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Rietveld refinement using neutron powder diffraction data is reported for the potential lead-free piezoelectric material KxNa1 - 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 K0.05Na0.95NbO3 shows the coexistence of rhombohedral and monoclinic phases, which indicates that the phase boundary is close to room temperature; the phase boundary for K0.30Na0.70NbO3 is found to be at approximately 180 K.

Supporting information

cif

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

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at50Ksup2.rtv
Contains datablock KNN05at50K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at100Ksup3.rtv
Contains datablock KNN05at100K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at150Ksup4.rtv
Contains datablock KNN05at150K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at200Ksup5.rtv
Contains datablock KNN05at200K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN05at250Ksup6.rtv
Contains datablock KNN05at250K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at100Ksup7.rtv
Contains datablock KNN30at100K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at120Ksup8.rtv
Contains datablock KNN30at120K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at140Ksup9.rtv
Contains datablock KNN30at140K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at160Ksup10.rtv
Contains datablock KNN30at160K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at180Ksup11.rtv
Contains datablock KNN30at180K

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768109011057/wf5039KNN30at200Ksup12.rtv
Contains datablock KNN30at200K

rtv

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
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
[Figure 6]
[Figure 7]
(KNN05at50K) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.71Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 50 K
a = 5.51848 (4) Åwhite
c = 13.78476 (15) Åcylinder, 20 × 50 mm
V = 363.55 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0502601 data points
Rwp = 0.066Excluded region(s): 145-160° 2θ
Rexp = 0.01724 parameters
χ2 = 3.842
Crystal data top
K0.05Na0.95NbO3V = 363.55 (1) Å3
Mr = 164.71Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.51848 (4) ÅT = 50 K
c = 13.78476 (15) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.050χ2 = 3.842
Rwp = 0.0662601 data points
Rexp = 0.01724 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.27285 (17)0.08 (3)0.95
K1000.27285 (17)0.08 (3)0.05
Nb1000.01599 (10)0.134 (19)
O10.10555 (19)0.3366 (3)0.083330.079 (15)
(KNN05at100K) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.71Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 100 K
a = 5.51972 (5) Åwhite
c = 13.78350 (16) Åcylinder, 20 × 50 mm
V = 363.68 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0502601 data points
Rwp = 0.067Excluded region(s): 145-160° 2θ
Rexp = 0.01824 parameters
χ2 = 3.497
Crystal data top
K0.05Na0.95NbO3V = 363.68 (1) Å3
Mr = 164.71Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.51972 (5) ÅT = 100 K
c = 13.78350 (16) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.050χ2 = 3.497
Rwp = 0.0672601 data points
Rexp = 0.01824 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.27240 (19)0.16 (4)0.95
K1000.27240 (19)0.16 (4)0.05
Nb1000.01596 (10)0.113 (19)
O10.1061 (2)0.3369 (3)0.083330.110 (16)
(KNN05at150K) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.71Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 150 K
a = 5.52229 (5) Åwhite
c = 13.78243 (16) Åcylinder, 20 × 50 mm
V = 363.99 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0532601 data points
Rwp = 0.070Excluded region(s): 145-160° 2θ
Rexp = 0.01924 parameters
χ2 = 3.610
Crystal data top
K0.05Na0.95NbO3V = 363.99 (1) Å3
Mr = 164.71Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.52229 (5) ÅT = 150 K
c = 13.78243 (16) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.053χ2 = 3.610
Rwp = 0.0702601 data points
Rexp = 0.01924 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2714 (2)0.14 (4)0.95
K1000.2714 (2)0.14 (4)0.05
Nb1000.01561 (11)0.091 (19)
O10.1067 (2)0.3365 (4)0.083330.040 (15)
(KNN05at200K) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.71Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 200 K
a = 5.52539 (5) Åwhite
c = 13.78058 (17) Åcylinder, 20 × 50 mm
V = 364.35 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0532601 data points
Rwp = 0.069Excluded region(s): 145-160° 2θ
Rexp = 0.01924 parameters
χ2 = 3.610
Crystal data top
K0.05Na0.95NbO3V = 364.35 (1) Å3
Mr = 164.71Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.52539 (5) ÅT = 200 K
c = 13.78058 (17) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.053χ2 = 3.610
Rwp = 0.0692601 data points
Rexp = 0.01924 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2707 (2)0.22 (4)0.95
K1000.2707 (2)0.22 (4)0.05
Nb1000.01538 (11)0.07 (2)
O10.1079 (2)0.3367 (4)0.083330.063 (15)
(KNN05at250K) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.71Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 250 K
a = 5.52922 (5) Åwhite
c = 13.77931 (17) Åcylinder, 20 × 50 mm
V = 364.83 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0502601 data points
Rwp = 0.067Excluded region(s): 145-160° 2θ
Rexp = ?24 parameters
RBragg = 0.019
χ2 = 3.648
Crystal data top
K0.05Na0.95NbO3V = 364.83 (1) Å3
Mr = 164.71Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.52922 (5) ÅT = 250 K
c = 13.77931 (17) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.050χ2 = 3.648
Rwp = 0.0672601 data points
Rexp = ?24 parameters
RBragg = 0.019
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2697 (2)0.40 (4)0.95
K1000.2697 (2)0.40 (4)0.05
Nb1000.01518 (11)0.06 (2)
O10.1092 (2)0.3370 (4)0.083330.151 (15)
(KNN30at100K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3Z = 6
Mr = 168.73Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 100 K
a = 5.59214 (6) Åwhite
c = 13.8430 (2) Åcylinder, 20 × 50 mm
V = 374.90 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0552601 data points
Rwp = 0.075Excluded region(s): 145-160° 2θ
Rexp = 0.02724 parameters
χ2 = 2.722
Crystal data top
K0.30Na0.70NbO3V = 374.90 (1) Å3
Mr = 168.73Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.59214 (6) ÅT = 100 K
c = 13.8430 (2) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.055χ2 = 2.722
Rwp = 0.0752601 data points
Rexp = 0.02724 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2666 (3)0.19 (4)0.7
K1000.2666 (3)0.19 (4)0.3
Nb1000.01564 (12)0.42 (2)
O10.1329 (2)0.3361 (4)0.083330.110 (17)
(KNN30at120K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3Z = 6
Mr = 168.73Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 120 K
a = 5.59326 (6) Åwhite
c = 13.8432 (2) Åcylinder, 20 × 50 mm
V = 375.06 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0552601 data points
Rwp = 0.075Excluded region(s): 145-160° 2θ
Rexp = 0.02724 parameters
χ2 = 2.722
Crystal data top
K0.30Na0.70NbO3V = 375.06 (1) Å3
Mr = 168.73Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.59326 (6) ÅT = 120 K
c = 13.8432 (2) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.055χ2 = 2.722
Rwp = 0.0752601 data points
Rexp = 0.02724 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2664 (3)0.23 (4)0.7
K1000.2664 (3)0.23 (4)0.3
Nb1000.01568 (12)0.41 (2)
O10.1338 (2)0.3363 (4)0.083330.120 (17)
(KNN30at140K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3Z = 6
Mr = 168.73Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 140 K
a = 5.59447 (6) Åwhite
c = 13.8429 (3) Åcylinder, 20 × 50 mm
V = 375.21 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0562601 data points
Rwp = 0.076Excluded region(s): 145-160° 2θ
Rexp = ?24 parameters
RBragg = 0.027
χ2 = 2.789
Crystal data top
K0.30Na0.70NbO3V = 375.21 (1) Å3
Mr = 168.73Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.59447 (6) ÅT = 140 K
c = 13.8429 (3) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.056χ2 = 2.789
Rwp = 0.0762601 data points
Rexp = ?24 parameters
RBragg = 0.027
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2662 (4)0.28 (4)0.7
K1000.2662 (4)0.28 (4)0.3
Nb1000.01564 (12)0.42 (2)
O10.1345 (2)0.3361 (4)0.083330.157 (18)
(KNN30at160K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3Z = 6
Mr = 168.73Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 160 K
a = 5.59575 (6) Åwhite
c = 13.8429 (3) Åcylinder, 20 × 50 mm
V = 375.38 (1) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0592601 data points
Rwp = 0.079Excluded region(s): 145-160° 2θ
Rexp = 0.02724 parameters
χ2 = 2.890
Crystal data top
K0.30Na0.70NbO3V = 375.38 (1) Å3
Mr = 168.73Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.59575 (6) ÅT = 160 K
c = 13.8429 (3) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.059χ2 = 2.890
Rwp = 0.0792601 data points
Rexp = 0.02724 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2660 (4)0.37 (4)0.7
K1000.2660 (4)0.37 (4)0.3
Nb1000.01559 (13)0.38 (2)
O10.1360 (3)0.3365 (4)0.083330.209 (19)
(KNN30at180K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3Z = 6
Mr = 168.73Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 180 K
a = 5.59717 (10) Åwhite
c = 13.8423 (4) Åcylinder, 20 × 50 mm
V = 375.56 (2) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromatorScan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.0852601 data points
Rwp = 0.114Excluded region(s): 145-160° 2θ
Rexp = 0.02724 parameters
χ2 = 4.202
Crystal data top
K0.30Na0.70NbO3V = 375.56 (2) Å3
Mr = 168.73Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.59717 (10) ÅT = 180 K
c = 13.8423 (4) Åcylinder, 20 × 50 mm
Data collection top
D2B
diffractometer
Scan method: step
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Data collection mode: reflection
Refinement top
Rp = 0.085χ2 = 4.202
Rwp = 0.1142601 data points
Rexp = 0.02724 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.2660 (6)0.55 (6)0.7
K1000.2660 (6)0.55 (6)0.3
Nb1000.0155 (2)0.29 (3)
O10.1388 (4)0.3370 (6)0.083330.39 (3)
(KNN05at300K1) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3V = 242.34 (1) Å3
Mr = 164.70Z = 4
Monoclinic, PmNeutron radiation, λ = 1.60 Å
a = 5.60123 (12) ÅT = 300 K
b = 7.79834 (15) Åwhite
c = 5.54800 (14) Åflat, ? × ? × ? mm
β = 90.051 (4)°
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromator2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Specimen mounting: Vanadium can packed with powder
Refinement top
Rp = 0.060? data points
Rwp = 0.07957 parameters
Rexp = ?
χ2 = 2.993
Crystal data top
K0.05Na0.95NbO3β = 90.051 (4)°
Mr = 164.70V = 242.34 (1) Å3
Monoclinic, PmZ = 4
a = 5.60123 (12) ÅNeutron radiation, λ = 1.60 Å
b = 7.79834 (15) ÅT = 300 K
c = 5.54800 (14) Åflat, ? × ? × ? mm
Data collection top
D2B
diffractometer
Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.060χ2 = 2.993
Rwp = 0.079? data points
Rexp = ?57 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na10.538 (2)00.0048 (15)00.95
K10.538 (2)00.0048 (15)00.05
Na20.038 (2)00.4952 (15)00.95
K20.038 (2)00.4952 (15)00.05
Na30.538 (2)0.50.0048 (15)00.95
K30.538 (2)0.50.0048 (15)00.05
Na40.038 (2)0.50.4952 (15)00.95
K40.038 (2)0.50.4952 (15)00.05
Nb10.0322 (8)0.250.004 (4)0
Nb20.5322 (8)0.250.504 (4)0
O10.0033 (15)00.0561 (8)0
O20.5033 (15)00.4439 (8)0
O70.0033 (15)0.50.0561 (8)0
O80.4967 (15)0.50.5561 (8)0
O30.2839 (9)0.2835 (9)0.2174 (9)0
O40.2174 (9)0.2311 (9)0.7161 (9)0
O50.7826 (9)0.2690 (9)0.2839 (9)0
O60.7161 (9)0.2165 (9)0.7826 (9)0
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Na10.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
K10.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
Na20.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
K20.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
Na30.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
K30.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
Na40.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
K40.017 (3)0.0173 (18)0.028 (3)00.020 (6)0
Nb10.0026 (13)0.0067 (10)0.0048 (10)0.0002 (16)0.002 (4)0.011 (3)
Nb20.0026 (13)0.0067 (10)0.0048 (10)0.0002 (16)0.002 (4)0.011 (3)
O10.021 (2)0.0027 (12)0.019 (2)00.023 (3)0
O20.021 (2)0.0027 (12)0.019 (2)00.023 (3)0
O70.021 (2)0.0027 (12)0.019 (2)00.023 (3)0
O80.021 (2)0.0027 (12)0.019 (2)00.023 (3)0
O30.0074 (9)0.0148 (13)0.0076 (8)0.0036 (9)0.010 (2)0.007 (2)
O40.0074 (9)0.0148 (13)0.0076 (8)0.0036 (9)0.010 (2)0.007 (2)
O50.0074 (9)0.0148 (13)0.0076 (8)0.0036 (9)0.010 (2)0.007 (2)
O60.0074 (9)0.0148 (13)0.0076 (8)0.0036 (9)0.010 (2)0.007 (2)
(KNN05at300K2) Sodium Potassium Niobate top
Crystal data top
K0.05Na0.95NbO3Z = 6
Mr = 164.70Neutron radiation, λ = 1.60 Å
Trigonal, R3cT = 300 K
a = 5.5298 (3) Åwhite
c = 13.7692 (11) Åflat, ? × ? × ? mm
V = 364.63 (5) Å3
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromator2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Specimen mounting: Vanadium can packed with powder
Refinement top
Rp = 0.060? data points
Rwp = 0.07957 parameters
Rexp = ?
χ2 = 2.993
Crystal data top
K0.05Na0.95NbO3V = 364.63 (5) Å3
Mr = 164.70Z = 6
Trigonal, R3cNeutron radiation, λ = 1.60 Å
a = 5.5298 (3) ÅT = 300 K
c = 13.7692 (11) Åflat, ? × ? × ? mm
Data collection top
D2B
diffractometer
Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.060χ2 = 2.993
Rwp = 0.079? data points
Rexp = ?57 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na1000.3209 (10)1.72 (16)0.95
K1000.3209 (10)1.72 (16)0.05
Nb1000.0578 (12)3.0 (4)
O10.007 (3)0.4425 (17)0.083330.66 (12)
(KNN30at200K) Sodium Potassium Niobate top
Crystal data top
K0.30Na0.70NbO3V = 125.36 (1) Å3
Mr = 168.73Z = 2
Monoclinic, PmNeutron radiation, λ = 1.60 Å
a = 5.65868 (12) ÅT = 200 K
b = 3.93856 (5) Åwhite
c = 5.62480 (13) Åflat, ? × ? × ? mm
β = 90.073 (3)°
Data collection top
D2B
diffractometer
Data collection mode: reflection
Ge [115] monochromator2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Specimen mounting: Vanadium can packed with powder
Refinement top
Rp = 0.058? data points
Rwp = 0.07639 parameters
Rexp = ?
χ2 = 2.016
Crystal data top
K0.30Na0.70NbO3β = 90.073 (3)°
Mr = 168.73V = 125.36 (1) Å3
Monoclinic, PmZ = 2
a = 5.65868 (12) ÅNeutron radiation, λ = 1.60 Å
b = 3.93856 (5) ÅT = 200 K
c = 5.62480 (13) Åflat, ? × ? × ? mm
Data collection top
D2B
diffractometer
Data collection mode: reflection
Specimen mounting: Vanadium can packed with powder2θmin = 0.10°, 2θmax = 160°, 2θstep = 0.05°
Refinement top
Rp = 0.058χ2 = 2.016
Rwp = 0.076? data points
Rexp = ?39 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/BeqOcc. (<1)
Na10.5389 (18)0.50.018 (2)00.7
K10.5389 (18)0.50.018 (2)00.3
Na20.0389 (18)0.50.518 (2)00.7
K20.0389 (18)0.50.518 (2)00.3
Nb10.0362 (5)00.003 (2)0
Nb20.5362 (5)00.497 (2)0
O100.500
O20.50.50.50
O30.2737 (9)00.2286 (10)0
O40.2286 (10)00.7263 (9)0
O50.7714 (10)00.2737 (9)0
O60.7263 (9)00.7714 (10)0
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Na10.009 (3)0.0031 (11)0.006 (3)00.038 (3)0
K10.009 (3)0.0031 (11)0.006 (3)00.038 (3)0
Na20.009 (3)0.0031 (11)0.006 (3)00.038 (3)0
K20.009 (3)0.0031 (11)0.006 (3)00.038 (3)0
Nb10.0000 (17)0.0000 (6)0.0000 (12)00.004 (2)0
Nb20.0000 (17)0.0000 (6)0.0000 (12)00.004 (2)0
O10.0109 (16)0.0000 (9)0.0146 (17)00.007 (3)0
O20.0109 (16)0.0000 (9)0.0146 (17)00.007 (3)0
O30.0012 (7)0.0108 (6)0.0002 (7)00.003 (2)0
O40.0012 (7)0.0108 (6)0.0002 (7)00.003 (2)0
O50.0012 (7)0.0108 (6)0.0002 (7)00.003 (2)0
O60.0012 (7)0.0108 (6)0.0002 (7)00.003 (2)0

Experimental details

(KNN05at50K)(KNN05at100K)(KNN05at150K)(KNN05at200K)
Crystal data
Chemical formulaK0.05Na0.95NbO3K0.05Na0.95NbO3K0.05Na0.95NbO3K0.05Na0.95NbO3
Mr164.71164.71164.71164.71
Crystal system, space groupTrigonal, R3cTrigonal, R3cTrigonal, R3cTrigonal, R3c
Temperature (K)50100150200
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, 12090, 90, 12090, 90, 12090, 90, 120
V3)363.55 (1)363.68 (1)363.99 (1)364.35 (1)
Z6666
Radiation typeNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 Å
Specimen shape, size (mm)Cylinder, 20 × 50Cylinder, 20 × 50Cylinder, 20 × 50Cylinder, 20 × 50
Data collection
DiffractometerD2B
diffractometer
D2B
diffractometer
D2B
diffractometer
D2B
diffractometer
Specimen mountingVanadium can packed with powderVanadium can packed with powderVanadium can packed with powderVanadium can packed with powder
Data collection modeReflectionReflectionReflectionReflection
Scan methodStepStepStepStep
2θ values (°)2θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.05
Refinement
R factors and goodness of fitRp = 0.050, Rwp = 0.066, Rexp = 0.017, χ2 = 3.842Rp = 0.050, Rwp = 0.067, Rexp = 0.018, χ2 = 3.497Rp = 0.053, Rwp = 0.070, Rexp = 0.019, χ2 = 3.610Rp = 0.053, Rwp = 0.069, Rexp = 0.019, χ2 = 3.610
No. of data points2601260126012601
No. of parameters24242424
No. of restraints????


(KNN05at250K)(KNN30at100K)(KNN30at120K)(KNN30at140K)
Crystal data
Chemical formulaK0.05Na0.95NbO3K0.30Na0.70NbO3K0.30Na0.70NbO3K0.30Na0.70NbO3
Mr164.71168.73168.73168.73
Crystal system, space groupTrigonal, R3cTrigonal, R3cTrigonal, R3cTrigonal, R3c
Temperature (K)250100120140
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, 12090, 90, 12090, 90, 12090, 90, 120
V3)364.83 (1)374.90 (1)375.06 (1)375.21 (1)
Z6666
Radiation typeNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 Å
Specimen shape, size (mm)Cylinder, 20 × 50Cylinder, 20 × 50Cylinder, 20 × 50Cylinder, 20 × 50
Data collection
DiffractometerD2B
diffractometer
D2B
diffractometer
D2B
diffractometer
D2B
diffractometer
Specimen mountingVanadium can packed with powderVanadium can packed with powderVanadium can packed with powderVanadium can packed with powder
Data collection modeReflectionReflectionReflectionReflection
Scan methodStepStepStepStep
2θ values (°)2θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.05
Refinement
R factors and goodness of fitRp = 0.050, Rwp = 0.067, Rexp = ?, RBragg = 0.019, χ2 = 3.648Rp = 0.055, Rwp = 0.075, Rexp = 0.027, χ2 = 2.722Rp = 0.055, Rwp = 0.075, Rexp = 0.027, χ2 = 2.722Rp = 0.056, Rwp = 0.076, Rexp = ?, RBragg = 0.027, χ2 = 2.789
No. of data points2601260126012601
No. of parameters24242424
No. of restraints????


(KNN30at160K)(KNN30at180K)(KNN05at300K1)(KNN05at300K2)
Crystal data
Chemical formulaK0.30Na0.70NbO3K0.30Na0.70NbO3K0.05Na0.95NbO3K0.05Na0.95NbO3
Mr168.73168.73164.70164.70
Crystal system, space groupTrigonal, R3cTrigonal, R3cMonoclinic, PmTrigonal, R3c
Temperature (K)160180300300
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, 12090, 90, 12090, 90.051 (4), 9090, 90, 120
V3)375.38 (1)375.56 (2)242.34 (1)364.63 (5)
Z6646
Radiation typeNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 ÅNeutron, λ = 1.60 Å
Specimen shape, size (mm)Cylinder, 20 × 50Cylinder, 20 × 50Flat, ? × ? × ?Flat, ? × ? × ?
Data collection
DiffractometerD2B
diffractometer
D2B
diffractometer
D2B
diffractometer
D2B
diffractometer
Specimen mountingVanadium can packed with powderVanadium can packed with powderVanadium can packed with powderVanadium can packed with powder
Data collection modeReflectionReflectionReflectionReflection
Scan methodStepStep??
2θ values (°)2θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.052θmin = 0.10 2θmax = 160 2θstep = 0.05
Refinement
R factors and goodness of fitRp = 0.059, Rwp = 0.079, Rexp = 0.027, χ2 = 2.890Rp = 0.085, Rwp = 0.114, Rexp = 0.027, χ2 = 4.202Rp = 0.060, Rwp = 0.079, Rexp = ?, χ2 = 2.993Rp = 0.060, Rwp = 0.079, Rexp = ?, χ2 = 2.993
No. of data points26012601??
No. of parameters24245757
No. of restraints????


(KNN30at200K)
Crystal data
Chemical formulaK0.30Na0.70NbO3
Mr168.73
Crystal system, space groupMonoclinic, 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
V3)125.36 (1)
Z2
Radiation typeNeutron, λ = 1.60 Å
Specimen shape, size (mm)Flat, ? × ? × ?
Data collection
DiffractometerD2B
diffractometer
Specimen mountingVanadium can packed with powder
Data collection modeReflection
Scan method?
2θ values (°)2θmin = 0.10 2θmax = 160 2θstep = 0.05
Refinement
R factors and goodness of fitRp = 0.058, Rwp = 0.076, Rexp = ?, χ2 = 2.016
No. of data points?
No. of parameters39
No. of restraints?

Computer programs: TOPAS Academic.

 

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