the study of pure and mn doped zno nanocrystals for gas-sensing applications

zno and zno: mn nanocrystals were synthesized via reverse micelle method. the structural properties of nanocrystals were investigated by xrd. the xrd results indicated that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. resistive gas sensors were fabricated by providing ohmic contacts on the tablet obtained from compressed nanocrystals powder and the installation of a custom made micro heater beneath the substrate. sensitivity (s= ra/rg) of zno and zno: mn nanocrystals were investigated as a function of temperature and concentration of ethanol and gasoline vapor. the obtained data indicated that optimum working temperatures of the zno and zno: mn nanocrystals sensors are about 360°c and 347°c for ethanol vapor and about 287°c and 335°c for gasoline vapor. based on gas sensing results, although mn impurity reduces the sensitivity but the sensor got saturated at much higher gas concentration.