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Single crystals of monoclinic Nd:LaVO
4 with dimensions up to Ø28 × 21 mm have been grown from the near-stoichiometric melt by the Czochralski method, making use of various seed orientations that are perpendicular to the (010), (10
), (001) and (00
) crystal planes. A sample was also prepared with the seed orientation in an arbitrary direction relative to the crystal. The anisotropic properties of the crystal are manifested in the growth morphology of the as-grown crystals, where different degrees of bulk spiral growth were observed. It was also found that employing the (001) or (00
) seed faces severely suppressed the bulk spiral growth, and thus high quality and large-scale Nd:LaVO
4 crystals were obtained. The constituent segregation coefficients and high-temperature stability, including the melting point, were determined and evaluated. Based on the attachment energy model of Hartman-Perdok theory, morphology predictions were made for monoclinic LaVO
4 and tetragonal YVO
4 orthovanadate single crystals. Correlating with the as-grown morphology of both crystals developed along different seed orientations, a theoretical explanation is provided for the influences of seed crystals on bulk spiral formation, crystal quality and utilization ratio. It suggests that breaking the axial symmetry of the ideal atomic level interface between crystal and melt plays a crucial triggering role in bulk spiral formation in the Czochralski growth of lanthanide orthovanadate single crystals. Selecting a proper seed orientation that yields such a highly axially symmetric surface structure consisting of a series of large-area facets with similar growth velocities can greatly reduce bulk spiral formation and thus is preferable in the Czochralski growth of large-sized low-symmetry oxide crystals.
Supporting information
Data collection: APEX2 Software Suite (Bruker,2005); cell refinement: APEX2 Software Suite (Bruker,2005); data reduction: APEX2 Software Suite (Bruker,2005); program(s) used to solve structure: SIR97 (Altomare,1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: WinGX (Farrugia,1999).
Crystal data top
LaO4V | F(000) = 448 |
Mr = 253.85 | Dx = 5.054 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 7.0492 (3) Å | Cell parameters from 2959 reflections |
b = 7.2827 (3) Å | θ = 3.7–33.2° |
c = 6.7250 (3) Å | µ = 15.26 mm−1 |
β = 104.901 (2)° | T = 293 K |
V = 333.63 (2) Å3 | Prism, colourless |
Z = 4 | 0.09 × 0.08 × 0.06 mm |
Data collection top
Bruker APEX2 CCD area-detector diffractometer | 1265 independent reflections |
Radiation source: fine-focus sealed tube | 1170 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
φ and ω scans | θmax = 33.2°, θmin = 3.7° |
Absorption correction: numerical APEX2 Software Suite (Bruker,2005) | h = −10→10 |
Tmin = 0.344, Tmax = 0.466 | k = −11→11 |
6077 measured reflections | l = −10→9 |
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)] = 0.016 | w = 1/[σ2(Fo2) + (0.015P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.034 | (Δ/σ)max < 0.001 |
S = 1.06 | Δρmax = 1.16 e Å−3 |
1265 reflections | Δρmin = −0.73 e Å−3 |
56 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0420 (9) |
Crystal data top
LaO4V | V = 333.63 (2) Å3 |
Mr = 253.85 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.0492 (3) Å | µ = 15.26 mm−1 |
b = 7.2827 (3) Å | T = 293 K |
c = 6.7250 (3) Å | 0.09 × 0.08 × 0.06 mm |
β = 104.901 (2)° | |
Data collection top
Bruker APEX2 CCD area-detector diffractometer | 1265 independent reflections |
Absorption correction: numerical APEX2 Software Suite (Bruker,2005) | 1170 reflections with I > 2σ(I) |
Tmin = 0.344, Tmax = 0.466 | Rint = 0.027 |
6077 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.016 | 56 parameters |
wR(F2) = 0.034 | 0 restraints |
S = 1.06 | Δρmax = 1.16 e Å−3 |
1265 reflections | Δρmin = −0.73 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 | x | y | z | Uiso*/Ueq | |
La1 | 0.276224 (17) | 0.157198 (16) | 0.103623 (17) | 0.00767 (6) | |
O1 | 0.2554 (2) | 0.4979 (2) | 0.0725 (2) | 0.0124 (3) | |
O2 | 0.6179 (2) | 0.2795 (2) | 0.2277 (2) | 0.0117 (3) | |
O3 | 0.5171 (2) | −0.1050 (2) | 0.1758 (2) | 0.0134 (3) | |
O4 | 0.1143 (3) | −0.1564 (2) | 0.0041 (3) | 0.0121 (3) | |
V1 | 0.30083 (5) | 0.16481 (5) | −0.38488 (5) | 0.00678 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La1 | 0.00755 (7) | 0.00725 (8) | 0.00790 (7) | 0.00017 (4) | 0.00144 (4) | 0.00099 (3) |
O1 | 0.0169 (8) | 0.0095 (8) | 0.0100 (7) | 0.0018 (6) | 0.0021 (6) | −0.0004 (5) |
O2 | 0.0090 (7) | 0.0159 (8) | 0.0108 (7) | −0.0021 (6) | 0.0040 (5) | −0.0017 (6) |
O3 | 0.0130 (8) | 0.0137 (8) | 0.0109 (7) | 0.0044 (6) | −0.0019 (6) | −0.0012 (5) |
O4 | 0.0114 (8) | 0.0104 (8) | 0.0154 (7) | 0.0005 (6) | 0.0052 (6) | −0.0021 (5) |
V1 | 0.00672 (15) | 0.00713 (18) | 0.00646 (15) | −0.00018 (11) | 0.00163 (12) | −0.00020 (10) |
Geometric parameters (Å, º) top
La1—O1 | 2.4912 (17) | O2—V1ix | 1.7039 (16) |
La1—O2 | 2.5015 (16) | O2—La1ix | 2.5292 (16) |
La1—O3 | 2.5182 (17) | O3—V1iv | 1.6990 (16) |
La1—O1i | 2.5275 (16) | O3—La1iv | 2.6845 (17) |
La1—O2ii | 2.5292 (16) | O4—V1x | 1.7154 (16) |
La1—O4 | 2.5640 (16) | O4—La1iii | 2.6604 (17) |
La1—O4iii | 2.6604 (17) | O4—La1i | 2.8898 (17) |
La1—O3iv | 2.6845 (17) | V1—O3iv | 1.6990 (16) |
La1—O4v | 2.8898 (17) | V1—O2ii | 1.7039 (16) |
La1—V1 | 3.3345 (4) | V1—O4viii | 1.7154 (16) |
La1—V1vi | 3.3998 (4) | V1—O1x | 1.7233 (17) |
La1—V1vii | 3.6124 (4) | V1—La1xi | 3.3998 (4) |
O1—V1viii | 1.7233 (17) | V1—La1xii | 3.6124 (4) |
O1—La1v | 2.5275 (16) | | |
| | | |
O1—La1—O2 | 72.80 (6) | O4iii—La1—V1vi | 93.18 (4) |
O1—La1—O3 | 142.54 (6) | O3iv—La1—V1vi | 144.57 (4) |
O2—La1—O3 | 70.25 (6) | O4v—La1—V1vi | 30.29 (3) |
O1—La1—O1i | 120.87 (4) | V1—La1—V1vi | 173.988 (13) |
O2—La1—O1i | 99.59 (5) | O1—La1—V1vii | 67.01 (4) |
O3—La1—O1i | 71.96 (5) | O2—La1—V1vii | 133.16 (4) |
O1—La1—O2ii | 74.53 (6) | O3—La1—V1vii | 148.34 (4) |
O2—La1—O2ii | 114.09 (5) | O1i—La1—V1vii | 81.86 (4) |
O3—La1—O2ii | 115.67 (5) | O2ii—La1—V1vii | 77.45 (4) |
O1i—La1—O2ii | 146.18 (5) | O4—La1—V1vii | 88.40 (4) |
O1—La1—O4 | 148.50 (6) | O4iii—La1—V1vii | 26.61 (3) |
O2—La1—O4 | 136.89 (6) | O3iv—La1—V1vii | 137.67 (4) |
O3—La1—O4 | 66.89 (5) | O4v—La1—V1vii | 80.99 (3) |
O1i—La1—O4 | 71.59 (5) | V1—La1—V1vii | 107.379 (10) |
O2ii—La1—O4 | 81.32 (6) | V1vi—La1—V1vii | 77.218 (7) |
O1—La1—O4iii | 86.84 (5) | V1viii—O1—La1 | 139.59 (9) |
O2—La1—O4iii | 158.71 (5) | V1viii—O1—La1v | 104.63 (8) |
O3—La1—O4iii | 130.54 (5) | La1—O1—La1v | 113.65 (6) |
O1i—La1—O4iii | 85.37 (5) | V1ix—O2—La1 | 135.25 (8) |
O2ii—La1—O4iii | 64.44 (5) | V1ix—O2—La1ix | 102.18 (7) |
O4—La1—O4iii | 64.34 (6) | La1—O2—La1ix | 122.54 (6) |
O1—La1—O3iv | 96.49 (5) | V1iv—O3—La1 | 133.02 (9) |
O2—La1—O3iv | 68.57 (5) | V1iv—O3—La1iv | 96.46 (7) |
O3—La1—O3iv | 64.35 (6) | La1—O3—La1iv | 115.65 (6) |
O1i—La1—O3iv | 136.24 (5) | V1x—O4—La1 | 127.79 (9) |
O2ii—La1—O3iv | 60.37 (5) | V1x—O4—La1iii | 109.38 (8) |
O4—La1—O3iv | 88.66 (5) | La1—O4—La1iii | 115.66 (6) |
O4iii—La1—O3iv | 121.27 (5) | V1x—O4—La1i | 91.53 (7) |
O1—La1—O4v | 66.73 (5) | La1—O4—La1i | 100.58 (6) |
O2—La1—O4v | 61.31 (5) | La1iii—O4—La1i | 105.20 (5) |
O3—La1—O4v | 99.89 (5) | O3iv—V1—O2ii | 100.96 (8) |
O1i—La1—O4v | 59.40 (5) | O3iv—V1—O4viii | 107.53 (9) |
O2ii—La1—O4v | 140.57 (5) | O2ii—V1—O4viii | 114.95 (8) |
O4—La1—O4v | 130.78 (4) | O3iv—V1—O1x | 114.08 (8) |
O4iii—La1—O4v | 105.32 (5) | O2ii—V1—O1x | 115.82 (8) |
O3iv—La1—O4v | 129.78 (5) | O4viii—V1—O1x | 103.61 (8) |
O1—La1—V1 | 85.27 (4) | O3iv—V1—La1 | 53.13 (6) |
O2—La1—V1 | 91.91 (4) | O2ii—V1—La1 | 47.85 (5) |
O3—La1—V1 | 89.95 (4) | O4viii—V1—La1 | 125.86 (6) |
O1i—La1—V1 | 153.51 (4) | O1x—V1—La1 | 130.49 (6) |
O2ii—La1—V1 | 29.96 (4) | O3iv—V1—La1xi | 131.64 (6) |
O4—La1—V1 | 83.69 (4) | O2ii—V1—La1xi | 127.31 (6) |
O4iii—La1—V1 | 92.53 (4) | O4viii—V1—La1xi | 58.18 (6) |
O3iv—La1—V1 | 30.42 (3) | O1x—V1—La1xi | 46.00 (5) |
O4v—La1—V1 | 145.31 (3) | La1—V1—La1xi | 173.988 (13) |
O1—La1—V1vi | 93.17 (4) | O3iv—V1—La1xii | 66.55 (6) |
O2—La1—V1vi | 82.09 (4) | O2ii—V1—La1xii | 137.42 (6) |
O3—La1—V1vi | 87.76 (4) | O4viii—V1—La1xii | 44.00 (6) |
O1i—La1—V1vi | 29.37 (4) | O1x—V1—La1xii | 106.11 (5) |
O2ii—La1—V1vi | 154.53 (4) | La1—V1—La1xii | 108.096 (10) |
O4—La1—V1vi | 100.49 (4) | La1xi—V1—La1xii | 77.904 (7) |
Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2; (ii) x−1/2, −y+1/2, z−1/2; (iii) −x, −y, −z; (iv) −x+1, −y, −z; (v) −x+1/2, y+1/2, −z+1/2; (vi) x, y, z+1; (vii) x−1/2, −y+1/2, z+1/2; (viii) −x+1/2, y+1/2, −z−1/2; (ix) x+1/2, −y+1/2, z+1/2; (x) −x+1/2, y−1/2, −z−1/2; (xi) x, y, z−1; (xii) x+1/2, −y+1/2, z−1/2. |
Experimental details
Crystal data |
Chemical formula | LaO4V |
Mr | 253.85 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 7.0492 (3), 7.2827 (3), 6.7250 (3) |
β (°) | 104.901 (2) |
V (Å3) | 333.63 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 15.26 |
Crystal size (mm) | 0.09 × 0.08 × 0.06 |
|
Data collection |
Diffractometer | Bruker APEX2 CCD area-detector diffractometer |
Absorption correction | Numerical APEX2 Software Suite (Bruker,2005) |
Tmin, Tmax | 0.344, 0.466 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6077, 1265, 1170 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.770 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.016, 0.034, 1.06 |
No. of reflections | 1265 |
No. of parameters | 56 |
Δρmax, Δρmin (e Å−3) | 1.16, −0.73 |
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