ISSN:
1573-482X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract An attempt was made to improve the electrical properties of SnO2 glass composites by dispersing metal particles having low resistivity and positive temperature coefficient of resistance (TCR) in the glass matrix. Cu metal particles were precipitated by reducing Cu2O by adding LaB6O as a reducing agent. The effects of LaB6O content and particle size on the microstructure and electrical properties of the SnO2 glass composites were monitored. When coarse LaB6O particles were used, the amount of the precipitated metal particles was large because SnO2 was also reduced as well as Cu2O during firing. However, in this case, the glass composite showed a porous microstructure including large pores because of the simultaneous evaporation of SnO formed as an intermediate product by reduction of SnO2. On the other hand, the glass composite prepared using fine LaB6O particles showed a dense microstructure uniformly dispersed with small pores. The porosity of the glass composite decreased by increasing the LaB6O content at first and then increased by further addition of LaB6O. The minimum of the porosity occurred at 2 wt % and 3 wt % LaB6O for the samples containing coarsest (4.81 μm) and finest (0.15 μm) LaB6O, respectively. Electrical conductivity (σ) and TCR of the glass composites containing LaB6O were higher and closer to zero, respectively, than those of a LaB6O free sample. The samples containing 2–3 wt % LaB6O showed 5–7 times higher σ and 50–70% smaller TCR in comparison with the sample without LaB6O. However, at high LaB6O content above 3–4 wt %, σ decreased and TCR moved in the negative direction with increase in LaB6O content. Especially, when coarse LaB6O was used, the declines σ and TCR at high LaB6O contents were remarkable. This was due to the decrease in the continuity of conductive paths related to the increase in number of the large pores caused by the evaporation of SnO.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008983624599
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