Core–shell-structure Ag–BaTiO3 composite nanopowders prepared directly by flame spray pyrolysis.

Abstract: Core–shell-structure Ag–BaTiO3 composite nanopowders are prepared directly by flame spray pyrolysis. The single-crystalline Ag was located in the core part of the composite powder, and the Ba and Ti components are uniformly distributed in the shell part. The X-ray diffraction (XRD) patterns of the Ag–BaTiO3 composite powders have the main crystal peaks of Ag and broad peaks at around 28°. The Ag–BaTiO3 pellets with low Ag contents (below 20 wt%) have a dense structure and fine grain size. Abnormal grain growth of the Ag(30 wt%)–BaTiO3 pellets occurs even at a low sintering temperature of 1000 °C. The Ag–BaTiO3 pellet had a mixed crystal structure of BaTiO3 and Ag phases. Silver is uniformly distributed in the BaTiO3 matrix without phase separation. The dielectric constants of the BaTiO3, Ag(10 wt%)–BaTiO3, and Ag(30 wt%)–BaTiO3 pellets are 830, 2130, and 4680, respectively. [Copyright &y& Elsevier]