Effect of Lanthanide on Bi3.25Ln0.75Ti3O12 (Ln=La, Ce, Nd, Sm) Nanofibers for Humidity Sensing Properties

Bi
_3.25
Ln
_0.75
Ti
₃
O
₁₂
(Ln= La, Ce, Nd, Sm) (BLnT) nanofibers are prepared by the electrospinning method and characterized by X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The humidity sensors based on BLnT nanofibers are fabricated and their humidity sensing properties are measured at room temperature within the relative humidity (RH) range of 11-95%. The optimum working frequencies of all BLnT humidity sensors are 10 Hz, and the impedance variation of Bi
_3.25
Sm
_0.75
Ti
₃
O
₁₂
(BST) humidity sensor is about six orders of magnitude within the whole humidity range from 11% to 95% RH, which is larger than it of other BLnT humidity sensors. The response time of BST humidity sensor is about 3 s and the maximum humidity hysteresis is 3% RH. The results indicate that the BST humidity sensor is of the best humidity sensitivity compared to other BLnT humidity sensors due to the low Ln-O binding energy and large lattice distortion. We expect that our work may offer the guidelines for the investigation of the relationship between binding energy and humidity sensing properties.