Effect of uniaxial pressure on the ferroelectric phase transition in Pb5Ge3O11: Ba crystals

The effect of uniaxial pressure up to 1 kbar applied perpendicular and parallel to c-axis, on the Curie temperature and electric permittivity ec of Ba-doped Pb5Ge3O11 single crystals was investigated. The Curie temperature decreases with uniaxial pressure and the coefficient γi (γi ≡ δT c/δXi) is determined as –7 and –11 K kbar−1 for the band c-axes, respectively. It was found that uniaxial pressure increases the phase transition diffuseness and the tricritical point cannot be achieved for this pyroelectric and ferroelectric single crystal.