Improved humidity sensitivity and possible energy harvesters in lithium modified potassium niobium tantalate oxide

The (K0.9Li0.1)[(Ta0.2Nb0.8)0.99Mn0.01]O3 (KLTN) electroceramics exhibit fast humidity response, long time resistance stability under various humidity conditions, and giant sensitivity (≈2.6×104) at 95% RH, which is approximately five times higher than pure KTa0.2Nb0.8O3 (KTN) polycrystalline sample. The KLTN shows a small hysteresis in resistance values during adsorption and desorption measurement within the humidity range of 15%–95%. The current-voltage data indicate the presence of an open-circuit voltage (VOCV) of 1.6 V with short circuit current (ISCC) 1–2 μA at 95% relative humidity, which in turn glows a standard red light-emitting diode (LED) after series and parallel connection of a few humidity sensors. This may be useful for energy harvesting in the remote and humid coastal region; however, it requires further optimization for real applications as energy harvesters. After several repeated cycles, the adsorption and desorption data suggest that KLTN may be a potential candidate for sensitive humidity sensors and energy harvesters.