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inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 67| Part 2| February 2011| Pages i18-i19
doi:10.1107/S1600536811002157

Redetermination of synthetic warwickite, Mg3TiO2(BO3)2

Tetsuya Kawanoa and Hisanori Yamanea*

aInstitute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
*Correspondence e-mail: yamane@tagen.tohoku.ac.jp

(Received 22 December 2010; accepted 14 January 2011; online 22 January 2011)

Single crystals of warwickite, trimagnesium titanium(IV) dioxide bis­(borate), Mg3TiO2(BO3)2, were prepared by slow cooling of the melt. The title compound is isotypic with Co3TiO2(BO3)2. In contrast to the previous refinement of warwickite [Moore & Araki (1974[Moore, P. B. & Araki, T. (1974). Am. Mineral. 59, 985-1004.]). Am. Mineral. 59, 985–1004], that reported only isotropic atomic displacement parameters for all atoms, anisotropic displacement parameters of all atoms were refined during the current redetermination. All atoms are situated on special positions (site symmetry .m.). One of the two Mg sites is statistically disordered with Ti atoms (ratio 1:1), while the other is fully occupied by Mg atoms. The occupancy ratio of the Mg and Ti atoms is similar to that reported in the previous study. Metal atoms (M) at the Ti/Mg and Mg sites are coordinated by six O atoms in form of distorted octa­hedra. Four edge-sharing MO6 octa­hedra form M4O18 units, which are connected by common corners into layers parallel to (010). Adjacent layers are linked along [010] into a framework structure by sharing common edges. The B atoms are located in the triangular prismatic tunnels of the framework.

Related literature

For the structure determination of natural warwickite, Mg3TiO2(BO3)2, see: Takéuchi et al. (1950[Takéuchi, Y., Watanabé, T. & Ito, T. (1950). Acta Cryst. 3, 98-107.]); Moore & Araki (1974[Moore, P. B. & Araki, T. (1974). Am. Mineral. 59, 985-1004.]). For the synthesis and crystal structure analysis of Co3MO2(BO3)2 (M = Ti, Zr), see: Utzolino & Bluhm (1995[Utzolino, A. & Bluhm, K. (1995). Z. Naturforsch. Teil B, 50, 1653-1657.]). For the synthesis of Mg5TiO4(BO3)2 and Mg3ZrO2(BO3)2, see: Konijnendijk & Blasse (1985[Konijnendijk, W. L. & Blasse, G. (1985). Mater. Chem. Phys. 12, 591-599.]). For the structure of Mg5TiO4(BO3)2, see: Kawano & Yamane (2010[Kawano, T. & Yamane, H. (2010). Acta Cryst. C66, i92-i94.]). For bond-valence-sum calculations, see: Brown & Altermatt (1985[Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244-247.]). For bond-valence parameters, see: Brese & O'Keeffe (1991[Brese, N. E. & O'Keeffe, M. (1991). Acta Cryst. B47, 192-197.]). For structure standardization, see: Gelato & Parthé (1987[Gelato, L. M. & Parthé, E. (1987). J. Appl. Cryst. 20, 139-143.]).

Experimental

Crystal data

  • Mg3TiO2(BO3)2

  • Mr = 270.45

  • Orthorhombic, P n m a

  • a = 9.3013 (5) Å

  • b = 3.10080 (14) Å

  • c = 9.3914 (6) Å

  • V = 270.86 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 1.94 mm−1

  • T = 293 K

  • 0.17 × 0.17 × 0.12 mm
Data collection

  • Rigaku R-AXIS RAPID II diffractometer

  • Absorption correction: numerical (NUMABS; Higashi, 1999[Higashi, T. (1999). NUMABS. Rigaku Corporation, Tokyo, Japan.]) Tmin = 0.791, Tmax = 0.839

  • 2510 measured reflections

  • 364 independent reflections

  • 348 reflections with I > 2σ(I)

  • Rint = 0.018
Refinement

  • R[F2 > 2σ(F2)] = 0.026

  • wR(F2) = 0.070

  • S = 1.20

  • 364 reflections

  • 44 parameters

  • Δρmax = 0.36 e Å−3

  • Δρmin = −0.59 e Å−3

Table 1
Selected geometric parameters (Å, °), M = (Mg, Ti)

M1—O4i 1.9702 (12)
M1—O4ii 1.9989 (19)
M1—O2 2.0730 (18)
M1—O1i 2.1565 (13)
Mg2—O3iii 2.0043 (12)
Mg2—O4iv 2.0698 (19)
Mg2—O1 2.1387 (19)
Mg2—O2v 2.1522 (13)
B1—O3 1.353 (3)
B1—O2 1.393 (3)
B1—O1 1.395 (3)
O3—B1—O2 119.1 (2)
O3—B1—O1 120.7 (2)
O2—B1—O1 120.3 (2)
Symmetry codes: (i) [-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]; (ii) [x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]; (iii) -x, -y, -z+1; (iv) [x-{\script{1\over 2}}, y, -z+{\script{3\over 2}}]; (v) [-x+{\script{1\over 2}}, -y+1, z+{\script{1\over 2}}].

Data collection: PROCESS-AUTO (Rigaku/MSC, 2005[Rigaku/MSC (2005). PROCESS-AUTO. Rigaku/MSC Inc., The Woodlands, Texas, USA.]); cell refinement: PROCESS-AUTO; data reduction: PROCESS-AUTO; program(s) used to solve structure: SIR2004 (Burla et al., 2005[Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381-388.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: VESTA (Momma & Izumi, 2008[Momma, K. & Izumi, F. (2008). J. Appl. Cryst. 41, 653-658.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811002157/wm2443sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811002157/wm2443Isup2.hkl

checkCIF report


Comment top

Crystal structure determinations of the mineral warwickite, Mg3TiO2(BO3)2, were reported by Takéuchi et al. (1950) and Moore & Araki (1974). The natural samples contained a few amount of Fe and Al. The crystal structure of synthetic Mg3TiO2(BO3)2 has not been analyzed up to now. We obtained single crystals of this compound during the preparation of Mg5TiO4(BO3)2 (Kawano & Yamane, 2010). Anisotropic atomic displacement parameters (Uij) of Mg, Ti, B and O atoms were refined in the present study. Moore & Araki (1974) refined isotropic atomic displacement parameters (Biso) of Mg, Ti, B and O atoms; neither U nor B-values were reported by Takéuchi et al. (1950).

Synthetic warwickite-type oxyborates with general composition MII3MIVO2(BO3)2 are known for Co3MO2(BO3)2 [M = Ti, Zr (Utzolino & Bluhm, 1995)] and Mg3ZrO2(BO3)2 (Konijnendijk & Blasse, 1985). However, only the crystal structures of Co3MO2(BO3)2 (M = Ti, Zr) were analyzed. The title compound Mg3TiO2(BO3)2 is isotypic with Co3MO2(BO3)2 [M = Ti, Zr (Utzolino & Bluhm, 1995)].

Figs. 1 and 2 show the coordination environments of the Mg, Ti, B and O atoms, and the crystal structure of Mg3TiO2(BO3)2, respectively. In the asymmetric unit, there is one Ti/Mg mixed site (M1) with occupancies of 0.5/0.5 and one Mg site (M2). Moore and Araki (1974) refined the site occupancy factors of Mg and Ti atoms at the M1 and M2 sites, ignoring Al and Fe atoms due to their similarities with the scattering profiles of Mg2+ and Ti4+, respectively. Refined occupancy factors were M1 = Mg0.96 (1)/Ti0.04 (1) and M2 = Mg0.62 (2)/Ti0.38 (2) and an ideal formula of Mg(Mg0.5Ti0.5)O2[BO3] was suggested (Moore & Araki, 1974). Our refinement (M1 = Mg1 and M2 = Mg0.5/Ti0.5) is consistent with the ideal formula. Although Takéuchi et al. (1950) reported the atomic coordinates of natural warwickite, site occupancy factors of the M1 and M2 sites were not reported.

All atoms are at special positions (x, 1/4, z), 4c, with site symmetries of (.m.). Mg and Ti atoms occupy six-coordinated oxygen-octahedral sites, forming layers composed of M4O18 (M = Ti/Mg, Mg) units. The layers are connected by edge-sharing O4 atoms of (Ti1/Mg1)O6 and Mg2O6 octahedra into a three-dimensional framework. B1 atoms are located in triangular prismatic tunnels of the framework.

Bond valence sums (BVS; Brown & Altermatt, 1985) of the Mg, Ti and B atoms were calculated with the bond valence parameters of 1.693 Å for Mg2+, 1.815 Å for Ti4+ and 1.371 Å for B3+ (Brese & O'Keeffe, 1991). The BVS values of the Mg2 and B1 atoms were 2.1 and 2.9, respectively. Those of the Ti1 and Mg1 atoms at the Ti1/Mg1 site were 3.22 and 2.31, respectively. The average of these value is 2.8 and close to the expected mean valence (+3) of Mg2+ and Ti4+. The B1—O distances of 1.353 (3)–1.395 (3) Å agree well with those of isotypic Co3MO2(BO3)2 (M = Ti, Zr): 1.36 (2)–1.39 (2) Å (Utzolino & Bluhm, 1995).

Warwickite-type Mg3TiO2(BO3)2 did not emit visible light under ultraviolet excitation at room temperature, while ludwigite-type Mg5TiO4(BO3)2 shows broad blue emission (435 nm) attributed to charge transfer transitions between Ti4+ and O2– (Konijnendijk & Blasse, 1985).

Related literature top

For the structure determination of natural warwickite, Mg3TiO2(BO3)2, see: Takéuchi et al. (1950); Moore & Araki (1974). For the synthesis and crystal structure analysis of Co3MO2(BO3)2 (M = Ti, Zr), see: Utzolino & Bluhm (1995). For the synthesis of Mg5TiO4(BO3)2 and Mg3ZrO2(BO3)2, see: Konijnendijk & Blasse (1985). For the structure of Mg5TiO4(BO3)2, see: Kawano & Yamane (2010). For bond-valence-sum calculations, see: Brown & Altermatt (1985). For bond-valence parameters, see: Brese & O'Keeffe (1991). For structure standardization, see: Gelato & Parthé (1987).

Experimental top

Starting materials were powders of MgO (99.9%, Rare Metallic), TiO2 (99.9%, Rare Metallic) and H3BO3 (99.99%, Sigma-Aldrich). MgO was heated at 1173–1273 K for 6–12 h in air before weighing. The powders were weighed with a molar ratio of MgO: TiO2: H3BO3 = 5: 1: 2.7 and mixed in an agate mortar with a pestle. The mixture was pressed into a pellet, placed in a Pt boat and heated at 1623 K for 6 h in air. Heating and cooling rates were 200 and 900 K/h, respectively. About 400 mg of the sample and 100 mg of H3BO3 were weighed and mixed. The mixture in the Pt boat was heated at 1723 K for 3 h in air and cooled to room temperature at a cooling rate of 900 K/h. The obtained sample was crushed into fragments and a colourless and transparent single-crystal of about 0.12–0.17 mm was picked up under an optical microscope.

Refinement top

The crystal structures of natural warwickites were described in the space group Pnam (no. 62) in the previous studies (Takéuchi et al., 1950; Moore & Araki, 1974). The original single-crystal X-ray diffraction data in the present study were indexed in a different setting in space group Pmnb and unit-cell parameters of a = 3.10080 (14), b = 9.3013 (5) and c = 9.3914 (6) Å. Structure parameters were eventually standardized based on the standard setting of the space group Pnma using the STRUCTURE TIDY program (Gelato & Parthé, 1987). In the final refinement, site occupation factors (s.o.f.'s) of the Ti and Mg atoms at the Ti1/Mg1 and Mg2 sites were fixed to 0.5/0.5 and 1.0, respectively, since the freely refined s.o.f.'s of the Ti and Mg atoms at the Ti1/Mg1 site were close to 1/2, and the s.o.f. of the Mg atom at the Mg2 site was about 1.0. The highest peak in the difference electron density map is 0.36 Å from O2 while the deepest hole is -0.59 Å from Ti1/Mg1.

Computing details top

Data collection: PROCESS-AUTO (Rigaku/MSC, 2005); cell refinement: PROCESS-AUTO (Rigaku/MSC, 2005); data reduction: PROCESS-AUTO (Rigaku/MSC, 2005); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: VESTA (Momma & Izumi, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The atomic arrangement around Mg, Ti, B and O atoms in the structure of Mg3TiO2(BO3)2. Displacement ellipsoids are drawn at the 95% probability level. Symmetry codes: (i) –x + 1/2, –y, z–1/2; (ii) –x + 1/2, –y + 1, z–1/2; (iii) x–1/2, y, –z + 1/2; (iv) –x, –y, –z + 1; (v) –x, –y + 1, –z + 1; (vi) x–1/2, y, –z + 3/2; (vii) –x + 1/2, –y + 1, z + 1/2; (viii) –x + 1/2, –y, z + 1/2.
[Figure 2] Fig. 2. The crystal structure of Mg3TiO2(BO3)2 in a representation using cation-centred oxygen polyhedra.
trimagnesium titanium(IV) dioxide bis(borate) top
Crystal data top
Mg3TiO2(BO3)2F(000) = 264
Mr = 270.45Dx = 3.316 Mg m−3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 2288 reflections
a = 9.3013 (5) Åθ = 3.1–27.5°
b = 3.10080 (14) ŵ = 1.94 mm−1
c = 9.3914 (6) ÅT = 293 K
V = 270.86 (3) Å3Block, colourless
Z = 20.17 × 0.17 × 0.12 mm
Data collection top
Rigaku R-AXIS RAPID II
diffractometer		364 independent reflections
Radiation source: fine-focus sealed tube348 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.018
Detector resolution: 10.0 pixels mm-1θmax = 27.5°, θmin = 3.1°
ω scansh = −12→11
Absorption correction: numerical
(NUMABS; Higashi, 1999)		k = −3→3
Tmin = 0.791, Tmax = 0.839l = −12→12
2510 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.026 w = 1/[σ2(Fo2) + (0.0347P)2 + 0.3981P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.070(Δ/σ)max < 0.001
S = 1.20Δρmax = 0.36 e Å−3
364 reflectionsΔρmin = −0.59 e Å−3
44 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.039 (7)
Crystal data top
Mg3TiO2(BO3)2V = 270.86 (3) Å3
Mr = 270.45Z = 2
Orthorhombic, PnmaMo Kα radiation
a = 9.3013 (5) ŵ = 1.94 mm−1
b = 3.10080 (14) ÅT = 293 K
c = 9.3914 (6) Å0.17 × 0.17 × 0.12 mm
Data collection top
Rigaku R-AXIS RAPID II
diffractometer		364 independent reflections
Absorption correction: numerical
(NUMABS; Higashi, 1999)		348 reflections with I > 2σ(I)
Tmin = 0.791, Tmax = 0.839Rint = 0.018
2510 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02644 parameters
wR(F2) = 0.0700 restraints
S = 1.20Δρmax = 0.36 e Å−3
364 reflectionsΔρmin = −0.59 e Å−3
Special details top

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
xyzUiso*/UeqOcc. (<1)
Ti10.11388 (7)0.25000.07167 (7)0.0115 (3)0.50
Mg10.11388 (7)0.25000.07167 (7)0.0115 (3)0.50
Mg20.10160 (8)0.25000.68497 (9)0.0055 (3)
B10.1708 (3)0.25000.3719 (3)0.0061 (5)
O10.24045 (19)0.25000.50344 (18)0.0088 (4)
O20.25030 (18)0.25000.24622 (19)0.0078 (4)
O30.0255 (2)0.25000.36441 (19)0.0100 (4)
O40.5095 (2)0.25000.61439 (18)0.0100 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ti10.0148 (4)0.0079 (4)0.0119 (4)0.000−0.0015 (2)0.000
Mg10.0148 (4)0.0079 (4)0.0119 (4)0.000−0.0015 (2)0.000
Mg20.0040 (4)0.0045 (5)0.0079 (4)0.0000.0001 (3)0.000
B10.0069 (12)0.0038 (13)0.0077 (12)0.000−0.0013 (9)0.000
O10.0071 (8)0.0139 (10)0.0054 (7)0.000−0.0006 (6)0.000
O20.0085 (8)0.0090 (9)0.0058 (7)0.0000.0004 (6)0.000
O30.0063 (9)0.0095 (10)0.0143 (9)0.000−0.0017 (7)0.000
O40.0102 (9)0.0128 (10)0.0071 (8)0.000−0.0020 (6)0.000
Geometric parameters (Å, º) top
Ti1—O4i1.9702 (12)Mg2—O4x2.0698 (19)
Ti1—O4ii1.9702 (12)Mg2—O12.1387 (19)
Ti1—O4iii1.9989 (19)Mg2—O2xi2.1522 (13)
Ti1—O22.0730 (18)Mg2—O2xii2.1522 (13)
Ti1—O1ii2.1565 (13)Mg2—Mg2vi3.1008 (1)
Ti1—O1i2.1565 (13)Mg2—Mg2vii3.1008 (1)
Ti1—Ti1iv2.9502 (11)Mg2—Ti1xi3.2465 (9)
Ti1—Mg1iv2.9502 (11)Mg2—Mg1xi3.2465 (9)
Ti1—Ti1v2.9502 (11)Mg2—Ti1xii3.2465 (9)
Ti1—Mg1v2.9502 (11)Mg2—Mg1xii3.2465 (9)
Ti1—Ti1vi3.1008 (1)B1—O31.353 (3)
Ti1—Ti1vii3.1008 (1)B1—O21.393 (3)
Mg2—O3viii2.0043 (12)B1—O11.395 (3)
Mg2—O3ix2.0043 (12)
O4i—Ti1—O4ii103.80 (9)Mg2—O1—Ti1xi98.20 (6)
O4i—Ti1—O4iii83.98 (6)B1—O1—Ti1xii123.71 (9)
O4ii—Ti1—O4iii83.98 (6)Mg2—O1—Ti1xii98.20 (6)
O4i—Ti1—O2101.28 (6)Mg1xi—O1—Ti1xii91.94 (7)
O4ii—Ti1—O2101.28 (6)Ti1xi—O1—Ti1xii91.94 (7)
O4iii—Ti1—O2171.31 (8)B1—O1—Mg1xii123.71 (9)
O4i—Ti1—O1ii172.87 (6)Mg2—O1—Mg1xii98.20 (6)
O4ii—Ti1—O1ii82.00 (5)Mg1xi—O1—Mg1xii91.94 (7)
O4iii—Ti1—O1ii92.60 (6)Ti1xi—O1—Mg1xii91.94 (7)
O2—Ti1—O1ii81.39 (6)B1—O2—Ti1110.19 (15)
O4i—Ti1—O1i82.00 (5)B1—O2—Mg2ii124.49 (8)
O4ii—Ti1—O1i172.87 (6)Ti1—O2—Mg2ii100.40 (6)
O4iii—Ti1—O1i92.60 (6)B1—O2—Mg2i124.49 (8)
O2—Ti1—O1i81.39 (6)Ti1—O2—Mg2i100.40 (6)
O1ii—Ti1—O1i91.94 (7)Mg2ii—O2—Mg2i92.17 (7)
O3viii—Mg2—O3ix101.34 (9)B1—O3—Mg2viii126.96 (6)
O3viii—Mg2—O4x88.08 (6)B1—O3—Mg2ix126.96 (6)
O3ix—Mg2—O4x88.08 (6)Mg2viii—O3—Mg2ix101.34 (9)
O3viii—Mg2—O199.89 (7)Mg1xii—O4—Mg1xi103.80 (9)
O3ix—Mg2—O199.89 (7)Ti1xii—O4—Mg1xi103.80 (9)
O4x—Mg2—O1167.30 (8)Mg1xii—O4—Ti1xi103.80 (9)
O3viii—Mg2—O2xi175.34 (6)Ti1xii—O4—Ti1xi103.80 (9)
O3ix—Mg2—O2xi83.24 (5)Mg1xii—O4—Mg1xiii96.02 (6)
O4x—Mg2—O2xi91.24 (6)Ti1xii—O4—Mg1xiii96.02 (6)
O1—Mg2—O2xi80.01 (6)Mg1xi—O4—Mg1xiii96.02 (6)
O3viii—Mg2—O2xii83.24 (5)Ti1xi—O4—Mg1xiii96.02 (6)
O3ix—Mg2—O2xii175.34 (6)Mg1xii—O4—Ti1xiii96.02 (6)
O4x—Mg2—O2xii91.24 (6)Ti1xii—O4—Ti1xiii96.02 (6)
O1—Mg2—O2xii80.01 (6)Mg1xi—O4—Ti1xiii96.02 (6)
O2xi—Mg2—O2xii92.17 (7)Ti1xi—O4—Ti1xiii96.02 (6)
O3—B1—O2119.1 (2)g1xii—O4—Mg2xiv115.24 (6)
O3—B1—O1120.7 (2)Ti1xii—O4—Mg2xiv115.24 (6)
O2—B1—O1120.3 (2)Mg1xi—O4—Mg2xiv115.24 (6)
B1—O1—Mg2115.18 (15)Ti1xi—O4—Mg2xiv115.24 (6)
B1—O1—Mg1xi123.71 (9)Mg1xiii—O4—Mg2xiv126.50 (10)
Mg2—O1—Mg1xi98.20 (6)Ti1xiii—O4—Mg2xiv126.50 (10)
B1—O1—Ti1xi123.71 (9)
Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) −x+1/2, −y+1, z−1/2; (iii) x−1/2, y, −z+1/2; (iv) −x, −y, −z; (v) −x, −y+1, −z; (vi) x, y+1, z; (vii) x, y−1, z; (viii) −x, −y, −z+1; (ix) −x, −y+1, −z+1; (x) x−1/2, y, −z+3/2; (xi) −x+1/2, −y+1, z+1/2; (xii) −x+1/2, −y, z+1/2; (xiii) x+1/2, y, −z+1/2; (xiv) x+1/2, y, −z+3/2.

Experimental details

Crystal data
Chemical formulaMg3TiO2(BO3)2
Mr270.45
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)293
a, b, c (Å)9.3013 (5), 3.10080 (14), 9.3914 (6)
V (Å3)270.86 (3)
Z2
Radiation typeMo Kα
µ (mm−1)1.94
Crystal size (mm)0.17 × 0.17 × 0.12
Data collection
DiffractometerRigaku R-AXIS RAPID II
diffractometer
Absorption correctionNumerical
(NUMABS; Higashi, 1999)
Tmin, Tmax0.791, 0.839
No. of measured, independent and
observed [I > 2σ(I)] reflections		2510, 364, 348
Rint0.018
(sin θ/λ)max (Å−1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.070, 1.20
No. of reflections364
No. of parameters44
Δρmax, Δρmin (e Å−3)0.36, −0.59

Computer programs: PROCESS-AUTO (Rigaku/MSC, 2005), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), VESTA (Momma & Izumi, 2008).

Selected geometric parameters (Å, º) top
Ti1—O4i1.9702 (12)Mg2—O4vi2.0698 (19)
Ti1—O4ii1.9702 (12)Mg2—O12.1387 (19)
Ti1—O4iii1.9989 (19)Mg2—O2vii2.1522 (13)
Ti1—O22.0730 (18)Mg2—O2viii2.1522 (13)
Ti1—O1ii2.1565 (13)B1—O31.353 (3)
Ti1—O1i2.1565 (13)B1—O21.393 (3)
Mg2—O3iv2.0043 (12)B1—O11.395 (3)
Mg2—O3v2.0043 (12)
O3—B1—O2119.1 (2)O2—B1—O1120.3 (2)
O3—B1—O1120.7 (2)
Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) −x+1/2, −y+1, z−1/2; (iii) x−1/2, y, −z+1/2; (iv) −x, −y, −z+1; (v) −x, −y+1, −z+1; (vi) x−1/2, y, −z+3/2; (vii) −x+1/2, −y+1, z+1/2; (viii) −x+1/2, −y, z+1/2.
 

Acknowledgements

This work was supported in part by the Global COE Program `Materials Integration, Tohoku University' and by a Grant-in-Aid for Scientific Research (B) (No. 21350113, 2009) from the Ministry of Education, Culture, Sports and Technology (MEXT), Japan.

References

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ISSN: 2056-9890
Volume 67| Part 2| February 2011| Pages i18-i19
doi:10.1107/S1600536811002157
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