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A series of cobalt-exchanged hydroxyapatite (CoHAp) powders with different Ca/Co ratios and nominal unit-cell contents Ca10−xCox(PO4)6(OH)2, x = 0, 0.5, 1.0, 1.5 and 2.0, were synthesized by hydrothermal treatment of a precipitate at 473 K for 8 h. Based on ICP (inductively coupled plasma) emission spectroscopy analysis, it was established that the maximum amount of cobalt incorporation saturated at ∼12 at.% under these conditions. The effects of cobalt content on the CoHAp powders were investigated using ICP emission spectroscopy, particle size analysis, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) analyses as well as X-ray powder diffraction (XRPD) including Rietveld analysis. According to XRPD, all the materials are single-phase HAp and CoHAp of low crystallinity. Rietveld analysis shows that Co enrichment causes the c cell parameter to decrease at a faster rate than the a cell parameter. A microstructural analysis showed anisotropic X-ray line broadening due to crystallite size reduction. In CoHAp there is significant crystal elongation in [001], and the average size decreases with increasing cobalt content. The crystallite morphology transforms from rod-like for the pure HAp to lamellae at the highest degree of Co substitution. The results of Rietveld refinement (symmetry, size and morphology of the crystallites) were confirmed by TEM and HRTEM analysis.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0021889809051395/ks5226sup1.cif
Contains datablocks HAp, Co5HAp, Co10HAp, Co15HAp, Co20HAp

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0021889809051395/ks5226sup2.rtv
Contains datablocks HAp, CO5HAp, CO10HAp, CO15HAP, Co20HAp

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]
(HAp) hydroxyapatite top
Crystal data top
HCa5O13P3V = 528.83 (1) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540562 Å
Hall symbol: -P 6cT = 293 K
a = 9.4210 (1) Å?, ? × ? × ? mm
c = 6.8800 (1) Å
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Radiation source: X-ray tube
Refinement top
Rp = 9.494Profile function: pseudo-Voigt
Rwp = 13.4924 parameters
Rexp = 10.1324 restraints
RBragg = 3.721
χ2 = NOT FOUNDBackground function: square polynomial for each range
5096 data points
Crystal data top
HCa5O13P3V = 528.83 (1) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540562 Å
a = 9.4210 (1) ÅT = 293 K
c = 6.8800 (1) Å?, ? × ? × ? mm
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Refinement top
Rp = 9.494χ2 = NOT FOUND
Rwp = 13.4925096 data points
Rexp = 10.1324 parameters
RBragg = 3.7214 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ca10.333300.666700.000920.01900*
Ca20.245250.993330.250000.01900*
P0.398110.369520.250000.01900*
O10.327110.484740.250000.01900*
O20.586160.465000.250000.01900*
O30.341520.255830.072610.01900*
O40.000000.000000.188190.01900*
(Co5HAp) cobalt exchanged hydroxyapatite top
Crystal data top
Ca9.57Co0.43(PO4)6(OH)2V = 527.38 (3) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
Hall symbol: -P 6cT = 293 K
a = ? Å?, ? × ? × ? mm
c = 6.8670 (2) Å
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Radiation source: X-ray tube
Refinement top
Rp = 9.424Profile function: pseudo-Voigt
Rwp = 12.02428 parameters
Rexp = 15.3464 restraints
RBragg = 5.094
χ2 = NOT FOUNDBackground function: square polynomial for each range
5096 data points
Crystal data top
Ca9.57Co0.43(PO4)6(OH)2V = 527.38 (3) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
a = ? ÅT = 293 K
c = 6.8670 (2) Å?, ? × ? × ? mm
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Refinement top
Rp = 9.424χ2 = NOT FOUND
Rwp = 12.0245096 data points
Rexp = 15.34628 parameters
RBragg = 5.0944 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.333300.666700.002250.01900*
Co10.333300.666700.002250.01900*0.01359
Ca20.244900.993350.250000.01900*0.978 (3)
Co20.244900.993350.250000.01900*0.03904
P0.396660.369680.250000.01900*
O10.329520.488250.250000.01900*
O20.584790.463720.250000.01900*
O30.344110.260130.068540.01900*
O40.000000.000000.177790.01900*0.50678
(Co10HAp) cobalt exchanged hydroxyapatite top
Crystal data top
Ca9.05Co0.95(PO4)6(OH)2V = 524.81 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540562 Å
Hall symbol: -P 6cT = 293 K
a = 9.4039 (4) Å?, ? × ? × ? mm
c = 6.8526 (4) Å
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Radiation source: X-ray tube
Refinement top
Rp = 4.382Profile function: pseudo-Voigt
Rwp = 5.55036 parameters
Rexp = 7.2004 restraints
RBragg = 3.841
χ2 = NOT FOUNDBackground function: square polynomial for each range
5096 data points
Crystal data top
Ca9.05Co0.95(PO4)6(OH)2V = 524.81 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540562 Å
a = 9.4039 (4) ÅT = 293 K
c = 6.8526 (4) Å?, ? × ? × ? mm
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Refinement top
Rp = 4.382χ2 = NOT FOUND
Rwp = 5.5505096 data points
Rexp = 7.20036 parameters
RBragg = 3.8414 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.333300.666700.002790.01900*1.000 (9)
Co10.333300.666700.002790.01900*0.052 (9)
Ca20.246710.996080.250000.01900*0.958 (12)
Co20.246710.996080.250000.01900*0.094 (12)
P0.396060.367490.250000.01900*
O10.329800.487010.250000.01900*
O20.584380.465060.250000.01900*
O30.344350.257650.068240.01900*
O40.000000.000000.183250.01900*0.52604
(Co15HAp) cobalt exchanged hydroxyapatite top
Crystal data top
Ca8.83Co1.17(PO4)6(OH)2V = 525.05 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
Hall symbol: -P 6cT = 293 K
a = 9.4109 (4) Å?, ? × ? × ? mm
c = 6.8456 (4) Å
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Radiation source: X-ray tube
Refinement top
Rp = 3.396Profile function: pseudo-Voigt
Rwp = 4.26722 parameters
Rexp = 5.5334 restraints
RBragg = 4.230
χ2 = NOT FOUNDBackground function: square polynomial for each range
5096 data points
Crystal data top
Ca8.83Co1.17(PO4)6(OH)2V = 525.05 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
a = 9.4109 (4) ÅT = 293 K
c = 6.8456 (4) Å?, ? × ? × ? mm
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Refinement top
Rp = 3.396χ2 = NOT FOUND
Rwp = 4.2675096 data points
Rexp = 5.53322 parameters
RBragg = 4.2304 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.333300.666700.005000.01900*
Co10.333300.666700.005000.01900*0.06105
Ca20.247590.998410.250000.01900*0.96239
Co20.247590.998410.250000.01900*0.09868
P0.395940.367770.250000.01900*
O10.333080.489920.250000.01900*
O20.584040.467110.250000.01900*
O30.345580.255910.070110.01900*
O40.000000.000000.178210.01900*0.53051
(Co20HAp) cobalt exchanged hydroxyapatite top
Crystal data top
Ca8.85Co1.15(PO4)6(OH)2V = 524.21 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
Hall symbol: -P 6cT = 293 K
a = ? Å?, ? × ? × ? mm
c = 6.8400 (2) Å
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Radiation source: X-ray tube
Refinement top
Rp = 3.942Profile function: pseudo-Voigt
Rwp = 4.93338 parameters
Rexp = 6.3534 restraints
RBragg = 3.720
χ2 = NOT FOUNDBackground function: square polynomial for each range
5096 data points
Crystal data top
Ca8.85Co1.15(PO4)6(OH)2V = 524.21 (4) Å3
Mr = ?Z = 2
Hexagonal, P63/MX-ray radiation, λ = 1.540560 Å
a = ? ÅT = 293 K
c = 6.8400 (2) Å?, ? × ? × ? mm
Data collection top
Philips 1050
diffractometer
2θmin = 8°, 2θmax = 110°, 2θstep = 0.02°
Refinement top
Rp = 3.942χ2 = NOT FOUND
Rwp = 4.9335096 data points
Rexp = 6.35338 parameters
RBragg = 3.7204 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.333330.666670.003110.01900*1.00 (3)
Co10.333330.666670.003110.01900*0.03 (3)
Ca20.246570.997610.250000.01900*0.91 (2)
Co20.246570.997610.250000.01900*0.12 (2)
P0.396270.367700.250000.01900*
O10.332490.489180.250000.01900*
O20.584520.465780.250000.01900*
O30.342950.257490.068360.01900*
O40.000000.000000.174980.01900*0.51464

Experimental details

(HAp)(Co5HAp)(Co10HAp)(Co15HAp)
Crystal data
Chemical formulaHCa5O13P3Ca9.57Co0.43(PO4)6(OH)2Ca9.05Co0.95(PO4)6(OH)2Ca8.83Co1.17(PO4)6(OH)2
Mr????
Crystal system, space groupHexagonal, P63/MHexagonal, P63/MHexagonal, P63/MHexagonal, P63/M
Temperature (K)293293293293
a, c (Å)9.4210 (1), 6.8800 (1)?, 6.8670 (2)9.4039 (4), 6.8526 (4)9.4109 (4), 6.8456 (4)
V3)528.83 (1)527.38 (3)524.81 (4)525.05 (4)
Z2222
Radiation typeX-ray, λ = 1.540562 ÅX-ray, λ = 1.540560 ÅX-ray, λ = 1.540562 ÅX-ray, λ = 1.540560 Å
Specimen shape, size (mm)?, ? × ? × ??, ? × ? × ??, ? × ? × ??, ? × ? × ?
Data collection
DiffractometerPhilips 1050
diffractometer
Philips 1050
diffractometer
Philips 1050
diffractometer
Philips 1050
diffractometer
Specimen mounting????
Data collection mode????
Scan method????
2θ values (°)2θmin = 8 2θmax = 110 2θstep = 0.022θmin = 8 2θmax = 110 2θstep = 0.022θmin = 8 2θmax = 110 2θstep = 0.022θmin = 8 2θmax = 110 2θstep = 0.02
Refinement
R factors and goodness of fitRp = 9.494, Rwp = 13.492, Rexp = 10.132, RBragg = 3.721, χ2 = NOT FOUNDRp = 9.424, Rwp = 12.024, Rexp = 15.346, RBragg = 5.094, χ2 = NOT FOUNDRp = 4.382, Rwp = 5.550, Rexp = 7.200, RBragg = 3.841, χ2 = NOT FOUNDRp = 3.396, Rwp = 4.267, Rexp = 5.533, RBragg = 4.230, χ2 = NOT FOUND
No. of data points5096509650965096
No. of parameters4283622
No. of restraints4444


(Co20HAp)
Crystal data
Chemical formulaCa8.85Co1.15(PO4)6(OH)2
Mr?
Crystal system, space groupHexagonal, P63/M
Temperature (K)293
a, c (Å)?, 6.8400 (2)
V3)524.21 (4)
Z2
Radiation typeX-ray, λ = 1.540560 Å
Specimen shape, size (mm)?, ? × ? × ?
Data collection
DiffractometerPhilips 1050
diffractometer
Specimen mounting?
Data collection mode?
Scan method?
2θ values (°)2θmin = 8 2θmax = 110 2θstep = 0.02
Refinement
R factors and goodness of fitRp = 3.942, Rwp = 4.933, Rexp = 6.353, RBragg = 3.720, χ2 = NOT FOUND
No. of data points5096
No. of parameters38
No. of restraints4

Computer programs: FULLPROF.

 

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