The characterrization of high temperature solution-grown crystals of Pb(Fe_1/2^Nb_1/2)O₃

Abstract

Polarization microscope studies on single crystal samples of Pb(Fe 1 /2Nb 1 / 2 )o 3 [PFN] have been made. Thin platelets (<60~) show large, homogeneous ferroelectric domains and optical characterization shows PFN is trigonal "••• at room temperature and optically negative. Birefringence measurements between 4.2K and 400K reveal the transition to the cubic structure takes place at 383K, in accordance with earlier work, but they also locate a previously undetected structural modification at 354K, accompanied simultaneously by a re-orientation of the index ellipsoid; both transitions manifest themselves by endothermic reactions on heating in DTA experiments. The new phase is very likely monoclinic.

Ferroic transitions in the multiferroic (1 −x)Pb(Fe1/2Nb1/2)O3–xPbTiO3 system and its phase diagram

“…Further, it has been argued in the recent years that the MPB effects in the PbTiO 3 -based solid solutions are essentially due to the stabilization of the MPB of pure PbTiO 3 observed at high pressure to ambient pressure by Zr 4+ , Mg 2+ /Nb 5+ , Zn 2+ /Nb 5+ substitutions [28]. The PFN-xPT system is unique as one of its end members, PFN, has already been reported to undergo a monoclinic to tetragonal phase transition at $355 K [29][30][31][32], whereas the other end member, PT, shows a tetragonal to monoclinic transition at high pressures at room temperature [28].…”

Tuning the multiferroic properties of Pb(Fe1/2Nb1/2)O3 by cationic substitution

“…Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) is a well-known ferroelectric material with a perovskite ABO 3 -type structure in which Fe 3+ and Nb 5+ occupy the octahedral B-site while the Pb 2+ ion resides in a 12 coordinated A-site [6][7][8]. PFN exhibits a broad ferroelectric transition B380 K and displays a high dielectric constant (>10,000) at T M : Magnetic measurements have shown that PFN undergoes two diffuse magnetic transitions at 150 and 9 K [4,9].…”

Elastic and anelastic relaxation behaviour of perovskite multiferroics I: PbZr0.53Ti0.47O3 (PZT)–PbFe0.5Nb0.5O3 (PFN)

“…At least in some samples, the low temperature structure may be rhombohedral (R3m) [21]. The first transition is close to tricritical in character and typically occurs at *380-390 K. The second, 20-40 K lower, is generally considered to be first order in character [21][22][23][24][25][26][27][28][29][30][31]. With increasing PT content along the PFN-PT binary join, the stability field of the monoclinic structure diminishes such that the P4mm-Cm transition point extrapolates to 0 K at *8-12 % PT [32,33].…”