized by XRD, SEM, and EDS. The gas-sensing properties of secondary grown embedded nanorods were reported for formaldehyde, ethanol, methanol, acetone, and ammonia at different concentrations and temperatures. A higher response and greater selectivity toward formaldehyde than other gases was observed. A sharp response with the best recovery time was achieved at an optimum temperature of 200 °C

Selective Detection of Formaldehyde Gas Using a Cd-Doped TiO2-SnO2 Sensor

We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas

Crystalline Nanoscale M 2 O 3 (M ¼ Gd, Nd) Thin Films Grown by Molecular Beam Epitaxy on Si(111)

We report the growth, crystal structures, and orientation relationships of nanoscale M 2 O 3 (M ¼ Gd, Nd) thin films on Si(111) substrates using molecular beam epitaxy. We find that the grown Gd 2 O 3 and Nd 2 O 3 layers share the cubic bixbyite structure, have single orientations, and are well crystallized. The epitaxial oxides are also found to be of threefold symmetry, having orientation relationships ½111 M2O3 == ½111 Si and ½1 " 1 10 M2O3 == ½ " 1 110 Si with respect to the Si substrates. Further investigations along in-plane direction show that the M 2 O 3 layers are well matched to the double unit cell of Si substrates, with slightly negative mismatch for the Gd 2 O 3 and positive for the Nd 2 O 3

UV light activation of TiO2-doped SnO2 thick film for sensing ethanol at room temperature

TiO 2 -doped SnO 2 nanopowder is synthesized via a sol-gel method and characterized by atomic force microscopy and X-ray diffraction. Using this nanopowder, we have fabricated a novel semiconductor gas sensor that is sensitive to UV light illumination. We find that gas-sensing properties of TiO 2 -doped SnO 2 sensor can be enhanced significantly under the exposure of UV light. The sensor exhibits a high sensitivity of 25 and rapid response-recovery times of 8 s and 24 s, respectively, under an ethanol gas of up to 100 ppm at room temperature (323 K). This suggests the possibility of development of a gas sensor for detecting ethanol at room temperature

Study on cyclic deformation behavior of extruded Mg–3Al–1Zn alloy

Fatigue properties and cyclic deformation behavior of an extruded Mg–3Al–1Zn (AZ31) alloy were investigated by performing the strain-controlled low-cycle fatigue tests at room temperature. We believed that the total strain amplitude should be closely related to fatigue properties and cyclic damage process. This study aimed to investigate the deformation mechanism from the viewpoint of strain amplitude. We found that when the total strain amplitude increased from 0.3% to 0.4%, there was a noticeable change in compressive peak stress amplitude, which might correspond to the competition between twinning–detwinning process and dislocation slips. Microstructure and fracture morphology were investigated using optical microscopy and scanning electron micrograph. At the total strain of great amplitude, fracture surfaces were characterized by the striation-like features and dimple-like structures

Effect of {10−12} Twinning on the Deformation Behavior of AZ31 Magnesium Alloy

Twinning process and dislocation characteristics were determined by means of quasi in-situ electron backscatter diffraction and high-resolution transmission electron microscopy techniques in a rolled AZ31 magnesium alloy under different strain paths (compression along rolling direction and tension along normal direction). It is demonstrated that the activation of different twin variants depends on the strain path, and thus these twin variants can further induce different texture characteristics. In addition, two independent slip systems were activated during deformation of both strain paths. However, the dislocation slip modes of the two kinds of deformation are different, resulting in different stress-strain response

Deformation Mechanisms in a Rolled Magnesium Alloy under Tension along the Rolling Direction

The twinning and slip modes of a rolled magnesium alloy sheet were investigated through quasi-in-situ tensile tests that were carried out along the rolling direction at room temperature with a constant strain rate. Scanning electron microscopy and electron backscattered diffraction observations were used to identify activated twinning and slip systems. Schmid factors were calculated to analyze different deformation modes. The analyses show that a small number of {10-12} tensile twins were present during deformation, and these twins resulted from the accommodation of compression along the tensile direction. Post-deformation examination revealed the dominance of prismatic \u3c a \u3e slip