Effect of Annealing Temperature on Ag-NaCl/TiO2-Ag and Ag-NaCl/Al2O3–Ag Capacitive and Resistive Humidity Sensors

Present paper reports the applications of NaCl/TiO2 and NaCl/Al2O3 as capacitive and resistive humidity sensors. The pellets are prepared with the addition of TiO2 and Al203 of different molar ratios (0.10, 0.50 and 0.80) to NaCl and annealed at 60, 80, 100 and 120 °C for 4 days. After of annealing, the pellets were exposed to humidity under controlled condition. Variations in resistance and capacitance with the relative humidity were recorded. Results show that the capacitance and resistance increase with the annealing temperature. From the Scanning Electron Microscopic studies, it is observed that as annealing temperature increases the porosity of samples increases and particle size decreases with concentration of TiO2 and Al2O3. XRD pattern shows that addition of TiO2 and Al2O3 to NaCl affects crystallite size. Results show that NaCl/TiO2 has a better scope for developed resistive sensors and NaCl/Al2O3 for capacitive sensors