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
CCDC references: 995087; 995088; 995089
Crystal data top
FeLaO3 | c = 7.85490 (17) Å |
Mr = 242.75 | V = 242.88 (1) Å3 |
Orthorhombic, Pbnm | Z = 4.0 |
a = 5.55494 (12) Å | Dx = 6.639 (1) Mg m−3 |
b = 5.56627 (9) Å | T = 293 K |
Data collection top
ID09 beamline, ESRF, Grenoble, France diffractometer | Data collection mode: transmission |
Radiation source: synchrotron radiation | 2θmin = 5°, 2θmax = 37.4°, 2θstep = 0.014° |
Water-cooled Si-(111) monochromator | |
Refinement top
Rp = 0.026 | 2774 data points |
Rwp = 3.761 | Profile function: fundamental parameter |
Rexp = 3.843 | Background function: Chebyshev polynom of 11th order |
RBragg = 1.107 | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Biso*/Beq | |
La1 | −0.00641 (17) | 0.02932 (7) | 0.25 | 0.318 (8) | |
Fe1 | 0 | 0.5 | 0 | 0.318 (8) | |
O1 | 0.0765 (19) | 0.4875 (9) | 0.25 | 0.318 (8) | |
O2 | −0.2817 (13) | 0.2853 (12) | 0.0366 (10) | 0.318 (8) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
? | ? | ? | ? | ? | ? | ? |
Crystal data top
FeLaO3 | c = 7.543 (3) Å |
Mr = 242.75 | V = 219.38 (9) Å3 |
Orthorhombic, Ibmm | Z = 4.0 |
a = 5.4290 (3) Å | Dx = 7.350 (3) Mg m−3 |
b = 5.3573 (6) Å | T = 293 K |
Data collection top
ID09 beamline, ESRF, Grenoble, France diffractometer | Data collection mode: transmission |
Radiation source: synchrotron radiation | 2θmin = 5°, 2θmax = 20.8°, 2θstep = 0.014° |
Water-cooled Si-(111) monochromator | |
Refinement top
Rp = 0.021 | 2371 data points |
Rwp = 3.302 | Profile function: fundamental parameter |
Rexp = 1.418 | Background 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 | x | y | z | Biso*/Beq | |
La1 | −0.0040 (13) | 0.0 | 0.25 | 0.31 (8) | |
Fe1 | 0 | 0.5 | 0 | 0.31 (8) | |
O1 | 0.068 (4) | 0.5 | 0.25 | 0.31 (8) | |
O2 | −0.25 | 0.25 | 0.033 (5) | 0.31 (8) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
? | ? | ? | ? | ? | ? | ? |
Crystal data top
FeLaO3 | c = 7.3063 (16) Å |
Mr = 242.75 | V = 201.95 (1) Å3 |
Orthorhombic, Ibmm | Z = 4.0 |
a = 5.2621 (19) Å | Dx = 7.984 (4) Mg m−3 |
b = 5.2528 (16) Å | T = 293 K |
Data collection top
ID09 beamline, ESRF, Grenoble, France diffractometer | Data collection mode: transmission |
Radiation source: synchrotron radiation | 2θmin = 5°, 2θmax = 20.8°, 2θstep = 0.014° |
Water-cooled Si-(111) monochromator | |
Refinement top
Rp = 0.020 | 2372 data points |
Rwp = 3.162 | Profile function: fundamental parameter |
Rexp = 1.291 | Background 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 | x | y | z | Biso*/Beq | |
La1 | −0..0082 (14) | 0.0 | 0.25 | 0.16 (9) | |
Fe1 | 0 | 0.5 | 0 | 0.16 (9) | |
O1 | 0.024 (9) | 0.5 | 0.25 | 0.16 (9) | |
O2 | −0.25 | 0.25 | 0.035 (3) | 0.16 (9) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
? | ? | ? | ? | ? | ? | ? |