Synthesis, structure, and magnetic characterization of La2-xRxRuO5 (R = Pr, Nd, Sm, Gd, Dy)

Polycrystalline samples of La2-xRxRuO5 (R = Pr, Nd, Sm, Gd, Dy) have been prepared, applying a soft-chemistry route based on the thermal decomposition of citric acid precursors. By powder x-ray and neutron diffraction the crystal structures have been investigated in detail. For the unsubstituted parent compound La2RuO5, synchrotron x-ray diffraction patterns reveal a broad structural phase transition regime around 170 K without any significant hysteresis. This structural transition is linked with a drastic reduction of the magnetic susceptibility. A similar behavior was also observed for the lanthanide-substituted compounds La2-xRxRuO5. Magnetic measurements reveal the coexistence of two weakly interacting magnetic sublattices. The effect of rare-earth substitution on the magnetic phase transition is resulting from structural modifications caused by the smaller radius of the R3+ ions. These ions are predominantly located within the LaO-layers, which are alternating with LaRuO4 layers. The transition temperatures determined by differential scanning calorimetry (DSC) are compared to data derived from the susceptibility measurements.