research papers
Single crystals of Rb2CaCu6(PO4)4O2 were synthesized by a hydrothermal method in the multicomponent system CuCl2–Ca(OH)2–RbCl–B2O3–Rb3PO4. The synthesis was carried out in the temperature range from 690 to 700 K and at the general pressure of 480–500 atm [1 atm = 101.325 kPa] from the mixture in the molar ratio 2CuO:CaO:Rb2O:B2O3:P2O5. The crystals studied by single-crystal X-ray analysis were found to be monoclinic, space group C2, a = 16.8913 (4), b = 5.6406 (1), c = 8.3591 (3) Å, β = 93.919 (3)°, V = 794.57 (4) Å3. The crystal structure of Rb2CaCu6(PO4)4O2 is similar to that of shchurovskyite and dmisokolovite and is based upon a heteropolyhedral open framework formed by polar layers of copper polyhedra linked via isolated PO4 tetrahedra. The presence of well-isolated 2D heteropolyhedral layers in the title compound suggests low-dimensional magnetic behavior which is masked, however, by the fierce competition between multiple ferromagnetic and antiferromagnetic exchange interactions. At TC = 25 K, Rb2CaCu6(PO4)4O2 reaches a magnetically ordered state with large residual magnetization.
Keywords: hydrothermal synthesis; copper oxophosphate; shchurovskyite; single-crystal X-ray diffraction; IR spectroscopy; structural complexity; magnetic properties.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520619008527/ra5054sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520619008527/ra5054Isup2.hkl | |
Portable Document Format (PDF) file https://doi.org/10.1107/S2052520619008527/ra5054sup3.pdf |
CCDC reference: 1870440
Computing details top
(I) top
Crystal data top
CaCu6O18P4Rb2 | F(000) = 944 |
Mr = 1004.2 | Dx = 4.196 Mg m−3 |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: C 2y | Cell parameters from 21970 reflections |
a = 16.8913 (4) Å | θ = 4.5–56.1° |
b = 5.6406 (1) Å | µ = 14.80 mm−1 |
c = 8.3591 (3) Å | T = 293 K |
β = 93.919 (3)° | Irregular grain, green |
V = 794.57 (4) Å3 | 0.24 × 0.22 × 0.15 mm |
Z = 2 |
Data collection top
Xcalibur, Sapphire3 with high theta cut-off diffractometer | 5108 independent reflections |
Radiation source: X-ray tube | 3914 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.064 |
Detector resolution: 16.0628 pixels mm-1 | θmax = 56.1°, θmin = 4.5° |
Absorption correction: multi-scan | h = −39→38 |
Tmin = 0.488, Tmax = 1.000 | k = −12→13 |
21970 measured reflections | l = −19→16 |
Refinement top
Refinement on F | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.000324F2) |
R[F2 > 2σ(F2)] = 0.050 | (Δ/σ)max = 0.041 |
wR(F2) = 0.050 | Δρmax = 1.21 e Å−3 |
S = 0.97 | Δρmin = −1.26 e Å−3 |
5108 reflections | Extinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974) |
153 parameters | Extinction coefficient: 370 (50) |
0 restraints | Absolute structure: 0 of Friedel pairs used in the refinement |
1 constraint |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
Rb1 | 0.29009 (5) | 0.20623 (17) | 0.15752 (15) | 0.03440 (16) | |
Cu1 | 0.32143 (2) | −0.25821 (9) | 0.47267 (5) | 0.00957 (9) | |
Cu2 | 0.5 | 0.42111 (10) | 0.5 | 0.01119 (14) | |
Cu3 | 0.5 | 0.91300 (10) | 0.5 | 0.00924 (13) | |
Cu4 | 0.08396 (3) | 0.18216 (9) | 0.22561 (5) | 0.01106 (9) | |
Ca1 | 0.5 | 0.17531 (18) | 0 | 0.01053 (18) | |
P1 | 0.64484 (5) | 0.20090 (15) | 0.35178 (10) | 0.00694 (16) | |
P2 | 0.41010 (5) | −0.29307 (17) | 0.14827 (11) | 0.00888 (17) | |
O1 | 0.33645 (15) | −0.2696 (6) | 0.2451 (3) | 0.0136 (6) | |
O2 | 0.57620 (14) | 0.1756 (5) | 0.4677 (3) | 0.0117 (5) | |
O4 | 0.07301 (13) | 0.1655 (4) | 0.4508 (3) | 0.0076 (4) | |
O5 | 0.47637 (17) | −0.1144 (5) | 0.2054 (4) | 0.0153 (7) | |
O6 | 0.4428 (2) | −0.5435 (5) | 0.1571 (4) | 0.0174 (8) | |
O7 | 0.3822 (2) | −0.2162 (7) | −0.0248 (4) | 0.0188 (8) | |
O8 | 0.71142 (15) | 0.3504 (5) | 0.4381 (4) | 0.0124 (6) | |
O9 | 0.67462 (15) | −0.0515 (4) | 0.3216 (3) | 0.0088 (5) | |
O10 | 0.61381 (18) | 0.3236 (5) | 0.1953 (4) | 0.0135 (6) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Rb1 | 0.02171 (19) | 0.0191 (2) | 0.0644 (4) | 0.00215 (16) | 0.0179 (2) | −0.0025 (2) |
Cu1 | 0.00617 (12) | 0.01417 (16) | 0.00841 (16) | 0.00142 (11) | 0.00088 (12) | −0.00108 (13) |
Cu2 | 0.0087 (2) | 0.00583 (17) | 0.0199 (3) | 0 | 0.0073 (2) | 0 |
Cu3 | 0.0080 (2) | 0.00605 (16) | 0.0142 (3) | 0 | 0.0041 (2) | 0 |
Cu4 | 0.01258 (15) | 0.01362 (16) | 0.00720 (16) | 0.00153 (13) | 0.00222 (13) | 0.00069 (14) |
Ca1 | 0.0136 (3) | 0.0096 (3) | 0.0087 (3) | 0 | 0.0026 (3) | 0 |
P1 | 0.0062 (2) | 0.0064 (3) | 0.0083 (3) | −0.0002 (2) | 0.0009 (2) | −0.0002 (2) |
P2 | 0.0081 (3) | 0.0117 (3) | 0.0069 (3) | 0.0022 (2) | 0.0014 (2) | 0.0009 (3) |
O1 | 0.0107 (8) | 0.0204 (11) | 0.0102 (10) | 0.0020 (9) | 0.0038 (8) | 0.0004 (9) |
O2 | 0.0099 (8) | 0.0092 (7) | 0.0169 (11) | 0.0005 (7) | 0.0069 (8) | 0.0003 (9) |
O4 | 0.0067 (7) | 0.0090 (7) | 0.0072 (8) | −0.0009 (6) | 0.0006 (6) | −0.0001 (7) |
O5 | 0.0110 (10) | 0.0160 (11) | 0.0186 (14) | −0.0035 (8) | −0.0006 (10) | 0.0010 (9) |
O6 | 0.0181 (13) | 0.0131 (10) | 0.0210 (16) | 0.0064 (9) | 0.0016 (12) | −0.0015 (10) |
O7 | 0.0200 (12) | 0.0291 (15) | 0.0074 (11) | 0.0110 (11) | 0.0007 (10) | 0.0014 (10) |
O8 | 0.0057 (8) | 0.0122 (9) | 0.0193 (13) | −0.0007 (7) | 0.0004 (8) | −0.0050 (9) |
O9 | 0.0088 (8) | 0.0077 (7) | 0.0101 (10) | 0.0018 (6) | 0.0022 (8) | −0.0001 (6) |
O10 | 0.0174 (11) | 0.0123 (9) | 0.0102 (11) | 0.0032 (8) | −0.0020 (9) | 0.0007 (8) |
Geometric parameters (Å, º) top
Rb1—Rb1i | 4.0294 (15) | Cu3—O2iv | 1.993 (3) |
Rb1—Rb1ii | 4.0294 (15) | Cu3—O2x | 1.993 (3) |
Rb1—Cu1 | 3.7272 (12) | Cu3—O4ix | 1.925 (2) |
Rb1—Cu1iii | 3.7337 (13) | Cu3—O4iii | 1.925 (2) |
Rb1—Cu4 | 3.5688 (11) | Cu4—O4 | 1.907 (3) |
Rb1—Ca1 | 3.8696 (10) | Cu4—O7ii | 1.899 (3) |
Rb1—P2 | 3.4740 (13) | Ca1—O5 | 2.423 (3) |
Rb1—P2iv | 3.4804 (13) | Ca1—O5xi | 2.423 (3) |
Rb1—O1 | 2.876 (3) | Ca1—O6iv | 2.312 (3) |
Rb1—O6iv | 2.940 (3) | Ca1—O6xii | 2.312 (3) |
Rb1—O9v | 2.814 (3) | P1—O2 | 1.568 (3) |
Cu1—O1 | 1.937 (3) | P1—O8 | 1.544 (3) |
Cu1—O4vi | 1.902 (2) | P1—O9 | 1.536 (2) |
Cu1—O8vii | 1.959 (3) | P1—O10 | 1.540 (3) |
Cu2—O2 | 1.922 (3) | P2—O1 | 1.536 (3) |
Cu2—O2viii | 1.922 (3) | P2—O5 | 1.557 (3) |
Cu2—O4ix | 1.913 (2) | P2—O6 | 1.517 (3) |
Cu2—O4iii | 1.913 (2) | P2—O7 | 1.553 (3) |
Rb1i—Rb1—Rb1ii | 88.84 (3) | O2viii—Cu2—O4ix | 175.59 (11) |
Rb1i—Rb1—Cu1 | 89.72 (3) | O2viii—Cu2—O4iii | 92.37 (11) |
Rb1i—Rb1—Cu1iii | 114.37 (3) | O4ix—Cu2—O4iii | 87.78 (10) |
Rb1i—Rb1—Cu4 | 77.85 (2) | O2iv—Cu3—O2x | 83.97 (11) |
Rb1i—Rb1—Ca1 | 91.20 (3) | O2iv—Cu3—O4ix | 94.64 (10) |
Rb1i—Rb1—P2 | 65.71 (3) | O2iv—Cu3—O4iii | 175.41 (11) |
Rb1i—Rb1—P2iv | 136.36 (4) | O2x—Cu3—O4ix | 175.41 (11) |
Rb1i—Rb1—O1 | 65.59 (6) | O2x—Cu3—O4iii | 94.64 (10) |
Rb1i—Rb1—O6iv | 126.22 (8) | O4ix—Cu3—O4iii | 87.07 (10) |
Rb1i—Rb1—O9v | 116.45 (6) | Rb1—Cu4—O4 | 108.72 (7) |
Rb1ii—Rb1—Cu1 | 168.25 (3) | Rb1—Cu4—O7ii | 59.43 (10) |
Rb1ii—Rb1—Cu1iii | 109.72 (3) | O4—Cu4—O7ii | 160.61 (13) |
Rb1ii—Rb1—Cu4 | 80.96 (2) | Rb1—Ca1—Rb1xi | 174.83 (4) |
Rb1ii—Rb1—Ca1 | 94.82 (3) | Rb1—Ca1—O5 | 65.80 (7) |
Rb1ii—Rb1—P2 | 136.34 (4) | Rb1—Ca1—O5xi | 118.08 (7) |
Rb1ii—Rb1—P2iv | 65.65 (3) | Rb1—Ca1—O6iv | 49.27 (8) |
Rb1ii—Rb1—O1 | 153.24 (7) | Rb1—Ca1—O6xii | 126.20 (9) |
Rb1ii—Rb1—O6iv | 85.34 (7) | Rb1xi—Ca1—O5 | 118.08 (7) |
Rb1ii—Rb1—O9v | 76.44 (6) | Rb1xi—Ca1—O5xi | 65.80 (7) |
Cu1—Rb1—Cu1iii | 60.52 (2) | Rb1xi—Ca1—O6iv | 126.20 (9) |
Cu1—Rb1—Cu4 | 87.34 (3) | Rb1xi—Ca1—O6xii | 49.27 (8) |
Cu1—Rb1—Ca1 | 96.87 (2) | O5—Ca1—O5xi | 95.21 (11) |
Cu1—Rb1—P2 | 52.48 (2) | O5—Ca1—O6iv | 87.97 (11) |
Cu1—Rb1—P2iv | 122.09 (3) | O5—Ca1—O6xii | 163.81 (11) |
Cu1—Rb1—O1 | 30.82 (6) | O5xi—Ca1—O6iv | 163.81 (11) |
Cu1—Rb1—O6iv | 104.84 (7) | O5xi—Ca1—O6xii | 87.97 (11) |
Cu1—Rb1—O9v | 93.81 (6) | O6iv—Ca1—O6xii | 93.39 (12) |
Cu1iii—Rb1—Cu4 | 46.927 (17) | O2—P1—O8 | 107.86 (16) |
Cu1iii—Rb1—Ca1 | 144.10 (3) | O2—P1—O9 | 106.34 (15) |
Cu1iii—Rb1—P2 | 112.96 (3) | O2—P1—O10 | 110.06 (16) |
Cu1iii—Rb1—P2iv | 107.60 (3) | O8—P1—O9 | 110.26 (14) |
Cu1iii—Rb1—O1 | 89.04 (6) | O8—P1—O10 | 110.24 (16) |
Cu1iii—Rb1—O6iv | 117.87 (8) | O9—P1—O10 | 111.93 (16) |
Cu1iii—Rb1—O9v | 33.34 (5) | Rb1xiii—P2—Rb1 | 108.40 (3) |
Cu4—Rb1—Ca1 | 168.29 (4) | Rb1xiii—P2—O1 | 64.17 (12) |
Cu4—Rb1—P2 | 123.36 (3) | Rb1xiii—P2—O5 | 157.84 (13) |
Cu4—Rb1—P2iv | 127.63 (3) | Rb1xiii—P2—O6 | 56.88 (13) |
Cu4—Rb1—O1 | 100.11 (6) | Rb1xiii—P2—O7 | 96.15 (14) |
Cu4—Rb1—O6iv | 152.11 (7) | Rb1—P2—O1 | 54.78 (12) |
Cu4—Rb1—O9v | 39.15 (5) | Rb1—P2—O5 | 82.91 (12) |
Ca1—Rb1—P2 | 53.58 (2) | Rb1—P2—O6 | 164.80 (14) |
Ca1—Rb1—P2iv | 58.69 (3) | Rb1—P2—O7 | 69.74 (14) |
Ca1—Rb1—O1 | 78.74 (6) | O1—P2—O5 | 111.94 (17) |
Ca1—Rb1—O6iv | 36.58 (7) | O1—P2—O6 | 111.10 (19) |
Ca1—Rb1—O9v | 150.39 (6) | O1—P2—O7 | 105.17 (17) |
P2—Rb1—P2iv | 108.40 (3) | O5—P2—O6 | 109.68 (17) |
P2—Rb1—O1 | 25.86 (6) | O5—P2—O7 | 105.74 (19) |
P2—Rb1—O6iv | 82.87 (6) | O6—P2—O7 | 113.1 (2) |
P2—Rb1—O9v | 146.04 (7) | Rb1—O1—Cu1 | 99.64 (12) |
P2iv—Rb1—O1 | 127.88 (6) | Rb1—O1—P2 | 99.36 (15) |
P2iv—Rb1—O6iv | 25.59 (6) | Cu1—O1—P2 | 133.29 (16) |
P2iv—Rb1—O9v | 92.34 (6) | Cu2—O2—Cu3xiii | 94.11 (11) |
O1—Rb1—O6iv | 102.99 (8) | Cu2—O2—P1 | 123.49 (16) |
O1—Rb1—O9v | 120.98 (8) | Cu3xiii—O2—P1 | 131.54 (17) |
O6iv—Rb1—O9v | 113.87 (9) | Cu1iii—O4—Cu2vii | 133.95 (13) |
Rb1—Cu1—Rb1vi | 124.58 (3) | Cu1iii—O4—Cu3vii | 111.33 (12) |
Rb1—Cu1—O1 | 49.54 (10) | Cu1iii—O4—Cu4 | 99.72 (11) |
Rb1—Cu1—O4vi | 118.76 (8) | Cu2vii—O4—Cu3vii | 92.57 (10) |
Rb1—Cu1—O8vii | 65.70 (9) | Cu2vii—O4—Cu4 | 110.80 (12) |
Rb1vi—Cu1—O1 | 156.71 (8) | Cu3vii—O4—Cu4 | 106.37 (11) |
Rb1vi—Cu1—O4vi | 102.94 (8) | Ca1—O5—P2 | 111.64 (17) |
Rb1vi—Cu1—O8vii | 67.17 (10) | Rb1xiii—O6—Ca1xiii | 94.14 (10) |
O1—Cu1—O4vi | 98.04 (11) | Rb1xiii—O6—P2 | 97.53 (15) |
O1—Cu1—O8vii | 92.97 (12) | Ca1xiii—O6—P2 | 140.9 (2) |
O4vi—Cu1—O8vii | 168.04 (12) | Cu4i—O7—P2 | 130.4 (2) |
O2—Cu2—O2viii | 87.82 (11) | Cu1ix—O8—P1 | 123.47 (17) |
O2—Cu2—O4ix | 92.37 (11) | Rb1xiv—O9—P1 | 140.85 (15) |
O2—Cu2—O4iii | 175.59 (11) |
Symmetry codes: (i) −x+1/2, y−1/2, −z; (ii) −x+1/2, y+1/2, −z; (iii) −x+1/2, y+1/2, −z+1; (iv) x, y+1, z; (v) x−1/2, y+1/2, z; (vi) −x+1/2, y−1/2, −z+1; (vii) x−1/2, y−1/2, z; (viii) −x+1, y, −z+1; (ix) x+1/2, y+1/2, z; (x) −x+1, y+1, −z+1; (xi) −x+1, y, −z; (xii) −x+1, y+1, −z; (xiii) x, y−1, z; (xiv) x+1/2, y−1/2, z. |