Abstract
III
Abstract
With the advance of science and technology, better performance is needed for
gas sensor. Since the gas sensor works in ambient air environment, the changes in
humidity have a significant impact on gas sensor response. It is one of the problems
how to improve the humidity tolerance of gas sensor. In this paper, It is studied how
to improve the humidity tolerance of gas sensor. Pure SnO
2
and doped SnO
2
were
prepared, and were characterized by FT-IR, XRD and SEM. the gas-sensing and
humidity tolerance of SnO
2
-based hot-wire gas sensor were measured. And the
sensing mechanism of the hot-wire gas sensor was discussed according to the
structure and experimental results.
Pure SnO
2
and Sb doped SnO
2
(ATO) sensitive material were prepared by nitric
acid oxidation and co-precipitation method, and the materials were characterized by
FT-IR, XRD and SEM. Comparative analysis showed that 6% Sb doped SnO
2
did not
produce a new crystalline phase and still were the quartet rutile structure. The gas
sensitivity and humidity tolerance of SnO
2
-based hot-wire gas sensor was measured.
With 6% ATO as the material of sensitive element, the results showed that the
maximum response value of the sensor was 435 mV. With Al
2
O
3
or SnO
2
as the
material of reference element, the response to 1000 ppm H
2
and humidity tolerance of
the sensor was quite different. When the material of reference element was SnO
2
, due
to the sensitive element and the reference element were the same with SnO
2
-based
material, the response of the sensor to the H
2
was reduced from 435 mV to 170 mV.
However, as the materials of two elements were the same base material, the sensor
was showed a good humidity tolerance when the relative humidity changed between
20% and 90%. The relative deviation of sensitivity caused by humidity changed from
± 14.0% to ± 7.3%.
In order to improve the situation of the sensor response decrease that was caused
by the material of the reference element replaced by SnO
2
. According to the special
structure of the hot-wire gas sensor and sensing mechanism, Zn, Mg, Cu and Si doped
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