PbTiO3 Ferroelectric Crystals Research Articles

Ferroelectric and Spectroscopic Properties of Ho3+/Yb3+ Co-Doped Pb(Mg1/3Nb2/3)O3-32PbTiO3 Crystal

In order to design a new multifunctional crystal with excellent ferroelectric and spectroscopic properties, experiments were carried out for Ho3+/Yb3+ co-doped Pb(Mg1/3Nb2/3)O3 -32PbTiO3 ferroelectric crystal using the flux method, the coercive field Ec of which is 11.86 kV/cm. Up-conversion luminescence emission bands, including an intense green emission band at 553 nm, a red band at 663 nm, and a weak infra-red band at 755 nm, are generated at 980 nm excitation. The main spectroscopic parameters, including radiative transition probability A(J′ − J), radiative lifetimes τrad, and branching ratios β, were predicted by applying Judd–Ofelt treatment. The obtained J-O intensity parameters are Ω2 = 0.531 × 10−20 cm2, Ω4 = 1.738 × 10−20 cm2, Ω6 = 0.530 × 10−20 cm2. The radiative lifetime of 5I7 level is 5.45 ms. The fluorescence lifetime of is 5F5 is 92.568 μs. The investigations show that Ho3+/Yb3+ co-doped Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 crystal is a new type of multifunctional crystal integrating ferroelectric and spectroscopic properties, which has a potential application in the developing innovative multifunctional devices and lasers.

Enhanced piezoelectric and dielectric properties of Pb(Yb1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals by combining alternating and direct current poling

As one of domain engineering methods, alternating current poling (ACP) has been proved a convenient, effective, economical method for the enhancement of the dielectric and piezoelectric properties of relaxor–PbTiO3 (PT) ferroelectric crystals. However, a shortcoming of ACP is that there are some non-rotational domains. To further improve the potential piezoelectric properties of relaxor–PT crystals, a modified poling method, combining alternating and direct current poling (ACP + DCP), was used for improving the piezoelectric properties of Pb(Yb1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3 (PYbN–PMN)–PT ferroelectric crystals. Compared with separate DCP and ACP, the piezoelectric coefficient d33 of [001]-oriented PYbN–PMN–PT crystals increased by 51% and 15% using ACP + DCP, respectively, indicating that applying an appropriate DCP on ACP samples is beneficial to further improve the piezoelectric properties. The domain analysis reveals that the full rotation of polarization, regular domain patterns, and domain boundaries are the key factors for the enhancement of piezoelectric and dielectric properties. We established the relationship between the position of the (300)c peaks, reflecting the degree of the stretch of the lattice, and piezoelectric properties. This work indicates that combining alternating and direct current poling methods is a better poling strategy for enhancing the piezoelectric properties of relaxor–PT ferroelectric crystals compared with separate DCP and ACP methods.

Partial dislocations at domain intersections in a tetragonal ferroelectric crystal

Domain behaviour under electric cycling was examined by transmission electron microscopyin a -oriented 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 ferroelectric crystal. Prior to electric cycling, the crystal contained two nonparallel sets of90° domain walls along the two {110} planes. For the most part, the domain walls remained planar,dividing the crystal into highly regular domain strips. As two nonparallel domain wallsapproached each other, the domain width tapered down to avoid full contact. Upon repeatedelectric cycling, the domains were forced into full contact, resulting in direct intersections of90° domain walls and charged wall segments along the domain intersection. At the domainintersection, partial dislocations were observed along with a stacking fault on a plane. These dislocations had a Burgers vector of and were of predominantly screw type. It is suggested that the partial dislocationsresulted from a shear displacement along [101] in the crystal as the domain switched itspolarization to form the intersection.