Structural origin of relaxor ferroelectrics—revisited

Structural origin of relaxor perovskites

Properties of gelatin-based films incorporated with chitosan-coated microparticles charged with rutin

Antiferroelectrics (AFE) are considered a promising energy storage material for components that require nanosecond-level discharge. Pb(Yb1/2Nb1/2)O3 (PYN) is an AFE material with potential energy storage applications. However, the unmatched critical phase transition field (EF) and breakdown electric field (EB) conceal most of energy storage capacitance. This work is aimed to settle imbalanced EF/EB via a compositional design strategy. EF and EB were tuned in order to obtain 5.18 J cm−3 in recoverable energy density, 65% energy efficiency, and thermal and frequency stability varying within 15%, producing excellent comprehensive energy storage properties. A modified kinetic model of energetic path was used to understand the mechanism governing the variation of EF. We expect our work to contribute to further development of novel AFE materials for energy storage.

Novel complex B-site lead oxide antiferroelectric system developed by compositional design for dielectric energy storage

The synthesis, crystal structure, and dielectric properties of the novel double perovskite Pb 2 TmSbO 6 are described. The room-temperature crystal structure was determined by ab initio procedures from neutron powder diffraction (NPD) and synchrotron X-ray powder diffraction (SXRPD) data in the monoclinicC2/c(No. 15) space group. This double perovskite contains a completely ordered array of alternating TmO 6 and SbO 6 octahedra sharing corners, tilted in antiphase along the three pseudocubic axes, with ana - b - b - tilting scheme, which is very unusual in the crystallochemistry of perovskites. The lead atoms occupy a highly asymmetric void with 8-fold coordination due to the stereoactivity of the Pb 2+ lone electron pair. This compound presents three successive phase transitions in a narrow temperature range (atT1)385 K,T2)444 K, andT3)460 K in the heating run) as shown by differential scanning calorimetry (DSC) data. The crystal structure and temperature-dependent NPD follow the space-group sequenceC2/cfP2 1 /nfR3 j fFm3 m. This is a novel polymorph succession in the high-temperature evolution of perovskite-type oxides. The Tm/Sb long-range ordering is preserved across the consecutive phase transitions. Dielectric permittivity measurements indicate the presence of a paraelectric/antiferroelectric transition (associated with the last structural transition), as suggested by the negative Curie temperature obtained from the Curie-Weiss fit of the reciprocal permittivity.

An original polymorph sequence in the high-temperature evolution of the perovskite Pb2TmSbO6.

The high-temperature phase of Pb(Mg1/2W1/2)O3, Pb(Co1/2W1/2)O3 and Pb(Yb1/2Nb1/2)O3 belongs to the space group Fm3m with the unit cell size of 2ac×2ac×2ac where ac is the lattice parameter of the cubic perovskite unit cell. All these complex perovskites undergo phase transition into low-temperature orthorhombic structures with a shrunken lattice parameter along the c-axis and the approximate √2a lattice parameters along the a0- and b0-axes, which are, respectively, parallel to the prototype [110]c and [10]c directions. The symmetry along the b0-axis of the perovskites is most prominently distinguished from that along the a0-axis in that the low-temperature structure is modulated in the b0-axis direction. For Pb(Mg1/2W1/2)O3, a diffraction pattern detrimental to the crystal structure determination well below the Curie temperature is presented. At the same time, the crystal structures of lock-in phases of the aforementioned oxides are compared with the well-known structure of PbZrO3.

https://iopscience.iop.org/article/10.1143/JJAP.32.4249/pdf

Jeong Rok Kwon

Papers

Crystal Structure and B-Site Ordering in Antiferroelectric Pb(Mg1/2W1/2)O3, Pb(Co1/2W1/2)O3 and Pb(Yb1/2Nb1/2)O3