research papers
This work is devoted to an investigation of the magnetic properties and thermal behaviour of the natural oxoborates vonsenite and hulsite in the temperature range 5–500 K. The local environment, the oxidation states of the Fe and Sn atoms, and the charge distribution were determined using Mössbauer spectroscopy and are in accordance with a refinement of the crystal structure of hulsite from single-crystal X-ray diffraction data (SCXRD) in anisotropic approximation for the first time. The magnetic properties were studied by vibrating sample magnetometry (VSM) (5 ≤ T ≤ 400 K) and are reported for the first time for iron-rich hulsite. Both oxoborates show a very complex magnetic behaviour. Cascades of magnetic transitions are revealed and the critical temperatures were determined. The sequences of magnetic transitions in both vonsenite and hulsite with increasing temperature were found to be as follows: magnetically ordered state → partial magnetic ordering → paramagnetic state. According to X-ray diffraction data (93 ≤ T ≤ 500 K), these processes are accompanied by anomalies in the unit-cell parameters and thermal expansion of the oxoborates at critical temperatures. A strong negative volume thermal expansion is observed for both oxoborates at temperatures below ∼120 K.
Keywords: vonsenite; hulsite; ludwigite group; pinakiolite group; crystal structure; Mössbauer spectroscopy.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520621010866/ra5102sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520621010866/ra5102Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520621010866/ra5102IIsup3.hkl | |
Portable Document Format (PDF) file https://doi.org/10.1107/S2052520621010866/ra5102sup4.pdf |
CCDC references: 2116500; 2120235
Computing details top
Data collection: CrysAlis PRO 1.171.39.46 (Rigaku OD, 2018) for (I). Cell refinement: CrysAlis PRO 1.171.39.46 (Rigaku OD, 2018) for (I). Data reduction: CrysAlis PRO 1.171.39.46 (Rigaku OD, 2018) for (I).
(I) top
Crystal data top
B1Fe2.654Mg0.346O5 | F(000) = 505 |
Mr = 247.4 | Dx = 4.716 Mg m−3 |
Orthorhombic, Pbam | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P -2xab;-2yab;-2z | Cell parameters from 1018 reflections |
a = 9.3166 (9) Å | θ = 4.0–32.1° |
b = 12.2751 (11) Å | µ = 10.86 mm−1 |
c = 3.0518 (3) Å | T = 100 K |
V = 349.01 (6) Å3 | Prism, black |
Z = 4 | 0.4 × 0.1 × 0.1 mm |
Data collection top
Xcalibur, Eos diffractometer | 633 independent reflections |
Radiation source: X-ray tube | 547 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.038 |
Detector resolution: 16.2096 pixels mm-1 | θmax = 32.4°, θmin = 2.7° |
ω scans | h = −13→8 |
Absorption correction: multi-scan CrysAlisPro 1.171.39.46 (Rigaku Oxford Diffraction, 2018) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. | k = −17→14 |
Tmin = 0.765, Tmax = 1 | l = −4→2 |
1752 measured reflections |
Refinement top
Refinement on F | 4 constraints |
R[F2 > 2σ(F2)] = 0.057 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
wR(F2) = 0.069 | (Δ/σ)max = 0.020 |
S = 2.48 | Δρmax = 1.84 e Å−3 |
633 reflections | Δρmin = −1.65 e Å−3 |
34 parameters | Extinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974) |
0 restraints | Extinction coefficient: 930 (130) |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Fe1 | 0 | 0 | 0 | 0.0011 (4)* | 0.76 |
Mg1' | 0 | 0 | 0 | 0.0011 (4)* | 0.24 |
Fe2 | 0.5 | 0 | 0.5 | 0.0168 (5) | |
Fe3 | 0.00119 (12) | 0.27600 (12) | 0 | 0.0106 (4)* | 0.77 |
Mg3' | 0.00119 (12) | 0.27600 (12) | 0 | 0.0106 (4)* | 0.25 |
Fe4 | 0.74311 (10) | 0.39731 (8) | 0.5 | 0.0036 (3) | |
O1 | 0.8465 (6) | 0.0439 (4) | 0.5 | 0.0059 (10)* | |
O2 | 0.3871 (6) | 0.0777 (4) | 0 | 0.0067 (10)* | |
O3 | 0.6233 (6) | 0.1410 (4) | 0.5 | 0.0057 (10)* | |
O4 | 0.1122 (5) | 0.1410 (4) | 0 | 0.0026 (9)* | |
O5 | 0.3460 (5) | 0.2622 (4) | 0.5 | 0.0042 (9)* | |
B1 | 0.2714 (8) | 0.3606 (6) | 0.5 | 0.0014 (13)* |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe4 | 0.0041 (5) | 0.0037 (5) | 0.0028 (5) | −0.0008 (4) | 0 | 0 |
Fe2 | 0.0174 (9) | 0.0146 (9) | 0.0184 (9) | −0.0007 (7) | 0 | 0 |
Geometric parameters (Å, º) top
Fe1—O1 | 2.077 (5) | Fe4—O3 | 2.075 (5) |
Fe1—O1i | 2.077 (5) | Fe4—O4iii | 2.076 (4) |
Fe1—O4ii | 2.084 (4) | Fe4—O4i | 2.076 (4) |
Fe1—O4 | 2.084 (4) | Fe4—O5 | 2.091 (5) |
Fe1—O4iii | 2.084 (4) | Fe2—O2 | 2.022 (5) |
Fe1—O4i | 2.084 (4) | Fe2—O2v | 2.022 (5) |
Mg1'—O1 | 2.077 (5) | Fe3—O2 | 1.950 (5) |
Mg1'—O1i | 2.077 (5) | Fe3—O4vi | 2.091 (5) |
Mg1'—O4ii | 2.084 (4) | Mg3'—O2 | 1.950 (5) |
Mg1'—O4 | 2.084 (4) | Mg3'—O4vi | 2.091 (5) |
Mg1'—O4iii | 2.084 (4) | B1—O1vii | 1.381 (9) |
Mg1'—O4i | 2.084 (4) | B1—O3 | 1.393 (9) |
Fe4—O2 | 1.985 (3) | B1—O5vi | 1.365 (9) |
Fe4—O2iv | 1.985 (3) | ||
O1—Fe1—O1i | 180.0 (5) | O4ii—Mg1'—O4i | 180.0 (5) |
O1—Fe1—O4ii | 95.86 (17) | O4—Mg1'—O4iii | 180.0 (5) |
O1—Fe1—O4 | 95.86 (17) | O4—Mg1'—O4i | 85.88 (15) |
O1—Fe1—O4iii | 84.14 (17) | O4iii—Mg1'—O4i | 94.12 (15) |
O1—Fe1—O4i | 84.14 (17) | O2—Fe4—O2iv | 100.49 (16) |
O1i—Fe1—O4ii | 84.14 (17) | O2—Fe4—O3 | 97.27 (16) |
O1i—Fe1—O4 | 84.14 (17) | O2—Fe4—O4iii | 82.42 (15) |
O1i—Fe1—O4iii | 95.86 (17) | O2—Fe4—O4i | 176.92 (16) |
O1i—Fe1—O4i | 95.86 (17) | O2—Fe4—O5 | 85.25 (16) |
O4ii—Fe1—O4 | 94.12 (15) | O2iv—Fe4—O3 | 97.27 (16) |
O4ii—Fe1—O4iii | 85.88 (15) | O2iv—Fe4—O4iii | 176.92 (16) |
O4ii—Fe1—O4i | 180.0 (5) | O2iv—Fe4—O4i | 82.42 (15) |
O4—Fe1—O4iii | 180.0 (5) | O2iv—Fe4—O5 | 85.25 (16) |
O4—Fe1—O4i | 85.88 (15) | O3—Fe4—O4iii | 83.28 (17) |
O4iii—Fe1—O4i | 94.12 (15) | O3—Fe4—O4i | 83.28 (17) |
O1—Mg1'—O1i | 180.0 (5) | O3—Fe4—O5 | 176.0 (2) |
O1—Mg1'—O4ii | 95.86 (17) | O4iii—Fe4—O4i | 94.64 (16) |
O1—Mg1'—O4 | 95.86 (17) | O4iii—Fe4—O5 | 94.03 (18) |
O1—Mg1'—O4iii | 84.14 (17) | O4i—Fe4—O5 | 94.03 (18) |
O1—Mg1'—O4i | 84.14 (17) | O2—Fe2—O2v | 180.0 (5) |
O1i—Mg1'—O4ii | 84.14 (17) | O2—Fe3—O4vi | 179.0 (2) |
O1i—Mg1'—O4 | 84.14 (17) | O2—Mg3'—O4vi | 179.0 (2) |
O1i—Mg1'—O4iii | 95.86 (17) | O1vii—B1—O3 | 119.1 (6) |
O1i—Mg1'—O4i | 95.86 (17) | O1vii—B1—O5vi | 121.6 (6) |
O4ii—Mg1'—O4 | 94.12 (15) | O3—B1—O5vi | 119.3 (6) |
O4ii—Mg1'—O4iii | 85.88 (15) |
Symmetry codes: (i) −x, −y, z; (ii) x, y, z−1; (iii) −x, −y, z−1; (iv) x, y, z+1; (v) −x−1, −y, z; (vi) −x−1/2, y+1/2, −z; (vii) x−1/2, −y+1/2, −z. |
(II) top
Crystal data top
BFe2.796Mg0.181O5Sn0.017 | F(000) = 245 |
Mr = 253.4 | Dx = 4.75 Mg m−3 |
Monoclinic, P2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2y | Cell parameters from 1449 reflections |
a = 10.638 (3) Å | θ = 1.9–29.2° |
b = 3.063 (2) Å | µ = 11.36 mm−1 |
c = 5.445 (5) Å | T = 293 K |
β = 93.38 (4)° | Tablet, black |
V = 177.1 (2) Å3 | 0.06 × 0.03 × 0.01 mm |
Z = 2 |
Data collection top
Bruker CCD diffractometer | 218 reflections with I > 3σ(I) |
Radiation source: X-ray tube | Rint = 0.081 |
Graphite monochromator | θmax = 29.2°, θmin = 1.9° |
Absorption correction: multi-scan (Krause et al., 2015) | h = −14→14 |
Tmin = 0.800, Tmax = 0.860 | k = −4→4 |
1449 measured reflections | l = −7→7 |
346 independent reflections |
Refinement top
Refinement on F | 3 restraints |
R[F2 > 2σ(F2)] = 0.063 | 25 constraints |
wR(F2) = 0.065 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
S = 1.74 | (Δ/σ)max = 0.046 |
346 reflections | Δρmax = 1.28 e Å−3 |
51 parameters | Δρmin = −1.14 e Å−3 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Fe1 | 0 | 0 | 0 | 0.019 (2) | 0.97 (2) |
Sn1' | 0 | 0 | 0 | 0.019 (2) | 0.03 (2) |
Fe2 | 0 | 0.5 | 0.5 | 0.030 (4) | 0.6 (2) |
Mg2' | 0 | 0.5 | 0.5 | 0.030 (4) | 0.4 (2) |
Fe3 | 0.5 | 0 | 0 | 0.024 (2) | |
Fe4 | 0.5 | 0 | 0.5 | 0.021 (2) | |
Fe5 | 0.2726 (4) | 0.5 | 0.2210 (6) | 0.0202 (17) | |
O1 | −0.6908 (16) | −1 | −0.499 (2) | 0.019 (4) | |
O2 | 0.4659 (14) | 0.5 | 0.242 (3) | 0.019 (4) | |
O3 | −0.6969 (16) | −1 | −0.059 (2) | 0.019 (4) | |
O4 | −0.8872 (13) | −1 | −0.291 (3) | 0.019 (4) | |
O5 | 0.0922 (17) | 0.5 | 0.183 (3) | 0.019 (4) | |
B1 | −0.7586 (14) | −1 | −0.295 (2) | 0.018 (5) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.037 (5) | 0.015 (3) | 0.003 (3) | 0 | −0.001 (2) | 0 |
Sn1' | 0.037 (5) | 0.015 (3) | 0.003 (3) | 0 | −0.001 (2) | 0 |
Fe2 | 0.045 (7) | 0.026 (6) | 0.019 (5) | 0 | −0.005 (3) | 0 |
Mg2' | 0.045 (7) | 0.026 (6) | 0.019 (5) | 0 | −0.005 (3) | 0 |
Fe3 | 0.042 (4) | 0.010 (3) | 0.020 (3) | 0 | 0.004 (3) | 0 |
Fe4 | 0.024 (4) | 0.024 (3) | 0.015 (3) | 0 | 0.000 (2) | 0 |
Fe5 | 0.038 (3) | 0.016 (2) | 0.007 (3) | 0 | 0.0010 (18) | 0 |
O1 | 0.031 (7) | 0.018 (6) | 0.006 (6) | 0 | −0.001 (3) | 0 |
O2 | 0.031 (7) | 0.018 (6) | 0.006 (6) | 0 | −0.001 (3) | 0 |
O3 | 0.031 (7) | 0.018 (6) | 0.006 (6) | 0 | −0.001 (3) | 0 |
O4 | 0.031 (7) | 0.018 (6) | 0.006 (6) | 0 | −0.001 (3) | 0 |
O5 | 0.031 (7) | 0.018 (6) | 0.006 (6) | 0 | −0.001 (3) | 0 |
B1 | 0.022 (11) | 0.016 (9) | 0.013 (8) | 0 | −0.008 (6) | 0 |
Geometric parameters (Å, º) top
Fe1—O4i | 2.042 (16) | Fe3—O3xii | 2.101 (17) |
Fe1—O4ii | 2.042 (16) | Fe4—O1vi | 2.030 (17) |
Fe1—O5iii | 2.046 (11) | Fe4—O1xii | 2.030 (17) |
Fe1—O5 | 2.046 (11) | Fe4—O2iii | 2.096 (10) |
Fe1—O5iv | 2.046 (11) | Fe4—O2 | 2.096 (10) |
Fe1—O5v | 2.046 (11) | Fe4—O2xiii | 2.096 (10) |
Fe2—O4vi | 2.219 (11) | Fe4—O2xiv | 2.096 (10) |
Fe2—O4vii | 2.219 (11) | Fe5—O1vi | 2.180 (10) |
Fe2—O4ii | 2.219 (11) | Fe5—O1vii | 2.180 (10) |
Fe2—O4viii | 2.219 (11) | Fe5—O2 | 2.054 (16) |
Fe2—O5 | 2.035 (16) | Fe5—O3i | 2.199 (10) |
Fe2—O5ix | 2.035 (16) | Fe5—O3xv | 2.199 (10) |
Fe3—O2iii | 2.066 (10) | Fe5—O5 | 1.918 (18) |
Fe3—O2 | 2.066 (10) | B1—O1 | 1.36 (2) |
Fe3—O2x | 2.066 (10) | B1—O3 | 1.408 (18) |
Fe3—O2xi | 2.066 (10) | B1—O4 | 1.37 (2) |
Fe3—O3i | 2.101 (17) | ||
O4i—Fe1—O4ii | 180.0 (5) | O2x—Fe3—O2xi | 95.7 (4) |
O4i—Fe1—O5iii | 95.2 (5) | O2x—Fe3—O3i | 96.5 (5) |
O4i—Fe1—O5 | 95.2 (5) | O2x—Fe3—O3xii | 83.5 (5) |
O4i—Fe1—O5iv | 84.8 (5) | O2xi—Fe3—O3i | 96.5 (5) |
O4i—Fe1—O5v | 84.8 (5) | O2xi—Fe3—O3xii | 83.5 (5) |
O4ii—Fe1—O5iii | 84.8 (5) | O3i—Fe3—O3xii | 180.0 (5) |
O4ii—Fe1—O5 | 84.8 (5) | O1vi—Fe4—O1xii | 180.0 (5) |
O4ii—Fe1—O5iv | 95.2 (5) | O1vi—Fe4—O2iii | 82.4 (5) |
O4ii—Fe1—O5v | 95.2 (5) | O1vi—Fe4—O2 | 82.4 (5) |
O5iii—Fe1—O5 | 96.9 (5) | O1vi—Fe4—O2xiii | 97.6 (5) |
O5iii—Fe1—O5iv | 83.1 (5) | O1vi—Fe4—O2xiv | 97.6 (5) |
O5iii—Fe1—O5v | 180.0 (5) | O1xii—Fe4—O2iii | 97.6 (5) |
O5—Fe1—O5iv | 180.0 (5) | O1xii—Fe4—O2 | 97.6 (5) |
O5—Fe1—O5v | 83.1 (5) | O1xii—Fe4—O2xiii | 82.4 (5) |
O5iv—Fe1—O5v | 96.9 (5) | O1xii—Fe4—O2xiv | 82.4 (5) |
O4vi—Fe2—O4vii | 87.3 (4) | O2iii—Fe4—O2 | 93.9 (4) |
O4vi—Fe2—O4ii | 92.7 (4) | O2iii—Fe4—O2xiii | 86.1 (4) |
O4vi—Fe2—O4viii | 180.0 (5) | O2iii—Fe4—O2xiv | 180.0 (5) |
O4vi—Fe2—O5 | 99.4 (5) | O2—Fe4—O2xiii | 180.0 (5) |
O4vi—Fe2—O5ix | 80.6 (5) | O2—Fe4—O2xiv | 86.1 (4) |
O4vii—Fe2—O4ii | 180.0 (5) | O2xiii—Fe4—O2xiv | 93.9 (4) |
O4vii—Fe2—O4viii | 92.7 (4) | O1vi—Fe5—O1vii | 89.3 (4) |
O4vii—Fe2—O5 | 99.4 (5) | O1vi—Fe5—O2 | 79.9 (5) |
O4vii—Fe2—O5ix | 80.6 (5) | O1vi—Fe5—O3i | 88.2 (4) |
O4ii—Fe2—O4viii | 87.3 (4) | O1vi—Fe5—O3xv | 161.2 (6) |
O4ii—Fe2—O5 | 80.6 (5) | O1vi—Fe5—O5 | 102.2 (5) |
O4ii—Fe2—O5ix | 99.4 (5) | O1vii—Fe5—O2 | 79.9 (5) |
O4viii—Fe2—O5 | 80.6 (5) | O1vii—Fe5—O3i | 161.2 (6) |
O4viii—Fe2—O5ix | 99.4 (5) | O1vii—Fe5—O3xv | 88.2 (4) |
O5—Fe2—O5ix | 180.0 (5) | O1vii—Fe5—O5 | 102.2 (5) |
O2iii—Fe3—O2 | 95.7 (4) | O2—Fe5—O3i | 81.4 (5) |
O2iii—Fe3—O2x | 84.3 (4) | O2—Fe5—O3xv | 81.4 (5) |
O2iii—Fe3—O2xi | 180.0 (5) | O2—Fe5—O5 | 177.0 (6) |
O2iii—Fe3—O3i | 83.5 (5) | O3i—Fe5—O3xv | 88.3 (4) |
O2iii—Fe3—O3xii | 96.5 (5) | O3i—Fe5—O5 | 96.5 (5) |
O2—Fe3—O2x | 180.0 (5) | O3xv—Fe5—O5 | 96.5 (5) |
O2—Fe3—O2xi | 84.3 (4) | O1—B1—O3 | 120.3 (14) |
O2—Fe3—O3i | 83.5 (5) | O1—B1—O4 | 126.4 (13) |
O2—Fe3—O3xii | 96.5 (5) | O3—B1—O4 | 113.3 (13) |
Symmetry codes: (i) x+1, y+1, z; (ii) −x−1, y+1, −z; (iii) x, y−1, z; (iv) −x, y−1, −z; (v) −x, y, −z; (vi) x+1, y+1, z+1; (vii) x+1, y+2, z+1; (viii) −x−1, y+2, −z; (ix) −x, y, −z+1; (x) −x+1, y−1, −z; (xi) −x+1, y, −z; (xii) −x, y+1, −z; (xiii) −x+1, y−1, −z+1; (xiv) −x+1, y, −z+1; (xv) x+1, y+2, z. |