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The origin of the complex reflection splitting in potassium sodium niobate doped with lithium and manganese was investigated using temperature-dependent high-resolution X-ray and neutron diffraction as well as electron probe microanalysis and scanning electron microscopy. Two structural models were developed from the diffraction data. A single-phase monoclinic Pm model is known from the literature and is able to reproduce the diffraction patterns perfectly. However, a model with phase coexistence of two classical orthorhombic Amm2 phases can also reproduce the diffraction data with equal accuracy. Scanning electron microscopy in combination with electron probe microanalysis revealed segregation of the A-site substituents potassium and sodium. This favours the model with phase coexistence and confirms the need for comprehensive analyses with complementary methods to cover a broad range of length scales as well as to assess both average and local structure.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600576718003916/aj5301sup1.cif
Contains datablocks global, orthorhombic_1_ND, orthorhombic_2_ND, orthorhombic_1_XRD, orthorhombic_2_XRD, monoclinic_ND, monoclinic_XRD, tetragonal_1_ND, tetragonal_2_ND, cubic_1_ND, cubic_2_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301monoclinic_NDsup2.hkl
Contains datablock monoclinic_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301monoclinic_NDsup3.rtv
Contains datablock monoclinic_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301monoclinic_XRDsup4.hkl
Contains datablock monoclinic_XRD

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301monoclinic_XRDsup5.rtv
Contains datablock monoclinic_XRD

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_1_NDsup6.hkl
Contains datablock orthorhombic_1_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_1_NDsup7.rtv
Contains datablock orthorhombic_1_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_1_XRDsup8.hkl
Contains datablock orthorhombic_1_XRD

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_1_XRDsup9.rtv
Contains datablock orthorhombic_1_XRD

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_2_NDsup10.hkl
Contains datablock orthorhombic_2_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_2_NDsup11.rtv
Contains datablock orthorhombic_2_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_2_XRDsup12.hkl
Contains datablock orthorhombic_2_XRD

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301orthorhombic_2_XRDsup13.rtv
Contains datablock orthorhombic_2_XRD

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301tetragonal_1_NDsup14.hkl
Contains datablock tetragonal_1_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301tetragonal_1_NDsup15.rtv
Contains datablock tetragonal_1_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301tetragonal_2_NDsup16.hkl
Contains datablock tetragonal_2_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301tetragonal_2_NDsup17.rtv
Contains datablock tetragonal_2_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301cubic_1_NDsup18.hkl
Contains datablock cubic_1_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301cubic_1_NDsup19.rtv
Contains datablock cubic_1_ND

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301cubic_2_NDsup20.hkl
Contains datablock cubic_2_ND

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600576718003916/aj5301cubic_2_NDsup21.rtv
Contains datablock cubic_2_ND

CCDC references: 1828074; 1828075; 1828076; 1828077; 1828078; 1828079; 1828080; 1828081; 1828082; 1828083

Computing details top

For all structures, program(s) used to refine structure: FULLPROF.

(orthorhombic_1_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3c = 5.6426 (2) Å
Mr = 170.23V = 125.50 (1) Å3
Orthorhombic, Amm2Z = 2
Hall symbol: A 2 -2Neutron radiation
a = 3.94590 (5) ÅT = 300 K
b = 5.6366 (2) Ågrey
Data collection top
Powder
diffractometer
2θmin = 1.216°, 2θmax = 151.866°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0333014 data points
Rwp = 0.04366 parameters
Rexp = 0.0160 restraints
RBragg = 0.023
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.250000.248 (3)0.0088 (5)*
O20.000000.000000.523 (2)0.0028 (8)*
Na10.000000.000000.000000.0120 (9)*0.48000
K10.000000.000000.000000.0120 (9)*0.48000
Li10.000000.000000.000000.0120 (9)*0.04000
Nb10.500000.000000.489 (2)0.0035 (4)*0.98000
Mn10.500000.000000.489 (2)0.0035 (4)*0.02000
(orthorhombic_2_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3c = 5.67416 (10) Å
Mr = 170.23V = 126.73 (1) Å3
Orthorhombic, Amm2Z = 2
Hall symbol: A 2 -2Neutron radiation
a = 3.94200 (5) ÅT = 300 K
b = 5.66580 (15) Ågrey
Data collection top
Powder
diffractometer
2θmin = 1.216°, 2θmax = 151.866°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0333014 data points
Rwp = 0.04366 parameters
Rexp = 0.0160 restraints
RBragg = 0.022
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.250000.2755 (18)0.0156 (8)*
O20.000000.000000.5344 (15)0.0067 (9)*
Na10.000000.000000.000000.0122 (9)*0.48000
K10.000000.000000.000000.0122 (9)*0.48000
Li10.000000.000000.000000.0122 (9)*0.04000
Nb10.500000.000000.4832 (15)0.0022 (4)*0.98000
Mn10.500000.000000.4832 (15)0.0022 (4)*0.02000
(orthorhombic_1_XRD) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3c = 5.6426 (2) Å
Mr = 170.23V = 125.50 (1) Å3
Orthorhombic, Amm2Z = 2
Hall symbol: A 2 -2Synchrotron radiation
a = 3.94590 (5) ÅT = 300 K
b = 5.6366 (2) Ågrey
Data collection top
Powder
diffractometer
2θmin = 9.000°, 2θmax = 49.492°, 2θstep = 0.002°
Radiation source: synchrotron, DESY/B2
Refinement top
Rp = 0.12220245 data points
Rwp = 0.16366 parameters
Rexp = 0.1150 restraints
RBragg = 0.074
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.250000.248 (3)0.0088 (5)*
O20.000000.000000.523 (2)0.0028 (8)*
Na10.000000.000000.000000.0120 (9)*0.48000
K10.000000.000000.000000.0120 (9)*0.48000
Li10.000000.000000.000000.0120 (9)*0.04000
Nb10.500000.000000.489 (2)0.0035 (4)*0.98000
Mn10.500000.000000.489 (2)0.0035 (4)*0.02000
(orthorhombic_2_XRD) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3c = 5.67416 (10) Å
Mr = 170.23V = 126.73 (1) Å3
Orthorhombic, Amm2Z = 2
Hall symbol: A 2 -2Synchrotron radiation
a = 3.94200 (5) ÅT = 300 K
b = 5.66580 (15) Ågrey
Data collection top
Powder
diffractometer
2θmin = 9.000°, 2θmax = 49.492°, 2θstep = 0.002°
Radiation source: synchrotron, DESY/B2
Refinement top
Rp = 0.12220245 data points
Rwp = 0.16366 parameters
Rexp = 0.1150 restraints
RBragg = 0.071
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.250000.2755 (18)0.0156 (8)*
O20.000000.000000.5344 (15)0.0067 (9)*
Na10.000000.000000.000000.0122 (9)*0.48000
K10.000000.000000.000000.0122 (9)*0.48000
Li10.000000.000000.000000.0122 (9)*0.04000
Nb10.500000.000000.4832 (15)0.0022 (4)*0.98000
Mn10.500000.000000.4832 (15)0.0022 (4)*0.02000
(monoclinic_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3β = 90°
Mr = 170.23V = 63.07 (1) Å3
Monoclinic, P11mZ = 1
Hall symbol: P -2Neutron radiation
a = 4.01035 (5) ÅT = 300 K
b = 3.98782 (5) Ågrey
c = 3.94398 (4) Å
Data collection top
Powder
diffractometer
2θmin = 1.213°, 2θmax = 151.863°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0343014 data points
Rwp = 0.04469 parameters
Rexp = 0.0160 restraints
RBragg = 0.027
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.540 (2)0.525 (3)0.000000.00841 (16)*
O20.5471 (15)0.014 (3)0.500000.00841 (16)*
O30.0407 (17)0.520 (2)0.500000.00841 (16)*
Na10.000000.000000.000000.0138 (4)*0.48000
K10.000000.000000.000000.0138 (4)*0.48000
Li10.000000.000000.000000.0138 (4)*0.04000
Nb10.5021 (16)0.489 (2)0.500000.00072 (18)*0.98000
Mn10.5021 (16)0.489 (2)0.500000.00072 (18)*0.02000
(monoclinic_XRD) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3β = 90°
Mr = 170.23V = 63.07 (1) Å3
Monoclinic, P11mZ = 1
Hall symbol: P -2Synchrotron radiation
a = 4.01035 (5) ÅT = 300 K
b = 3.98782 (5) Ågrey
c = 3.94398 (4) Å
Data collection top
Powder
diffractometer
2θmin = 8.999°, 2θmax = 49.491°, 2θstep = 0.002°
Radiation source: synchrotron, DESY/B2
Refinement top
Rp = 0.11120245 data points
Rwp = 0.15269 parameters
Rexp = 0.1150 restraints
RBragg = 0.072
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.540 (2)0.525 (3)0.000000.00841 (16)*
O20.5471 (15)0.014 (3)0.500000.00841 (16)*
O30.0407 (17)0.520 (2)0.500000.00841 (16)*
Na10.000000.000000.000000.0138 (4)*0.48000
K10.000000.000000.000000.0138 (4)*0.48000
Li10.000000.000000.000000.0138 (4)*0.04000
Nb10.5021 (16)0.489 (2)0.500000.00072 (18)*0.98000
Mn10.5021 (16)0.489 (2)0.500000.00072 (18)*0.02000
(tetragonal_1_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3V = 63.37 (1) Å3
Mr = 170.23Z = 1
Tetragonal, P4mmNeutron radiation
Hall symbol: P 4 -2T = 526 K
a = 3.96592 (8) Ågrey
c = 4.02904 (7) Å
Data collection top
Powder
diffractometer
2θmin = 0.941°, 2θmax = 151.891°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0363014 data points
Rwp = 0.05641 parameters
Rexp = 0.0160 restraints
RBragg = 0.037
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.000000.520 (2)0.0100 (6)*
O20.500000.500000.010 (3)0.0152 (7)*
Na10.000000.000000.000000.0168 (9)*0.48000
K10.000000.000000.000000.0168 (9)*0.48000
Li10.000000.000000.000000.0168 (9)*0.04000
Nb10.500000.500000.478 (2)0.0008 (6)*0.98000
Mn10.500000.500000.478 (2)0.0008 (6)*0.01000
(tetragonal_2_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3V = 63.01 (1) Å3
Mr = 170.23Z = 1
Tetragonal, P4mmNeutron radiation
Hall symbol: P 4 -2T = 526 K
a = 3.95807 (10) Ågrey
c = 4.0220 (2) Å
Data collection top
Powder
diffractometer
2θmin = 0.941°, 2θmax = 151.891°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0363014 data points
Rwp = 0.05641 parameters
Rexp = 0.0160 restraints
RBragg = 0.038
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.000000.565 (4)0.0195 (12)*
O20.500000.500000.066 (4)0.0214 (14)*
Na10.000000.000000.000000.030 (2)*0.48000
K10.000000.000000.000000.030 (2)*0.48000
Li10.000000.000000.000000.030 (2)*0.04000
Nb10.500000.500000.525 (3)0.0131 (12)*0.98000
Mn10.500000.500000.525 (3)0.0131 (12)*0.01000
(cubic_1_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3V = 63.52 (1) Å3
Mr = 170.23Z = 1
Cubic, Pm3mNeutron radiation
Hall symbol: -P 4 2 3T = 776 K
a = 3.99001 (5) Ågrey
Data collection top
Powder
diffractometer
2θmin = 1.241°, 2θmax = 151.891°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0383014 data points
Rwp = 0.06426 parameters
Rexp = 0.0160 restraints
RBragg = 0.043
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.000000.500000.0132 (7)*
Na10.000000.000000.000000.0257 (10)*0.48000
K10.000000.000000.000000.0257 (10)*0.48000
Li10.000000.000000.000000.0257 (10)*0.03984
Nb10.500000.500000.500000.0043 (7)*0.98016
Mn10.500000.500000.500000.0043 (7)*0.01008
(cubic_2_ND) top
Crystal data top
K0.48Na0.48Li0.04Nb0.98Mn0.02O3V = 63.21 (1) Å3
Mr = 170.23Z = 1
Cubic, Pm3mNeutron radiation
Hall symbol: -P 4 2 3T = 776 K
a = 3.98346 (7) Ågrey
Data collection top
Powder
diffractometer
2θmin = 1.241°, 2θmax = 151.891°, 2θstep = 0.050°
Radiation source: nuclear reactor, FRMII/SPODI
Refinement top
Rp = 0.0383014 data points
Rwp = 0.06426 parameters
Rexp = 0.0160 restraints
RBragg = 0.043
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.500000.000000.500000.0250 (7)*
Na10.000000.000000.000000.0377 (11)*0.48000
K10.000000.000000.000000.0377 (11)*0.48000
Li10.000000.000000.000000.0377 (11)*0.03984
Nb10.500000.500000.500000.0142 (7)*0.98016
Mn10.500000.500000.500000.0142 (7)*0.01008
 

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