“…ABO 3-δ perovskite type oxides (0 £ δ £ 0.5, A= Lanthanide or alkaline earth, B= transition metal) have a great technological interest due to their electrical, magnetic and catalytic properties. They have been extensively used as catalyst in redox reactions, as in the reduction of nitrogen oxides and SO 2 , hydrogenation of hydrocarbons and in the elimination of atmospheric pollution. In the specific case of A=lanthanum, its oxides are particular suitable for applications as a material for sensors, for the detection of vapors and gases such as humidity, alcohol, oxygen, hydrocarbons, CO and NO 2 3-5 .…”