Acta Cryst. (2009). E65, i73 [ doi:10.1107/S1600536809038100 ]
The title compound, pentairon tripraseodymium dodecaoxide (PrIG), has an iron garnet structure. There are two Fe site symmetries. One of the Fe atoms is coordinated by six O atoms, forming a slightly distorted octahedron, and has 
site symmetry. The other Fe atom is coordinated by four O atoms, forming a slightly distorted tetrahedron, and has 
site symmetry. FeO6 octahedra and FeO4 tetrahedra are linked together by corners. The Pr atom is coordinated by eight O atoms, forming a distorted dodecahedron, and has 222 site symmetry. The O atoms occupy the general positions.
Single crystals of praseodymium iron garnet were prepared by low temperature liquid phase epitaxy on Sm3(ScGa)5O12 seeds with lattice parameters near the projected values for PrIG.
X-ray intensities were measured avoiding multiple diffraction. (Takenaka et al., 2008).
Data collection: AFC-5, specially designed for PF-BL14A (Rigaku, 1984) and IUANGLE (Tanaka et al., 1994).; cell refinement: RSLC-3 UNICS system (Sakurai & Kobayashi, 1979); data reduction: RDEDIT (Tanaka, 2008); program(s) used to solve structure: QNTAO (Tanaka et al., 2008); program(s) used to refine structure: QNTAO (Tanaka et al., 2008); molecular graphics: ATOMS for Windows (Dowty, 2000); software used to prepare material for publication: RDEDIT (Tanaka, 2008).
![[Figure 1]](./br2121fig1thm.gif)
| Fig. 1. The structure of Pr3Fe5O12. Small red and large green spheres represent O and Pr atoms, respectively. Purple octahedron and blue tetrahedron represent FeO6 and FeO4 units, respectively. |
![[Figure 2]](./br2121fig2thm.gif)
| Fig. 2. View of PrO8 with displacement ellipsoids at the 90% probability level. Green and red ellipsoids represent Pr and O atoms, in Fig.1. |
| Pr3Fe5O12 | Dx = 5.894 Mg m−3 |
| Mr = 893.98 | Synchrotron radiation, λ = 0.67171 Å |
| Cubic, Ia3d | Cell parameters from 9 reflections |
| Hall symbol: -I 4bd 2c 3 | θ = 17.5–52.3° |
| a = 12.6302 (3) Å | µ = 17.41 mm−1 |
| V = 2014.79 (8) Å3 | T = 298 K |
| Z = 8 | Sphere, black |
| F(000) = 3224 | 0.04 mm (radius) |
| Rigaku AFC four-circle diffractometer | 1728 independent reflections |
| Si 111 | 1728 reflections with F > 3σ(F) |
| Detector resolution: 1.25 × 1.25° pixels mm-1 | Rint = 0.016 |
| ω/2θ scans | θmax = 68.3°, θmin = 3.7° |
| Absorption correction: for a sphere [Transmission coefficients for spheres tabulated in International Tables C (1992), Table 6.3.3.3, were interpolated with Lagrange's method (four-point interpolation (Yamauchi et al., 1965)] | h = −9→34 |
| Tmin = 0.413, Tmax = 0.441 | k = −9→32 |
| 9351 measured reflections | l = −9→34 |
| Refinement on F | Primary atom site location: isomorphous structure methods |
| Least-squares matrix: full | Weighting scheme based on measured s.u.'s |
| R[F2 > 2σ(F2)] = 0.019 | (Δ/σ)max = 0.003 |
| wR(F2) = 0.021 | Δρmax = 2.52 e Å−3 |
| S = 1.06 | Δρmin = −3.16 e Å−3 |
| 9351 reflections | Extinction correction: B–C type 1 Gaussian isotropic (Becker & Coppens, 1975) |
| 17 parameters | Extinction coefficient: 0.255 (5) |
| Pr3Fe5O12 | Z = 8 |
| Mr = 893.98 | Synchrotron radiation, λ = 0.67171 Å |
| Cubic, Ia3d | µ = 17.41 mm−1 |
| a = 12.6302 (3) Å | T = 298 K |
| V = 2014.79 (8) Å3 | 0.04 mm (radius) |
| Rigaku AFC four-circle diffractometer | 1728 independent reflections |
| Absorption correction: for a sphere [Transmission coefficients for spheres tabulated in International Tables C (1992), Table 6.3.3.3, were interpolated with Lagrange's method (four-point interpolation (Yamauchi et al., 1965)] | 1728 reflections with F > 3σ(F) |
| Tmin = 0.413, Tmax = 0.441 | Rint = 0.016 |
| 9351 measured reflections | θmax = 68.3° |
| R[F2 > 2σ(F2)] = 0.019 | Δρmax = 2.52 e Å−3 |
| wR(F2) = 0.021 | Δρmin = −3.16 e Å−3 |
| S = 1.06 | Absolute structure: ? |
| 9351 reflections | Flack parameter: ? |
| 17 parameters | Rogers parameter: ? |
| ? restraints |
| x | y | z | Uiso*/Ueq | ||
| Pr1 | 0.125000 | 0.000000 | 0.250000 | 0.00531 (1) | |
| Fe1 | 0.000000 | 0.000000 | 0.000000 | 0.00512 (1) | |
| Fe2 | 0.375000 | 0.000000 | 0.250000 | 0.00533 (1) | |
| O1 | −0.029622 (2) | 0.052553 (2) | 0.149166 (2) | 0.00711 (5) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Pr1 | 0.00406 (2) | 0.00594 (2) | 0.00594 (2) | 0 | 0 | 0.00111 (1) |
| Fe1 | 0.00512 (2) | 0.00512 (2) | 0.00512 (2) | −0.00023 (1) | −0.00023 (1) | −0.00023 (1) |
| Fe2 | 0.00411 (3) | 0.00594 (2) | 0.00594 (2) | 0 | 0 | 0 |
| O1 | 0.00718 (8) | 0.00829 (8) | 0.00587 (7) | −0.00004 (6) | 0.00080 (6) | 0.00038 (6) |
| Pr1—O1 | 2.42410 (10) | Fe1—O1i | 2.03220 (10) |
| Pr1—O1i | 2.54010 (10) | Fe1—O1viii | 2.03220 (10) |
| Pr1—O1ii | 2.42410 (10) | Fe1—O1ix | 2.03220 (10) |
| Pr1—O1iii | 2.54010 (10) | Fe1—O1x | 2.03220 (10) |
| Pr1—O1iv | 2.42410 (10) | Fe1—O1xi | 2.03220 (10) |
| Pr1—O1v | 2.54010 (10) | Fe2—O1xii | 1.87450 (10) |
| Pr1—O1vi | 2.42410 (10) | Fe2—O1iv | 1.87450 (10) |
| Pr1—O1vii | 2.54010 (10) | Fe2—O1xiii | 1.87450 (10) |
| Fe1—O1 | 2.03220 (10) | Fe2—O1vi | 1.87450 (10) |
| O1—Pr1—O1i | 67.75 (1) | O1—Fe1—O1viii | 85.87 (1) |
| O1—Pr1—O1ii | 72.66 (1) | O1—Fe1—O1ix | 180.00 |
| O1—Pr1—O1iii | 124.91 (1) | O1—Fe1—O1x | 94.13 (1) |
| O1—Pr1—O1iv | 111.18 (1) | O1—Fe1—O1xi | 94.13 (1) |
| O1—Pr1—O1v | 73.25 (1) | O1xii—Fe2—O1vi | 114.39 (1) |
| O1—Pr1—O1vi | 159.51 (1) | O1xii—Fe2—O1iv | 114.39 (1) |
| O1—Pr1—O1vii | 95.43 (1) | O1xii—Fe2—O1xiii | 100.02 (1) |
| O1—Fe1—O1i | 85.87 (1) |
| Symmetry codes: (i) z, x, y; (ii) x, −y, −z+1/2; (iii) z, −x, −y+1/2; (iv) −x+1/4, −z+1/4, −y+1/4; (v) −z+1/4, −y+1/4, −x+1/4; (vi) −x+1/4, z−1/4, y+1/4; (vii) −z+1/4, y−1/4, x+1/4; (viii) y, z, x; (ix) −x, −y, −z; (x) −z, −x, −y; (xi) −y, −z, −x; (xii) x+1/2, y, −z+1/2; (xiii) x+1/2, −y, z. |
| Pr1—O1 | 2.42410 (10) | Fe1—O1 | 2.03220 (10) |
| Pr1—O1i | 2.54010 (10) | Fe2—O1ii | 1.87450 (10) |
| O1—Fe1—O1i | 85.87 (1) | O1ii—Fe2—O1iv | 100.02 (1) |
| O1ii—Fe2—O1iii | 114.39 (1) |
| Symmetry codes: (i) z, x, y; (ii) x+1/2, y, −z+1/2; (iii) −x+1/4, z−1/4, y+1/4; (iv) x+1/2, −y, z. |
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The title compound, Pr3Fe5O12 (PrIG), was difficult to be grown. It was grown by the low-temperature-liquid-phase epitaxy for the first time by Fratello et al. (1986). Though the crystal structure was assumed as iron-garnet-type structure by lattice constant and extinction rule, the complete structure was not determined. In this paper, we determine the O atom position and the complete structure by the full matrix least-squares program QNTAO. Since the R-factor is small and the residual density has no significant peaks where no atoms exists, the structure was finally determined to be iron-garnet structure. It is isotypic with the Ia3d form of Y3Fe5O12 (YIG). (Bonnet et al., 1975). The Pr atom is coordinated by eight oxygen atoms. It forms a distorted dodecahedron. There are two Fe site symmetries. One of the Fe atom is coordinated by six oxygen atoms. It forms a slitely distorted octahedron. The other Fe atom is coordinated by four oxygen atoms. It forms a slightly distorted tetrahedron. FeO6 octahedron and FeO4 tetrahedron are linked together by corners. The structure of PrIG is drawn in Fig.1. And displacement ellipsoids of PrO8 is drawn in Fig.2.