Structures of K0.05Na0.95NbO3 (50–300 K) and K0.30Na0.70NbO3 (100–200 K)

Zhang, N.; Glazer, A.M.; Baker, D.; Thomas, P.A.

doi:10.1107/S0108768109011057

Structures of K_0.05Na_0.95NbO₃ (50-300 K) and K_0.30Na_0.70NbO₃ (100-200 K)

N. Zhang, A. M. Glazer, D. Baker and P. A. Thomas

Rietveld refinement using neutron powder diffraction data is reported for the potential lead-free piezoelectric material K_xNa_1 - xNbO₃ (x = 0.05, x = 0.3) at low temperatures. The structures were determined to be of rhombohedral symmetry, space group R3c, with the tilt system a^-a^-a^- for both compositions. It was found that some of the structural parameters differ significantly in the two structures, and particularly the NbO₆ octahedral strains as a function of temperature. The 300 K profile for K_0.05Na_0.95NbO₃ shows the coexistence of rhombohedral and monoclinic phases, which indicates that the phase boundary is close to room temperature; the phase boundary for K_0.30Na_0.70NbO₃ is found to be at approximately 180 K.

Keywords: Rietveld refinement; neutron powder diffraction; piezoelectric material; phase boundary.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768109011057/wf5039sup1.cif Contains datablocks KNN05at50K, KNN05at100K, KNN05at150K, KNN05at200K, KNN05at250K, KNN30at100K, KNN30at120K, KNN30at140K, KNN30at160K, KNN30at180K, KNN05at300K1, KNN05at300K2, KNN30at200K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at50Ksup2.rtv Contains datablock KNN05at50K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at100Ksup3.rtv Contains datablock KNN05at100K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at150Ksup4.rtv Contains datablock KNN05at150K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at200Ksup5.rtv Contains datablock KNN05at200K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at250Ksup6.rtv Contains datablock KNN05at250K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at100Ksup7.rtv Contains datablock KNN30at100K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at120Ksup8.rtv Contains datablock KNN30at120K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at140Ksup9.rtv Contains datablock KNN30at140K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at160Ksup10.rtv Contains datablock KNN30at160K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at180Ksup11.rtv Contains datablock KNN30at180K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at200Ksup12.rtv Contains datablock KNN30at200K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at300Ksup13.rtv Contains datablock KNN05at300K

Computing details top

For all compounds, program(s) used to refine structure: TOPAS Academic.

Figures top

(KNN05at50K) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.71	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 50 K
a = 5.51848 (4) Å	white
c = 13.78476 (15) Å	cylinder, 20 × 50 mm
V = 363.55 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.050	2601 data points
R_wp = 0.066	Excluded region(s): 145-160° 2θ
R_exp = 0.017	24 parameters
χ² = 3.842

Crystal data top

K_0.05Na_0.95NbO₃	V = 363.55 (1) Å³
M_r = 164.71	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.51848 (4) Å	T = 50 K
c = 13.78476 (15) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.050	χ² = 3.842
R_wp = 0.066	2601 data points
R_exp = 0.017	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.27285 (17)	0.08 (3)	0.95
K1	0	0	0.27285 (17)	0.08 (3)	0.05
Nb1	0	0	0.01599 (10)	−0.134 (19)
O1	0.10555 (19)	0.3366 (3)	0.08333	0.079 (15)

(KNN05at100K) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.71	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 100 K
a = 5.51972 (5) Å	white
c = 13.78350 (16) Å	cylinder, 20 × 50 mm
V = 363.68 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.050	2601 data points
R_wp = 0.067	Excluded region(s): 145-160° 2θ
R_exp = 0.018	24 parameters
χ² = 3.497

Crystal data top

K_0.05Na_0.95NbO₃	V = 363.68 (1) Å³
M_r = 164.71	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.51972 (5) Å	T = 100 K
c = 13.78350 (16) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.050	χ² = 3.497
R_wp = 0.067	2601 data points
R_exp = 0.018	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.27240 (19)	0.16 (4)	0.95
K1	0	0	0.27240 (19)	0.16 (4)	0.05
Nb1	0	0	0.01596 (10)	−0.113 (19)
O1	0.1061 (2)	0.3369 (3)	0.08333	0.110 (16)

(KNN05at150K) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.71	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 150 K
a = 5.52229 (5) Å	white
c = 13.78243 (16) Å	cylinder, 20 × 50 mm
V = 363.99 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.053	2601 data points
R_wp = 0.070	Excluded region(s): 145-160° 2θ
R_exp = 0.019	24 parameters
χ² = 3.610

Crystal data top

K_0.05Na_0.95NbO₃	V = 363.99 (1) Å³
M_r = 164.71	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.52229 (5) Å	T = 150 K
c = 13.78243 (16) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.053	χ² = 3.610
R_wp = 0.070	2601 data points
R_exp = 0.019	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2714 (2)	0.14 (4)	0.95
K1	0	0	0.2714 (2)	0.14 (4)	0.05
Nb1	0	0	0.01561 (11)	−0.091 (19)
O1	0.1067 (2)	0.3365 (4)	0.08333	0.040 (15)

(KNN05at200K) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.71	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 200 K
a = 5.52539 (5) Å	white
c = 13.78058 (17) Å	cylinder, 20 × 50 mm
V = 364.35 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.053	2601 data points
R_wp = 0.069	Excluded region(s): 145-160° 2θ
R_exp = 0.019	24 parameters
χ² = 3.610

Crystal data top

K_0.05Na_0.95NbO₃	V = 364.35 (1) Å³
M_r = 164.71	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.52539 (5) Å	T = 200 K
c = 13.78058 (17) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.053	χ² = 3.610
R_wp = 0.069	2601 data points
R_exp = 0.019	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2707 (2)	0.22 (4)	0.95
K1	0	0	0.2707 (2)	0.22 (4)	0.05
Nb1	0	0	0.01538 (11)	−0.07 (2)
O1	0.1079 (2)	0.3367 (4)	0.08333	0.063 (15)

(KNN05at250K) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.71	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 250 K
a = 5.52922 (5) Å	white
c = 13.77931 (17) Å	cylinder, 20 × 50 mm
V = 364.83 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.050	2601 data points
R_wp = 0.067	Excluded region(s): 145-160° 2θ
R_exp = ?	24 parameters
R_Bragg = 0.019
χ² = 3.648

Crystal data top

K_0.05Na_0.95NbO₃	V = 364.83 (1) Å³
M_r = 164.71	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.52922 (5) Å	T = 250 K
c = 13.77931 (17) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.050	χ² = 3.648
R_wp = 0.067	2601 data points
R_exp = ?	24 parameters
R_Bragg = 0.019

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2697 (2)	0.40 (4)	0.95
K1	0	0	0.2697 (2)	0.40 (4)	0.05
Nb1	0	0	0.01518 (11)	−0.06 (2)
O1	0.1092 (2)	0.3370 (4)	0.08333	0.151 (15)

(KNN30at100K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	Z = 6
M_r = 168.73	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 100 K
a = 5.59214 (6) Å	white
c = 13.8430 (2) Å	cylinder, 20 × 50 mm
V = 374.90 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.055	2601 data points
R_wp = 0.075	Excluded region(s): 145-160° 2θ
R_exp = 0.027	24 parameters
χ² = 2.722

Crystal data top

K_0.30Na_0.70NbO₃	V = 374.90 (1) Å³
M_r = 168.73	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.59214 (6) Å	T = 100 K
c = 13.8430 (2) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.055	χ² = 2.722
R_wp = 0.075	2601 data points
R_exp = 0.027	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2666 (3)	0.19 (4)	0.7
K1	0	0	0.2666 (3)	0.19 (4)	0.3
Nb1	0	0	0.01564 (12)	−0.42 (2)
O1	0.1329 (2)	0.3361 (4)	0.08333	0.110 (17)

(KNN30at120K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	Z = 6
M_r = 168.73	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 120 K
a = 5.59326 (6) Å	white
c = 13.8432 (2) Å	cylinder, 20 × 50 mm
V = 375.06 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.055	2601 data points
R_wp = 0.075	Excluded region(s): 145-160° 2θ
R_exp = 0.027	24 parameters
χ² = 2.722

Crystal data top

K_0.30Na_0.70NbO₃	V = 375.06 (1) Å³
M_r = 168.73	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.59326 (6) Å	T = 120 K
c = 13.8432 (2) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.055	χ² = 2.722
R_wp = 0.075	2601 data points
R_exp = 0.027	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2664 (3)	0.23 (4)	0.7
K1	0	0	0.2664 (3)	0.23 (4)	0.3
Nb1	0	0	0.01568 (12)	−0.41 (2)
O1	0.1338 (2)	0.3363 (4)	0.08333	0.120 (17)

(KNN30at140K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	Z = 6
M_r = 168.73	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 140 K
a = 5.59447 (6) Å	white
c = 13.8429 (3) Å	cylinder, 20 × 50 mm
V = 375.21 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.056	2601 data points
R_wp = 0.076	Excluded region(s): 145-160° 2θ
R_exp = ?	24 parameters
R_Bragg = 0.027
χ² = 2.789

Crystal data top

K_0.30Na_0.70NbO₃	V = 375.21 (1) Å³
M_r = 168.73	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.59447 (6) Å	T = 140 K
c = 13.8429 (3) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.056	χ² = 2.789
R_wp = 0.076	2601 data points
R_exp = ?	24 parameters
R_Bragg = 0.027

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2662 (4)	0.28 (4)	0.7
K1	0	0	0.2662 (4)	0.28 (4)	0.3
Nb1	0	0	0.01564 (12)	−0.42 (2)
O1	0.1345 (2)	0.3361 (4)	0.08333	0.157 (18)

(KNN30at160K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	Z = 6
M_r = 168.73	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 160 K
a = 5.59575 (6) Å	white
c = 13.8429 (3) Å	cylinder, 20 × 50 mm
V = 375.38 (1) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.059	2601 data points
R_wp = 0.079	Excluded region(s): 145-160° 2θ
R_exp = 0.027	24 parameters
χ² = 2.890

Crystal data top

K_0.30Na_0.70NbO₃	V = 375.38 (1) Å³
M_r = 168.73	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.59575 (6) Å	T = 160 K
c = 13.8429 (3) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.059	χ² = 2.890
R_wp = 0.079	2601 data points
R_exp = 0.027	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2660 (4)	0.37 (4)	0.7
K1	0	0	0.2660 (4)	0.37 (4)	0.3
Nb1	0	0	0.01559 (13)	−0.38 (2)
O1	0.1360 (3)	0.3365 (4)	0.08333	0.209 (19)

(KNN30at180K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	Z = 6
M_r = 168.73	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 180 K
a = 5.59717 (10) Å	white
c = 13.8423 (4) Å	cylinder, 20 × 50 mm
V = 375.56 (2) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.085	2601 data points
R_wp = 0.114	Excluded region(s): 145-160° 2θ
R_exp = 0.027	24 parameters
χ² = 4.202

Crystal data top

K_0.30Na_0.70NbO₃	V = 375.56 (2) Å³
M_r = 168.73	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.59717 (10) Å	T = 180 K
c = 13.8423 (4) Å	cylinder, 20 × 50 mm

Data collection top

D2B diffractometer	Scan method: step
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Data collection mode: reflection

Refinement top

R_p = 0.085	χ² = 4.202
R_wp = 0.114	2601 data points
R_exp = 0.027	24 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.2660 (6)	0.55 (6)	0.7
K1	0	0	0.2660 (6)	0.55 (6)	0.3
Nb1	0	0	0.0155 (2)	−0.29 (3)
O1	0.1388 (4)	0.3370 (6)	0.08333	0.39 (3)

(KNN05at300K1) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	V = 242.34 (1) Å³
M_r = 164.70	Z = 4
Monoclinic, Pm	Neutron radiation, λ = 1.60 Å
a = 5.60123 (12) Å	T = 300 K
b = 7.79834 (15) Å	white
c = 5.54800 (14) Å	flat, ? × ? × ? mm
β = 90.051 (4)°

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Specimen mounting: Vanadium can packed with powder

Refinement top

R_p = 0.060	? data points
R_wp = 0.079	57 parameters
R_exp = ?
χ² = 2.993

Crystal data top

K_0.05Na_0.95NbO₃	β = 90.051 (4)°
M_r = 164.70	V = 242.34 (1) Å³
Monoclinic, Pm	Z = 4
a = 5.60123 (12) Å	Neutron radiation, λ = 1.60 Å
b = 7.79834 (15) Å	T = 300 K
c = 5.54800 (14) Å	flat, ? × ? × ? mm

Data collection top

D2B diffractometer	Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.060	χ² = 2.993
R_wp = 0.079	? data points
R_exp = ?	57 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0.538 (2)	0	0.0048 (15)	0	0.95
K1	0.538 (2)	0	0.0048 (15)	0	0.05
Na2	0.038 (2)	0	0.4952 (15)	0	0.95
K2	0.038 (2)	0	0.4952 (15)	0	0.05
Na3	0.538 (2)	0.5	0.0048 (15)	0	0.95
K3	0.538 (2)	0.5	0.0048 (15)	0	0.05
Na4	0.038 (2)	0.5	0.4952 (15)	0	0.95
K4	0.038 (2)	0.5	0.4952 (15)	0	0.05
Nb1	0.0322 (8)	0.25	0.004 (4)	0
Nb2	0.5322 (8)	0.25	0.504 (4)	0
O1	−0.0033 (15)	0	0.0561 (8)	0
O2	0.5033 (15)	0	0.4439 (8)	0
O7	0.0033 (15)	0.5	−0.0561 (8)	0
O8	0.4967 (15)	0.5	0.5561 (8)	0
O3	0.2839 (9)	0.2835 (9)	0.2174 (9)	0
O4	0.2174 (9)	0.2311 (9)	0.7161 (9)	0
O5	0.7826 (9)	0.2690 (9)	0.2839 (9)	0
O6	0.7161 (9)	0.2165 (9)	0.7826 (9)	0

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
K1	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
Na2	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
K2	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
Na3	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
K3	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
Na4	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
K4	0.017 (3)	0.0173 (18)	0.028 (3)	0	−0.020 (6)	0
Nb1	0.0026 (13)	0.0067 (10)	0.0048 (10)	0.0002 (16)	−0.002 (4)	−0.011 (3)
Nb2	0.0026 (13)	0.0067 (10)	0.0048 (10)	0.0002 (16)	−0.002 (4)	−0.011 (3)
O1	0.021 (2)	0.0027 (12)	0.019 (2)	0	−0.023 (3)	0
O2	0.021 (2)	0.0027 (12)	0.019 (2)	0	−0.023 (3)	0
O7	0.021 (2)	0.0027 (12)	0.019 (2)	0	−0.023 (3)	0
O8	0.021 (2)	0.0027 (12)	0.019 (2)	0	−0.023 (3)	0
O3	0.0074 (9)	0.0148 (13)	0.0076 (8)	−0.0036 (9)	−0.010 (2)	0.007 (2)
O4	0.0074 (9)	0.0148 (13)	0.0076 (8)	−0.0036 (9)	−0.010 (2)	0.007 (2)
O5	0.0074 (9)	0.0148 (13)	0.0076 (8)	−0.0036 (9)	−0.010 (2)	0.007 (2)
O6	0.0074 (9)	0.0148 (13)	0.0076 (8)	−0.0036 (9)	−0.010 (2)	0.007 (2)

(KNN05at300K2) Sodium Potassium Niobate top

Crystal data top

K_0.05Na_0.95NbO₃	Z = 6
M_r = 164.70	Neutron radiation, λ = 1.60 Å
Trigonal, R3c	T = 300 K
a = 5.5298 (3) Å	white
c = 13.7692 (11) Å	flat, ? × ? × ? mm
V = 364.63 (5) Å³

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Specimen mounting: Vanadium can packed with powder

Refinement top

R_p = 0.060	? data points
R_wp = 0.079	57 parameters
R_exp = ?
χ² = 2.993

Crystal data top

K_0.05Na_0.95NbO₃	V = 364.63 (5) Å³
M_r = 164.70	Z = 6
Trigonal, R3c	Neutron radiation, λ = 1.60 Å
a = 5.5298 (3) Å	T = 300 K
c = 13.7692 (11) Å	flat, ? × ? × ? mm

Data collection top

D2B diffractometer	Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.060	χ² = 2.993
R_wp = 0.079	? data points
R_exp = ?	57 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0	0	0.3209 (10)	−1.72 (16)	0.95
K1	0	0	0.3209 (10)	−1.72 (16)	0.05
Nb1	0	0	0.0578 (12)	3.0 (4)
O1	0.007 (3)	0.4425 (17)	0.08333	0.66 (12)

(KNN30at200K) Sodium Potassium Niobate top

Crystal data top

K_0.30Na_0.70NbO₃	V = 125.36 (1) Å³
M_r = 168.73	Z = 2
Monoclinic, Pm	Neutron radiation, λ = 1.60 Å
a = 5.65868 (12) Å	T = 200 K
b = 3.93856 (5) Å	white
c = 5.62480 (13) Å	flat, ? × ? × ? mm
β = 90.073 (3)°

Data collection top

D2B diffractometer	Data collection mode: reflection
Ge [115] monochromator	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°
Specimen mounting: Vanadium can packed with powder

Refinement top

R_p = 0.058	? data points
R_wp = 0.076	39 parameters
R_exp = ?
χ² = 2.016

Crystal data top

K_0.30Na_0.70NbO₃	β = 90.073 (3)°
M_r = 168.73	V = 125.36 (1) Å³
Monoclinic, Pm	Z = 2
a = 5.65868 (12) Å	Neutron radiation, λ = 1.60 Å
b = 3.93856 (5) Å	T = 200 K
c = 5.62480 (13) Å	flat, ? × ? × ? mm

Data collection top

D2B diffractometer	Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder	2θ_min = 0.10°, 2θ_max = 160°, 2θ_step = 0.05°

Refinement top

R_p = 0.058	χ² = 2.016
R_wp = 0.076	? data points
R_exp = ?	39 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	B_iso*/B_eq	Occ. (<1)
Na1	0.5389 (18)	0.5	0.018 (2)	0	0.7
K1	0.5389 (18)	0.5	0.018 (2)	0	0.3
Na2	0.0389 (18)	0.5	0.518 (2)	0	0.7
K2	0.0389 (18)	0.5	0.518 (2)	0	0.3
Nb1	0.0362 (5)	0	−0.003 (2)	0
Nb2	0.5362 (5)	0	0.497 (2)	0
O1	0	0.5	0	0
O2	0.5	0.5	0.5	0
O3	0.2737 (9)	0	0.2286 (10)	0
O4	0.2286 (10)	0	0.7263 (9)	0
O5	0.7714 (10)	0	0.2737 (9)	0
O6	0.7263 (9)	0	0.7714 (10)	0

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.009 (3)	0.0031 (11)	0.006 (3)	0	−0.038 (3)	0
K1	0.009 (3)	0.0031 (11)	0.006 (3)	0	−0.038 (3)	0
Na2	0.009 (3)	0.0031 (11)	0.006 (3)	0	−0.038 (3)	0
K2	0.009 (3)	0.0031 (11)	0.006 (3)	0	−0.038 (3)	0
Nb1	0.0000 (17)	0.0000 (6)	0.0000 (12)	0	−0.004 (2)	0
Nb2	0.0000 (17)	0.0000 (6)	0.0000 (12)	0	−0.004 (2)	0
O1	0.0109 (16)	0.0000 (9)	0.0146 (17)	0	0.007 (3)	0
O2	0.0109 (16)	0.0000 (9)	0.0146 (17)	0	0.007 (3)	0
O3	0.0012 (7)	0.0108 (6)	0.0002 (7)	0	0.003 (2)	0
O4	0.0012 (7)	0.0108 (6)	0.0002 (7)	0	0.003 (2)	0
O5	0.0012 (7)	0.0108 (6)	0.0002 (7)	0	0.003 (2)	0
O6	0.0012 (7)	0.0108 (6)	0.0002 (7)	0	0.003 (2)	0

Experimental details

	(KNN05at50K)	(KNN05at100K)	(KNN05at150K)	(KNN05at200K)
Crystal data
Chemical formula	K_0.05Na_0.95NbO₃	K_0.05Na_0.95NbO₃	K_0.05Na_0.95NbO₃	K_0.05Na_0.95NbO₃
M_r	164.71	164.71	164.71	164.71
Crystal system, space group	Trigonal, R3c	Trigonal, R3c	Trigonal, R3c	Trigonal, R3c
Temperature (K)	50	100	150	200
a, b, c (Å)	5.51848 (4), 5.51848 (4), 13.78476 (15)	5.51972 (5), 5.51972 (5), 13.78350 (16)	5.52229 (5), 5.52229 (5), 13.78243 (16)	5.52539 (5), 5.52539 (5), 13.78058 (17)
α, β, γ (°)	90, 90, 120	90, 90, 120	90, 90, 120	90, 90, 120
V (Å³)	363.55 (1)	363.68 (1)	363.99 (1)	364.35 (1)
Z	6	6	6	6
Radiation type	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å
Specimen shape, size (mm)	Cylinder, 20 × 50	Cylinder, 20 × 50	Cylinder, 20 × 50	Cylinder, 20 × 50

Data collection
Diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer
Specimen mounting	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder
Data collection mode	Reflection	Reflection	Reflection	Reflection
Scan method	Step	Step	Step	Step
2θ values (°)	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05

Refinement
R factors and goodness of fit	R_p = 0.050, R_wp = 0.066, R_exp = 0.017, χ² = 3.842	R_p = 0.050, R_wp = 0.067, R_exp = 0.018, χ² = 3.497	R_p = 0.053, R_wp = 0.070, R_exp = 0.019, χ² = 3.610	R_p = 0.053, R_wp = 0.069, R_exp = 0.019, χ² = 3.610
No. of data points	2601	2601	2601	2601
No. of parameters	24	24	24	24
No. of restraints	?	?	?	?

	(KNN05at250K)	(KNN30at100K)	(KNN30at120K)	(KNN30at140K)
Crystal data
Chemical formula	K_0.05Na_0.95NbO₃	K_0.30Na_0.70NbO₃	K_0.30Na_0.70NbO₃	K_0.30Na_0.70NbO₃
M_r	164.71	168.73	168.73	168.73
Crystal system, space group	Trigonal, R3c	Trigonal, R3c	Trigonal, R3c	Trigonal, R3c
Temperature (K)	250	100	120	140
a, b, c (Å)	5.52922 (5), 5.52922 (5), 13.77931 (17)	5.59214 (6), 5.59214 (6), 13.8430 (2)	5.59326 (6), 5.59326 (6), 13.8432 (2)	5.59447 (6), 5.59447 (6), 13.8429 (3)
α, β, γ (°)	90, 90, 120	90, 90, 120	90, 90, 120	90, 90, 120
V (Å³)	364.83 (1)	374.90 (1)	375.06 (1)	375.21 (1)
Z	6	6	6	6
Radiation type	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å
Specimen shape, size (mm)	Cylinder, 20 × 50	Cylinder, 20 × 50	Cylinder, 20 × 50	Cylinder, 20 × 50

Data collection
Diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer
Specimen mounting	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder
Data collection mode	Reflection	Reflection	Reflection	Reflection
Scan method	Step	Step	Step	Step
2θ values (°)	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05

Refinement
R factors and goodness of fit	R_p = 0.050, R_wp = 0.067, R_exp = ?, R_Bragg = 0.019, χ² = 3.648	R_p = 0.055, R_wp = 0.075, R_exp = 0.027, χ² = 2.722	R_p = 0.055, R_wp = 0.075, R_exp = 0.027, χ² = 2.722	R_p = 0.056, R_wp = 0.076, R_exp = ?, R_Bragg = 0.027, χ² = 2.789
No. of data points	2601	2601	2601	2601
No. of parameters	24	24	24	24
No. of restraints	?	?	?	?

	(KNN30at160K)	(KNN30at180K)	(KNN05at300K1)	(KNN05at300K2)
Crystal data
Chemical formula	K_0.30Na_0.70NbO₃	K_0.30Na_0.70NbO₃	K_0.05Na_0.95NbO₃	K_0.05Na_0.95NbO₃
M_r	168.73	168.73	164.70	164.70
Crystal system, space group	Trigonal, R3c	Trigonal, R3c	Monoclinic, Pm	Trigonal, R3c
Temperature (K)	160	180	300	300
a, b, c (Å)	5.59575 (6), 5.59575 (6), 13.8429 (3)	5.59717 (10), 5.59717 (10), 13.8423 (4)	5.60123 (12), 7.79834 (15), 5.54800 (14)	5.5298 (3), 5.5298 (3), 13.7692 (11)
α, β, γ (°)	90, 90, 120	90, 90, 120	90, 90.051 (4), 90	90, 90, 120
V (Å³)	375.38 (1)	375.56 (2)	242.34 (1)	364.63 (5)
Z	6	6	4	6
Radiation type	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å	Neutron, λ = 1.60 Å
Specimen shape, size (mm)	Cylinder, 20 × 50	Cylinder, 20 × 50	Flat, ? × ? × ?	Flat, ? × ? × ?

Data collection
Diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer	D2B diffractometer
Specimen mounting	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder	Vanadium can packed with powder
Data collection mode	Reflection	Reflection	Reflection	Reflection
Scan method	Step	Step	?	?
2θ values (°)	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05

Refinement
R factors and goodness of fit	R_p = 0.059, R_wp = 0.079, R_exp = 0.027, χ² = 2.890	R_p = 0.085, R_wp = 0.114, R_exp = 0.027, χ² = 4.202	R_p = 0.060, R_wp = 0.079, R_exp = ?, χ² = 2.993	R_p = 0.060, R_wp = 0.079, R_exp = ?, χ² = 2.993
No. of data points	2601	2601	?	?
No. of parameters	24	24	57	57
No. of restraints	?	?	?	?

	(KNN30at200K)
Crystal data
Chemical formula	K_0.30Na_0.70NbO₃
M_r	168.73
Crystal system, space group	Monoclinic, Pm
Temperature (K)	200
a, b, c (Å)	5.65868 (12), 3.93856 (5), 5.62480 (13)
α, β, γ (°)	90, 90.073 (3), 90
V (Å³)	125.36 (1)
Z	2
Radiation type	Neutron, λ = 1.60 Å
Specimen shape, size (mm)	Flat, ? × ? × ?

Data collection
Diffractometer	D2B diffractometer
Specimen mounting	Vanadium can packed with powder
Data collection mode	Reflection
Scan method	?
2θ values (°)	2θ_min = 0.10 2θ_max = 160 2θ_step = 0.05

Refinement
R factors and goodness of fit	R_p = 0.058, R_wp = 0.076, R_exp = ?, χ² = 2.016
No. of data points	?
No. of parameters	39
No. of restraints	?

Computer programs: TOPAS Academic.

Format		BIBTeX
		EndNote
		RefMan
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		CIF
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Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Text
		Plain Text

Structures of K0.05Na0.95NbO3 (50-300 K) and K0.30Na0.70NbO3 (100-200 K)

Supporting information

Structures of K_0.05Na_0.95NbO₃ (50-300 K) and K_0.30Na_0.70NbO₃ (100-200 K)