Microstructure and thermoelectric properties of Ca0.9Yb0.1MnO3/Pd nanocomposite prepared by electroless plating

We have fabricated a Ca0.9Yb0.1MnO3/Pd nanocomposite in which a palladium layer made up of particles with a size of about 50 nm exists at grain boundaries in the Ca0.9Yb0.1MnO3 matrix. The nanocomposite was produced by plating Ca0.9Yb0.1MnO3 powder with palladium and then carrying out spark plasma sintering. The palladium particles contained 10 wt.% phosphorus, independent of the palladium content, and had an amorphous structure. The as-plated phosphorous-containing palladium particles transformed into crystalline palladium and amorphous palladium phosphide after sintering at 1023 K. The thermoelectric properties of the Ca0.9Yb0.1MnO3/Pd nanocomposite bulk degraded with increasing palladium content, mainly as a result of the high electrical resistivity. This is probably because the palladium-phosphorus phase located at the grain boundaries inhibits electrical conductance, which leads to lower electrical mobility. (C) 2013 Elsevier B.V. All rights reserved.