Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1−xScx)2∕3W1∕3O3 solid solutions

Abstract

Ceramic samples of the multiferroic perovskite Pb(Fe1−xScx) 2/3 W 1/3 O3 with 0 ≤ x ≤ 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (F m3m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B and B sites. As the non-magnetic Sc 3+ ions replace the magnetic Fe 3+ cations, the antiferromagnetic state of PbFe 2/3 W 1/3 O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B and B sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1−xScx) 2/3 W 1/3 O3 and possibly also in the undoped PbFe 2/3 W 1/3 O3.

Structure of Pb(Fe2/3W1/3)O3 single crystals with partial cation order

“…This is not surprising given that there are smaller differences in size between Fe 3+ (0.645 A) and W 6+ (0.6 A). The cation ordering in PFWO can be enhanced by both thermal treatment (thermal annealing and quenching) and cation substitution [37][38][39][40][41][42][43][44][45][46][47][48] . In Ref.…”

“…It was observed also that the ordering degree in PFWO is hardly modified by annealing treatments, but is very sensitive to doping [28][29][30][31][32][33][34][35][36] . Investigations of the effects of different additives on the order in the PFWO-based ceramics demonstrated that relatively small alterations in the chemistry can produce very large changes in the thermodynamic stability of the ordered structure and induce significant modifications in the magnetic behavior and dielectric/ferroelectric properties, for example, the influences of the Na, Mg, Ti, Zr, Sc, and Yb dopings [37][38][39][40][41][42][43][44][45][46][47][48] . Small amounts of Na, Sc and Yb cation substitutions promote a transformation to an ordered cubic (Fm − 3m) structure.…”

Neutron Diffraction Magnetic and Mossbauer Spectroscopic Studies of Pb0.8Bi0.2Fe0.728W0.264O3 and Pb0.7Bi0.3Fe0.762W0.231O3 Ceramics

“…These materials exhibit Bsite 1:1 long-range order leading to the ferrimagnetic nature of a larger spontaneous magnetic moment without affecting the relaxor ferroelectric nature [23][24][25]. However, the Sc-doped PFW shows the weak chemical cation ordering of about a < 5-nm range as nanodomains exhibiting the uncompensated ferrimagnetic moment [23]. The magnetic moment was larger than the disordered simple perovskites and Bi(Fe 1/2 Cr 1/2 )O 3 epitaxial thin film [26].…”

“…A similar behavior was observed in other compounds such as Pb(Mg 1/3 Nb 2/3 )O 3 , Sr(Fe 2/3 W 1/3 )O 3 , and Ba(Fe 2/3 W 1/3 )O 3 [21,22]. Ivanov et.al demonstrated the ferrimagnetic nature in the Sc-doped PFW and (1 −x)(0.79PbFe 2/3 W 1/3 O 3 -0.21PbSc 2/3 W 1/3 O 3 )-(x)BiFeO 3 (PFSW-BFO) solid solution [23]. These materials exhibit Bsite 1:1 long-range order leading to the ferrimagnetic nature of a larger spontaneous magnetic moment without affecting the relaxor ferroelectric nature [23][24][25].…”

“…Ivanov et.al demonstrated the ferrimagnetic nature in the Sc-doped PFW and (1 −x)(0.79PbFe 2/3 W 1/3 O 3 -0.21PbSc 2/3 W 1/3 O 3 )-(x)BiFeO 3 (PFSW-BFO) solid solution [23]. These materials exhibit Bsite 1:1 long-range order leading to the ferrimagnetic nature of a larger spontaneous magnetic moment without affecting the relaxor ferroelectric nature [23][24][25]. However, the Sc-doped PFW shows the weak chemical cation ordering of about a < 5-nm range as nanodomains exhibiting the uncompensated ferrimagnetic moment [23].…”