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In situ synchrotron powder X-ray diffraction (PXRD) is used to study the formation of LiFePO4 nanoparticles during hydrothermal synthesis from LiOH, H3PO4, and two different iron precursors, FeSO4 and (NH4)2Fe(SO4)2. Furthermore, the synthesis of Li(Fe1-xMnx)PO4 (x = 0.25, 0.50 and 0.75) from LiOH, H3PO4 and FeSO4/MnSO4 is studied. The reactions involve an unknown intermediate phase, which is not the previously observed intermediate NH4FePO4·H2O. The intermediate phase quickly transforms into LiFePO4 and Li(Fe1-xMnx)PO4 even at rather low temperatures. The presence of ammonium enhances the formation of LiFePO4, and it also leads to a significant reduction in the concentration of Li-Fe antisite defects. The in situ PXRD technique allows one to follow the influence of time, temperature and manganese doping on the antisite defect concentration, and it is shown that even under supercritical conditions a reaction time of several minutes is required to suppress the defects. This makes flow synthesis of defect-free LiFePO4 and Li(Fe1-xMnx)PO4 nanoparticles challenging.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0021889811006522/ko5132sup1.cif
Contains datablocks global, LiFePO4345, LiFe075Mn025PO4345, LiFe050Mn050PO4345, LiFe025Mn075PO4345

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0021889811006522/ko5132sup2.hkl
Contains datablock profile1

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0021889811006522/ko5132sup3.hkl
Contains datablock profile1

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0021889811006522/ko5132sup4.hkl
Contains datablock profile1

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0021889811006522/ko5132sup5.hkl
Contains datablock profile1

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0021889811006522/ko5132sup6.pdf
Supplementary figures and Rietveld refinement data

Computing details top

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

Figures top
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
[Figure 6]
[Figure 7]
(LiFePO4345) top
Crystal data top
?c = 4.7325 (2) Å
Mr = ?V = 297.91 (2) Å3
Orthorhombic, PnmaZ = ?
Hall symbol: -P 2ac 2n? radiation, λ = 0.998140 Å
a = 10.4008 (4) Å?, ? × ? × ? mm
b = 6.0523 (2) Å
Data collection top
Radiation source: Synchrotron2θmin = 3.204°, 2θmax = 41.754°, 2θstep = 0.035°
Refinement top
Rp = 0.3841096 data points
Rwp = 0.62041 parameters
Rexp = 0.1790 restraints
RBragg = 4.198
χ2 = NOT FOUND
Crystal data top
?c = 4.7325 (2) Å
Mr = ?V = 297.91 (2) Å3
Orthorhombic, PnmaZ = ?
a = 10.4008 (4) Å? radiation, λ = 0.998140 Å
b = 6.0523 (2) Å?, ? × ? × ? mm
Data collection top
2θmin = 3.204°, 2θmax = 41.754°, 2θstep = 0.035°
Refinement top
Rp = 0.384χ2 = NOT FOUND
Rwp = 0.6201096 data points
Rexp = 0.17941 parameters
RBragg = 4.1980 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Li10.000000.000000.000000.00000*0.996 (4)
Fe10.2822 (3)0.250000.9769 (11)0.00000*0.996 (4)
P10.0991 (8)0.250000.416 (2)0.00000*
O10.094 (2)0.250000.726 (4)0.00000*
O20.458 (2)0.250000.207 (2)0.00000*
O30.1638 (13)0.046 (2)0.2807 (17)0.00000*
Fe20.000000.000000.000000.00000*0.010 (4)
Li20.2822 (3)0.250000.9769 (11)0.00000*0.010 (4)
(LiFe075Mn025PO4345) top
Crystal data top
?c = 4.72107 (7) Å
Mr = ?V = 295.93 (1) Å3
Orthorhombic, PnmaZ = ?
Hall symbol: -P 2ac 2n? radiation, λ = 0.944490 Å
a = 10.37894 (15) Å?, ? × ? × ? mm
b = 6.03945 (9) Å
Data collection top
Radiation source: Synchrotron2θmin = 3.628°, 2θmax = 43.965°, 2θstep = 0.037°
Refinement top
Rp = 0.3121081 data points
Rwp = 0.37344 parameters
Rexp = 0.0040 restraints
RBragg = 1.441
χ2 = NOT FOUND
Crystal data top
?c = 4.72107 (7) Å
Mr = ?V = 295.93 (1) Å3
Orthorhombic, PnmaZ = ?
a = 10.37894 (15) Å? radiation, λ = 0.944490 Å
b = 6.03945 (9) Å?, ? × ? × ? mm
Data collection top
2θmin = 3.628°, 2θmax = 43.965°, 2θstep = 0.037°
Refinement top
Rp = 0.312χ2 = NOT FOUND
Rwp = 0.3731081 data points
Rexp = 0.00444 parameters
RBragg = 1.4410 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Li10.000000.000000.000000.00000*1.0000 (17)
Fe10.28314 (11)0.250000.9735 (4)0.00000*0.4981 (17)
Li20.28314 (11)0.250000.9735 (4)0.00000*0.0038 (17)
0.00000.0968 (3)0.250000.4151 (5)0.00000*
O10.0947 (6)0.250000.7343 (10)0.00000*
O20.4551 (7)0.250000.2079 (9)0.00000*
O30.1660 (5)0.0496 (8)0.2829 (6)0.00000*
Fe0.000000.000000.000000.00000*0.0038 (17)
Mn0.28314 (11)0.250000.9735 (4)0.00000*0.50193
(LiFe050Mn050PO4345) top
Crystal data top
?c = 4.73357 (13) Å
Mr = ?V = 298.63 (1) Å3
Orthorhombic, PnmaZ = ?
Hall symbol: -P 2ac 2n? radiation, λ = 0.944490 Å
a = 10.4072 (3) Å?, ? × ? × ? mm
b = 6.06188 (14) Å
Data collection top
Radiation source: Synchrotron2θmin = 3.442°, 2θmax = 43.966°, 2θstep = 0.037°
Refinement top
Rp = 0.4141086 data points
Rwp = 0.61048 parameters
Rexp = 0.3330 restraints
RBragg = 3.948
χ2 = NOT FOUND
Crystal data top
?c = 4.73357 (13) Å
Mr = ?V = 298.63 (1) Å3
Orthorhombic, PnmaZ = ?
a = 10.4072 (3) Å? radiation, λ = 0.944490 Å
b = 6.06188 (14) Å?, ? × ? × ? mm
Data collection top
2θmin = 3.442°, 2θmax = 43.966°, 2θstep = 0.037°
Refinement top
Rp = 0.414χ2 = NOT FOUND
Rwp = 0.6101086 data points
Rexp = 0.33348 parameters
RBragg = 3.9480 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Li10.000000.000000.000000.00000*0.999 (3)
Fe10.2828 (2)0.250000.9705 (7)0.00000*0.497 (3)
Mn10.2828 (2)0.250000.9705 (7)0.00000*0.50175
P10.0952 (6)0.250000.4169 (11)0.00000*
O10.0939 (13)0.250000.731 (2)0.00000*
O20.4495 (15)0.250000.2062 (14)0.00000*
O30.1604 (8)0.0537 (14)0.2778 (12)0.00000*
Fe20.000000.000000.000000.00000*0.004 (3)
Li20.2828 (2)0.250000.9705 (7)0.00000*0.004 (3)
(LiFe025Mn075PO4345) top
Crystal data top
?c = 4.74531 (18) Å
Mr = ?V = 300.97 (2) Å3
Orthorhombic, PnmaZ = ?
Hall symbol: -P 2ac 2n? radiation, λ = 0.944490 Å
a = 10.4303 (3) Å?, ? × ? × ? mm
b = 6.08084 (19) Å
Data collection top
Radiation source: Synchrotron2θmin = 3.444°, 2θmax = 43.968°, 2θstep = 0.037°
Refinement top
Rp = 0.3631086 data points
Rwp = 0.48946 parameters
Rexp = 0.3530 restraints
RBragg = 3.567
χ2 = NOT FOUND
Crystal data top
?c = 4.74531 (18) Å
Mr = ?V = 300.97 (2) Å3
Orthorhombic, PnmaZ = ?
a = 10.4303 (3) Å? radiation, λ = 0.944490 Å
b = 6.08084 (19) Å?, ? × ? × ? mm
Data collection top
2θmin = 3.444°, 2θmax = 43.968°, 2θstep = 0.037°
Refinement top
Rp = 0.363χ2 = NOT FOUND
Rwp = 0.4891086 data points
Rexp = 0.35346 parameters
RBragg = 3.5670 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Li10.000000.000000.000000.00000*1.000 (2)
Fe10.28274 (17)0.250000.9712 (6)0.00000*0.244 (2)
Mn10.28274 (17)0.250000.9712 (6)0.00000*0.75623
P10.0944 (5)0.250000.4155 (10)0.00000*
O10.0988 (11)0.250000.7297 (18)0.00000*
O20.4542 (12)0.250000.2048 (12)0.00000*
O30.1600 (7)0.0515 (12)0.2797 (10)0.00000*
Fe20.000000.000000.000000.00000*0.008 (2)
Li20.28274 (17)0.250000.9712 (6)0.00000*0.008 (2)

Experimental details

(LiFePO4345)(LiFe075Mn025PO4345)(LiFe050Mn050PO4345)(LiFe025Mn075PO4345)
Crystal data
Chemical formula????
Mr????
Crystal system, space groupOrthorhombic, PnmaOrthorhombic, PnmaOrthorhombic, PnmaOrthorhombic, Pnma
Temperature (K)????
a, b, c (Å)10.4008 (4), 6.0523 (2), 4.7325 (2)10.37894 (15), 6.03945 (9), 4.72107 (7)10.4072 (3), 6.06188 (14), 4.73357 (13)10.4303 (3), 6.08084 (19), 4.74531 (18)
V3)297.91 (2)295.93 (1)298.63 (1)300.97 (2)
Z????
Radiation type?, λ = 0.998140 Å?, λ = 0.944490 Å?, λ = 0.944490 Å?, λ = 0.944490 Å
Specimen shape, size (mm)?, ? × ? × ??, ? × ? × ??, ? × ? × ??, ? × ? × ?
Data collection
Diffractometer????
Specimen mounting????
Data collection mode????
Scan method????
2θ values (°)2θmin = 3.204 2θmax = 41.754 2θstep = 0.0352θmin = 3.628 2θmax = 43.965 2θstep = 0.0372θmin = 3.442 2θmax = 43.966 2θstep = 0.0372θmin = 3.444 2θmax = 43.968 2θstep = 0.037
Refinement
R factors and goodness of fitRp = 0.384, Rwp = 0.620, Rexp = 0.179, RBragg = 4.198, χ2 = NOT FOUNDRp = 0.312, Rwp = 0.373, Rexp = 0.004, RBragg = 1.441, χ2 = NOT FOUNDRp = 0.414, Rwp = 0.610, Rexp = 0.333, RBragg = 3.948, χ2 = NOT FOUNDRp = 0.363, Rwp = 0.489, Rexp = 0.353, RBragg = 3.567, χ2 = NOT FOUND
No. of data points1096108110861086
No. of parameters41444846

Computer programs: FULLPROF.

 

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