Structure Refinements of Co3(PO4)2. A Note on the Reliability of Powder Diffraction Studies.

Nord, Anders G.; Stefanidis, T.; Møllendal, Harald; Priebe, H.; Nielsen, O. Faurskov

doi:10.3891/acta.chem.scand.37a-0715

Cited by 15 publications

(8 citation statements)

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“…The oxygen−oxygen distance between nearest-neighbor oxygen atoms in the basal plane of LiCoO 2 (2.816 Å) is very similar to the oxygen distances in the orthophosphate molecule, and previous crystallographic comparisons on other materials have shown that the bidentate conformation of phosphate on the surface of other metal oxides is geometrically feasible. 53 The oxygen−oxygen distances in LiCoO 2 are further comparable to the oxygen−oxygen bond distances in several bulk cobalt phosphates where oxygen− oxygen distances are 2.5−2.8 Å on average for cobalt tetrametaphosphate, 54 cobalt phosphate, 55 and cobalt diphosphate, 56 which further supports the model of a bidentate surface adsorption and formation of an inorganic cobalt phosphate coating presented here. 54−56 While the concentrations of phosphate studied here are higher than typical environmental concentrations, the final coordination of phosphate on the surface of LiCoO 2 at 100 μM phosphate is the same as we determined in our previous study at a more environmentally relevant concentration of 1 μM phosphate.…”

Section: ■ Results and Discussionsupporting

confidence: 79%

Interaction of Phosphate with Lithium Cobalt Oxide Nanoparticles: A Combined Spectroscopic and Calorimetric Study

Laudadio

Ilani-Kashkouli²,

Green

et al. 2019

Langmuir

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Adsorption of small ions such as phosphates to the surfaces of metal oxides can significantly alter the behavior of these materials, especially when present in the nanoscale form. Lithium cobalt oxide is a good model system for understanding smallmolecule interactions with emerging nanomaterials because of its widespread use in lithium ion batteries and its known activity as a water oxidation catalyst. Here, we present a thermodynamic analysis of phosphate adsorption to LiCoO 2 and corroborate the results with additional in situ techniques, including zeta potential measurements and attenuated total reflectance−Fourier transform infrared (ATR−FTIR) spectroscopy, at pH values relevant to potential environmental release scenarios. Flow microcalorimetry measurements of phosphate interaction with LiCoO 2 at pH 7.4 show that there are two distinct exothermic processes taking place. Time-sequence in situ ATR−FTIR with two-dimensional correlation analysis reveals the spectroscopic signatures of these processes. We interpret the data as an interaction of phosphate with LiCoO 2 that occurs through the release of two water molecules and is therefore, best described as a condensation process rather than a simple adsorption, consistent with prior studies, demonstrating that phosphate interaction with LiCoO 2 is highly irreversible. Additional measurements for over longer times of 5 months show that phosphate adsorption terminates with one surface layer and that continued transformation over longer periods of time arises from H + /Li + exchange and slow transformation to a cobalt hydroxide, with phosphate adsorbed to the surface only. To the best of our knowledge, this is the first time that flow microcalorimetry and two-dimensional correlation spectroscopy have been applied in tandem to clarify the specific chemical reactions that occur at the interface of solids and adsorbates.

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Section: ■ Results and Discussionsupporting

confidence: 79%

Interaction of Phosphate with Lithium Cobalt Oxide Nanoparticles: A Combined Spectroscopic and Calorimetric Study

Laudadio

Ilani-Kashkouli²,

Green

et al. 2019

Langmuir

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“…The MO 6 octahedron is very distorted due to the edge sharing with the P(2)O 4 tetrahedron. Indeed, the M-O distances are highly dispersed [ 15 ], 2.120 Å for Mg [ 16 ], 2.142 Å for Co [ 17 ]). The FeO 5 polyhedron is also highly distorted in view of the great discrepancy of Fe-O distances, varying between 1.891(2)-2.012(2) Å for KNi, 1.898(2)-2.013(2) Å for KMg-LT, and 1.892(2)-2.001(2) Å for KCo-LT.…”

Section: Resultsmentioning

confidence: 99%

CRYSTAL STRUCTURE AND THERMAL STABILITY OF NEW IRON PHOSPHATES KMFe(PO4)2 (M = Ni, Mg, and Co)

2015

JSC

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Three isostructural iron monophosphates KNiFe(PO 4) 2 (KNi), KMgFe(PO 4) 2 (KMg-LT, where LT means ″low-temperature stable phase″), and KCoFe(PO 4) 2 (KCo-LT) are synthesized and structurally characterized from X-ray diffraction data. They crystallize in the monoclinic system with the space group P2 1 /c. Their structures have in common a three-dimensional framework, built up by infinite zigzag chains of edge-sharing MO 6 (M = Ni, Mg or Co) octahedra, linked by FeO 5 and PO 4 polyhedra via vertices and edges to form a rigid skeleton. The K + ions are located in formed tunnels. DTA showed that KNi has a congruent melting at 941 °C, whereas KMg-LT and KCo-LT undergo irreversible phase transitions from P2 1 /c to different high-temperature structures with the C2/c symmetry. IR absorption bands are assigned to different vibrations of the PO 4 tetrahedron.

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“…These bands are in good accordance with the presence of Co 2+ ions in both octahedral and trigonal bipyramidal coordination, which are the two crystallographic sites for the cobalt ion in the diphosphate (Co 2 P 2 O 7 ) and orthophosphate (Co 3 (PO 4 ) 2 ) structures. 30,31 In effect, the bands around 1238, 591 and 525 can be assigned to ν 1 ( 4 T 1 (F) → 4 T 2 (F)), ν 2 ( 4 T 1 (F) → 4 A 2 (F)), and ν 3 ( 4 T 1 (F) → 4 T 1 (P)) spin-allowed transitions of Co 2+ ions in an octahedral ligand field, respectively. 23 On the other hand, the bands around 1683, 850 and 472 nm could correspond to 4 A 2 → 4 A 1 (2500-1111 nm), 4 A 2 → 4 E (1000-676 nm) and 4 A 2 → 4 E (P) (582-476 nm) transitions of Co 2+ in high spin trigonal bipyramidal sites.…”

Section: Electron Microscopy Characterization (Sem/edx)mentioning

confidence: 99%

Blue-violet ceramic pigments based on Co and Mg Co2−xMgxP2O7 diphosphates

Llusar¹,

Zielińska²,

Tena³

et al. 2010

Journal of the European Ceramic Society

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Structure Refinements of Co3(PO4)2. A Note on the Reliability of Powder Diffraction Studies.

Cited by 15 publications

References 0 publications

Interaction of Phosphate with Lithium Cobalt Oxide Nanoparticles: A Combined Spectroscopic and Calorimetric Study

Interaction of Phosphate with Lithium Cobalt Oxide Nanoparticles: A Combined Spectroscopic and Calorimetric Study

CRYSTAL STRUCTURE AND THERMAL STABILITY OF NEW IRON PHOSPHATES KMFe(PO4)2 (M = Ni, Mg, and Co)

Blue-violet ceramic pigments based on Co and Mg Co2−xMgxP2O7 diphosphates

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