Effect of chromium doping on structural and gas sensing properties of cobalt aluminate

Nanocrystalline aluminates Co0.2Cr0.8Al2O4 with a cubic spinel structure and an average crystallite 82 nm were synthesized by the co precipitation method. The X-ray diffraction pattern showed broad peaks corresponding to cobalt aluminate spinel-like phase. Fourier transform infrared resonance spectroscopy (FTIR) confirms the formation of Co0.2Cr0.8Al2O4. The morphology of the film was observed through Scanning electron microscopy with Energy Dispersive X-ray analysis (SEM-EDAX). The response of prepared Co0.2Cr0.8Al2O4 materials toward different reducing gases was investigated. The sensor response largely depends on the composition, temperature and the test gas species. The enhanced LPG sensing properties can be mainly attributed to the selectivity to LPG at an optimal operating temperature (328 K). Furthermore, the sensor exhibited a fast response and a good recovery. The sensor was found to be stable and repeatable with good response and Co0.2Cr0.8Al2O4 has been discussed elaborately.