No abstract

Two different types of BaTiO 3 seed particles, normal and twinned seeds of ϳ30 m on the average, were prepared from crushed sintered specimens. Normal seeds were obtained from the usual BaTiO 3 sintered compacts, while twinned seeds containing a double twin were obtained from BaTiO 3 compacts sintered with 2 mol% of SiO 2 . The BaTiO 3 powder compacts were again prepared with 5 wt% of seed grains and sintered under various conditions. The microstructural evolution was quite different in the two cases: the growth of normal seed grains was ultimately limited but that of the twinned seeds continued extensively. The observed difference is discussed in terms of the growth mechanism and the atomic structure of interfaces.

No abstract

An electrochemical NO 2 sensor is fabricated using yttria-stabilized zirconia as electrolyte and SnO 2 -NiO nanocomposites as sensing electrodes. The SnO 2 -NiO nanocomposites with varying molar ratio (Sn:Ni = 1:3, 1:1, 3:1) were synthesized by a citric acidassisted hydrothermal route and sintered over a YSZ-electrolyte to form the sensing electrode of the sensor. The phase structure and morphology of the electrodes were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) techniques. The NO 2 sensing performance of the fabricated sensor was measured at 700°C with varying NO 2 and O 2 concentrations. Furthermore, the electrochemical polarization curves were studied for the analysis of the sensing mechanism. It was found that the sensing response ( V), sensitivity, response/recovery dynamics as well as cross-sensitivity of these sensors were greatly dependent over the cationic molar ratio (Sn: Ni) of the nanocomposite sensing electrode. Moreover, the SnO 2 -NiO nanocomposites displayed high sensitivity, high stability and low cross-sensitivity; projecting it as a potential sensing electrode material for the electrochemical NO 2 sensors.