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Sequential Rietveld refinements were applied on high-pressure synchrotron powder X-ray diffraction measurements of lanthanum ferrite (LaFeO3) revealing two phase transitions on the room-temperature isotherm up to a pressure of 48 GPa. The first structural phase transition of second order occurs at a pressure of 21.1 GPa, changing the space group from Pbnm to Ibmm. The second transition, involving a isostructural first-order phase transition, occurs at approximately 38 GPa, indicating a high-spin to low-spin transition of the Fe3+ ion. Following the behavior of the volume up to the hydrostatic limit of methanol-ethanol it was possible to use inverted equations of state (EoS) to determine a bulk modulus of B0 = 172 GPa and a corresponding pressure derivative of B'0 = 4.3. In addition, the linearized version of the inverted EoS were used to determine the corresponding moduli and pressure derivatives for each lattice direction.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520614007379/zb5036sup1.cif
Contains datablocks global, I, II, III

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520614007379/zb5036Isup2.rtv
Contains datablock I

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520614007379/zb5036IIsup3.rtv
Contains datablock LaFeO3-Ibmm-24.8GPa-Etter-ea

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S2052520614007379/zb5036IIIsup4.rtv
Contains datablock LaFeO3-Ibmm-43.1GPa-Etter-ea

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S2052520614007379/zb5036sup5.pdf
Atomic coordinates and overall isotropic atomic displacement parameters

CCDC references: 995087; 995088; 995089

Computing details top

(I) top
Crystal data top
FeLaO3c = 7.85490 (17) Å
Mr = 242.75V = 242.88 (1) Å3
Orthorhombic, PbnmZ = 4.0
a = 5.55494 (12) ÅDx = 6.639 (1) Mg m3
b = 5.56627 (9) ÅT = 293 K
Data collection top
ID09 beamline, ESRF, Grenoble, France
diffractometer
Data collection mode: transmission
Radiation source: synchrotron radiation2θmin = 5°, 2θmax = 37.4°, 2θstep = 0.014°
Water-cooled Si-(111) monochromator
Refinement top
Rp = 0.0262774 data points
Rwp = 3.761Profile function: fundamental parameter
Rexp = 3.843Background function: Chebyshev polynom of 11th order
RBragg = 1.107
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
La10.00641 (17)0.02932 (7)0.250.318 (8)
Fe100.500.318 (8)
O10.0765 (19)0.4875 (9)0.250.318 (8)
O20.2817 (13)0.2853 (12)0.0366 (10)0.318 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
???????
(II) top
Crystal data top
FeLaO3c = 7.543 (3) Å
Mr = 242.75V = 219.38 (9) Å3
Orthorhombic, IbmmZ = 4.0
a = 5.4290 (3) ÅDx = 7.350 (3) Mg m3
b = 5.3573 (6) ÅT = 293 K
Data collection top
ID09 beamline, ESRF, Grenoble, France
diffractometer
Data collection mode: transmission
Radiation source: synchrotron radiation2θmin = 5°, 2θmax = 20.8°, 2θstep = 0.014°
Water-cooled Si-(111) monochromator
Refinement top
Rp = 0.0212371 data points
Rwp = 3.302Profile function: fundamental parameter
Rexp = 1.418Background function: Chebyshev polynom of 11th order
RBragg = 0.427
Special details top

Refinement. Spherical Harmonics of 4t h order

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
La10.0040 (13)0.00.250.31 (8)
Fe100.500.31 (8)
O10.068 (4)0.50.250.31 (8)
O20.250.250.033 (5)0.31 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
???????
(III) top
Crystal data top
FeLaO3c = 7.3063 (16) Å
Mr = 242.75V = 201.95 (1) Å3
Orthorhombic, IbmmZ = 4.0
a = 5.2621 (19) ÅDx = 7.984 (4) Mg m3
b = 5.2528 (16) ÅT = 293 K
Data collection top
ID09 beamline, ESRF, Grenoble, France
diffractometer
Data collection mode: transmission
Radiation source: synchrotron radiation2θmin = 5°, 2θmax = 20.8°, 2θstep = 0.014°
Water-cooled Si-(111) monochromator
Refinement top
Rp = 0.0202372 data points
Rwp = 3.162Profile function: fundamental parameter
Rexp = 1.291Background function: Chebyshev polynom of 11th order
RBragg = 0.676
Special details top

Refinement. Spherical Harmonics of 4t h order

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
La10..0082 (14)0.00.250.16 (9)
Fe100.500.16 (9)
O10.024 (9)0.50.250.16 (9)
O20.250.250.035 (3)0.16 (9)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
???????
 

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