Phase diagram studies in the quasi binary systems LaMnO3-SrMnO3 and LaMnO3-CaMnO3

The quasi binary systems LaMnO3-SrMnO3 and LaMnO3-CaMnO3 were studied. Both systems show a miscibility gap at intermediate La:Sr and La:Ca ratios belo w about 1400 degrees C in air. This phenomenon causes the decomposition of single-phase (La,Sr)MnO3-x and (La,Ca)MnO3-x solid solution into La-rich Sr MnO3-x + Sr-rich LaMnO3-x and La-rich CaMnO3-x + Ca-rich LaMnO3-x at lower temperatures, respectively. At 1400 degrees C in the system LaMnO3-SrMnO3, a structure transformation of (La,Sr)MnO3 from orthorhombic to rhombohedral with increasing Sr content was not observed, and the structure of La0.7Sr0 .3MnO3 was determined to be orthorhombic with a = 0.54927 +/- 0.0009 nm, b = 0.54582 +/- 0.0009 nm, and c = 0.76772 +/- 0.0034 nm.