Transition metal oxides with strong electron correlation show a variety of unusual properties. Establishing the electronic and magnetic phase diagrams as a function of composition and temperature is a first step in understanding their behavior, and sometimes a crucial step in discovering novel properties. This article reviews phase-diagram studies on RCoO3, RMnO3, RMn2O5, and Y2 －x BixRu
O7 (R ＝ rare earth), where heat capacity measurements were instrumental in identifying the phase transitions and understanding the complex properties. High-pressure synthesis and synchrotron powder x-ray structural analysis also played important roles in constructing and understanding the phase diagrams.
Keywords:Transition metal oxides; heat capacity; phase diagram