PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. Oct 1, 2012; 68(Pt 10): i78–i79.
Published online Sep 29, 2012. doi:  10.1107/S1600536812040457
PMCID: PMC3470124
Redetermination of clinobaryl­ite, BaBe2Si2O7
Adrien J. Di Domizio,a* Robert T. Downs,a and Hexiong Yanga
aDepartment of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721-0077, USA
Correspondence e-mail: ajdidomizio727/at/email.arizona.edu
Received August 31, 2012; Accepted September 25, 2012.
Clinobaryl­ite, ideally BaBe2Si2O7 (chemical name barium diberyllium disilicate), is a sorosilicate mineral and dimorphic with baryl­ite. It belongs to a group of compounds characterized by the general formula BaM 2+ 2Si2O7, with M 2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobaryl­ite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia). The structure of clinobaryl­ite can be considered as a framework of BeO4 and SiO4 tetra­hedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO4 tetra­hedra share corners, forming chains parallel to the c axis, which are inter­linked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations (site symmetry m..) are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si—Obr (bridging O atom, at site symmetry m..) bond length, the Si—Onbr (non-bridging O atoms) bond lengths, and the Si—O—Si angle within the Si2O7 unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004 [triangle]). N. Jb. Miner. Mh. pp. 373–384].
For clinobaryl­ite, see: Chukanov et al. (2003 [triangle]); Rastsvetaeva & Chukanov (2003 [triangle]); Krivovichev et al. (2004 [triangle]). For clinobaryl­ite-related minerals and compounds, see: Lin et al. (1999 [triangle]); Fleet & Liu (2001 [triangle]); Kolitsch et al. (2009 [triangle]); Yang et al. (2012 [triangle]). For general information on applications of clinobaryl­ite-related materials, see: Barry (1970 [triangle]); Robinson & Fang (1977 [triangle]); Adams & Layland (1996 [triangle]); Yao et al. (1998 [triangle]); Lu et al. (2000 [triangle]); Yamada et al. (2001 [triangle]); Ohta et al. (2004 [triangle]); Bertaina & Hayn (2006 [triangle]); Zvyagin (2006 [triangle]); Zheludev et al. (2007 [triangle]); Yang et al. (2012 [triangle]).
Crystal data  
  • BaBe2O7Si2
  • M r = 323.54
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-68-00i78-efi1.jpg
  • a = 11.6491 (5) Å
  • b = 4.9175 (2) Å
  • c = 4.6746 (2) Å
  • V = 267.78 (2) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 7.85 mm−1
  • T = 293 K
  • 0.05 × 0.05 × 0.04 mm
Data collection  
  • Bruker APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2005 [triangle]) T min = 0.695, T max = 0.744
  • 3929 measured reflections
  • 965 independent reflections
  • 947 reflections with I > 2σ(I)
  • R int = 0.020
Refinement  
  • R[F 2 > 2σ(F 2)] = 0.011
  • wR(F 2) = 0.026
  • S = 1.08
  • 965 reflections
  • 60 parameters
  • 1 restraint
  • Δρmax = 0.47 e Å−3
  • Δρmin = −0.42 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 399 Friedel pairs
  • Flack parameter: 0.502 (12)
Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: XtalDraw (Downs & Hall-Wallace, 2003 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]).
Table 1
Table 1
Selected geometric parameters (Å, °)
Supplementary Material
Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536812040457/wm2678sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812040457/wm2678Isup2.hkl
Additional supplementary materials: crystallographic information; 3D view; checkCIF report
Acknowledgments
We gratefully acknowledge support of this study by the Arizona Science Foundation.
supplementary crystallographic information
Comment
Clinobarylite, ideally BaBe2Si2O7, is a sorosilicate mineral and dimorphic with the mineral barylite (Chukanov et al., 2003). It belongs to a group of compounds characterized by the general formula BaM2+2Si2O7, with M2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu (Yang et al., 2012). In addition to the Be-member, the Fe- and Cu-members of this group have also been found in nature, and are known as andrémeyerite and scottyite, respectively. The BaM2Si2O7 compounds have been the subject of numerous investigations for scientific and industrial interests. For example, the materials with M = Be, Mg, and Zn are suitable hosts for luminescent activating ions. In particular, Pb2+-doped BaBe2Si2O7 is used commercially as an UV-emitting material in moth-killing lamps and (Eu2+/Mn2+)-doped BaMg2Si2O7 is a deep-red luminescent emitter through effective energy transfers from Eu2+ to Mn2+ (Barry, 1970; Yao et al., 1998). Moreover, the compounds with M = Cu, Co, and Mn are ideal prototypical quasi-one-dimensional quantum spin (S = 1/2, 3/2, and 5/2, respectively) Heisenberg antiferromagnets with adjustable superexchange interactions, vital for our understanding of high-Tc superconductivity (e.g., Adams & Layland, 1996; Lu et al., 2000; Yamada et al., 2001; Ohta et al., 2004; Bertaina & Hayn, 2006; Zvyagin, 2006; Zheludev et al., 2007).
Clinobarylite was first described by Chukanov et al. (2003) as monoclinic with space group Pm and unit-cell parameters a = 11.618 (3), b = 4.904 (1), c = 4.655 (1) Å, β = 89.92 (2)°. Its structure was subsequently determined by Rastsvetaeva & Chukanov (2003), yielding a reliability factor R = 0.052 with isotropic displacement parameters for all atoms. However, Krivovichev et al. (2004) examined the monoclinic structure reported by Rastsvetaeva & Chukanov (2003) and noted that a shift of 0.0088 Å along b in all the atomic positions would result in a change of symmetry from monoclinic Pm to orthorhombic Pmn21. They subsequently collected single-crystal X-ray diffraction data from a new sample, and found that systematic intensity absences were consistent with space group Pmn21 and a racemic twinning model (R1 = 0.030). Yet, they were unable to obtain positive definite anisotropic displacement parameters for Be and O atoms, and attributed that to the effect of the dominant Ba scattering factor. The resulting geometric parameters, such as bond lengths and angles, matched those obtained from the Pm structural model determined by Rastsvetaeva & Chukanov (2003). An examination of the clinobarylite structure reported by Krivovichev et al. (2004), nevertheless, reveals a rather peculiar feature: The Si—Obr (bridging O atom) distance (1.597 Å) is significantly shorter than the Si—Onbr (non-bridging O atoms) distances (1.619–1.631 Å). This contradicts the previous observations specifically for disilicate compounds (e.g., Lin et al., 1999; Fleet & Liu, 2001; Kolitsch et al., 2009), including all other compounds in the BaM2+2Si2O7 group (Yang et al., 2012). The present study was conducted to clarify this controversy.
The crystal structure of clinobarylite is based on a framework of SiO4 and BeO4 tetrahedra, with one of the O atoms (O2) coordinated to two Be and one Si, one (O3) coordinated to two Si, and two O atoms (O1, O4) coordinated to one Si and one Be. The BeO4 tetrahedra share corners to form chains parallel to the c axis, which are interlinked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations are situated in the framework channels and are coordinated in form of irregular polyhedra by eleven O atoms if Ba—O distances < 3.4 Å are considered as relevant (Figs. 1, 2). The average Si—O, Be—O, and Ba—O bond lengths in clinobarylite are 1.630, 1.941, and 2.825 Å, respectively. Our study confirmed the space group Pmn21 for clinobarylite, as determined by Krivovichev et al. (2004), but revealed different bond length from those given by Krivovichev et al. (2004): The Si—Obr bond length [1.6566 (10) Å] is, in fact, substantially longer than the Si—Onbr bond lengths [1.6065 (13) - 1.6315 (14) Å], in marked contrast to the corresponding values of 1.597 (4) Å, 1.619 (6)–1.631 (7) Å as reported by Krivovichev et al. (2004). Moreover, the Si—Obr—Si angle within the Si2O7 disilicate unit from our study is 128.82 (13)°, in contrast to 138.5° (Krivovichev et al., 2004).
The Raman spectrum of clinobarylite is plotted in Fig. 3, along with that of barylite (R060620 from the RRUFF Project) for comparison. Evidently, the two Raman spectra are quite similar. In general, they can be divided into four regions. Region 1, between 800 and 1100 cm-1, contains bands attributable to the Si—O symmetric and anti-symmetric stretching vibrations (ν1 and ν3 modes) within the SiO4 tetrahedra. Region 2, between 660 and 700 cm-1, includes bands resulting from the Si—Obr—Si bending vibrations within the Si2O7 tetrahedral dimers. Major bands in region 3, ranging from 420 to 660 cm-1, are ascribed to the O—Si—O symmetric and anti-symmetric bending vibrations (ν2 and ν4 modes) within the SiO4 tetrahedra. The bands in region 4, below 420 cm-1, are mainly associated with the rotational and translational modes of SiO4 tetrahedra, as well as the Be—O interactions and lattice vibrational modes.
One of the noticeable features in Fig. 3 is that the wavenumbers of the bands due to the Si—Obr—Si bending mode for barylite and clinobarylite are nearly identical (~685 cm-1), indicating that the Si—Obr bond lengths and the Si—Obr—Si angles in these two minerals are rather comparable. This is indeed the case. The Si—Obr distance and the Si—Obr—Si angle are 1.657 Å and 128.59°, respectively, in barylite (Robinson & Fang, 1977), and 1.6566 (10) Å and 128.82 (13)° in clinobarylite.
Experimental
The clinobarylite sample used in this study is from the type locality Yukspor Mountain, Khibiny Massif, Kola Peninsula, Russia, and is in the collection of the RRUFF project (deposition, http://rruff.info/ R060606). The chemical composition of the sample was analyzed with a CAMECA SX50 electron microprobe. The average composition (12 analysis points) is (%wt) BaO 47.5 (2), SiO2 37.0 (2), TiO2 0.19 (2), and BeO 15.3 (estimated by the difference from 100%). The empirical chemical formula, calculated on the basis of 7 O atoms, is Ba1.0Be2.0Si2.0O7.
The Raman spectrum of clinobarylite was collected from a randomly oriented crystal at 100% power on a Thermo Almega microRaman system, using a solid-state laser with a wavelength of 532 nm, and a thermoelectrically cooled CCD detector. The laser is partially polarized with 4 cm-1 resolution and a spot size of 1 µm.
Refinement
For better comparison with the previous determination of barylite (Krivovichev et al., 2004), the same atom numbering was used, along with the given coordinates as starting parameters for the subsequent refinement. An inversion twin was introduced in the refinement, giving a twin ratio of 0.502 (12):0.498 (12). All atoms were refined with anisotropic displacement parameters. The ideal chemistry, BaBe2Si2O7, was assumed during the final refinement. The highest residual peak (0.47 e-3) in the difference Fourier maps was located at (0, 0.7651, 0.2479), 0.75 Å from Ba, and the deepest hole (-0.42 e-3) at (0, 0.3845, 0.0984), 1.75 Å from O4.
Figures
Fig. 1.
Fig. 1.
Crystal structure of clinobarylite. The gray spheres represent Ba atoms. The yellow and purple tetrahedra represent BeO4 and SiO4 groups, respectively.
Fig. 2.
Fig. 2.
Atoms in clinobarylite with corresponding ellipsoids at the 99.9% probability level. The gray, yellow, green, and red ellipsoids represent Ba, Be, Si, and O atoms, respectively.
Fig. 3.
Fig. 3.
Raman Spectrum of clinobarylite, along with that of barylite for comparison. The spectra are shown with vertical offset for more clarity.
Crystal data
BaBe2O7Si2F(000) = 296
Mr = 323.54Dx = 4.013 Mg m3
Orthorhombic, Pmn21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac -2Cell parameters from 3074 reflections
a = 11.6491 (5) Åθ = 3.5–32.6°
b = 4.9175 (2) ŵ = 7.85 mm1
c = 4.6746 (2) ÅT = 293 K
V = 267.78 (2) Å3Cuboid, colourless
Z = 20.05 × 0.05 × 0.04 mm
Data collection
Bruker APEXII CCD area-detector diffractometer965 independent reflections
Radiation source: fine-focus sealed tube947 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.020
[var phi] and ω scanθmax = 32.6°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 2005)h = −17→16
Tmin = 0.695, Tmax = 0.744k = −7→7
3929 measured reflectionsl = −6→7
Refinement
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullw = 1/[σ2(Fo2) + (0.0139P)2] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.011(Δ/σ)max < 0.001
wR(F2) = 0.026Δρmax = 0.47 e Å3
S = 1.08Δρmin = −0.42 e Å3
965 reflectionsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
60 parametersExtinction coefficient: 0.0160 (9)
1 restraintAbsolute structure: Flack (1983), 399 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.502 (12)
Special details
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)
xyzUiso*/Ueq
Ba0.50000.20316 (2)0.59050.00932 (5)
Be0.75108 (15)0.1693 (4)0.0849 (14)0.0070 (4)
Si0.62826 (4)0.67528 (8)0.0692 (2)0.00526 (12)
O10.63895 (10)0.3560 (2)0.1367 (3)0.0073 (3)
O20.77699 (10)0.1340 (2)−0.2702 (3)0.0066 (2)
O30.50000.7764 (3)0.1793 (5)0.0077 (3)
O40.63272 (12)0.7295 (2)−0.2716 (3)0.0082 (2)
Atomic displacement parameters (Å2)
U11U22U33U12U13U23
Ba0.01102 (6)0.00872 (6)0.00823 (7)0.0000.0000.00004 (8)
Be0.0052 (7)0.0071 (7)0.0087 (10)−0.0001 (5)−0.0020 (17)0.0017 (18)
Si0.00460 (16)0.00420 (14)0.0070 (3)−0.00035 (10)0.0000 (3)−0.0001 (2)
O10.0077 (4)0.0055 (4)0.0088 (10)0.0007 (3)0.0022 (4)0.0011 (4)
O20.0079 (5)0.0051 (4)0.0067 (6)−0.0008 (4)0.0007 (4)0.0003 (4)
O30.0045 (7)0.0082 (7)0.0103 (9)0.0000.000−0.0024 (6)
O40.0075 (6)0.0109 (5)0.0064 (7)−0.0016 (4)−0.0007 (5)0.0000 (4)
Geometric parameters (Å, º)
Ba—O1i2.7721 (13)Ba—O2vi3.3093 (12)
Ba—O12.7721 (13)Be—O4vii1.591 (3)
Ba—O3ii2.8459 (18)Be—O11.615 (2)
Ba—O4iii2.8689 (13)Be—O2viii1.670 (4)
Ba—O4iv2.8689 (13)Be—O21.696 (7)
Ba—O4v3.0831 (12)Si—O11.6065 (13)
Ba—O4vi3.0831 (12)Si—O41.616 (2)
Ba—O1v3.1151 (14)Si—O2vii1.6315 (14)
Ba—O1vi3.1151 (14)Si—O31.6566 (10)
Ba—O2v3.3093 (12)
O4vii—Be—O1116.6 (2)O1—Si—O2vii114.78 (8)
O4vii—Be—O2viii106.0 (3)O4—Si—O2vii109.70 (8)
O1—Be—O2viii106.8 (2)O1—Si—O3107.59 (8)
O4vii—Be—O2107.1 (2)O4—Si—O3106.60 (10)
O1—Be—O2110.4 (3)O2vii—Si—O3107.14 (8)
O2viii—Be—O2109.90 (19)Sii—O3—Si128.82 (13)
O1—Si—O4110.64 (8)
Symmetry codes: (i) −x+1, y, z; (ii) x, y−1, z; (iii) −x+1, y−1, z+1; (iv) x, y−1, z+1; (v) x, y, z+1; (vi) −x+1, y, z+1; (vii) −x+3/2, −y+1, z+1/2; (viii) −x+3/2, −y, z+1/2.
Footnotes
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2678).
  • Adams, R. D. & Layland, R. (1996). Inorg. Chem. 35, 3492–3497.
  • Barry, T. L. (1970). J. Electrochem. Soc. 117, 381–385.
  • Bertaina, S. & Hayn, R. (2006). Phys. Rev. B, 73, 212409.
  • Bruker (2004). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Chukanov, N. V., Pekov, I. V., Rastsvetaeva, R. K., Shilov, G. V. & Zadov, A. E. (2003). Z. Vseros. Miner. Obsh. 132, 29–37.
  • Downs, R. T. & Hall-Wallace, M. (2003). Am. Mineral. 88, 247–250.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Fleet, M. E. & Liu, X. (2001). J. Solid State Chem. 161, 166–172.
  • Kolitsch, U., Wierzbicka-Wieczorek, M. & Tillmanns, E. (2009). Can. Mineral. 47, 421–431.
  • Krivovichev, S. V., Yakovenchuk, V. N., Armbuster, T., Mikhailova, Y. & Pakhomovsky, Y. A. (2004). N. Jb. Miner. Mh. pp. 373–384.
  • Lin, J. H., Lu, G. X., Du, J., Su, M. Z., Loong, C.-K. & Richardson, J. W. Jr (1999). J. Phys. Chem. Solids, 60, 975–983.
  • Lu, G. X., Yang, L. Q. & Lin, J. H. (2000). Solid State Commun. 114, 113–116.
  • Ohta, H., Okubo, S., Inagaki, Y., Hiroi, Z. & Kikuchi, H. (2004). Physica B, 346–347, 38–44.
  • Rastsvetaeva, R. K. & Chukanov, N. V. (2003). Dokl. Akad. Nauk, 388, 205–207.
  • Robinson, P. D. & Fang, J. H. (1977). Am. Mineral. 62, 167–169.
  • Sheldrick, G. M. (2005). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
  • Yamada, T., Hiroi, Z. & Takano, M. (2001). J. Solid State Chem. 156, 101–109.
  • Yang, H., Downs, R. T., Evans, S. H. & Pinch, W. W. (2012). Am. Mineral In the press.
  • Yao, G. Q., Lin, J. H., Zhang, L., Lu, G. X., Gong, M. L. & Su, M. Z. (1998). J. Mater. Chem. 8, 585–, 588.
  • Zheludev, A., Masuda, T., Dhalenne, G., Revcolevschi, A., Frost, C. & Perring, T. (2007). Phys. Rev. B, 75, 054409.
  • Zvyagin, A. A. (2006). Low Temp. Phys. 32, 158–161.
Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of
International Union of Crystallography