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

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.