  We measured the temperature dependences of the capacity and dielectric losses
of the tape-casted dense ferroelectric composites consisting of 28 vol.% BaTiO3
nanoparticles (average size 24 nm) in the polyvinyl butyral polymer and 35
vol.% BaTiO3 microparticles (0.5-0.7 {\mu}m) dispersed in the ethyl-cellulose,
as well as the ceramics made from the nanoparticles using the annealing at
1250oC. The composite films were covered with Ag electrodes and the
measurements were performed in a wide frequency range. Using the Lichtenecker
effective media approximation, we analysed the effective dielectric response of
the dense ferroelectric composites. To establish the phase state of the
nanoparticles, we analysed the static 137Ba NMR spectra of BaTiO3 nanoparticles
in a wide temperature range from 200 to 400 K. Obtained results revealed that
the ferroelectric properties of the nanoparticles contribute to the effective
dielectric response of the composites in a significantly different way than
predicted by the effective media model. This counterintuitive conclusion
indicates on the strong crosstalk effects in the dense ferroelectric
nanocomposites, which can be very promising for their applications in
nanoelectronics and energy storage.
