Characteristic Structural Phase Transition in Perovskite-Type Compounds

Müller, K. A.; Berlinger, W.; Waldner, F.

doi:10.1103/physrevlett.21.814

Cited by 329 publications

(124 citation statements)

References 22 publications

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“…Furthermore, it has been proposed in the literature that BaZrO 3 undergoes a pressure-induced phase transition to the tilted a − a − a − perovskite structure 53 (Glazer's notations 52 ). Assuming that the BaZrO 3 inclusions adopt the latter structure in BTZ relaxors, the tilt angle calculated from the buckling angle of the Zr-O-Zr bonds is about 11 o , which is a reasonable value for a tilted perovskite 54,55,56 . In summary, within our simplified picture, BaZrO 3 inclusions do not adopt the cubic bulk structure of BaZrO 3 but present considerable distortions away from it.…”

Section: Concluding Discussionmentioning

confidence: 99%

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
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Extended X-ray absorption fine structure (EXAFS) experiments at the Zr K-edge were carried out on perovskite relaxor ferroelectrics BaTi1−xZrxO3 (BTZ) (x = 0.25, 0.30, 0.35), and on BaZrO3 for comparison. Structural information up to 4.5Å around the Zr atoms is obtained, revealing that the local structure differs notably from the average Pm3m cubic structure deduced from X-ray diffraction. In particular, our results show that the distance between Zr atoms and their first oxygen neighbors is independent of the Zr substitution rate x and equal to that measured in BaZrO3, while the X-ray cubic cell parameter increases linearly with x. Furthermore, we show that the Zr atoms tend to segregate in Zr-rich regions. We propose that the relaxor behavior in BTZ is linked to random elastic fields generated by this particular chemical arrangement, rather than to random electric fields as is the case in most relaxors.

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Section: Concluding Discussionmentioning

confidence: 99%

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
View full text Add to dashboard Cite

show abstract

“…The electronic total energy is converged within 10 -6 eV/cell for each electronic self-consistent field calculation. Experimentally, the ground state structure of LAO below 820K is a rhombohedral perovskite ( c R3 ) with the tilted AlO 6 octahedra network [41][42][43][44]. We calculate the rhombohedral cell angle α in the ground state structure to be 60.1°.…”

Section: Methodsmentioning

confidence: 99%

First-principles study of polar LaAlO (001) surface stabilization by point defects

Seo

Demkov

2011

Phys. Rev. B

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We use density functional theory to investigate the influence of surface vacancies on the surface stability of a stoichiometric free-standing LaAlO 3 (001) thin film. Defect-free three and five unit cell thick LaAlO 3 (001) thin films show macroscopic electric fields of 0.28 V/Å and 0.22 V/Å, respectively. The built-in electric field is sufficiently strong for the five unit cell thick film to undergo a dielectric breakdown in the local density approximation. We show that the electric field can be effectively compensated by La vacancies on the LaO surface, O vacancies on the AlO 2 surface, or both types of vacancy present at the same time. Comparing surface Gibbs free energies we show that several surface vacancy structures are thermodynamically stable.

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“…This rotation angle has been identified as the order parameter for this phase transition [3]. Correspondingly, the intensities of the superlattice peaks are proportional to the square of the order parameter and can be used to track the phase transition.…”

mentioning

confidence: 99%

Anomalous phase transition in strained SrTiO3 thin films

Wells

Shapiro

et al. 2003

Applied Physics Letters

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We have studied the cubic to tetragonal phase transition in epitaxial SrTiO3 films under various biaxial strain conditions using synchrotron X-ray diffraction. Measuring the superlattice peak associated with TiO6 octahedra rotation in the low temperature tetragonal phase indicates the presence of a phase transition whose critical temperature is a strong function of strain, with TC as much as 50K above the corresponding bulk temperature. Surprisingly, the lattice constants evolve smoothly through the transition with no indication of a phase change. This signals an important change in the nature of the phase transition due to the epitaxy strain and substrate clamping effect. The internal degrees of freedom (TiO6 rotations) have become uncoupled from the overall lattice shape.Perovskite films have received a great deal of interest lately due to the potential for creating working technologies based on a variety of interesting properties such as high-T C superconductivity, colossal magneto-resistivity, ferro-electricity, and variable dielectric constants. These properties can be quite different in thin films versus nominally similar bulk samples. The primary reasons for the changes in properties are believed to be strain and defects. There is also an emerging theoretical effort to treat the effects of strain. To understand the mechanisms for these changes we must be able to conduct detailed microscopic measurements of the atomic and electronic structure.SrTiO 3 (STO) is a nearly ferroelectric material with a large dielectric nonlinearity and low dielectric loss at cryogenic temperature, making it ideal for tunable microwave devices [1]. STO is also a good model system for studying structural phase transitions. Bulk STO crystals are cubic at room temperature, with space group Pm3m(O 1 h ), but become tetragonal, space group I4/mcm(D 18 4h ), below about 105K. This phase transition involves the rotation of TiO 6 octahedra and has been featured historically in the study of structural phase transitions as the classic example of a soft-mode phase transition [2]. The unit cell of the tetragonal phase has a volume four times that of the cubic unit cell, with approximate unit cell of √ 2a× √ 2a×2a, where a is the lattice parameter of cubic unit cell. In this paper we describe the tetragonal phase as pseudo-cubic, in order to compare the structure before and after the phase transition. In this pseudo-cubic frame, the tetragonal phase has additional superlattice peaks at half integer index positions. These superlattice peaks disappear as the temperature is raised through the tetragonal-cubic phase transition. * Present Address: HASYLAB at DESY, Notkestr. 85, 22603 Hamburg, GermanyIn the bulk, the deviation from cubic symmetry is directly related to the rotation angle of the TiO 6 octahedra. This rotation angle has been identified as the order parameter for this phase transition [3]. Correspondingly, the intensities of the superlattice peaks are proportional to the square of the order parameter and can be used to track the phas...

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Characteristic Structural Phase Transition in Perovskite-Type Compounds

Cited by 329 publications

References 22 publications

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
View full text Add to dashboard Cite

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
View full text Add to dashboard Cite

First-principles study of polar LaAlO (001) surface stabilization by point defects

Anomalous phase transition in strained SrTiO3 thin films

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Characteristic Structural Phase Transition in Perovskite-Type Compounds

Cited by 329 publications

References 22 publications

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the ZrLaulhé1, Hippert2, Kreisel3 et al. 2006Phys. Rev. B1042651View full textAdd to dashboardCite

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the ZrLaulhé1, Hippert2, Kreisel3 et al. 2006Phys. Rev. B1042651View full textAdd to dashboardCite

First-principles study of polar LaAlO (001) surface stabilization by point defects

Anomalous phase transition in strained SrTiO3 thin films

Contact Info

Product

Resources

About

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
View full text Add to dashboard Cite

EXAFS study of lead-free relaxor ferroelectricBaTi1−xZrxO3at the Zr
Laulhé
¹
,
Hippert
²
,
Kreisel
³

et al. 2006
Phys. Rev. B
104
2
65
1
View full text Add to dashboard Cite