Synthesis, crystal structure and luminescence properties of a new samarium borate phosphate, CsNa₂Sm₂(BO₃)(PO₄)₂

A new caesium sodium samarium borate phosphate, CsNa₂Sm₂(BO₃)(PO₄)₂, has been obtained successfully by the high-temperature solution growth (HTSG) method and single-crystal X-ray diffraction analysis reveals that it crystallizes in the ortho­rhom­bic space group Cmcm. The structure contains BO₃, PO₄, NaO₇ and SmO₇ polyhedra which are inter­connected via corner- or edge-sharing O atoms to form a three-dimensional [Na₂Sm₂(BO₃)(PO₄)₂]_∞ network. This network delimits large cavities where large Cs⁺ cations reside to form the total structure. Under 402 nm light excitation, CsNa₂Sm₂(BO₃)(PO₄)₂ exhibits three emission bands due to the 4f→4f transitions of Sm³⁺. Furthermore, we introduced Gd³⁺ into Sm³⁺ sites to optimize the Sm³⁺ concentration and improve the luminescence intensity. The optimal concentration is Gd/Sm = 98/2. The luminescent lifetime of a series of CsNa₂Gd_2(1–x)Sm_2x(BO₃)(PO₄)₂ phosphors shows a gradual degradation of lifetime from 2.196 to 0.872 ms for x = 0.01–0.10. The Commission Internationale de l'Eclairage (CIE) 1931 calculation reveals that CsNa₂Gd_1.96Sm_0.04(BO₃)(PO₄)₂ can emit orange light under 402 nm excitation.

Computing details

Data collection: APEX2 (Bruker, 2017); cell refinement: SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017); program(s) used to solve structure: SHELXS (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2020).

Caesium disodium disamarium borate bis(phosphate)

Crystal data

CsNa2Sm2(BO3)(PO4)2	Dx = 4.177 Mg m^−3
Mr = 728.34	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmcm	Cell parameters from 1320 reflections
a = 7.0631 (6) Å	θ = 2.3–24.4°
b = 15.2881 (15) Å	µ = 13.54 mm^−1
c = 10.725 (1) Å	T = 296 K
V = 1158.10 (19) Å^3	Block, colorless
Z = 4	0.15 × 0.15 × 0.10 mm
F(000) = 1296

Data collection

Bruker SMART APEXII CCD area detector diffractometer	812 independent reflections
Radiation source: fine-focus sealed tube	727 reflections with I > 2σ(I)
Detector resolution: 83.33 pixels mm^-1	Rint = 0.037
ω scans	θmax = 28.3°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −9→4
Tmin = 0.158, Tmax = 0.590	k = −19→19
3854 measured reflections	l = −14→14

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0233P)^2 + 0.2713P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.022	(Δ/σ)max = 0.001
wR(F^2) = 0.048	Δρmax = 1.09 e Å^−3
S = 1.05	Δρmin = −1.54 e Å^−3
812 reflections	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
59 parameters	Extinction coefficient: 0.00072 (6)

Special details

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 suitable single crystal with dimensions of 0.15 × 0.15 × 0.05 mm was selected and mounted on a glass fiber for the single-crystal X-ray diffraction (SC-XRD) experiments. Data collection was performed using a Bruker Smart Apex2 CCD diffractometer with graphite-monochromated Mo-Ka (λ = 0.71073 Å) radiation at a temperature of 293 K. The data set was corrected for Lorentz and polarization factors and for absorption by applying the ω-scan technique (Bruker, 2017). The structure was solved by direct method and refined by full-matrix least-squares fitting on F² by Shelx-2017 (Sheldrick, 2015). The observed intensities are consistent with an orthorhombic C-centered space group Cmcm.

The final refined solution obtained was checked with the Addsym algorithm in the program PLATON (Spek, 2020), and no higher symmetry was found. Crystallographic data and structural refinement were summarized in Table 1. The atomic coordinates and thermal parameters are given as supporting information (Table S1, S2), and some important bond distances are summarized in Table S3. Further details of the crystal structure investigations can be obtained from the CCDC database on quoting the depository number of 2031718

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

	x	y	z	Uiso*/Ueq
Cs1	0.500000	0.48636 (5)	0.750000	0.0370 (2)
Na1	0.7563 (3)	0.74620 (18)	0.750000	0.0248 (6)
Sm1	1.000000	0.61983 (2)	0.52841 (3)	0.00667 (11)
B1	1.000000	0.5156 (7)	0.750000	0.0109 (19)
P1	0.500000	0.68276 (10)	0.52246 (13)	0.0083 (3)
O1	1.000000	0.4772 (3)	0.6361 (4)	0.0167 (10)
O2	1.000000	0.6087 (4)	0.750000	0.0183 (14)
O3	0.500000	0.7613 (3)	0.6133 (4)	0.0127 (9)
O4	0.500000	0.7240 (3)	0.3918 (4)	0.0141 (9)
O5	0.6758 (4)	0.62691 (19)	0.5449 (3)	0.0196 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cs1	0.0384 (4)	0.0263 (4)	0.0463 (5)	0.000	0.000	0.000
Na1	0.0134 (13)	0.0473 (19)	0.0138 (13)	−0.0010 (12)	0.000	0.000
Sm1	0.00608 (16)	0.00696 (17)	0.00696 (17)	0.000	0.000	−0.00011 (11)
B1	0.008 (4)	0.023 (5)	0.002 (4)	0.000	0.000	0.000
P1	0.0050 (7)	0.0097 (7)	0.0101 (7)	0.000	0.000	0.0016 (6)
O1	0.031 (3)	0.007 (2)	0.012 (2)	0.000	0.000	−0.0042 (17)
O2	0.038 (4)	0.009 (3)	0.008 (3)	0.000	0.000	0.000
O3	0.015 (2)	0.013 (2)	0.010 (2)	0.000	0.000	−0.0034 (17)
O4	0.017 (2)	0.017 (2)	0.008 (2)	0.000	0.000	−0.0008 (17)
O5	0.0075 (15)	0.0171 (17)	0.034 (2)	0.0028 (11)	−0.0006 (14)	0.0071 (14)

Geometric parameters (Å, º)

Cs1—O5^i	3.316 (3)	Na1—O5^i	2.913 (4)
Cs1—O5^ii	3.316 (3)	Sm1—O5^x	2.299 (3)
Cs1—O5^iii	3.316 (3)	Sm1—O5	2.299 (3)
Cs1—O5	3.316 (3)	Sm1—O1^xi	2.305 (4)
Cs1—O4^iv	3.557 (4)	Sm1—O3^ix	2.369 (4)
Cs1—O4^v	3.557 (4)	Sm1—O2	2.3826 (5)
Cs1—O1	3.7393 (14)	Sm1—O1	2.468 (4)
Cs1—O1^vi	3.7393 (14)	Sm1—O4^ix	2.537 (4)
Cs1—O1^i	3.7393 (14)	B1—O1	1.355 (6)
Cs1—O1^vii	3.7393 (14)	B1—O1^i	1.355 (6)
Na1—O3^i	2.341 (3)	B1—O2	1.423 (11)
Na1—O3	2.341 (3)	P1—O5	1.526 (3)
Na1—O4^viii	2.342 (3)	P1—O5^iii	1.526 (3)
Na1—O4^ix	2.342 (3)	P1—O4	1.537 (4)
Na1—O2	2.717 (5)	P1—O3	1.546 (4)
Na1—O5	2.913 (4)
O1—B1—O1^i	128.6 (9)	O5^iii—P1—O4	111.92 (16)
O1—B1—O2	115.7 (4)	O5—P1—O3	109.57 (16)
O1^i—B1—O2	115.7 (4)	O5^iii—P1—O3	109.57 (16)
O5—P1—O5^iii	108.9 (2)	O4—P1—O3	104.8 (2)
O5—P1—O4	111.92 (16)

Symmetry codes: (i) x, y, −z+3/2; (ii) −x+1, y, −z+3/2; (iii) −x+1, y, z; (iv) −x+1, −y+1, −z+1; (v) −x+1, −y+1, z+1/2; (vi) x−1, y, z; (vii) x−1, y, −z+3/2; (viii) −x+3/2, −y+3/2, z+1/2; (ix) −x+3/2, −y+3/2, −z+1; (x) −x+2, y, z; (xi) −x+2, −y+1, −z+1.