In a basic water-alcohol mixing solution without any other toxically organic solvents, the single crystalline SnO2 nanorods with diameters of 4–15 nm and lengths of 100–200 nm were synthesized using SnCl4 as a precursor. The sensors fabricated from the nanorods exhibited the sensitivity of 31.4 for 300 ppm of ethanol. Both the response and recovery time are short, around 1 s. Moreover, a linear dependence of the sensitivity on the ethanol concentration was observed. These behaviors were well explained by considering the high surface-to-volume ratio of the nanorods.

Using state-of-the-art aberration-corrected annular-bright-field and high-angle annular-dark-field scanning transmission electron microscopy, we investigated domain wall structures in multiferroic hexagonal TmMnO 3 and LuMnO 3 ceramics at the atomic scale. Two types of 180• domain walls (DWs), i.e., the transverse and the longitudinal DWs with uniform displacements of a/3 and 2a/3, respectively, were identified along the b direction, which is in agreement with the interlock between the ferroelectric and structural translation domain walls that had been predicted previously. Across the domain wall the arrangement of MnO 5 polyhedra was not found to be inversed, indicating that (i) it has negligible effects on the polarization and (ii) the structures of the neighbor domains with opposite polarizations are not exactly the same. These wall structures are different from the polarization inversion in conventional ferroelectrics and may be used to explain the unusual transport properties and magnetoelectic effects.