Preparation, structure, resistance and methane-gas sensing properties of nominal La1−xMgxFeO3

The nominal La1−xMgxFeO3 powder was prepared by a sol–gel method using citric acid. The compound crystals were of a perovskite phase with orthorhombic structure when x ≤ 0.1. It was a mixture of spinel and perovskite when x > 0.1, and the p–n heterojunctions were formed, which affected the resistance and response to methane of the samples (x > 0.1). Among all La1−xMgxFeO3 (x ≤ 0.7) samples, the La0.9Mg0.1FeO3-based sensors with high sensitivity, low operating temperature, and excellent stability in air can be used as a new type of gas sensing material for detecting methane gas.