Selectivity problem of SnO2 based materials in the presence of water vapors

dx.doi.org/10.1016/j.snb.2011.01.01

Two new species and one new species record of Trichosanthes (Cucurbitaceae) from Vietnam

Two new species endemic to Vietnam are described: Trichosanthes conferta and Trichosanthes epibracteata. Trichosanthes laceribractea is a new record for Vietnam

A sol-gel synthesis and gas-sensing properties of finely dispersed ZrTiO4

The transparent titanium-zirconium-containing gel was obtained using heteroligand coordination compounds (namely, alkoxoacetylacetonates) as the precursors. The high-dispersive system “ZrTiO4 – carbon” formed after drying of such gel and carbonization of the obtained xerogel, was used to study the evolution of microstructure for the product (ZrTiO4) during thermal treatment in air for 1 h in the temperature range from 500 °C to 1000°С. It was stated that the formation of crystalline phase occurred in the narrow range 690-730°С. The thermal treatment at 500 °C and 600°С allowed obtaining micro- and mesoporous X-ray amorphous products of the composition ZrTiO4, with the specific surface area falling in the range 82–150 m2/g. At the higher temperatures the single-phase nanocrystalline powder was prepared (the specific surface area amounted to 2.5–15 m2/g). Particle coarsening took place more extensively at temperatures ≥700°С was shown. For the ZrTiO4 nanopowder crystallized under the mildest conditions at the temperature of 700 °C, chemoresistive gas-sensitive properties were studied for the first time. The material showed a high reproducible response at 1–20% O2 and 200–10,000 ppm H2 at a relatively low detection operating temperature of 450 °C. © 2019 Elsevier B.V