| The complex oxide powders of La1-xSrxMnO3 (x=0.2,0.3,0.4 and 0.5), which have perovskite type structures, were prepared by Sol-gel process. The films with a dense, contiguous structure and certain thickness were desposited on aluminum oxide substrate by screen printing method. The slurry used in printing was made by powders and organic intermixture which mixed by terpilenol and Ethyl cellulose (EC). In the thesis, the electrical, thermal sensitive and thermal fatigue resistance properties were discused. It was founded that a seris of NTC films, which had a stable property, perfect adhesion, high reliability and long working life, could be prepared though controlling the relatively parameters.It was investigated by SEM and XRD that the effects on micromorphology and phase composition of La1-xSrxMnO3 base films caused by dopant amount, slurry composition and sintering temperature. The results show that the organic intermixture addition had a main influence on microstructure while the films conductive phase was up to the Sr doped quantity and the grains size decreased with the increasing doping level x. The films were obtained with a smooth surface, few microcracks and good electric conductivity when the mass ratio of organic intermixture with 2 wt% EC and powders was 3:2.The study indicated that the amount of Sr doped had a significant influence on the electrical performance of the films. The electrical resistivity primo decreased and then increased with the increasing doping level x, and reached minimum at x=0.4. The curve linear relationship of resistence-temperature show a conductivity transittion from metal to semiconductor form (IMT), and the transition temperature (Tp) range was about-90℃～-60℃. The break point temperature was related to the amount of Sr, and rised with the increasing dopant. The films resistivity behaviours were consistent with the law of semiconductor conductivity, and to be precise it complied with the Arrhenius formula. The favorable temperature of Arrhenius curve became higher with the increasing level x. It indicated that the film samples had a better thermoelectic property, the local heating temperature attained over 1000℃and the average heating temperature of film surface reached 545℃when a suitable voltage of alternating current was added on the both ends of samples. The max on-load voltage could be 45V and the max current reached 2.69A. An overloaded voltage or current would cause a electrical sparkle in the thinner zone, which broke the films components and made them lose effectiveness.The blending constituent films were prepared from the perovskite phases, La0.9Ca0.1MnO3 and La0.7Sr0.3MO3 powders. The doped phase made the value of B much bigger, and the films conduction were mode correspond consisted with small polaron conduction model more accurately. Because of the increased temperature-sensitivity coefficient a during room-temperature～200℃and 650℃～800℃, the elements had a higher testing accuracy and wider range of working temperature. The most suitable sintering temperature had a direct relation to the powders, and a series of films with perfect microstructure and electrical conductivity could be obtained when the mass ratio of La0.9Ca0.1MnO3 and Lao.7Sr0.3MO3 powders was 1:4, and sintered in 1300℃.In addition, the bond strength between films and Al2O3 substrates was tested by scratching method, and it was founded that the determinant factor to the adhesion was not the films component but the sintering temperature. The thermal fatigue resistance of films was investigated though reheat testing. The results indicated that the films electrical resistivity increased obviously with the test times, which had tend to be steady. The change rate of samples resistivity was lower than±1% when the test was repeated over 6 times. Moreover, the dope of printing frit enhanced the adhesion obviously but destroyed the conductivity and reheating stabilization severely.
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