The size effect of Pt/C nanoparticles with diameters ranging from 2 to 28 nm have been studied using X-ray diffraction.

We investigated the effect of huge electric field up to E=55 MV/m on tetragonal ferroelectric phase of BaTiO3 single crystal. Both lattice parameters and the dielectric susceptibility along the polar axis were determined. The induced polarization shows a continuous increase up to 20% of the spontaneous polarization. The longitudinal d33 and transverse d31 piezoelectric coefficients were also determined. The experimental data are described by a phenomenological approach. Interestingly, an intermediate critical electric field value of E∼25 MV/m was evidenced suggesting that the physics below and above this value are different.

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Ferroelectric rhombohedral phase (R3m) in PbZr 0.958 Ti 0.042 O 3 and antiferroelectric orthorhombic phase (Pbam) in PbZrO 3 and PbHfO 3 are examined via X-ray diffraction and dielectric methods in DC electric fields of 0 ࣘ Е ࣘ 3.010 7 V/m. Induced polarization P i (E) and piezoelectric coefficient d 33 (Е) are found as functions of field from the experimental dependences of unit-cell parameters and dielectric permittivity on the electric field E and exhibit similar behavior for BaTiO 3 and PbZr 0.958 Ti 0.042 O 3 single crystals. The unit-cell parameters of antiferroelectric phases in PbZrO 3 and PbHfO 3 single crystals remain constant, while the electric fields correspond to induced phase transitions, and the dielectric permittivity slightly increases with the electric field.

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