Abstract
We have studied the crystal structure of mixed-valence Sr 0.7Ce 0.3MnO 3 from 4.2 to 973 K using high-resolution neutron powder diffraction. The crystal structure is tetragonal in space group I4/mcm at 4.2-923 K and cubic in Pm3̄m at T 948 K. Lattice parameters and Mn-O bond distances, obtained by Rietveld refinement, have been used to derive the spontaneous strains and MnO 6 octahedral distortion, which are interpreted in terms of strain/order parameter coupling using a single Landau free-energy expansion for a Pm3̄m reference structure with two instabilities (R4+ and Γ3+). Two phase transitions were proposed: an octahedral tilting transition at T c,φ ∼ 938 K (Pm3̄m I4/mcm, R4+), and an isosymmetric, electronically driven (Jahn-Teller-like) transition at T c,JT ∼ 770 K (I4/mcm, R4+ I4/mcm, R4+ and Γ3+). The nature of the tilting transition appears to be tricritical, while that of the Jahn-Teller-like transition is second order. In addition to the contributions from octahedral tilting and Jahn-Teller-like distortions, there is an excess octahedral distortion at temperatures below 250 K; this is speculated to be associated with an anomaly observed over the temperature range of 275-300 K in the heat-capacity measurements.
| Original language | English |
|---|---|
| Article number | 174110 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 85 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - May 24 2012 |
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ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
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Crystal structures, strain analysis, and physical properties of Sr 0.7Ce 0.3MnO 3 . / Zhang, Zhaoming; Kennedy, Brendan J.; Howard, Christopher J.; Carpenter, Michael A.; Miiller, Wojciech; Knight, Kevin S.; Matsuda, Motohide; Miyake, Michihiro.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 85, No. 17, 174110, 24.05.2012.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Crystal structures, strain analysis, and physical properties of Sr 0.7Ce 0.3MnO 3
AU - Zhang, Zhaoming
AU - Kennedy, Brendan J.
AU - Howard, Christopher J.
AU - Carpenter, Michael A.
AU - Miiller, Wojciech
AU - Knight, Kevin S.
AU - Matsuda, Motohide
AU - Miyake, Michihiro
PY - 2012/5/24
Y1 - 2012/5/24
N2 - We have studied the crystal structure of mixed-valence Sr 0.7Ce 0.3MnO 3 from 4.2 to 973 K using high-resolution neutron powder diffraction. The crystal structure is tetragonal in space group I4/mcm at 4.2-923 K and cubic in Pm3̄m at T 948 K. Lattice parameters and Mn-O bond distances, obtained by Rietveld refinement, have been used to derive the spontaneous strains and MnO 6 octahedral distortion, which are interpreted in terms of strain/order parameter coupling using a single Landau free-energy expansion for a Pm3̄m reference structure with two instabilities (R4+ and Γ3+). Two phase transitions were proposed: an octahedral tilting transition at T c,φ ∼ 938 K (Pm3̄m I4/mcm, R4+), and an isosymmetric, electronically driven (Jahn-Teller-like) transition at T c,JT ∼ 770 K (I4/mcm, R4+ I4/mcm, R4+ and Γ3+). The nature of the tilting transition appears to be tricritical, while that of the Jahn-Teller-like transition is second order. In addition to the contributions from octahedral tilting and Jahn-Teller-like distortions, there is an excess octahedral distortion at temperatures below 250 K; this is speculated to be associated with an anomaly observed over the temperature range of 275-300 K in the heat-capacity measurements.
AB - We have studied the crystal structure of mixed-valence Sr 0.7Ce 0.3MnO 3 from 4.2 to 973 K using high-resolution neutron powder diffraction. The crystal structure is tetragonal in space group I4/mcm at 4.2-923 K and cubic in Pm3̄m at T 948 K. Lattice parameters and Mn-O bond distances, obtained by Rietveld refinement, have been used to derive the spontaneous strains and MnO 6 octahedral distortion, which are interpreted in terms of strain/order parameter coupling using a single Landau free-energy expansion for a Pm3̄m reference structure with two instabilities (R4+ and Γ3+). Two phase transitions were proposed: an octahedral tilting transition at T c,φ ∼ 938 K (Pm3̄m I4/mcm, R4+), and an isosymmetric, electronically driven (Jahn-Teller-like) transition at T c,JT ∼ 770 K (I4/mcm, R4+ I4/mcm, R4+ and Γ3+). The nature of the tilting transition appears to be tricritical, while that of the Jahn-Teller-like transition is second order. In addition to the contributions from octahedral tilting and Jahn-Teller-like distortions, there is an excess octahedral distortion at temperatures below 250 K; this is speculated to be associated with an anomaly observed over the temperature range of 275-300 K in the heat-capacity measurements.
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U2 - 10.1103/PhysRevB.85.174110
DO - 10.1103/PhysRevB.85.174110
M3 - Article
AN - SCOPUS:84861707372
VL - 85
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 17
M1 - 174110
ER -