Lattice effect on magnetic and electrical transport properties of Ln2/3Pb1/3MnO3 （Ln=La, Pr, Nd） films prepared by RF magnetron sputtering technique were investigated. With the decrease of the average ions radius ...Lattice effect on magnetic and electrical transport properties of Ln2/3Pb1/3MnO3 （Ln=La, Pr, Nd） films prepared by RF magnetron sputtering technique were investigated. With the decrease of the average ions radius 〈rA〉, the structure of Ln2/3Pb1/3MnO3 （Ln=La, Pr, Nd） targets transit from the rhombohedral phase to the orthorhombic phase, and the Curie temperature reduces rapidly with the decrease of 〈rA〉. The electrical properties show that films are the metallic state which can be fitted to the formula： ρ（T）=ρ0 ＋ ρ1T^2 ＋ ρ2T^4.5 at low temperatures. The temperature range of the ferromagnetic metallic state becomes narrow with the decrease of 〈rA〉. The phenomenon can be explained by the lattice effect.展开更多
Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2...Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2) for different intervals of time and fired at 500℃ for 12 h. The grains of MnO2 would disperse around the grains of ZnO base material. The MnO2 modified ZnO films dipped for 30 min were observed to be sensitive and highly selective to NH3 gas at room temperature. An exceptional sensitivity was found to low concentration (50 ppm) of NH3 gas at room temperature and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The effects of surface microstructure and MnO2 concentrations on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH3and other gases were studied and discussed. The better performance could be attributed to an optimum number of surface misfits in terms of MnO2 on the ZnO films.展开更多
基金the National Natural Science Foundation of China under grant No.50572088Xi'an University of Science Technology Breeding Foundation No.200737.
文摘Lattice effect on magnetic and electrical transport properties of Ln2/3Pb1/3MnO3 （Ln=La, Pr, Nd） films prepared by RF magnetron sputtering technique were investigated. With the decrease of the average ions radius 〈rA〉, the structure of Ln2/3Pb1/3MnO3 （Ln=La, Pr, Nd） targets transit from the rhombohedral phase to the orthorhombic phase, and the Curie temperature reduces rapidly with the decrease of 〈rA〉. The electrical properties show that films are the metallic state which can be fitted to the formula： ρ（T）=ρ0 ＋ ρ1T^2 ＋ ρ2T^4.5 at low temperatures. The temperature range of the ferromagnetic metallic state becomes narrow with the decrease of 〈rA〉. The phenomenon can be explained by the lattice effect.
文摘Pure ZnO thick film, prepared by screen-printing technique, was almost insensitive to NH3. Pure ZnO thick films were surface modified with MnO2 by dipping them into 0.01 M aqueous solution of manganese chloride (MnCl2) for different intervals of time and fired at 500℃ for 12 h. The grains of MnO2 would disperse around the grains of ZnO base material. The MnO2 modified ZnO films dipped for 30 min were observed to be sensitive and highly selective to NH3 gas at room temperature. An exceptional sensitivity was found to low concentration (50 ppm) of NH3 gas at room temperature and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The effects of surface microstructure and MnO2 concentrations on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH3and other gases were studied and discussed. The better performance could be attributed to an optimum number of surface misfits in terms of MnO2 on the ZnO films.
