A new potassium niobate, KNb₅O₁₃

The structure of KNb₅O₁₃ consists of two-dimensional slabs of edge- and corner-sharing NbO₆ octa­hedra, and these slabs are inter­connected to form the three-dimensional framework. The K⁺ cations reside in the empty channels. Among the three crystallographically independent Nb atoms, the coordination around the Nb atom bridging the slabs is more regular than those of the other Nb atoms. A bond-valence calculation indicates that the charge balance should be represented by [K⁺][Nb⁵⁺]₅[O^2-]₁₃.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](b-O)= 0.002 Å
• R factor = 0.019
• wR factor = 0.045
• Data-to-parameter ratio = 13.2

checkCIF/PLATON results

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Computing details

Data collection: RAPID-AUTO (Rigaku, 2005); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: locally modified version of ORTEPII (Johnson, 1965); software used to prepare material for publication: WinGX (Farrugia, 1999).

(I)

Crystal data

KNb5O13	F(000) = 1312
Mr = 711.65	Dx = 4.636 Mg m^−3
Orthorhombic, Pbcm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2c 2b	Cell parameters from 9114 reflections
a = 5.672 (2) Å	θ = 3.1–27.5°
b = 10.737 (5) Å	µ = 5.93 mm^−1
c = 16.742 (6) Å	T = 150 K
V = 1019.7 (7) Å^3	Needle, black
Z = 4	0.20 × 0.04 × 0.04 mm

Data collection

Rigaku R-AXIS RAPID diffractometer	1147 reflections with I > 2σ(I)
ω scans	Rint = 0.035
Absorption correction: numerical (Higashi, 2000)	θmax = 27.5°, θmin = 3.6°
Tmin = 0.750, Tmax = 0.790	h = −7→7
9248 measured reflections	k = −13→13
1205 independent reflections	l = −21→19

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0113P)^2 + 3.9558P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.019	(Δ/σ)max < 0.001
wR(F^2) = 0.046	Δρmax = 0.59 e Å^−3
S = 1.19	Δρmin = −0.73 e Å^−3
1205 reflections	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
91 parameters	Extinction coefficient: 0.00360 (19)

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

	x	y	z	Uiso*/Ueq
K1	0.7871 (2)	0.32683 (13)	0.25	0.0260 (3)
Nb1	0.16752 (5)	0.43808 (2)	0.076718 (16)	0.00794 (10)
Nb2	0.33738 (5)	0.13515 (3)	0.136796 (16)	0.00924 (10)
Nb3	0.67240 (6)	0.25	0	0.00699 (11)
O1	0.0915 (4)	0.0171 (2)	0.13820 (13)	0.0102 (4)
O2	0.1265 (4)	0.2821 (2)	0.12599 (13)	0.0098 (4)
O3	0.1293 (4)	0.6059 (2)	0.00428 (12)	0.0076 (4)
O4	0.3612 (4)	0.1239 (2)	0.01261 (12)	0.0078 (4)
O5	0.5920 (4)	0.0042 (2)	0.13687 (13)	0.0105 (4)
O6	0.5969 (4)	0.2532 (2)	0.11116 (12)	0.0083 (4)
O7	0.3683 (6)	0.1567 (3)	0.25	0.0118 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0307 (6)	0.0353 (7)	0.0120 (5)	−0.0163 (5)	0	0
Nb1	0.00806 (15)	0.00846 (16)	0.00730 (15)	0.00056 (9)	−0.00037 (10)	−0.00001 (9)
Nb2	0.00973 (15)	0.00986 (16)	0.00812 (15)	−0.00192 (10)	0.00076 (10)	0.00050 (10)
Nb3	0.00627 (18)	0.00682 (19)	0.00789 (19)	0	0	0.00135 (13)
O1	0.0095 (10)	0.0102 (11)	0.0108 (11)	−0.0022 (8)	−0.0012 (8)	0.0001 (8)
O2	0.0093 (10)	0.0088 (10)	0.0113 (10)	−0.0005 (8)	0.0021 (8)	0.0010 (8)
O3	0.0065 (9)	0.0066 (10)	0.0096 (9)	−0.0004 (8)	−0.0013 (8)	0.0002 (8)
O4	0.0081 (9)	0.0084 (10)	0.0070 (9)	−0.0007 (8)	−0.0002 (8)	−0.0003 (8)
O5	0.0118 (10)	0.0095 (11)	0.0100 (11)	0.0024 (8)	0.0006 (8)	−0.0002 (8)
O6	0.0088 (10)	0.0091 (10)	0.0070 (10)	−0.0019 (8)	−0.0004 (8)	−0.0015 (8)
O7	0.0121 (15)	0.0141 (16)	0.0093 (14)	0.0002 (13)	0	0

Geometric parameters (Å, º)

K1—O6	2.682 (2)	Nb2—O4	2.087 (2)
K1—O6^i	2.682 (2)	Nb2—Nb3	3.2214 (8)
K1—O1^ii	2.855 (3)	Nb3—O6	1.910 (2)
K1—O1^iii	2.855 (3)	Nb3—O6^vi	1.910 (2)
K1—O2^iv	2.872 (2)	Nb3—O3^ix	1.915 (2)
K1—O2^v	2.872 (2)	Nb3—O3^x	1.915 (2)
K1—O7	2.996 (4)	Nb3—O4	2.234 (2)
Nb1—O5^iii	1.838 (2)	Nb3—O4^vi	2.234 (2)
Nb1—O2	1.881 (2)	Nb3—Nb2^vi	3.2214 (9)
Nb1—O4^vi	1.972 (2)	O1—Nb1^xi	1.984 (2)
Nb1—O1^vii	1.984 (2)	O1—K1^ix	2.855 (3)
Nb1—O3	2.182 (2)	O2—K1^xii	2.872 (2)
Nb1—O3^viii	2.213 (2)	O3—Nb3^x	1.915 (2)
Nb2—O1	1.885 (2)	O3—Nb1^viii	2.213 (2)
Nb2—O7	1.9175 (9)	O4—Nb1^vi	1.972 (2)
Nb2—O2	1.989 (2)	O5—Nb1^ix	1.838 (2)
Nb2—O6	1.989 (2)	O7—Nb2^i	1.9175 (9)
Nb2—O5	2.015 (2)
O6—K1—O6^i	120.16 (10)	O7—Nb2—O2	92.82 (12)
O6—K1—O1^ii	151.19 (8)	O1—Nb2—O6	168.16 (9)
O6^i—K1—O1^ii	74.92 (7)	O7—Nb2—O6	93.93 (11)
O6—K1—O1^iii	74.92 (7)	O2—Nb2—O6	85.41 (9)
O6^i—K1—O1^iii	151.19 (8)	O1—Nb2—O5	93.51 (10)
O1^ii—K1—O1^iii	81.92 (10)	O7—Nb2—O5	91.03 (11)
O6—K1—O2^iv	147.89 (8)	O2—Nb2—O5	169.96 (9)
O6^i—K1—O2^iv	66.03 (7)	O6—Nb2—O5	85.08 (10)
O1^ii—K1—O2^iv	58.93 (7)	O1—Nb2—O4	91.24 (9)
O1^iii—K1—O2^iv	115.58 (8)	O7—Nb2—O4	170.31 (11)
O6—K1—O2^v	66.03 (7)	O2—Nb2—O4	89.67 (9)
O6^i—K1—O2^v	147.89 (8)	O6—Nb2—O4	76.93 (8)
O1^ii—K1—O2^v	115.58 (8)	O5—Nb2—O4	85.06 (9)
O1^iii—K1—O2^v	58.93 (7)	O6—Nb3—O6^vi	154.09 (13)
O2^iv—K1—O2^v	92.61 (10)	O6—Nb3—O3^ix	96.30 (9)
O6—K1—O7	60.09 (5)	O6^vi—Nb3—O3^ix	98.84 (9)
O6^i—K1—O7	60.09 (5)	O6—Nb3—O3^x	98.84 (9)
O1^ii—K1—O7	128.86 (7)	O6^vi—Nb3—O3^x	96.30 (9)
O1^iii—K1—O7	128.86 (7)	O3^ix—Nb3—O3^x	108.05 (13)
O2^iv—K1—O7	115.44 (7)	O6—Nb3—O4	75.03 (8)
O2^v—K1—O7	115.44 (7)	O6^vi—Nb3—O4	84.50 (8)
O5^iii—Nb1—O2	101.27 (10)	O3^ix—Nb3—O4	88.32 (9)
O5^iii—Nb1—O4^vi	97.61 (10)	O3^x—Nb3—O4	163.21 (9)
O2—Nb1—O4^vi	95.80 (9)	O6—Nb3—O4^vi	84.50 (8)
O5^iii—Nb1—O1^vii	95.74 (10)	O6^vi—Nb3—O4^vi	75.03 (8)
O2—Nb1—O1^vii	93.53 (9)	O3^ix—Nb3—O4^vi	163.21 (9)
O4^vi—Nb1—O1^vii	161.89 (9)	O3^x—Nb3—O4^vi	88.32 (9)
O5^iii—Nb1—O3	93.40 (9)	O4—Nb3—O4^vi	75.64 (12)
O2—Nb1—O3	165.05 (9)	Nb1—O2—Nb2	132.21 (12)
O4^vi—Nb1—O3	84.98 (9)	Nb3^x—O3—Nb1	129.03 (11)
O1^vii—Nb1—O3	82.05 (9)	Nb3^x—O3—Nb1^viii	126.61 (11)
O5^iii—Nb1—O3^viii	169.34 (9)	Nb1—O3—Nb1^viii	103.89 (9)
O2—Nb1—O3^viii	89.13 (9)	Nb1^vi—O4—Nb2	137.65 (11)
O4^vi—Nb1—O3^viii	83.52 (9)	Nb1^vi—O4—Nb3	124.97 (10)
O1^vii—Nb1—O3^viii	81.13 (9)	Nb2—O4—Nb3	96.34 (8)
O3—Nb1—O3^viii	76.11 (9)	Nb1^ix—O5—Nb2	143.21 (12)
O1—Nb2—O7	97.86 (12)	Nb3—O6—Nb2	111.39 (10)
O1—Nb2—O2	95.14 (10)	Nb2—O7—Nb2^i	162.6 (2)

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