Synthesis and characterization of layered titanium oxides NaRTiO4 (R = La, Nd and Gd)

The layered titanium oxides NaRTiO4 (R = La, Nd and Gd) have been synthesized at 850 °C. The lattice parameter a decreases with decreasing of the ionic size of R, in contrast to the results previously reported for samples synthesized at higher temperature, 1050 °C. X-ray Rietveld refinement of NaNdTiO4 confirmed the ordering of Na and R and the large displacement of Ti from the center of the oxygen coordination octahedra, resulting in one strong and one weak TiO bonds along c-axis. Magnetic susceptibility of the rocksalt-type (NdO)2 layer in NaNdTiO4 resembles that of the fluorite-type Nd2O2 layer in Nd2CuO4.