Phase stability study of La1.2Ca1.8Mn2O7

We report that the composition of La1.2Ca1.8Mn2O7 does not form as a single phase, and consists of a mixture of La0.6Ca0.4MnO3 and CaO. The XRD patterns show the presence of a peak at 2θ ∼ 37°, which is a specific peak to indicate the existence of CaO with space group Fm3m and a unit cell of a = 4.8152(3) Å. After a few days, the intensity of this peak decreases and CaO transforms to Ca(OH)2. The electrical and magnetic measurements show that the colossal magnetoresistance (CMR) behavior corresponds to that exhibited by La0.6Ca0.4MnO3.