PRECURSOR-BASED SYNTHETIC PATHWAYS TO NANOMETER NDNIO3-X PARTICLES

The oxygen deficient neodymium nickel perovskite, NdNiO3-x, has been o btained by different low temperature-low oxygen pressure synthetic pro cedures. Besides a solid-matrix based route, both ordered and disorder ed chemical-precursors have been used as starting products. X-ray powd er diffraction shows that the structure of this defective perovskite i s orthorhombic. The study of the grain morphology of the products as r esulting from the different synthetic procedures indicates that the ma in parameter determining the average panicle size, which is in the nan ometer range, is the maximum temperature achieved in the synthesis. Re sistivity and DSC measurements show the existence of a metal to insula tor transition at ca. 175 K. The anomalous behaviour of the resistivit y in the insulator zone is discussed.