Crystal Chemistry, Properties and Applications of Phosphates

Abdelaziz El Jazouli

University Hassan II, Casablanca, Morocco Wake Forest University, Winston-Salem, North Carolina, USA ----------------------------------------------------------------------------------

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Crystallography for the next generation

The Legacy of the International Year of Crystallography Rabat, 22-24 April 2015

Outline - General introduction on phosphates - Structures and properties of some phosphates * Oxyphosphates * Monophosphates * Diphosphates

General introduction on phosphates

- Use of phosphates - Classification of phosphates

Uses of phosphates Inorganic phosphates exit in both crystalline and glassy form. P2O5 is an forming oxide like SiO2 and B2O3. Phosphate-based materials have potential applications in many fields : Biomaterials

Electrodes for batteries Optical components : Lasers, LEDs, Catalysists Stock of radioelements Pigments Cosmetics,…..

Some important phosphate families: Apatite : Biomaterials Nasicon (Na super ionic conductor) : ionic conductors, electrode materials, photoctalysists, sensors

Zeolite : Catalysis,… Olivine : Li-batteries KTP (KTiOPO4) : No Linear Optical Materials ---------------------------------------------

Glasses : Lasers, bioglasses , stock of nuclear waste

Lasers

Luminophores Pigments

Electric vehicles LiFePO4

Biomaterials

Classification of phosphates*

The basic unit of phosphate structures is the PO4 tetrahedron.

O2

O/P > 4 : Oxyphosphates :

K(TiO)(PO4) ; Ca10O(PO4)6

O/P = 4 : Monophosphates : Na3PO4; FePO4

O/P < 4 : Condensed Phosphates* : Na4P2O7 ; Na5P3O10; NaPO3

Remarks: WVIP2O8 (O/P=4) : WVIO(P2O7) oxydiphosphate Mixt anions :

O3

O1

Li9Fe3(P2O7)3(PO4)2

* A. Durif. Crystal Chemistry of Condensed Phosphates, (1995), NY-L, Plenum Press.

O4

Monophosphates

4 kinds of PO4 groups Qn notation n is the number of the bridging oxygens

O

P

π

Branching group Q3 (P2O5)

Middle group Q2

(NaPO3)

Terminal group Q1 (TiP2O7)

Isolated group

Q0 (FePO4)

Oxyphosphates M(VO)2(PO4)2

(M = Co, Ni)

M(TiO)2(PO4)2

(M = Mg, Fe, Co, Ni, Cu, Zn)

PbFe3O(PO4)3

Co(VO)2(PO4)2

; PbFe3O(PO4)3

Elaboration

Co(VO)2(PO4)2

Powder : V2O3 + V2O5 + 2Co(PO3)2

2Co(VO)2(PO4)2

- Alpha phase () :

T= 700°C (under vacuum)

- Beta phase () :

T= 900°C (under vacuum)

Single crystals : - Alpha phase () : Crystalline powder of -phase contains microcrystals (dimensions : ~ 20 m)

- Beta phase : Melting of  powder at 1100°C (under vacuum) + slow cooling (5°C/h)

single crystals

(dimensions: ~ 80/60/60 m) -------------------------------------------------------------------------------------------------------------------------------------------------Syntheses and Crystal Structures of new vanadium (IV) oxyphosphates M(VO)2(PO4)2 with M= Co, Ni.

S. Kaoua, P. Gravereau, J. P. Chaminade, S. Pechev, S. Krimi, and A. El Jazouli. J. State Sciences, 11 (3), 2009, 628 - 634.

VO6

PO4 Co

Co(VO)2(PO4)2 Vanadium atom is displaced from the centre of the octahedron giving rise to an alternating long (2.369Å) and short (1.616Å) V-O1 bonds. The four remaining V-O bond distances have intermediate values ranging between 1.914Å and 2.040Å. R(O2-) + Ri(V4+) = 1.96Å

VO6

O1

(VO6) octahedra linked by corners along c axis V− O(1)−V −O(1)−V −O(1) −V −O(1) ~ 2.37Å~ 1.62 Å ~ 2.37 Å ~ 1.62 Å ~ 2.37 Å ~ 1.62 Å

Vanadyl ion (VO)2+ Vanadyl phosphate

(VO6) octahedra and PO4 tetrahedra in -M(VO)2(PO4)2 (M= Co, Ni)

Co(VO)2(PO4)2 -

Co2+ion: triangular based antiprism,located between two VO6 octahedra Co-O distances : 2.087Å - 2.103Å Ionic radii sum of O2- and Co2+ : 2.12Å Slight covalent character of Co-O bonds

CoO6

Co(VO)2(PO4)2

PO4 tetrahedra are quite regular

P-O distances : 1.506Å - 1.548Å O-P-O angles : 106.5° - 112.2°.

PO4

Raman spectra

α - Co(VO)2(PO4)2

Co(TiO)2(PO4)2

V-O : 1.62 – 2.25 Å

Ti-O : 1.70 – 2.30 Å

-V-O-V-O-V-O-V-

850 cm-1

-Ti-O-Ti-O-Ti-O-Ti-

750

25000

cm-1

25000

Phase 

20000

20000 15000

15000 10000

10000

External modes

External modes

PO4 (v1, v3)

PO4 (v2, v4)

Phase 

5000

PO4 (v2, v4) 0

PO4 (v1, v3)

5000

200 200

400

400

600

800 1000 1200 1400

600

800

-1

1000  (cm )

cm-1 0 200

400

600

800

1000

cm-1

Magnetic properties Co(TiO)2(PO4)2

Co(VO)2(PO4)2 Co2+ : 3d7 ; V4+ : 3d1

χ

χ-1

0,07

Co2+ : 3d7 ; Ti4+ : 3d0

100

χ-1

0,06

80 0,05

chimol

60

0,03 40

invchimol

0,04

0,02

0,01

20

0,00 0

50

100

150

200

T(K)

250

300

350

d(Co – Co) = 5.21A

PbFe3O(PO4)3 Syntehsis, structure and magnetic properties Powder:

Co-precipitation : Pb(NO3)2, Fe(NO3)3.9H2O)9 and (NH4)2HPO4 Solid state : SrCO3 (CaCO3), Fe2O3 and (NH4)HPO4

Thermal treatments 100°C, 200°C, 400°C and 880°C, 72 h Powder color : red

Single crystal: Combination of flux and Bridgman methods

PbFe3O(PO4)3 structure determination by single crystal XRD (1)

Mirror plane m passing through O6, O8, O9 and O10 (1.9% deviation from perfect octahedron/1.8% deviation from inversion point)

Infinite chain parallel to b

Mirror plane m passing through O3, O5 and O8 (4.2% deviation from perfect square base pyramid/6% deviation from perfect triangle bi-pyramid/21.4% deviation from inversion point)

Inversion point (1% deviation from perfect octahedron)

Structure of PbFe3O(PO4)3

Planes are connected by [PO4] tetrahedra. Pb2+ cations occupy cavities located between these planes

3D framework showing channels along the b direction

Static susceptibility measurements

Comparison of thermodynamic response functions in both PbFe3O(PO4)3 single crystals and sintered pellets

PbFe3O(PO4)3 : Mössbauer study

Purely magnetic and temperature reversible phase transition at 32 and 10 K

Magnetic structure of PbFe3O(PO4)3 at 30 K (single crystal neutron scattering, Collaboration With G. Nénert, ILL, Grenoble)

Fe1 Fe2 Fe3

All magnetic moments are practically lined up parallel to b direction

Monophosphates Na(5-2x)Ca2xTi(PO4)3 (0≤x≤1)

Crystalline and vitreous materials Synthesis : Glasses : Melting + quenching Powder: crystallisation of glasses. solid state reaction. Single crystals :Melting + slow cooling

Characterizations : XRD, DTA, Density, Raman, UV-VIS, Ionic conductivity, Bioactivity

Crystalline phases XRD : Na5Ti(PO4)3 (Nasicon) 116 122

113 003 101 012

10

205

006 104 110

202

024

211

20

30

Cell parameters Hexagonal, S. G. : R32 ah = 9.061 Å ch = 21.734 Å

214 300 018

2 

(°)

Na(5-2x)CaxTi(PO4)3 (0≤x≤1) solid solution x=1

x = 0.75

x = 0.5

x = 0.25

x=0

20

40

2



(°)

Structure of Na3CaTi(PO4)3 PO4

TiO6

Na : M1 and M2 sites CaO6 PO4

Raman Na5Ti(PO4)3 -Ti - O - Ti - O -Ti – O – Ti -

Glass

Crystal

400

800 -1 Frequency (Cm )

1200 30

Ionic Conductivity at 300°C Na5-2xCax☐xTi(PO4)3 4 -1 -1  x 10 ( Cm )

Crystalline phases

4 3

2 1 0

0.0

0.5

Composition x

1.0

Activation energy Na5-2xCaxTi(PO4)3 crystalline phases Ea (eV) 0.88 0.84 0.80 0.76 0.72

0.0

0.2

0.4

0.6

0.8

Composition x

 Empty sites (vacancies) 2+ 2+  A (Ca ) in [A] sites (framework) + Displacement of Na ions is facilitated

1.0

Activation energy Na(5-2x)CaxTi(PO4)3

glasses

Ea(eV) 1.0 0.9 0.8 0.7 0.6 0.0

0.2

0.4

0.6

0.8

1.0

Composition x

Replacement of Na

+

ions by Ca

2+

Na(5-x)CaxTi(PO4)3 Bioglasses Cell Culture

Tests of human cells, isolated from human bone marrow

Na5-2xCaxTi(PO4)3

: Bioglasses

Guenching

Glass bars are cut. The pellets are used for bioactivity tests

IN VITRO TESTS

Attachment test with HBMSC

(Human

Bone Marrow Stromal Cells)

Plastic 100% Attachment

Very good attachment on bioglass compared to plastic.

Proliferation test with HBMSC Periods : 1, 3, 6, 9 and 13 days

Very good growth of cells on bioglasses .

IN VIVO TESTS

Anesthesia of the rats

Preparation of the surgical area and isolation of the bone Creation of the implantation site Implantation of the glass

Rearrangement of the area Histological study

Diphosphate: Cs2MnP2O7

MnO5 and P2O7 groups form infinite chains [MnOP2O7]∞, along b axis.

Connexion of [MnOP2O7]∞ chains by O13 to form sheets paralel to (b,c) plane

Projection on (a,c) plane Cesium atoms are located between the scheets in two sites, 9-fold and 10-fold coordination

Cesium plolyhedra in Cs2MnP2O7

Cesium atoms are located between the scheets in two sites nine fold + ten fold coordination

Summary Phosphates exist in both crystalline and vitreous forms Numerous and diverses crystal structures Structures of phosphates accommodate all most of the periodic table elements Numerous properties Energetical, medical and environmental applications

Acknowledgements Casablanca :

Saida Kaoua, Saida Krimi, Samiha Lamrhari,

Bordeaux :

Jean-Pierre Chaminade, Pierre Gravereau, Stanislav Pechev, Matias Velazquez,

Hassan El hafid, Joelle Amédée

Pretoria :

Danita de Waal

Wake Forest : Abdou Lachgar, Cinthya Day

Thank you for your attention