Phase coexistence near a morphotropic phase boundary in Sm-doped BiFeO3 films

Abstract

We have investigated heteroepitaxial films of Sm-doped BiFeO 3 with a Sm-concentration near a morphotropic phase boundary. Our high-resolution synchrotron X-ray diffraction, carried out in a temperature range of 25°C to 700°C, reveals substantial phase coexistence as one changes temperature to crossover from a low-temperature PbZrO 3 -like phase to a high-temperature orthorhombic phase. We also examine changes due to strain for films exhibiting anisotropic misfit between film and substrate. Additionally, thicker films exhibit a substantial volume collapse associated with the structural transition that is suppressed in thinner films.

Substitution-driven structural and magnetic phase transitions in Bi0.86(La, Sm)0.14FeO3 system

“…compound confirmed the expected coexistence [13][14][15] of the orthorhombic (~63 %) and rhombohedral (~37 %) phases ( [16]. However, it was also proven that this NaNbO 3 -like tilting is not strong and/or sufficiently ordered to give any superlattice reflections in Xray or neutron diffraction experiments [16,20].…”

“…1) retains the structural motif characteristic of parent BiFeO 3 [24]. With respect to ideal Pm 3 m perovskite, the This fact implies a similarity of nature of the substitution-induced structural evolution in Bi 1-x Ln x FeO 3 [13][14][15][16][17][18] and Bi 0.86 La 0.14-x Sm x FeO 3 systems and confirms that not only a concentration of polar-active Bi 3+ ions, but also a geometrical factor determines the doping-driven ferroelectric-to-antiferroelectric phase transformation in (Bi, Ln)FeO 3 .…”

“…It was recently proven that the crystal structure of Bi 1-x Ln x FeO 3 (Ln= Sm, Nd, La) compounds undergoes a ferroelectric-to-antiferroelectric structural phase transition at x~0.14-0.18 (the concentration boundary of the phase transformation shifts towards smaller x with decreasing ionic radius of substituting element) [13][14][15][16][17][18]. The antiferroelectric phase has the orthorhombic structure closely related to that characteristic of PbZrO 3 perovskite [19] and demonstrates a weak ferromagnetic behavior with a typical spontaneous magnetization of~0.25 emu/g [18,20].…”

Complex antipolar2×4×22structure withPnmasymmetry inProsandeev1, Khalyavin2, Raevski3 et al. 2014Phys. Rev. B201120View full textAdd to dashboardCite

“…For example, solid solutions of BFO with SmFeO 3 [19] showed transformation of the polar R3c structure of BFO into the orthorhombic √ 2 × 2 × √ 2 P nma structure inherent to SmFeO 3 . Between these two phases, experiment [19] revealed the existence of a more complex structure, which was probably close to the P bam structure of PbZrO 3 . Later, a similar structure in the solid solution of BFO and NdFeO 3 was identified as a √ 2 × 4 × 2 √ 2 structure with P nma symmetry [5].…”

Ultrafast Terahertz Gating of the Polarization and Giant Nonlinear Optical Response in BiFeO3 Thin Films

“…A spatial gradient in the doping profi le enabled measurements at a range of doping values from 0% to 45%, enabling in particular measurements near the morphotropic phase boundary between the rhombohedral ferroelectric and the orthorhombic paraelectric phase. [ 18,40,41 ] Additionally, the lower dielectric constant of LSAT enables more effi cient coupling of the applied fi eld with the thin fi lm. [ 42 ] The expected response in the static SHG is observed as the probe beam is scanned across the doping gradient, as shown in Figure 2 a.…”