Natural perovskite: (CaII0.95 (1)CeIII0.011 (2)NaI0.010 (4))(FeIII0.022 (2)TiIV0.98 (1))O3

Gravina, É.G.; Ayala, J.D.; Fernandes, N.G.

doi:10.1107/S1600536808026421

inorganic compounds

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Volume 64| Part 9| September 2008| Page i65

doi:10.1107/S1600536808026421

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Natural perovskite: (Ca^II_0.95 (1)Ce^III_0.011 (2)Na^I_0.010 (4))(Fe^III_0.022 (2)Ti^IV_0.98 (1))O₃

Érica G. Gravina,^a José D. Ayala ^a and Nelson G. Fernandes ^a ^*

^aDepartment of Chemistry, Federal University of Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, Brazil
^*Correspondence e-mail: ngfernandes@ufmg.br

(Received 16 July 2008; accepted 16 August 2008; online 30 August 2008)

A natural sample of perovskite (calcium caesium sodium iron titanium oxide) from the Tapira Alkaline Complex in southeastern Brazil was found by electron microprobe analysis to have the chemical formula (Ca²⁺_0.95 (1)Ce³⁺_0.011 (2)Na⁺_0.010 (4))(Fe³⁺_0.022 (2)Ti⁴⁺_0.98 (1))O²⁻₃ and by IR spectroscopy to be an anhydrous mineral. Oxygen anions are arranged around Ti⁴⁺ in an almost perfect octahedron and around Ca²⁺ in a distorted 12-fold polyhedron.

Related literature

For related literature, see: Banfield & Veblen (1992 ); Beran et al. (1996 ); Chakhmouradian & Mitchell (1998 ); Haggerty & Mariano (1983 ); Kay & Bailey (1957 ); Lloyd & Bailey (1991 ); Mariano & Mitchell (1991 ); Seer & Moraes (1988 ); Sgarbi & Gaspar (1995 ); Sgarbi & Valença (1994 ); Soubies et al. (1991 ).

Experimental

Crystal data

Na_0.01Ca_0.96Fe_0.02Ti_0.98Ce_0.01O₃
M_r = 136.40
Orthorhombic, P b n m
a = 5.3818 (4) Å
b = 5.4431 (4) Å
c = 7.6450 (5) Å
V = 223.95 (3) Å³
Z = 4
Mo Kα radiation
μ = 5.94 mm⁻¹
T = 298 (2) K
0.2 × 0.15 × 0.15 mm

Data collection

Siemens P4 diffractometer
Absorption correction: refined from ΔF (SHELXL97; Sheldrick, 2008 ) T_min = 0.356, T_max = 0.409
2383 measured reflections
1594 independent reflections
1527 reflections with I > 2s(I)
R_int = 0.033
3 standard reflections every 197 reflections intensity decay: 0.8%

Refinement

R[F² > 2σ(F²)] = 0.041
wR(F²) = 0.103
S = 1.25
1594 reflections
31 parameters
Δρ_max = 2.01 e Å⁻³
Δρ_min = −2.88 e Å⁻³

Table 1
Selected geometric parameters (Å ,° ), where A represents the Ca²⁺, Na⁺ and Ce³⁺ cations, on a 12-coordinated site and B represents Fe³⁺ and Ti⁴⁺ cations on an octahedral site

A—O₁	2.359 (2)	O₁^iv—A—O₁^iv	162.30 (6)
A—O₁^iv	2.481 (2)	O₂^iv—A—O₂^viii	80.97 (4)
A—O₁^iv	3.027 (2)	O₁—A—O₂^vii	118.03 (2)
A—O₁	3.052 (2)	O₂ⁱⁱ—A—O₁^iv	65.08 (3)
A—O₂^viii	2.378 (1)
A—O₂ⁱⁱ	2.620 (1)
A—O₂^iv	2.667 (1)
A—O₂^vi	3.233 (1)
B—O₁ⁱⁱ	1.9513 (3)	O₁—B—O₁ⁱⁱ	180.0
B—O₂^vii	1.956 (1)	O₂—B—O₂^vii	89.41 (1)
B—O₂^v	1.959 (1)	O₁—B—O₂	89.58 (6)
Symmetry code: (ii) $[-x, -y, z + {\script{1\over 2}}]$ ; (iii) $[(x + {\script{1\over 2}}) -1, -y + {\script{1\over 2}}, -z]$ ; (iv) $[-x + {\script{1\over 2}}, (y + {\script{1\over 2}}) - 1, 1- (-z + {\script{1\over 2}})]$ ; (v) -x, -y, -z; (vi) $[x, y, 1 - (-z + {\script{1\over 2}})]$ ; (vii) $[-x + {\script{1\over 2}}, y + {\script{1\over 2}}, z]$ ; (viii) $[(x + {\script{1\over 2}}) - 1, -y + {\script{1\over 2}}, z + {\script{1\over 2}}]$ ; (ix) $[-x, -y + 1, (z + {\script{1\over 2}}) -1]$ .

Data collection: XSCANS (Siemens, 1991 ); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker, 2007 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808026421/mg2053sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808026421/mg2053Isup2.hkl

checkCIF report

Comment top

The term perovskite refers to both natural and synthetic compounds ABX₃ based on the mineral CaTiO₃. CaTiO₃ itself is the most commonly occurring perovskite in the Earth's crust (Chakhmouradian & Mitchell, 1998) and an important material to immobilize high-level radioactive waste. The first structure determination was reported for a synthetic material (Kay & Bailey, 1957), but structural studies of natural CaTiO₃ are quite rare and have been mostly limited to twinned crystals (Beran et al., 1996). In central and southeastern Brazil, perovskite can be found as essential and accessory minerals of the Alto Paranaíba Igneous Province (Seer & Moraes, 1988; Sgarbi & Valença, 1994; Sgarbi & Gaspar, 1995), where they form part of five important carbonatite complexes, as in Tapira (Lloyd & Bailey, 1991). In these complexes, the conversion of perovskite in anatase (Soubies et al., 1991) resulted in some of the biggest known titanium concentrations, but even so these deposits are not still economically explored for technological reasons. There are many geological studies (Haggerty & Mariano, 1983; Mariano & Mitchell, 1991; and others) describing crystals of perovskite in the Brazilian carbonatite complexes as belonging to the system lueshite (NaNbO₃)-loparite [(NaCe)TiO₃]-perovskite (CaTiO₃) but with the end member perovskite sensu stricto as the principal component.

In this work, a naturally occurring perovskite from the Tapira Alkaline Complex, localized at Minas Gerais State in Brazil (19°52' south and 46°50' west), has been investigated. The economic importance of this complex is due to the phosphates, titanium, and lanthanide and actinide elements drifts, which were formed by intemperism from primary magmatic rocks. From electron microprobe analyses (major elements: Ca - 38.9 (8) wt% CaO; Ti - 56.6 (9) wt% TiO₂; minor elements: Na - 0.224 (8) wt% Na₂O; Fe - 1.2 (1) wt% Fe₂O₃; Ce - 1.4 (3) wt% Ce₂O₃), it can be concluded that the sample is essentially the mineral CaTiO₃, with the calculated formula: Ca²⁺_0.96 (2) Ce³⁺_0.011 (2) Na⁺_0.010 (4) Fe³⁺_0.022 (2) Ti⁴⁺_0.98 (1) O^2-₃. The infrared spectra reveal characteristic bands for Ti-O and Ca-O, but importantly, the absence of bands related to OH^- and water suggests that the Tapira perovskite is indeed an anhydrous mineral. The bands at 348, 423, 528, 695 and 703 cm^-1 observed are also present in spectra of TiO₂ polymorphs, especially anatase and TiO₂(B) as reported by Banfield & Veblen (1992). This could be due to the octahedral TiO₆ or even to the Ca²⁺ leaching from the perovskite, which has those two polymorphs as byproducts. Figure 1 shows the perovskite structure.

Related literature top

For related literature, see: Banfield & Veblen (1992); Beran et al. (1996); Chakhmouradian & Mitchell (1998); Haggerty & Mariano (1983); Kay & Bailey (1957); Lloyd & Bailey (1991); Mariano & Mitchell (1991); Seer & Moraes (1988); Sgarbi & Gaspar (1995); Sgarbi & Valença (1994); Soubies et al. (1991).

Experimental top

Among crystals averaging 1-2 cm³ in size, some have carbonate incrustations and alterations due to intemperism. The cleanest crystals were separated and the biggest were chosen for polished sections for chemical analysis. Electron microprobe analyses were performed for four crystals on a JEOL JXA-8900 RL microscope, qualitatively with wavelength-dispersive mode and quantitatively with energy-dispersive mode. Standards used included rutile (TiO₂) for Ti, anorthite (CaAl₂Si₂O₈) for Ca, olivine [(Mg,Fe)₂SiO₄] for Fe, albite (NaAlSi₃O₈) for Na, and synthetic glasses for the lanthanide content. Infrared spectra were recorded for ground crystals on a Perkin Elmer GX spectrophotometer. Crystals were examined by polarizing microscope.

Initial refinements were performed using scattering factors for the neutral atoms of the major elements, with site occupancies based on the microprobe analyses (Ca_0.96 (2)Ti_0.98 (1)O₃), giving R = 0.0436, wR = 0.1099, and S = 1.315. The minor elements were added next, with the cation distribution based on the loparite (Na and Ce at A site) and latrappite structures (Fe at B site), and with the constraints that the displacement parameters of atoms within each of these sites be equal. The site occupancies for Ca and Ti were refined whereas those for the Na, Ce, and Fe atoms (including their uncertainties) were taken from the chemical analysis. In the final model, scattering factors for the ions were used and electroneutrality was found to be maintained with a total cation charge of +5.89 (2), according to the chemical formula (Ca²⁺_0.95 (1) Ce³⁺_0.011 (2) Na⁺_0.010 (4)) (Fe³⁺_0.022 (2)Ti⁴⁺_0.98 (1))O^2-₃.

Computing details top

Data collection: XSCANS (Siemens, 1991); cell refinement: XSCANS (Siemens, 1991); data reduction: XSCANS (Siemens, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker, 2007); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

Fig. 1. Part of the unit cell with the A site represented in dark blue, the B site in dark grey, and the oxygen ions in dark red. The bonds of the AO₁₂ are also all represented in blue. Displacement ellipsoids are drawn at the 70% probability level [symmetry codes: (i) x, y, z; (ii) -x, -y, z+1/2; (iii) (x+1/2)-1, -y+1/2, -z; (iv) -x+1/2, (y+1/2)-1, 1-(-z+1/2); (v) -x, -y, -z; (vi) x, y, 1-(-z+1/2); (vii) -x+1/2, y+1/2, z; (viii) (x+1/2)-1, -y+1/2, z+1/2; (ix) -x, -y+1, (z+1/2)-1].

calcium caesium sodium iron titanium oxide top

Crystal data top

Na_0.01Ca_0.96Fe_0.02Ti_0.98Ce_0.01O₃	F(000) = 262.9
M_r = 136.40	D_x = 4.045 Mg m⁻³
Orthorhombic, Pbnm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2c 2ab	Cell parameters from 40 reflections
a = 5.3818 (4) Å	θ = 4.6–56.8°
b = 5.4431 (4) Å	µ = 5.94 mm⁻¹
c = 7.6450 (5) Å	T = 298 K
V = 223.95 (3) Å³	Octahedral, grey
Z = 4	0.2 × 0.15 × 0.15 mm

Data collection top

Siemens P4 diffractometer	1527 reflections with I > 2s(I)
Radiation source: fine-focus sealed tube	R_int = 0.033
Graphite monochromator	θ_max = 56.8°, θ_min = 4.6°
θ/2θ scans	h = −1→12
Absorption correction: part of the refinement model (ΔF) (SHELXL97; Sheldrick, 2008)	k = −1→12
T_min = 0.356, T_max = 0.409	l = −1→18
2383 measured reflections	3 standard reflections every 197 reflections
1594 independent reflections	intensity decay: 0.8%

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.041	w = 1/[σ²(F_o²) + (0.0192P)² + 1.1174P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.103	(Δ/σ)_max < 0.001
S = 1.25	Δρ_max = 2.01 e Å⁻³
1594 reflections	Δρ_min = −2.88 e Å⁻³
31 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.045 (5)

Crystal data top

Na_0.01Ca_0.96Fe_0.02Ti_0.98Ce_0.01O₃	V = 223.95 (3) Å³
M_r = 136.40	Z = 4
Orthorhombic, Pbnm	Mo Kα radiation
a = 5.3818 (4) Å	µ = 5.94 mm⁻¹
b = 5.4431 (4) Å	T = 298 K
c = 7.6450 (5) Å	0.2 × 0.15 × 0.15 mm

Data collection top

Siemens P4 diffractometer	1527 reflections with I > 2s(I)
Absorption correction: part of the refinement model (ΔF) (SHELXL97; Sheldrick, 2008)	R_int = 0.033
T_min = 0.356, T_max = 0.409	3 standard reflections every 197 reflections
2383 measured reflections	intensity decay: 0.8%
1594 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.041	31 parameters
wR(F²) = 0.103	0 restraints
S = 1.25	Δρ_max = 2.01 e Å⁻³
1594 reflections	Δρ_min = −2.88 e Å⁻³

Special details top

Experimental. Room temperature single-crystal X-ray diffraction standard experiment

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ca	0.50660 (7)	0.53492 (7)	0.2500	0.00739 (7)	0.951 (7)
Ce	0.50660 (7)	0.53492 (7)	0.2500	0.0074 (11)	0.01
Na	0.50660 (7)	0.53492 (7)	0.2500	0.0074 (11)	0.01
Ti	0.0000	0.5000	0.5000	0.00487 (6)	0.977 (7)
Fe	0.0000	0.5000	0.5000	0.0049 (11)	0.02
O1	0.0713 (3)	0.4842 (3)	0.2500	0.00743 (19)
O2	0.21101 (17)	0.21143 (18)	0.53714 (14)	0.00728 (15)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ca	0.00587 (16)	0.00800 (13)	0.00831 (13)	0.00138 (8)	0.000	0.000
Ce	0.006 (3)	0.00800 (16)	0.00831 (13)	0.00138 (13)	0.000	0.000
Na	0.006 (3)	0.00800 (16)	0.00831 (13)	0.00138 (13)	0.000	0.000
Ti	0.00482 (11)	0.00595 (10)	0.00384 (9)	0.00000 (6)	−0.00004 (6)	−0.00027 (6)
Fe	0.005 (3)	0.00595 (11)	0.00384 (10)	0.00000 (6)	−0.00004 (6)	−0.00027 (9)
O1	0.0072 (4)	0.0104 (4)	0.0047 (4)	−0.0005 (3)	0.000	0.000
O2	0.0060 (3)	0.0072 (3)	0.0087 (3)	0.0020 (2)	0.0005 (2)	0.0010 (2)

Geometric parameters (Å, º) top

Ca—O1	2.3586 (16)	Fe—O2ⁱⁱⁱ	1.9555 (9)
Ca—O2ⁱ	2.3783 (11)	Fe—O2^x	1.9555 (9)
Ca—O2ⁱⁱ	2.3783 (11)	Fe—O2^ix	1.9589 (9)
Ca—O1ⁱⁱⁱ	2.4814 (16)	Fe—O2	1.9589 (9)
Ca—O2^iv	2.6199 (11)	Fe—Ce^xi	3.1721 (4)
Ca—O2^v	2.6199 (11)	Fe—Ca^xi	3.1721 (4)
Ca—O2^vi	2.6671 (11)	Fe—Ce^vii	3.1721 (4)
Ca—O2ⁱⁱⁱ	2.6671 (11)	Fe—Ca^vii	3.1721 (4)
Ca—O1^vii	3.0266 (16)	Fe—Ca^xii	3.2772 (3)
Ca—O1^viii	3.0518 (16)	Fe—Ce^xii	3.2772 (3)
Ti—O1	1.9513 (3)	O1—Fe^xiii	1.9513 (3)
Ti—O1^ix	1.9513 (3)	O1—Ti^xiii	1.9513 (3)
Ti—O2ⁱⁱⁱ	1.9555 (9)	O1—Ca^vii	2.4814 (16)
Ti—O2^x	1.9555 (9)	O1—Ce^vii	2.4814 (16)
Ti—O2^ix	1.9589 (9)	O1—Caⁱⁱⁱ	3.0266 (16)
Ti—O2	1.9589 (9)	O1—Ca^xii	3.0518 (16)
Ti—Ce^xi	3.1721 (4)	O2—Feⁱⁱ	1.9555 (9)
Ti—Ca^xi	3.1721 (4)	O2—Tiⁱⁱ	1.9555 (9)
Ti—Ce^vii	3.1721 (4)	O2—Ca^x	2.3783 (11)
Ti—Ca^vii	3.1721 (4)	O2—Ce^x	2.3783 (11)
Ti—Ca^xii	3.2772 (3)	O2—Ca^iv	2.6199 (11)
Ti—Ce^xii	3.2772 (3)	O2—Ce^iv	2.6199 (11)
Fe—O1	1.9513 (3)	O2—Ce^vii	2.6671 (11)
Fe—O1^ix	1.9513 (3)	O2—Ca^vii	2.6671 (11)

O1—Ca—O2ⁱ	113.17 (4)	O2^ix—Fe—O2	180.0
O1—Ca—O2ⁱⁱ	113.17 (4)	O1—Fe—Ce^xi	128.54 (5)
O2ⁱ—Ca—O2ⁱⁱ	86.35 (5)	O1^ix—Fe—Ce^xi	51.46 (5)
O1—Ca—O1ⁱⁱⁱ	86.98 (4)	O2ⁱⁱⁱ—Fe—Ce^xi	55.53 (3)
O2ⁱ—Ca—O1ⁱⁱⁱ	129.34 (3)	O2^x—Fe—Ce^xi	124.47 (3)
O2ⁱⁱ—Ca—O1ⁱⁱⁱ	129.34 (3)	O2^ix—Fe—Ce^xi	56.90 (3)
O1—Ca—O2^iv	129.62 (3)	O2—Fe—Ce^xi	123.10 (3)
O2ⁱ—Ca—O2^iv	116.99 (3)	O1—Fe—Ca^xi	128.54 (5)
O2ⁱⁱ—Ca—O2^iv	66.66 (2)	O1^ix—Fe—Ca^xi	51.46 (5)
O1ⁱⁱⁱ—Ca—O2^iv	65.08 (3)	O2ⁱⁱⁱ—Fe—Ca^xi	55.53 (3)
O1—Ca—O2^v	129.62 (3)	O2^x—Fe—Ca^xi	124.47 (3)
O2ⁱ—Ca—O2^v	66.66 (2)	O2^ix—Fe—Ca^xi	56.90 (3)
O2ⁱⁱ—Ca—O2^v	116.99 (3)	O2—Fe—Ca^xi	123.10 (3)
O1ⁱⁱⁱ—Ca—O2^v	65.08 (3)	O1—Fe—Ce^vii	51.46 (5)
O2^iv—Ca—O2^v	76.80 (5)	O1^ix—Fe—Ce^vii	128.54 (5)
O1—Ca—O2^vi	66.80 (3)	O2ⁱⁱⁱ—Fe—Ce^vii	124.47 (3)
O2ⁱ—Ca—O2^vi	80.97 (4)	O2^x—Fe—Ce^vii	55.53 (3)
O2ⁱⁱ—Ca—O2^vi	165.78 (3)	O2^ix—Fe—Ce^vii	123.10 (3)
O1ⁱⁱⁱ—Ca—O2^vi	64.58 (3)	O2—Fe—Ce^vii	56.90 (3)
O2^iv—Ca—O2^vi	125.177 (19)	Ce^xi—Fe—Ce^vii	180.0
O2^v—Ca—O2^vi	63.491 (11)	Ca^xi—Fe—Ce^vii	180.0
O1—Ca—O2ⁱⁱⁱ	66.80 (3)	O1—Fe—Ca^vii	51.46 (5)
O2ⁱ—Ca—O2ⁱⁱⁱ	165.78 (3)	O1^ix—Fe—Ca^vii	128.54 (5)
O2ⁱⁱ—Ca—O2ⁱⁱⁱ	80.97 (4)	O2ⁱⁱⁱ—Fe—Ca^vii	124.47 (3)
O1ⁱⁱⁱ—Ca—O2ⁱⁱⁱ	64.58 (3)	O2^x—Fe—Ca^vii	55.53 (3)
O2^iv—Ca—O2ⁱⁱⁱ	63.491 (11)	O2^ix—Fe—Ca^vii	123.10 (3)
O2^v—Ca—O2ⁱⁱⁱ	125.177 (19)	O2—Fe—Ca^vii	56.90 (3)
O2^vi—Ca—O2ⁱⁱⁱ	110.78 (5)	Ce^xi—Fe—Ca^vii	180.0
O1—Ca—O1^vii	75.32 (5)	Ca^xi—Fe—Ca^vii	180.0
O2ⁱ—Ca—O1^vii	60.38 (3)	O1—Fe—Ca^xii	65.84 (4)
O2ⁱⁱ—Ca—O1^vii	60.38 (3)	O1^ix—Fe—Ca^xii	114.16 (4)
O1ⁱⁱⁱ—Ca—O1^vii	162.30 (6)	O2ⁱⁱⁱ—Fe—Ca^xii	134.03 (3)
O2^iv—Ca—O1^vii	127.03 (3)	O2^x—Fe—Ca^xii	45.97 (3)
O2^v—Ca—O1^vii	127.03 (3)	O2^ix—Fe—Ca^xii	53.08 (3)
O2^vi—Ca—O1^vii	107.21 (3)	O2—Fe—Ca^xii	126.92 (3)
O2ⁱⁱⁱ—Ca—O1^vii	107.21 (3)	Ce^xi—Fe—Ca^xii	108.311 (8)
O1—Ca—O1^viii	168.10 (7)	Ca^xi—Fe—Ca^xii	108.311 (8)
O2ⁱ—Ca—O1^viii	59.23 (3)	Ce^vii—Fe—Ca^xii	71.689 (8)
O2ⁱⁱ—Ca—O1^viii	59.23 (3)	Ca^vii—Fe—Ca^xii	71.689 (8)
O1ⁱⁱⁱ—Ca—O1^viii	104.92 (5)	O1—Fe—Ce^xii	65.84 (4)
O2^iv—Ca—O1^viii	57.99 (3)	O1^ix—Fe—Ce^xii	114.16 (4)
O2^v—Ca—O1^viii	57.99 (3)	O2ⁱⁱⁱ—Fe—Ce^xii	134.03 (3)
O2^vi—Ca—O1^viii	118.03 (2)	O2^x—Fe—Ce^xii	45.97 (3)
O2ⁱⁱⁱ—Ca—O1^viii	118.03 (2)	O2^ix—Fe—Ce^xii	53.08 (3)
O1^vii—Ca—O1^viii	92.78 (5)	O2—Fe—Ce^xii	126.92 (3)
O1—Ti—O1^ix	180.0	Ce^xi—Fe—Ce^xii	108.311 (8)
O1—Ti—O2ⁱⁱⁱ	90.66 (5)	Ca^xi—Fe—Ce^xii	108.311 (8)
O1^ix—Ti—O2ⁱⁱⁱ	89.34 (5)	Ce^vii—Fe—Ce^xii	71.689 (8)
O1—Ti—O2^x	89.34 (5)	Ca^vii—Fe—Ce^xii	71.689 (8)
O1^ix—Ti—O2^x	90.66 (5)	Fe^xiii—O1—Fe	156.74 (9)
O2ⁱⁱⁱ—Ti—O2^x	180.0	Ti^xiii—O1—Fe	156.74 (9)
O1—Ti—O2^ix	90.42 (6)	Fe^xiii—O1—Ti	156.74 (9)
O1^ix—Ti—O2^ix	89.58 (6)	Ti^xiii—O1—Ti	156.74 (9)
O2ⁱⁱⁱ—Ti—O2^ix	90.586 (13)	Fe^xiii—O1—Ca	100.97 (4)
O2^x—Ti—O2^ix	89.414 (13)	Ti^xiii—O1—Ca	100.97 (4)
O1—Ti—O2	89.58 (6)	Fe—O1—Ca	100.97 (4)
O1^ix—Ti—O2	90.42 (6)	Ti—O1—Ca	100.97 (4)
O2ⁱⁱⁱ—Ti—O2	89.414 (13)	Fe^xiii—O1—Ca^vii	90.58 (5)
O2^x—Ti—O2	90.586 (13)	Ti^xiii—O1—Ca^vii	90.58 (5)
O2^ix—Ti—O2	180.0	Fe—O1—Ca^vii	90.58 (5)
O1—Ti—Ce^xi	128.54 (5)	Ti—O1—Ca^vii	90.58 (5)
O1^ix—Ti—Ce^xi	51.46 (5)	Ca—O1—Ca^vii	106.45 (6)
O2ⁱⁱⁱ—Ti—Ce^xi	55.53 (3)	Fe^xiii—O1—Ce^vii	90.58 (5)
O2^x—Ti—Ce^xi	124.47 (3)	Ti^xiii—O1—Ce^vii	90.58 (5)
O2^ix—Ti—Ce^xi	56.90 (3)	Fe—O1—Ce^vii	90.58 (5)
O2—Ti—Ce^xi	123.10 (3)	Ti—O1—Ce^vii	90.58 (5)
O1—Ti—Ca^xi	128.54 (5)	Ca—O1—Ce^vii	106.45 (6)
O1^ix—Ti—Ca^xi	51.46 (5)	Fe^xiii—O1—Caⁱⁱⁱ	85.94 (5)
O2ⁱⁱⁱ—Ti—Ca^xi	55.53 (3)	Ti^xiii—O1—Caⁱⁱⁱ	85.94 (5)
O2^x—Ti—Ca^xi	124.47 (3)	Fe—O1—Caⁱⁱⁱ	85.94 (5)
O2^ix—Ti—Ca^xi	56.90 (3)	Ti—O1—Caⁱⁱⁱ	85.94 (5)
O2—Ti—Ca^xi	123.10 (3)	Ca—O1—Caⁱⁱⁱ	91.25 (5)
O1—Ti—Ce^vii	51.46 (5)	Ca^vii—O1—Caⁱⁱⁱ	162.30 (6)
O1^ix—Ti—Ce^vii	128.54 (5)	Ce^vii—O1—Caⁱⁱⁱ	162.30 (6)
O2ⁱⁱⁱ—Ti—Ce^vii	124.47 (3)	Fe^xiii—O1—Ca^xii	78.47 (4)
O2^x—Ti—Ce^vii	55.53 (3)	Ti^xiii—O1—Ca^xii	78.47 (4)
O2^ix—Ti—Ce^vii	123.10 (3)	Fe—O1—Ca^xii	78.47 (4)
O2—Ti—Ce^vii	56.90 (3)	Ti—O1—Ca^xii	78.47 (4)
Ce^xi—Ti—Ce^vii	180.0	Ca—O1—Ca^xii	168.10 (7)
Ca^xi—Ti—Ce^vii	180.0	Ca^vii—O1—Ca^xii	85.45 (4)
O1—Ti—Ca^vii	51.46 (5)	Ce^vii—O1—Ca^xii	85.45 (4)
O1^ix—Ti—Ca^vii	128.54 (5)	Caⁱⁱⁱ—O1—Ca^xii	76.85 (4)
O2ⁱⁱⁱ—Ti—Ca^vii	124.47 (3)	Feⁱⁱ—O2—Ti	155.77 (6)
O2^x—Ti—Ca^vii	55.53 (3)	Tiⁱⁱ—O2—Ti	155.77 (6)
O2^ix—Ti—Ca^vii	123.10 (3)	Feⁱⁱ—O2—Fe	155.77 (6)
O2—Ti—Ca^vii	56.90 (3)	Tiⁱⁱ—O2—Fe	155.77 (6)
Ce^xi—Ti—Ca^vii	180.0	Feⁱⁱ—O2—Ca^x	97.78 (4)
Ca^xi—Ti—Ca^vii	180.0	Tiⁱⁱ—O2—Ca^x	97.78 (4)
O1—Ti—Ca^xii	65.84 (4)	Ti—O2—Ca^x	106.45 (4)
O1^ix—Ti—Ca^xii	114.16 (4)	Fe—O2—Ca^x	106.45 (4)
O2ⁱⁱⁱ—Ti—Ca^xii	134.03 (3)	Feⁱⁱ—O2—Ce^x	97.78 (4)
O2^x—Ti—Ca^xii	45.97 (3)	Tiⁱⁱ—O2—Ce^x	97.78 (4)
O2^ix—Ti—Ca^xii	53.08 (3)	Ti—O2—Ce^x	106.45 (4)
O2—Ti—Ca^xii	126.92 (3)	Fe—O2—Ce^x	106.45 (4)
Ce^xi—Ti—Ca^xii	108.311 (8)	Feⁱⁱ—O2—Ca^iv	86.50 (4)
Ca^xi—Ti—Ca^xii	108.311 (8)	Tiⁱⁱ—O2—Ca^iv	86.50 (4)
Ce^vii—Ti—Ca^xii	71.689 (8)	Ti—O2—Ca^iv	90.22 (4)
Ca^vii—Ti—Ca^xii	71.689 (8)	Fe—O2—Ca^iv	90.22 (4)
O1—Ti—Ce^xii	65.84 (4)	Ca^x—O2—Ca^iv	98.07 (4)
O1^ix—Ti—Ce^xii	114.16 (4)	Ce^x—O2—Ca^iv	98.07 (4)
O2ⁱⁱⁱ—Ti—Ce^xii	134.03 (3)	Feⁱⁱ—O2—Ce^iv	86.50 (4)
O2^x—Ti—Ce^xii	45.97 (3)	Tiⁱⁱ—O2—Ce^iv	86.50 (4)
O2^ix—Ti—Ce^xii	53.08 (3)	Ti—O2—Ce^iv	90.22 (4)
O2—Ti—Ce^xii	126.92 (3)	Fe—O2—Ce^iv	90.22 (4)
Ce^xi—Ti—Ce^xii	108.311 (8)	Ca^x—O2—Ce^iv	98.07 (4)
Ca^xi—Ti—Ce^xii	108.311 (8)	Ce^x—O2—Ce^iv	98.07 (4)
Ce^vii—Ti—Ce^xii	71.689 (8)	Feⁱⁱ—O2—Ce^vii	91.02 (4)
Ca^vii—Ti—Ce^xii	71.689 (8)	Tiⁱⁱ—O2—Ce^vii	91.02 (4)
O1—Fe—O1^ix	180.0	Ti—O2—Ce^vii	85.12 (4)
O1—Fe—O2ⁱⁱⁱ	90.66 (5)	Fe—O2—Ce^vii	85.12 (4)
O1^ix—Fe—O2ⁱⁱⁱ	89.34 (5)	Ca^x—O2—Ce^vii	99.03 (4)
O1—Fe—O2^x	89.34 (5)	Ce^x—O2—Ce^vii	99.03 (4)
O1^ix—Fe—O2^x	90.66 (5)	Ca^iv—O2—Ce^vii	162.90 (4)
O2ⁱⁱⁱ—Fe—O2^x	180.0	Ce^iv—O2—Ce^vii	162.90 (4)
O1—Fe—O2^ix	90.42 (6)	Feⁱⁱ—O2—Ca^vii	91.02 (4)
O1^ix—Fe—O2^ix	89.58 (6)	Tiⁱⁱ—O2—Ca^vii	91.02 (4)
O2ⁱⁱⁱ—Fe—O2^ix	90.586 (13)	Ti—O2—Ca^vii	85.12 (4)
O2^x—Fe—O2^ix	89.414 (13)	Fe—O2—Ca^vii	85.12 (4)
O1—Fe—O2	89.58 (6)	Ca^x—O2—Ca^vii	99.03 (4)
O1^ix—Fe—O2	90.42 (6)	Ce^x—O2—Ca^vii	99.03 (4)
O2ⁱⁱⁱ—Fe—O2	89.414 (13)	Ca^iv—O2—Ca^vii	162.90 (4)
O2^x—Fe—O2	90.586 (13)	Ce^iv—O2—Ca^vii	162.90 (4)

Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x+1/2, −y+1/2, −z+1; (iii) −x+1/2, y+1/2, z; (iv) −x+1, −y+1, −z+1; (v) −x+1, −y+1, z−1/2; (vi) −x+1/2, y+1/2, −z+1/2; (vii) −x+1/2, y−1/2, z; (viii) x+1, y, z; (ix) −x, −y+1, −z+1; (x) x−1/2, −y+1/2, −z+1; (xi) x−1/2, −y+3/2, −z+1; (xii) x−1, y, z; (xiii) −x, −y+1, z−1/2.

Experimental details

Crystal data
Chemical formula	Na_0.01Ca_0.96Fe_0.02Ti_0.98Ce_0.01O₃
M_r	136.40
Crystal system, space group	Orthorhombic, Pbnm
Temperature (K)	298
a, b, c (Å)	5.3818 (4), 5.4431 (4), 7.6450 (5)
V (Å³)	223.95 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.94
Crystal size (mm)	0.2 × 0.15 × 0.15

Data collection
Diffractometer	Siemens P4 diffractometer
Absorption correction	Part of the refinement model (ΔF) (SHELXL97; Sheldrick, 2008)
T_min, T_max	0.356, 0.409
No. of measured, independent and observed [I > 2s(I)] reflections	2383, 1594, 1527
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	1.178

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.103, 1.25
No. of reflections	1594
No. of parameters	31
Δρ_max, Δρ_min (e Å⁻³)	2.01, −2.88

Computer programs: XSCANS (Siemens, 1991), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), CrystalMaker (CrystalMaker, 2007), WinGX (Farrugia, 1999).

Selected geometric parameters (Å ,° ), where A represents the Ca²⁺, Na⁺ and Ce³⁺ cations, on 12-coordinated site and B represents Fe³⁺ and Ti⁴⁺ cations on octahedral site top

A-O₁	2.359 (2)	O₁^iv-A-O₁^iv	162.30 (6)
A-O₁^iv	2.481 (2)	O₂^iv-A-O₂^viii	80.97 (4)
A-O₁^iv	3.027 (2)	O₁-A-O₂^vii	118.03 (2)
A-O₁	3.052 (2)	O₂ⁱⁱ-A-O₁^iv	65.08 (3)
A-O₂^viii	2.378 (1)
A-O₂ⁱⁱ	2.620 (1)
A-O₂^iv	2.667 (1)
A-O₂^vi	3.233 (1)
B-O₁ⁱⁱ	1.9513 (3)	O₁-B-O₁ⁱⁱ	180.0
B-O₂^vii	1.956 (1)	O₂-B-O₂^vii	89.41 (1)
B-O₂^v	1.959 (1)	O₁-B-O₂	89.58 (6)

Notes: [Symmetry code: i) x, y, z; ii) -x, -y, z + 1/2; iii) (x + 1/2) -1, -y + 1/2, -z; iv) -x + 1/2, (y + 1/2) - 1, 1- (-z + 1/2); v) -x, -y, -z; vi) x, y, 1 - (-z + 1/2); vii) -x + 1/2, y + 1/2, z; viii) (x + 1/2) - 1, -y + 1/2, z + 1/2; ix) -x, -y + 1, (z + 1/2) -1].

Acknowledgements

The authors are grateful to Dr José Affonso Brod, University of Brasília, Brazil, for providing the perovskite samples, and to Mr William T. Soares for the microprobe analysis. This work was supported by the Minas Gerais Foundation for Research Development, FAPEMIG (Grant CEX 1123/90). EGG is grateful to the Brazilian Science Research Council, CNPq, for providing a graduate fellowship.

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