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Oriented single crystals of the high-temperature phase of KNO3 (phase III), a ferroelectric compound that may also occur as an atmospheric aerosol particle, were grown at room temperature and pressure by atomizing a solution of KNO3 in water and allowing droplets to dry on a glass substrate. The crystals are up to 1 mm across and are stable unless mechanically disturbed. There is no evidence of the spontaneous transformation of phase III to the room-temperature stable phase (phase II), even after several months. Single-crystal structure determinations of phase III were obtained at 295 and 123 K. The unit cell regained its room-temperature dimensions after warming from 123 K. The phase-III KNO3 structure can be viewed as the stacking parallel to the c axis of alternating K atoms and planar NO3 groups. The NO3 groups connect the planes of K atoms, where each O is fourfold coordinated to one N and three K. Each K atom has nine O nearest neighbors, with three bonds at 2.813 and six at 2.9092 Å. The interatomic K-N-K distance alternates from 5.051 to 3.941 along the c axis. The N-O distances increase from 1.245 (2) Å at 295 K to 1.2533 (15) Å at 123 K. The nitrate group has a slight non-planarity, with the N atoms 0.011 Å above the O plane and directed toward the more distant K of the K-N-K chain.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768109041019/bp5023sup1.cif
Contains datablocks rt, 123K

fcf

Structure factor file (CIF format) https://doi.org/10.1107/S0108768109041019/bp5023123Ksup2.fcf
Contains datablock 123K

fcf

Structure factor file (CIF format) https://doi.org/10.1107/S0108768109041019/bp5023rtsup3.fcf
Contains datablock rt

Computing details top

For both compounds, data collection: SMART V5.632; cell refinement: SAINT V6.45A; data reduction: SAINT V6.45A; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL Version 6.14 (Sheldrick, 2003b); software used to prepare material for publication: SHELXTL Version 6.14 (Sheldrick, 2003b).

(rt) top
Crystal data top
KNO3Dx = 2.162 Mg m3
Mr = 101.11Mo Kα radiation, λ = 0.71073 Å
Hexagonal, R3mCell parameters from 715 reflections
Hall symbol: R 3 -2"θ = 4.9–27.4°
a = 5.4698 (8) ŵ = 1.50 mm1
c = 8.992 (3) ÅT = 298 K
V = 232.99 (8) Å3Plate, colorless
Z = 30.11 × 0.08 × 0.02 mm
F(000) = 150
Data collection top
Bruker SMART APEX
diffractometer
157 independent reflections
Radiation source: fine-focus sealed tube157 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
ω scanθmax = 27.4°, θmin = 4.9°
Absorption correction: multi-scan
SADABS Version 2.10 (Sheldrick, 2003a)
h = 77
Tmin = 0.858, Tmax = 0.966k = 77
764 measured reflectionsl = 1111
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0348P)2 + 0.0102P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.022(Δ/σ)max < 0.001
wR(F2) = 0.054Δρmax = 0.13 e Å3
S = 1.23Δρmin = 0.16 e Å3
157 reflectionsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
13 parametersExtinction coefficient: 0.157 (16)
0 restraintsAbsolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.03 (8)
Special details top

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. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
K10.00000.00000.50000.0357 (4)
N10.66670.33330.3950 (4)0.0312 (8)
O10.5352 (2)0.0705 (4)0.3961 (2)0.0467 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
K10.0298 (4)0.0298 (4)0.0475 (5)0.01488 (19)0.0000.000
N10.0296 (12)0.0296 (12)0.0345 (13)0.0148 (6)0.0000.000
O10.0403 (10)0.0267 (9)0.0685 (13)0.0133 (5)0.0002 (4)0.0003 (8)
Geometric parameters (Å, º) top
K1—O1i2.813 (2)K1—K1v4.3540 (7)
K1—O1ii2.814 (2)N1—O1vi1.245 (2)
K1—O1iii2.9092 (9)O1—K1vii2.9092 (8)
K1—N1iv3.2962 (11)
O1i—K1—O1ii72.14 (7)O1i—K1—K1v138.713 (16)
O1i—K1—O1iii145.89 (7)O1ii—K1—K1v138.712 (15)
O1ii—K1—O1iii99.06 (4)O1viii—K1—K1v90.67 (5)
O1viii—K1—O1iii73.80 (2)O1iii—K1—K1v39.65 (4)
O1iii—K1—O1ix43.52 (8)O1ix—K1—K1v72.29 (4)
O1iii—K1—O1140.13 (8)O1—K1—K1v114.27 (4)
O1ix—K1—O1110.20 (4)N1iv—K1—K1v56.99 (4)
O1iii—K1—O1x69.42 (8)N1iii—K1—K1v57.00 (4)
O1ix—K1—O1x110.21 (4)O1vi—N1—O1119.993 (6)
O1i—K1—O1xi73.798 (19)O1vi—N1—O1xii119.994 (6)
O1i—K1—N1iv83.37 (5)O1—N1—O1xii119.992 (6)
O1ii—K1—N1iv149.48 (8)O1vi—N1—K1vii162.9 (2)
O1iii—K1—N1iv91.03 (4)O1—N1—K1vii61.22 (5)
O1ix—K1—N1iv129.28 (6)K1vii—N1—K1xiii112.14 (5)
O1x—K1—N1iv22.03 (4)N1—O1—K1xiv132.4 (2)
O1xi—K1—N1iv22.04 (4)N1—O1—K196.74 (7)
O1ii—K1—N1iii83.36 (5)K1xiv—O1—K199.06 (4)
N1iv—K1—N1iii112.14 (5)K1—O1—K1vii140.13 (8)
Symmetry codes: (i) x+y+2/3, x+1/3, z+1/3; (ii) x1/3, y+1/3, z+1/3; (iii) x1, y, z; (iv) x1, y1, z; (v) x2/3, y1/3, z1/3; (vi) x+y+1, x+1, z; (vii) x+1, y, z; (viii) y1/3, xy2/3, z+1/3; (ix) y, xy, z; (x) x+y, x, z; (xi) y, xy1, z; (xii) y+1, xy, z; (xiii) x+1, y+1, z; (xiv) x+1/3, y1/3, z1/3.
(123K) top
Crystal data top
KNO3Dx = 2.233 Mg m3
Mr = 101.11Mo Kα radiation, λ = 0.71073 Å
Hexagonal, R3mCell parameters from 750 reflections
Hall symbol: R 3 -2"θ = 4.9–27.5°
a = 5.4325 (2) ŵ = 1.55 mm1
c = 8.8255 (7) ÅT = 123 K
V = 225.56 (2) Å3Plate, colorless
Z = 30.11 × 0.08 × 0.02 mm
F(000) = 150
Data collection top
Bruker SMART APEX
diffractometer
155 independent reflections
Radiation source: fine-focus sealed tube155 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.014
ω scanθmax = 27.5°, θmin = 4.9°
Absorption correction: multi-scan
SADABS Version 2.10 (Sheldrick, 2003a)
h = 77
Tmin = 0.854, Tmax = 0.965k = 77
755 measured reflectionsl = 1111
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.017 w = 1/[σ2(Fo2) + (0.0254P)2 + 0.214P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.041(Δ/σ)max < 0.001
S = 1.14Δρmax = 0.18 e Å3
155 reflectionsΔρmin = 0.19 e Å3
12 parametersAbsolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
0 restraintsAbsolute structure parameter: 0.05 (7)
Special details top

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. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
K10.00000.00000.50000.0153 (2)
N10.66670.33330.3975 (3)0.0133 (6)
O10.53347 (16)0.0669 (3)0.39836 (16)0.0185 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
K10.0130 (2)0.0130 (2)0.0200 (3)0.00650 (12)0.0000.000
N10.0128 (9)0.0128 (9)0.0142 (11)0.0064 (4)0.0000.000
O10.0163 (7)0.0101 (7)0.0271 (8)0.0051 (3)0.0001 (3)0.0003 (5)
Geometric parameters (Å, º) top
K1—O1i2.7799 (14)K1—K1iv4.3002 (2)
K1—O1ii2.8778 (5)N1—O1v1.2533 (15)
K1—N1iii3.2643 (9)O1—K1vi2.7798 (14)
O1i—K1—O1vii71.84 (5)O1i—K1—K1iv138.615 (9)
O1i—K1—O1ii98.93 (3)O1vii—K1—K1iv138.614 (9)
O1vii—K1—O1ii145.09 (5)O1viii—K1—K1iv90.52 (3)
O1viii—K1—O1ii73.299 (11)O1ii—K1—K1iv39.69 (3)
O1ii—K1—O1ix44.32 (6)O1ix—K1—K1iv72.96 (3)
O1ii—K1—O1x141.42 (5)O1x—K1—K1iv115.02 (3)
O1ix—K1—O1x110.75 (3)N1iii—K1—K1iv57.32 (3)
O1vii—K1—O1xi98.92 (3)O1v—N1—O1119.996 (4)
O1viii—K1—O1xi73.298 (11)O1v—N1—K1xii61.18 (4)
O1ii—K1—O1xi69.04 (6)O1x—N1—K1xii163.6 (2)
O1i—K1—N1iii83.01 (4)K1xii—N1—K1xiii112.63 (4)
O1vii—K1—N1iii148.73 (6)N1—O1—K1vi132.30 (16)
O1ii—K1—N1iii22.43 (3)N1—O1—K196.39 (6)
O1x—K1—N1iii130.28 (5)K1vi—O1—K198.93 (3)
O1xi—K1—N1iii91.08 (3)K1—O1—K1xii141.42 (5)
N1iii—K1—N1xi112.63 (5)
Symmetry codes: (i) x+y+2/3, x+1/3, z+1/3; (ii) x+y, x, z; (iii) x1, y1, z; (iv) x2/3, y1/3, z1/3; (v) y+1, xy, z; (vi) x+1/3, y1/3, z1/3; (vii) x1/3, y+1/3, z+1/3; (viii) y1/3, xy2/3, z+1/3; (ix) y, xy1, z; (x) x+y+1, x+1, z; (xi) x1, y, z; (xii) x+1, y, z; (xiii) x+1, y+1, z.
 

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