The phase structure and dielectric properties around a new type of phase boundary in a lead ytterbium niobite based solid solution.

The phase boundaries of dielectric materials have constantly been valuable for instructing the design of phase structures, revealing correlations between compositions and structures, and attaining the desired functional properties for piezoelectric, pyroelectric, electrostriction, electrocaloric, energy storage and energy harvesting applications. We here observe a new type of phase boundary in a solid solution of xPbTiO3·(1 - x)Pb(Yb1/2Nb1/2)O3 (x = 0.00-0.20), which is between an antiferroelectric (AFE) phase and a relaxor ferroelectric (RFE) phase. x = 0.10 is confirmed as the phase boundary. XRD, TEM, PFM and Raman spectroscopy analysis reveal two fundamental traits of the phase structure: (1) the polar state changes from AFE to FE order; and (2) the domain range evolves from micrometer-sized to nanometer-sized, both of which are normally separated but coexist around the phase boundary. The intriguing phase structure contributes to the distinctive dielectric properties: (1) a broad compositional zone (x < 0.10 and x ≥ 0.14) features low remnant polarization, low hysteresis and highly reversible domain wall motion, and is expected to be utilized for dielectric energy storage and electrostriction applications; and (2) a narrow nonergodic RFE zone (0.10 ≤ x < 0.14) demonstrates remnant and maximum polarization, co-dominated by composition and temperature, and has potential for pyroelectric and electrocaloric applications.