Structure and magnetic properties of ternary potassium lanthanide oxides KLnO2 (Ln = Y, Nd, Sm-Lu)

Crystal structures of ternary potassium lanthanide oxides KLnO2 (Ln = Y, Nd, Sm-Lu) have been determined by powder X-ray diffraction using the Rietveld analysis method. All of the KLnO2 compounds have the same hexagonal α-NaFeO2 structure with space group R3¯m. Magnetic susceptibility measurements for these compounds show paramagnetic behavior down to 1.8 K. The specific heat measurements indicate that the Gd, Dy, Ho and Er compounds have a magnetic anomaly at 1.1, 1.8, 1.2 and 0.8 K, respectively. The 151Eu Mössbauer spectrum for KEuO2 has been investigated at room temperature.