High-pressure synthesis of novel lithium niobate-type oxides

Inaguma, Yoshiyuki; Yoshida, Masashi; Tsuchiya, Takeshi; Aimi, Akihisa; Tanaka, Kie; Katsumata, Tetsuhiro; Mori, Daisuke

doi:10.1088/1742-6596/215/1/012131

Cited by 31 publications

(47 citation statements)

References 22 publications

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“…Further experiments as well as computational simulations are required to clarify this issue. A possible interesting study is a search for new compounds with the anti-ilmenite and anti-LiNbO 3 structures, which will highlight the important role of the tolerance factor as well as the covalent bonding38.…”

Section: Discussionmentioning

confidence: 99%

Post-perovskite Transition in Anti-structure

Wang¹,

Ohgushi²

2016

Sci Rep

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The discovery of the post-perovskite transition, which is the structural transition from the perovskite to post-perovskite structure in MgSiO3 under pressure, has aroused great interests in geosciences. Despite of previous extensive studies, key factors of the post-perovsktie transition are still under hot debate primarily due to the big difficulty in performing systematic experiments under extreme conditions. Hence, search for new materials showing the post-perovskite transition under ambient pressure has been highly expected. We here report a new-type of materials Cr3AX (A = Ga, Ge; X = C, N), which exhibits the post-perovskite transition as a function of “chemical pressure” at ambient physical pressure. The detailed structural analysis indicates that the tolerance factor, which is the measure of the ionic radius mismatch, plays the key role in the post-perovskite transition. Moreover, we found a tetragonal perovskite structure with loss of inversion symmetry between the cubic perovskite and orthorhombic post-perovskite structures. This finding stimulates a search for a ferroelectric state in MgSiO3.

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Section: Discussionmentioning

confidence: 99%

Post-perovskite Transition in Anti-structure

Wang¹,

Ohgushi²

2016

Sci Rep

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“…In situ energy dispersive x-ray diffraction experiments revealed that a phase transition between the two phases could be realized irreversibly in PbNiO 3 if the appropriate thermodynamic conditions, 400 • C and 3 GPa are established [63]. The structural phase transition in CdPbO 3 strongly depends on heating temperature and there are temperature ranges in which both phases are seen to coexist [64]. Additionally, Goldschmit diagram analysis [63,64] suggests a boundary between the orthorhombic and rhombohedral phase in the vicinity of t = 0.85.…”

Section: Introductionmentioning

confidence: 99%

Structural and ferroelectric transitions in magnetic nickelate PbNiO₃

et al. 2014

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Density functional calculations have been tremendously useful in understanding the microscopic origin of multiferroicity and in quantifying relevant properties in many multiferroics and magnetoelectrics. Here, we focus on a relatively new and promising compound, PbNiO 3 . The structural, electronic and magnetic properties of its two polymorphs, i.e. the orthorhombic structure with space group Pnma and the rhombohedral LiNbO 3 -type structure with space group R3c have been studied by using density functional calculations within DFT+U and hybrid functional schemes. Our data convey an accurate description of the pressure-induced phase transition from the rhombohedral to orthorhombic phase at a predicted critical pressure of 5 GPa in agreement with the measured value of 3 GPa. Both phases show the G-type antiferromagnetic configuration as a magnetic ground state, but differ in the spatial anisotropy associated with nearest-neighbor exchange couplings, which is strongly weakened in the rhombohedral LiNbO 3 -type phase. The predicted large ferroelectric polarization of the rhombohedral phase (Hao et al 2012 Phys. Rev. B 014116) has been reexplored and analyzed in detail using partial density of states, Born effective New J. Phys. 16 (2014) 015030 X F Hao et al charge tensors, charge density difference, electron localization function analysis and distortion mode analysis. The asymmetric bonding between the Pb 6s and O 2p orbitals along the [111]-direction is responsible for the polar cationic displacement, giving rise to a predicted large ferroelectric polarization as high as ∼100 µC cm −2 .

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“…If the A ion is too small, tilts of octahedra occur for t < 0.9, serving to reduce the coordination number of A. The resulting structures are often orthorhombic or, as t decreases past 0.85, of the LiNbO 3 and later ilmenite types 8 . On the other hand, when A is too large and t > 1, face-sharing of octahedra is commonly observed along with unit cells of hexagonal symmetry.…”

Section: Introductionmentioning

confidence: 99%

Phase stability of theSrMnO3hexagonal perovskite system at high pressure and temperature

et al. 2014

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SrMnO 3 is a perovskite compound which, unlike most perovskites, can be synthesized in three different but closely related polymorphs. In this paper, the first experimental equation of state of the 6H polymorphs is reported. The experimentally determined bulk modulus of SrMnO 3 increases from 115.6(11) GPa in the 4H polymorph to 143.7(17) GPa in the 6H polymorph, while DFT calculations predict a further increase to 172.5(4) GPa in the 3C polymorph. The first in situ observations of transformations between the three known polymorphs, under high pressure and high temperature conditions are also reported. The results are compared with extensive DFT calculations and literature, and it is demonstrated that the 6H polymorph is the thermodynamically stable phase between 5.9(3) and 18.1(2) GPa at zero kelvin. The effect of possible oxygen sub-stoichiometry is also explored, used DFT. Finally, the findings are combined with the existing knowledge of the phase behavior in this system to outline where further knowledge needs to be collected before a PT phase diagram can be constructed for this system. I. INTRODUCTIONInorganic compounds with the formula ABX 3 very often crystallize in the well-known perovskite structure, or distorted derivatives thereof. In the ideal cubic structure, the unit cell can be described by an AX 3 cubic close-packed layer, with B ions in the octahedral holes that are surrounded only by X anions. The packing sequence is abc, a being the first hexagonal layer, b the second layer that covers half the holes in a, and c the third placed on top of b to cover the other half. This class of materials covers a wide range of technologically relevant compounds that can display piezoelectric 1 , ferroelectric 2 , (anti)ferromagnetic 3 , catalytic 4 , semiconducting 5 , metallic 6 or insulating 6 behavior. Due to the widespread use of materials with this structure, it is worthwhile trying to gain a deeper insight into the factors governing phase stability in this type of system.

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High-pressure synthesis of novel lithium niobate-type oxides

Cited by 31 publications

References 22 publications

Post-perovskite Transition in Anti-structure

Post-perovskite Transition in Anti-structure

Structural and ferroelectric transitions in magnetic nickelate PbNiO₃

Phase stability of theSrMnO3hexagonal perovskite system at high pressure and temperature

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High-pressure synthesis of novel lithium niobate-type oxides

Cited by 31 publications

References 22 publications

Post-perovskite Transition in Anti-structure

Post-perovskite Transition in Anti-structure

Structural and ferroelectric transitions in magnetic nickelate PbNiO3

Phase stability of theSrMnO3hexagonal perovskite system at high pressure and temperature

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Structural and ferroelectric transitions in magnetic nickelate PbNiO₃