Effect of Bi3+ ions on the humidity sensitive properties of copper ferrite nanoparticles

The response of humidity sensitivity factor of bismuth substituted copper ferrite nanoparticles is prepared by solution combustion route by using metal nitrates. From this preparation technique, bismuth substituted copper ferrites were confirmed to demonstrate the cubic spinel structure by X-ray diffraction measurement and FTIR spectral absorption bands observed at ν1 = 560 cm−1 to 580 cm−1 and ν2 = 404 cm−1 to 407 cm−1 for tetrahedral and octahedral sites in cubic spinel structure of ferrites. The prepared nanoparticles of ferrites are extremely resistive in the range of mega-ohm (MΩ) at room temperature and their humidity sensitivity is also very high. The electrical resistance is decreased for different concentration of bismuth in copper ferrites, noticeably with increasing the relative humidity. The relative humidity of BixCuFe2-xO4 nanoparticles in the range from 10% RH to 90% RH at room temperature is generated. With the substitution of bismuth, the sensitivity factor is decreased at low relative humidity. The maximum humidity sensitivity factor Sf = 925.64 was achieved for Bi0.1CuFe1.9O4 nanoparticles.