Phase Transitions in Perovskitelike Compounds of the Rare Earths

Geller, S.; Raccah, P. M.

doi:10.1103/physrevb.2.1167

Cited by 145 publications

(76 citation statements)

References 9 publications

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“…Division of an image into A, A', B and B' components for orthorhombic and rhombohedral phases may be interpreted as cross-twinning in the {100} and {110} systems simultaneously. ** The observed phase transition 'orthorhombic-rhombohedral' at 412.5 K contradicts the suggestion that a similar phase transition occurs at T= 1148 K (Geller, Curlander & Ruse, 1974;Geller & Raccah, 1970). Additional work is required to prove this.…”

Section: (A)contrasting

confidence: 48%

“…According to Geller, Curlander & Ruse (1974), under conventional conditions it has an orthorhombic unit cell with a = 5.519, b = 5.494, c = 7.770A. Some papers describe a phase transition to a rhombohedral phase at 1148 K (Geller, Curlander & Ruse, 1974;Geller & Raccah, 1970). A change of the LaGaO 3 thermal expansion coefficient has also been observed at 423 K (Sandstrom, Giess, Gallagher, Segmuller, Cooper, Chisholm, Gupta, Shinde & Laibowitz, 1988).…”

Section: Introductionmentioning

confidence: 99%

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Twinning of LaGaO₃single crystals

Bdikin¹,

Шмытько²,

Balbashov³

et al. 1993

J Appl Cryst

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LaGaO3 single crystals, grown by the method of zone melting without a crucible, with radiation heating, were investigated by X-ray topography and diffractometry. It has been found that at 293 K these crystals have an orthorhombic unit cell with a = 5.520(2), b = 5.490(2), c=7.770 (I)A and twinning in the { 110}/(IT0) and { 112}/(1]-0) systems simultaneously. Regions of cross-twinning have been discovered in these systems. A first-order phase transition from orthorhombic to rhombohedral has been observed at 412.5K, the cell parameters being a=3.889A, = 89.50 ° (423 K). The rhombohedral phase has a developed twin structure in the {100}/(001) and {110}/(001) systems. During transformation the structure undergoes an inherited change to the twin structure of the orthorhombic phase.

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Section: (A)contrasting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Twinning of LaGaO₃single crystals

Bdikin¹,

Шмытько²,

Balbashov³

et al. 1993

J Appl Cryst

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“…At elevated temperatures both compounds undergo structural phase transitions. PrAlO 3 with rhombohedral structure continuously transforms to the cubic perovskite structure at 1770 K [1][2][3][4][5], whereas a first-order phase transition from an orthorhombic to a rhombohedral structure occurs in SmAlO 3 within the temperature range of 1023-1058 K [6][7][8]. One more phase transition from the rhombohedral to the cubic perovskite structure was observed in SmAlO 3 at 2223 K [7]; however, this transition has not been confirmed by other research groups.…”

Section: Introductionmentioning

confidence: 88%

Phase and Structural Behaviour of the PrAlO₃-SmAlO₃System

et al. 2010

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High resolution in situ X-ray powder diffraction applying synchrotron radiation and differential thermal analysis/scanning calorimetry methods have been used to examine the pseudo-binary system PrAlO 3 -SmAlO 3 . Two kinds of solid solutions with rhombohedral and orthorhombic structure exist at room temperature. At elevated temperatures, a continuous phase transition P m3m ↔ R3c and a first-order transformation R3c ↔ P bmn occur in the two respective phases. A sequence of low-temperature phase transformations R3c ↔ Imma ↔ C2/m has been detected in Pr 1−x Sm x AlO 3 samples with x < 0.35. Based on in situ powder diffraction and differential thermal analysis/scanning calorimetry data, the phase diagram of the pseudo-binary system PrAlO 3 -SmAlO 3 has been constructed.

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“…Note that the temperature range for the C p -T curves is well below the orthorhombic to rhombohedral phase transition observed at T Ϸ 533 K for undoped LaCrO 3 . 30 Jumps in the heat capacity are evident for a long-range cooperative ordering transition. The -peak shifts to higher temperatures as the doping level increases.…”

Section: Heat Capacitymentioning

confidence: 99%

Structure, magnetic, and thermal properties of Nd1−xLaxCrO3 (≤x≤1.0)

Cheng

Wang

et al. 2010

Journal of Applied Physics

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Perovskite-type Nd 1−x La x CrO 3 (0 ≤ x ≤1.0) polycrystalline samples were synthesized using solid state reaction. Structural studies indicate that the lattice parameters, metal-oxygen bond lengths, and angles of Nd 1−x La x CrO 3 strongly depend on the La content. Two magnetic transition temperatures, Cr 3+ antiferromagnetic ordering temperature (T N ) and the spin reorientation phase transition temperature (T SRPT ), have been observed in the M-T curves. The increase in T N and decrease in T SRPT with increasing x value can be explained by the change in the magnetic interactions due to La doping. The heat capacity of Nd 1−x La x CrO 3 measured from 2 to 300 K reveals that the lattice, electronic, and magnetic contributions to heat capacity can be well interpreted quantitatively using the Debye and Schottky models. The splitting energy of the Cr 3 + 3dt 2g orbital and the Nd 3+ ground state have been calculated by fitting to the Schottky anomaly at very low temperature. The Cr-Nd interaction is suppressed gradually by La doping, which is verified by the calculation of the mean-field interaction parameter. This doping dependence provides directed evidence of TM-RE magnetic interactions in perovskite compounds, in agreement with the proposed model. Perovskite-type Nd 1−x La x CrO 3 ͑0 Յ x Յ 1.0͒ polycrystalline samples were synthesized using solid state reaction. Structural studies indicate that the lattice parameters, metal-oxygen bond lengths, and angles of Nd 1−x La x CrO 3 strongly depend on the La content. Two magnetic transition temperatures, Cr 3+ antiferromagnetic ordering temperature ͑T N ͒ and the spin reorientation phase transition temperature ͑T SRPT ͒, have been observed in the M-T curves. The increase in T N and decrease in T SRPT with increasing x value can be explained by the change in the magnetic interactions due to La doping. The heat capacity of Nd 1−x La x CrO 3 measured from 2 to 300 K reveals that the lattice, electronic, and magnetic contributions to heat capacity can be well interpreted quantitatively using the Debye and Schottky models. The splitting energy of the Cr 3+ 3dt 2g orbital and the Nd 3+ ground state have been calculated by fitting to the Schottky anomaly at very low temperature. The Cr-Nd interaction is suppressed gradually by La doping, which is verified by the calculation of the mean-field interaction parameter. This doping dependence provides directed evidence of TM -RE magnetic interactions in perovskite compounds, in agreement with the proposed model.

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Phase Transitions in Perovskitelike Compounds of the Rare Earths

Cited by 145 publications

References 9 publications

Twinning of LaGaO₃single crystals

Twinning of LaGaO₃single crystals

Phase and Structural Behaviour of the PrAlO₃-SmAlO₃System

Structure, magnetic, and thermal properties of Nd1−xLaxCrO3 (≤x≤1.0)

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Phase Transitions in Perovskitelike Compounds of the Rare Earths

Cited by 145 publications

References 9 publications

Twinning of LaGaO3single crystals

Twinning of LaGaO3single crystals

Phase and Structural Behaviour of the PrAlO3-SmAlO3System

Structure, magnetic, and thermal properties of Nd1−xLaxCrO3 (≤x≤1.0)

Contact Info

Product

Resources

About

Twinning of LaGaO₃single crystals

Twinning of LaGaO₃single crystals

Phase and Structural Behaviour of the PrAlO₃-SmAlO₃System