Novel tantalum phosphate Na₁₃Sr₂Ta₂(PO₄)₉: synthesis, crystal structure, DFT calculations and Dy³⁺-activated fluorescence performance

A new tantalum phosphate, trideca­sodium distrontium ditantalum nona­phosphate, Na₁₃Sr₂Ta₂(PO₄)₉, was prepared using the high-temperature flux method. The structure can be described as a three-dimensional open framework containing isolated [Ta^V₂(PO₄)₉]¹⁷⁻ units that are inter­locked by Na and Sr ions. Band structure studies by the first-principles method revealed that Na₁₃Sr₂Ta₂(PO₄)₉ is an insulator with an indirect band gap of 4.78 eV, which makes it suitable as a luminescent host matrix. A series of solid solutions, i.e. Na₁₃Sr_2–xTa₂(PO₄)₉:xDy³⁺ (x = 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12 and 0.14), were prepared and their photoluminescence properties studied. Under 350 nm light excitation, these emit two typical emissions of the Dy³⁺ ion, i.e. the ⁴F_9/2→⁶H_15/2 transition centred at 476 nm and the ⁴F_9/2→⁶H_13/2 transition centred at 570 nm.

Computing details

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Tridecasodium distrontium ditantalum nonaphosphate

Crystal data

Na13Sr2Ta2(PO4)9	Dx = 3.453 Mg m^−3
Mr = 1690.74	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/m	Cell parameters from 617 reflections
a = 9.0062 (5) Å	θ = 2.4–24.5°
c = 23.1525 (12) Å	µ = 10.72 mm^−1
V = 1626.3 (2) Å^3	T = 296 K
Z = 2	Parallelopiped, colorless
F(000) = 1576	0.20 × 0.20 × 0.04 mm

Data collection

Bruker SMART APEXII CCD area detector diffractometer	1382 independent reflections
Radiation source: fine-focus sealed tube	1296 reflections with I > 2σ(I)
Detector resolution: 83.33 pixels mm^-1	Rint = 0.043
ω scans	θmax = 28.3°, θmin = 1.8°
Absorption correction: multi-scan (APEX2; Bruker, 2014)	h = −11→12
Tmin = 0.392, Tmax = 0.715	k = −11→8
10998 measured reflections	l = −23→30

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0218P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.019	(Δ/σ)max = 0.001
wR(F^2) = 0.042	Δρmax = 0.68 e Å^−3
S = 1.06	Δρmin = −1.32 e Å^−3
1382 reflections	Extinction correction: SHELXL2016 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
102 parameters	Extinction coefficient: 0.00258 (14)

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. Refined as a 2-component twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Na1	0.03444 (18)	0.35671 (19)	0.04715 (6)	0.0214 (3)
Na2	0.333333	0.666667	0.17305 (11)	0.0218 (6)
Na3	0.3865 (3)	0.3975 (3)	0.250000	0.0150 (4)
Na4	0.666667	0.333333	0.00910 (9)	0.0141 (5)
Sr1	0.666667	0.333333	0.16076 (2)	0.00917 (11)
Ta1	0.000000	0.000000	0.14844 (2)	0.00495 (8)
P1	0.34762 (11)	0.33999 (11)	0.09335 (3)	0.00755 (16)
P2	0.28920 (15)	0.01818 (16)	0.250000	0.0055 (2)
O1	0.4195 (4)	0.4350 (4)	0.14930 (10)	0.0196 (6)
O2	0.4403 (3)	0.2445 (3)	0.07626 (10)	0.0166 (6)
O3	0.3452 (4)	0.4536 (3)	0.04555 (11)	0.0192 (6)
O4	0.1498 (3)	0.1977 (3)	0.10115 (9)	0.0112 (6)
O5	0.1934 (3)	0.0383 (3)	0.19715 (11)	0.0182 (6)
O6	0.2812 (4)	−0.1514 (4)	0.250000	0.0135 (8)
O7	0.4687 (4)	0.1709 (4)	0.250000	0.0082 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Na1	0.0124 (8)	0.0186 (8)	0.0328 (9)	0.0074 (6)	−0.0027 (7)	0.0034 (7)
Na2	0.0224 (8)	0.0224 (8)	0.0204 (12)	0.0112 (4)	0.000	0.000
Na3	0.0126 (10)	0.0170 (11)	0.0194 (11)	0.0103 (8)	0.000	0.000
Na4	0.0148 (7)	0.0148 (7)	0.0129 (11)	0.0074 (4)	0.000	0.000
Sr1	0.01062 (16)	0.01062 (16)	0.0063 (2)	0.00531 (8)	0.000	0.000
Ta1	0.00532 (9)	0.00532 (9)	0.00422 (11)	0.00266 (4)	0.000	0.000
P1	0.0065 (4)	0.0071 (4)	0.0078 (4)	0.0024 (3)	0.0007 (3)	0.0016 (3)
P2	0.0049 (6)	0.0057 (6)	0.0059 (5)	0.0027 (5)	0.000	0.000
O1	0.0198 (15)	0.0201 (15)	0.0130 (13)	0.0056 (13)	−0.0006 (10)	−0.0055 (10)
O2	0.0125 (13)	0.0169 (15)	0.0237 (13)	0.0098 (12)	0.0042 (11)	−0.0007 (11)
O3	0.0155 (13)	0.0197 (15)	0.0203 (14)	0.0071 (12)	0.0018 (12)	0.0146 (12)
O4	0.0068 (12)	0.0099 (12)	0.0132 (13)	0.0013 (10)	−0.0002 (9)	0.0039 (9)
O5	0.0166 (14)	0.0225 (15)	0.0152 (13)	0.0094 (12)	−0.0097 (11)	−0.0008 (10)
O6	0.0147 (19)	0.0119 (18)	0.0152 (18)	0.0075 (16)	0.000	0.000
O7	0.0044 (17)	0.0058 (16)	0.0120 (17)	0.0007 (13)	0.000	0.000

Geometric parameters (Å, º)

Na1—O2^i	2.286 (3)	Sr1—O7^xi	2.642 (2)
Na1—O3^ii	2.422 (3)	Sr1—O7	2.642 (2)
Na1—O3^iii	2.478 (3)	Sr1—O7^v	2.642 (2)
Na1—O3	2.481 (3)	Sr1—O2^xi	2.645 (2)
Na1—O4	2.486 (3)	Sr1—O2^xii	2.645 (2)
Na2—O6^iv	2.617 (3)	Sr1—O2	2.645 (2)
Na2—O6^i	2.617 (3)	Sr1—O1^xi	2.812 (3)
Na2—O6^v	2.617 (3)	Sr1—O1^xii	2.812 (3)
Na2—O1^ii	2.622 (3)	Sr1—O1	2.812 (3)
Na2—O1^vi	2.622 (3)	Ta1—O4^xiii	1.946 (2)
Na2—O1	2.622 (3)	Ta1—O4	1.946 (2)
Na3—O6^i	2.292 (4)	Ta1—O4^i	1.946 (2)
Na3—O1	2.353 (2)	Ta1—O5	1.956 (2)
Na3—O1^vii	2.353 (2)	Ta1—O5^i	1.956 (2)
Na3—O7^v	2.472 (4)	Ta1—O5^xiii	1.956 (2)
Na3—O7	2.495 (4)	P1—O1	1.509 (2)
Na3—O6^v	2.512 (4)	P1—O3	1.515 (2)
Na4—O3^viii	2.345 (3)	P1—O2	1.520 (2)
Na4—O3^ix	2.345 (3)	P1—O4	1.602 (3)
Na4—O3^x	2.345 (3)	P2—O6	1.493 (4)
Na4—O2^xi	2.363 (3)	P2—O7	1.511 (3)
Na4—O2	2.363 (3)	P2—O5^vii	1.559 (3)
Na4—O2^xii	2.363 (3)	P2—O5	1.559 (3)
O4^xiii—Ta1—O4	91.45 (10)	O5^i—Ta1—O5^xiii	90.07 (11)
O4^xiii—Ta1—O4^i	91.45 (10)	O1—P1—O3	113.02 (16)
O4—Ta1—O4^i	91.45 (10)	O1—P1—O2	110.11 (16)
O4^xiii—Ta1—O5	87.71 (10)	O3—P1—O2	112.91 (15)
O4—Ta1—O5	90.81 (10)	O1—P1—O4	110.31 (14)
O4^i—Ta1—O5	177.61 (10)	O3—P1—O4	103.70 (14)
O4^xiii—Ta1—O5^i	177.61 (10)	O2—P1—O4	106.39 (14)
O4—Ta1—O5^i	87.71 (10)	O6—P2—O7	114.44 (19)
O4^i—Ta1—O5^i	90.81 (10)	O6—P2—O5^vii	111.86 (12)
O5—Ta1—O5^i	90.07 (11)	O7—P2—O5^vii	107.26 (13)
O4^xiii—Ta1—O5^xiii	90.81 (10)	O6—P2—O5	111.86 (12)
O4—Ta1—O5^xiii	177.61 (10)	O7—P2—O5	107.26 (13)
O4^i—Ta1—O5^xiii	87.71 (10)	O5^vii—P2—O5	103.4 (2)
O5—Ta1—O5^xiii	90.07 (11)

Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x+1, z; (iii) x−y, x, −z; (iv) x, y+1, z; (v) −x+y+1, −x+1, −z+1/2; (vi) −y+1, x−y+1, z; (vii) x, y, −z+1/2; (viii) x−y+1, x, −z; (ix) y, −x+y, −z; (x) −x+1, −y+1, −z; (xi) −y+1, x−y, z; (xii) −x+y+1, −x+1, z; (xiii) −x+y, −x, z.