Crystallographic Nanojunctions of Bismuth Ferrite for Unconventional Detection of Carbon Monoxide

The present work reported, for the very first time, acrystallographicjunction formed of (002) and (110) oriented crystals of bismuth ferrite(BFO) for ultrasensitive carbon monoxide (CO) detection. Growth orientationand crystallinity of the solution-processed BFO were controlled byvarying calcination times. The sensor demonstrated a maximum responseof six times for 30 ppm of CO, with response and recovery times of149 and 226 s, respectively, with a significant specificity over otherchemically compatible species. The device showed excellent stabilitywhen tested continuously for a period of 150 days with a maximum responsedeviation of +/- 0.35 times for 30 ppm of CO. The sensitivity ofthe sensor significantly increased in comparison to other polycrystallinevariants with less or no junctions. In order to understand the effectof crystallographic junctions on sensing performance, an analyticalmodel was put forward. The proposed model established the dependencyof the sensor response pattern on the carrier diffusion coefficient(D (g)) of the exposed gas and the ease ofcarrier diffusion through the gas-surface junction, which iscontrolled by the junction bias and the drift current. Hence, theproposed junction-based sensor provides additional control over thesensor efficiency in comparison to its resistive counterparts, therebysignificantly improving the device performance without significantlycomplicating the device.

Automated summary

This study reports the formation of a crystallographic junction consisting of (002) and (110) oriented crystals of bismuth ferrite (BFO) for ultrasensitive carbon monoxide (CO) detection. The growth orientation and crystallinity of the solution-processed BFO were controlled by varying calcination times. The junction-based sensor showed a significantly higher response and specificity for CO compared to other chemically compatible species, and demonstrated excellent stability during continuous testing.