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An anhydrous orthophosphate, K3Eu5(PO4)6 (tripotassium pentaeuropium hexaphosphate), has been prepared by a high-temperature solid-state reaction combined with hydrothermal synthesis, and its crystal structure was determined by single-crystal X-ray diffraction analysis (SC-XRD). The results show that the compound crystallizes in the monoclinic space group C2/c and the structure features a three-dimensional framework of [Eu5(PO4)6]∞, with the tunnel filled by K+ ions. The IR spectrum, UV–Vis spectrum and luminescence properties of polycrystalline samples of K3Eu5(PO4)6, annealed at temperatures of 650, 700, 750, 800 and 850 °C, were investigated. Although with a full Eu3+ concentration (9.96 × 1021 ions cm−3), the self-activated phosphor K3Eu5(PO4)6 shows s strong luminescence emission intensity with a quantum yield of 37%. Under near-UV light excitation (393 nm), the series of samples shows the characteristic emissions of Eu3+ ions in the visible region from 575 to 715 nm. The sample sintered at 800 °C gives the strongest emission and its lifetime sintered at 800 °C (1.88 ms) is also the longest of all.
Supporting information
CCDC reference: 1919592
Data collection: APEX2 (Bruker, 2017); cell refinement: APEX2 (Bruker, 2017); data reduction: APEX2 (Bruker, 2017); program(s) used to solve structure: SHELXT2017 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015b); molecular graphics: ?; software used to prepare material for publication: SHELXL2017 (Sheldrick, 2015b).
Tripotassium pentaeuropium hexaphosphate
top
Crystal data top
K3Eu5(PO4)6 | F(000) = 2616 |
Mr = 1446.92 | Dx = 4.786 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 17.4950 (11) Å | Cell parameters from 1295 reflections |
b = 6.9483 (4) Å | θ = 2.0–24.9° |
c = 18.1452 (12) Å | µ = 16.61 mm−1 |
β = 114.447 (1)° | T = 296 K |
V = 2008.0 (2) Å3 | Block, colorless |
Z = 4 | 0.20 × 0.15 × 0.15 mm |
Data collection top
Bruker APEXII CCD diffractometer | 2117 reflections with I > 2σ(I) |
Detector resolution: 83.33 pixels mm-1 | Rint = 0.031 |
ω scans | θmax = 28.3°, θmin = 2.5° |
Absorption correction: multi-scan SADABS (Bruker, 2017) | h = −19→23 |
Tmin = 0.085, Tmax = 0.413 | k = −9→7 |
6490 measured reflections | l = −23→23 |
2460 independent reflections | |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.027P)2] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.026 | (Δ/σ)max = 0.001 |
wR(F2) = 0.062 | Δρmax = 1.13 e Å−3 |
S = 1.01 | Δρmin = −1.47 e Å−3 |
2460 reflections | Extinction correction: SHELXL2017 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
174 parameters | Extinction coefficient: 0.00040 (2) |
Special details top
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell esds are taken
into account individually in the estimation of esds in distances, angles
and torsion angles; correlations between esds in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. A single crystal with dimensions of
0.20 × 0.15 × 0.15 mm was mounted on a glass fiber for SC-XRD
experiments. A set of intensity data was collected using a Bruker SMART APEX2
CCD equipped with a graphite-monochromated Mo Kα radiation source
(λ = 0.71073 Å) with a tube power of 50 kV and 20 mA. The frames were
collected at ambient temperature with a scan width of 0.5 in ω and integrated
with the Bruker SAINT software package using a narrow-frame integration
algorithm (Bruker, 2017). The unit cells were determined and refined by
least-squares upon the refinement of XYZ-centeroids of reflections above
2σ(I). The data were then scaled for absorption using the SADABS
programme of APEX2 package. Intensities of all measured reflections
were corrected for Lp and multi-scan crystal absorption effects. The crystal
structures of title complexes were solved using SHELX2017 crystallographic
computing system (Sheldrick, 2015). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
K1 | −0.07658 (9) | 0.09710 (19) | −0.07467 (8) | 0.0177 (3) | |
K2 | 0.000000 | −0.1711 (3) | 0.250000 | 0.0477 (8) | |
Eu1 | 0.000000 | 0.36450 (5) | 0.250000 | 0.00466 (10) | |
Eu2 | 0.14403 (2) | 0.58607 (4) | 0.48109 (2) | 0.00453 (9) | |
Eu3 | 0.22012 (2) | 0.12515 (4) | 0.29233 (2) | 0.00454 (9) | |
P1 | 0.20791 (9) | 0.61898 (19) | 0.34185 (8) | 0.0042 (3) | |
P2 | 0.13583 (9) | 0.08484 (19) | 0.41326 (8) | 0.0041 (3) | |
P3 | 0.07312 (8) | 0.4036 (2) | 0.11707 (7) | 0.0039 (3) | |
O1 | 0.1227 (2) | 0.2509 (6) | 0.4603 (2) | 0.0095 (8) | |
O2 | 0.0975 (2) | −0.1012 (5) | 0.4269 (2) | 0.0099 (8) | |
O3 | 0.0928 (2) | 0.1276 (5) | 0.3200 (2) | 0.0064 (8) | |
O4 | 0.2286 (2) | 0.0676 (5) | 0.4260 (2) | 0.0068 (8) | |
O5 | 0.2554 (2) | 0.4596 (5) | 0.3180 (2) | 0.0080 (8) | |
O6 | 0.1207 (2) | 0.5480 (5) | 0.3297 (2) | 0.0068 (8) | |
O7 | 0.2538 (2) | 0.6711 (5) | 0.4307 (2) | 0.0066 (8) | |
O8 | 0.1999 (2) | 0.7859 (5) | 0.2837 (2) | 0.0082 (8) | |
O9 | 0.0997 (2) | 0.2527 (6) | 0.1859 (2) | 0.0087 (8) | |
O10 | 0.0048 (2) | 0.5229 (5) | 0.1291 (2) | 0.0072 (8) | |
O11 | 0.1462 (2) | 0.5361 (5) | 0.1234 (2) | 0.0091 (8) | |
O12 | 0.0475 (2) | 0.3043 (5) | 0.0357 (2) | 0.0070 (8) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
K1 | 0.0158 (7) | 0.0120 (7) | 0.0187 (7) | 0.0032 (5) | 0.0007 (5) | −0.0042 (5) |
K2 | 0.0331 (14) | 0.0055 (11) | 0.0623 (17) | 0.000 | −0.0225 (12) | 0.000 |
Eu1 | 0.00403 (19) | 0.00320 (19) | 0.00728 (19) | 0.000 | 0.00288 (15) | 0.000 |
Eu2 | 0.00473 (15) | 0.00307 (15) | 0.00693 (15) | 0.00021 (10) | 0.00355 (11) | 0.00003 (9) |
Eu3 | 0.00474 (15) | 0.00313 (15) | 0.00682 (15) | 0.00011 (10) | 0.00344 (11) | 0.00051 (9) |
P1 | 0.0052 (7) | 0.0028 (7) | 0.0067 (7) | −0.0015 (5) | 0.0047 (6) | −0.0005 (5) |
P2 | 0.0045 (7) | 0.0026 (7) | 0.0068 (6) | 0.0009 (5) | 0.0040 (5) | 0.0015 (5) |
P3 | 0.0023 (7) | 0.0053 (7) | 0.0048 (7) | 0.0005 (5) | 0.0021 (6) | 0.0001 (5) |
O1 | 0.011 (2) | 0.005 (2) | 0.012 (2) | 0.0020 (16) | 0.0049 (16) | −0.0043 (15) |
O2 | 0.008 (2) | 0.003 (2) | 0.019 (2) | −0.0006 (15) | 0.0063 (17) | 0.0021 (15) |
O3 | 0.0067 (19) | 0.0059 (19) | 0.0057 (18) | −0.0013 (15) | 0.0018 (15) | 0.0003 (14) |
O4 | 0.0074 (19) | 0.0041 (19) | 0.011 (2) | −0.0011 (15) | 0.0054 (16) | 0.0011 (15) |
O5 | 0.011 (2) | 0.005 (2) | 0.010 (2) | −0.0002 (16) | 0.0077 (16) | 0.0011 (15) |
O6 | 0.0066 (19) | 0.0042 (19) | 0.012 (2) | 0.0003 (15) | 0.0060 (16) | 0.0009 (15) |
O7 | 0.0064 (19) | 0.0065 (19) | 0.0079 (18) | 0.0010 (15) | 0.0038 (15) | −0.0021 (15) |
O8 | 0.010 (2) | 0.004 (2) | 0.012 (2) | −0.0007 (16) | 0.0070 (16) | 0.0014 (15) |
O9 | 0.009 (2) | 0.008 (2) | 0.011 (2) | 0.0036 (16) | 0.0063 (16) | 0.0031 (15) |
O10 | 0.0051 (19) | 0.010 (2) | 0.010 (2) | 0.0011 (15) | 0.0064 (15) | −0.0008 (15) |
O11 | 0.0058 (19) | 0.010 (2) | 0.012 (2) | −0.0043 (16) | 0.0039 (16) | −0.0008 (16) |
O12 | 0.008 (2) | 0.0048 (19) | 0.0100 (19) | 0.0014 (15) | 0.0055 (15) | 0.0006 (15) |
Geometric parameters (Å, º) top
K1—O12 | 2.683 (4) | Eu2—O2viii | 2.385 (4) |
K1—O1i | 2.736 (4) | Eu2—O12ix | 2.409 (3) |
K1—O5ii | 2.801 (4) | Eu2—O4x | 2.416 (4) |
K1—O11iii | 2.806 (4) | Eu2—O7xi | 2.497 (4) |
K1—O12iv | 2.871 (4) | Eu2—O7 | 2.515 (3) |
K1—O2v | 3.034 (4) | Eu2—O10i | 2.581 (4) |
K1—O9iv | 3.077 (4) | Eu2—O6 | 2.618 (3) |
K1—O2i | 3.168 (4) | Eu2—O11ix | 2.703 (4) |
K1—O10iii | 3.248 (4) | Eu3—O11xii | 2.287 (4) |
K2—O3 | 2.617 (4) | Eu3—O9 | 2.363 (4) |
K2—O3i | 2.617 (4) | Eu3—O8vii | 2.379 (4) |
K2—O6vi | 2.798 (4) | Eu3—O5 | 2.400 (4) |
K2—O6vii | 2.798 (4) | Eu3—O4 | 2.402 (3) |
K2—O2i | 2.986 (4) | Eu3—O3 | 2.478 (4) |
K2—O2 | 2.986 (4) | Eu3—O5xii | 2.495 (3) |
K2—O10vii | 3.080 (4) | Eu3—O8xii | 2.590 (3) |
K2—O10vi | 3.080 (4) | P1—O7 | 1.518 (4) |
K2—O8vi | 3.305 (4) | P1—O6 | 1.531 (4) |
K2—O8vii | 3.305 (4) | P1—O8 | 1.535 (4) |
Eu1—O3 | 2.291 (4) | P1—O5 | 1.550 (4) |
Eu1—O3i | 2.291 (4) | P2—O1 | 1.508 (4) |
Eu1—O6 | 2.376 (4) | P2—O2 | 1.523 (4) |
Eu1—O6i | 2.376 (4) | P2—O4 | 1.547 (4) |
Eu1—O10i | 2.486 (4) | P2—O3 | 1.570 (4) |
Eu1—O10 | 2.486 (4) | P3—O12 | 1.519 (4) |
Eu1—O9i | 2.585 (3) | P3—O11 | 1.541 (4) |
Eu1—O9 | 2.585 (3) | P3—O10 | 1.543 (4) |
Eu2—O1 | 2.364 (4) | P3—O9 | 1.548 (4) |
| | | |
O7—P1—O6 | 106.7 (2) | O1—P2—O3 | 110.3 (2) |
O7—P1—O8 | 114.1 (2) | O2—P2—O3 | 106.8 (2) |
O6—P1—O8 | 110.0 (2) | O4—P2—O3 | 100.5 (2) |
O7—P1—O5 | 111.0 (2) | O12—P3—O11 | 104.2 (2) |
O6—P1—O5 | 110.4 (2) | O12—P3—O10 | 116.6 (2) |
O8—P1—O5 | 104.8 (2) | O11—P3—O10 | 109.6 (2) |
O1—P2—O2 | 112.2 (2) | O12—P3—O9 | 110.2 (2) |
O1—P2—O4 | 111.8 (2) | O11—P3—O9 | 112.4 (2) |
O2—P2—O4 | 114.5 (2) | O10—P3—O9 | 104.0 (2) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) x−1/2, −y+1/2, z−1/2; (iii) −x, −y+1, −z; (iv) −x, −y, −z; (v) x, −y, z−1/2; (vi) −x, y−1, −z+1/2; (vii) x, y−1, z; (viii) x, y+1, z; (ix) x, −y+1, z+1/2; (x) −x+1/2, −y+1/2, −z+1; (xi) −x+1/2, −y+3/2, −z+1; (xii) −x+1/2, y−1/2, −z+1/2. |
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