The ferroelectric phase of CdTiO3: A powder neutron diffraction study

Kennedy, Brendan J.; Zhou, Qingdi; Avdeev, Maxim

doi:10.1016/j.jssc.2011.08.028

Cited by 31 publications

(33 citation statements)

References 41 publications

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“…The The Pmc2 1 structure of 0.72BFTM-0.28LFO (Section 3.1, Supporting Information) is adopted at low temperature by the high-pressure form of the B-site-driven CdTiO 3 ferroelectric, [9] (though more recent neutron diffraction studies have cast doubt on this [10] ), the high field form of NaNbO 3 [11] and sol-gel synthesized NaNbO 3 . [12] There are one B site and two A sites in the asymmetric unit, with the Rietveld refinement showing no indication of Bi/La cation ordering.…”

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confidence: 99%

Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

et al. 2012

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Piezoelectrics are key functional materials in actuator and sensor applications. [1] Current technology exploits lead-based materials displaying a morphotropic phase boundary (MPB) between two ferroelectric solid solutions of different symmetries and polarization directions. This is best exemplified by the PbZr 1Àx Ti x O 3 (PZT) perovskite system where the distortions driving the piezo response are produced by the stereo-active electron lone pair of the Pb 2+ cation on the A site of the ABO 3 perovskite structure. [2] Due to the environmental impact of lead, there is a considerable focus on the synthesis of lead-free electroceramics. It is not however clear if the complex crystal chemistry underlying the structural phase boundaries at the MPB in lead-based systems can be simply translated into lead-free analogues. In particular the balance between distortions driven by the A and B site cations and the role of octahedral tilting and tolerance factor considerations are expected to be quite different in non-lead systems, as Pb 2+ is significantly larger than the more highly charged Bi 3+ often considered as an alternative polarizationgenerating cation. [3] However, the smaller size of bismuth ions generally requires high-pressure synthesis conditions to form a perovskite. Only a small group of known perovskites exist with A-site bismuth cations that are stable at ambient pressure, based on BiFeO 3 , [4] Bi 2 Mn 4/3 Ni 2/3 O 6 , [5] and Bi(Fe 2/8 -Ti 3/8 Mg 3/8 )O 3 (BFTM). [6] Bi 2 Mn 4/3 Ni 2/3 O 6 is antiferrodisplacive, [5] while both BiFeO 3 and BFTM adopt the R' R3c structure where the [111] p displacements of untilted R (space group R3m in the PZT case) are coupled with octahedral rotation about the same axis (the prime symbol denotes the presence of tilts). In order to access MPBs, polar structures with distinct polarization directions away from [111] p in these Bi-based families are required.We investigated the pseudoternary phase field BFTMLaFeO 3 (LFO)-La 2 MgTiO 6 (LMT) where the introduction of LFO (tolerance factor t = 0.95) would alter the average structural asymmetry on the A site by combining the aspherical Bi 3+ and spherical La 3+ cations, and the addition of Mg 2+ and Ti 4+ from LMT (t = 0.95) on the B site would reduce the dielectric loss caused by the increase in Fe 3+ content. LFO adopts the Pmnb structure of GdFeO 3 with an a + b À b À tilt system and 0.18antiferrodistortive La 3+ displacements along the [110] p direction. LMT (P2 1 /a) has the same A-site displacement pattern and tilt system plus rock salt ordered B-site cations. [7] Phases in the BFTM-LMT-LFO (BLFTM) field (Figure 1 a) were prepared according to the protocol set out in Section 1 of the Supporting Information. Four distinct classes of powder diffraction patterns are observed. BFTM (t = 0.96) is the only material with the rhombohedral R3c space group, and is surrounded by a two-phase region. At low LFO content and along the BFTM-LMT line, an orthorhombic perovskite phase and an Aurivillius phase coexist (XRD data Figure S...

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Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

et al. 2012

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“…Sasaki et al showed that CdTiO 3 has Pbnm phase in their experiment . Kennedy et al demonstrated that the phase of CdTiO 3 at room temperature is either R

\bar{3}

or Pbnm phase . Tanaka et al found that there was a small difference in both structure and energy between Pnma and Pna2 1 phase of CdTiO 3 in their computational studies .…”

Section: Resultsmentioning

confidence: 99%

“…Seven materials, MgSnO 3 , ZnSnO 3 , MgTiO 3 , ZnTiO 3 , MgGeO 3 , ZnGeO 3 , and CdTiO 3 , out of the 12 materials examined showed zone center instability, whereas polar instability was not found in the high tolerance factor materials in room temperature is either R 3 or Pbnm phase. [34] Tanaka et al found that there was a small difference in both structure and energy between…”

Section: Polar Instability Of Pnma Phase and The Bond Length/valencmentioning

confidence: 99%

First-principles examination of low tolerance factor perovskites

Kang

2017

Int J Quantum Chem

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Perovskites are generally formed in the non‐polar Pnma phase. The materials found in the polar subgroup of Pnma are not common. This article reports how perovskites having a low tolerance factor display ferroelectric instabilities in artificially constrained Pnma phase. The bond length distribution and the bond valence sum were analyzed to examine the origin of the ferroelectric behavior of low tolerance factor materials. However, the ground state structure of low tolerance perovskite is not Pnma phase, but either ilmenite (R 3¯) or lithium niobate (R3c) phase. Here, epitaxial strain was used as a tuning parameter to stabilize the polar subgroup of Pnma. The rationalized principles from these studies will be valuable for designing new ferroelectric materials in the future.

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“…2), i.e. the symmetry reduction cannot be explained by a unique irrep, as the symmetry of the distorted phase is not an isotropy subgroup of the archetype phase; this is quite common in distorted perovskite structures [16,17,28,29]. In Fig.…”

Section: Resultsmentioning

confidence: 99%

A structural study of the CaLn2CuTi2O9 (Ln=Pr, Nd, Sm) and BaLn2CuTi2O9 (Ln=La, Pr, Nd) triple perovskite series

Iturbe‐Zabalo

Igartua²,

Aatiq

et al. 2013

Journal of Molecular Structure

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The ferroelectric phase of CdTiO3: A powder neutron diffraction study

Cited by 31 publications

References 41 publications

Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

First-principles examination of low tolerance factor perovskites

A structural study of the CaLn2CuTi2O9 (Ln=Pr, Nd, Sm) and BaLn2CuTi2O9 (Ln=La, Pr, Nd) triple perovskite series

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The ferroelectric phase of CdTiO3: A powder neutron diffraction study

Cited by 31 publications

References 41 publications

Perovskite B‐Site Compositional Control of [110]p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

Perovskite B‐Site Compositional Control of [110]p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

First-principles examination of low tolerance factor perovskites

A structural study of the CaLn2CuTi2O9 (Ln=Pr, Nd, Sm) and BaLn2CuTi2O9 (Ln=La, Pr, Nd) triple perovskite series

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Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric

Perovskite B‐Site Compositional Control of [110]_p Polar Displacement Coupling in an Ambient‐Pressure‐Stable Bismuth‐based Ferroelectric