New Ceramic Pigments on the Basis of Phosphate Apatites
Containing Oxocuprate Ions in the Hexagonal Channels
Andrey S. Karpov, Jürgen Nuss, Martin Jansen
Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
Pavel E. Kazin, Yuri D. Tretyakov
Department of Chemistry, Moscow State University, 119992 Moscow, Russia
Introduction
Electron Absorption Spectra
Ceramic pigments are widely used to impart colour and are usually
incorporated as fine particles in paints, plastics, and other materials. Although
many chemical compounds are effectively applied as pigments there is still a
need to find new compounds and mixtures which show bright colours and are
relatively cheap, stable towards heating and light, non-toxic and environment
friendly.
Effect of copper content
Effect of cation composition
intervalence electron transition
d-d electron transitions
Ba5(PO 4)3Cu0.3OH y
(Sr 0.5Ba0.5)5(PO4 )3Cu0.3 OH y
Sr5 (PO4 )3 Cu0.3 OHy , ox.
Sr5 (PO4 )3 Cu0.1 OHy , ox.
Sr5 (PO4 )3 Cu0.3OHy
We report on new types of ceramic pigments based on apatites containing
linear copper(I,II) oxyanions in hexagonal channels, partly substituting the
hydroxyl groups. In spite of the fact that only a small share of copper is in the
divalent state, the compounds are brilliantly coloured.
Preparation
Sr5 (PO4 )3 Cu0.5 OHy
Sr5 (PO4 )3 Cu0.3 OHy
(Ca0.5 Sr0.5)5 (PO 4)3Cu0.3OHy
Sr5 (PO4 )3 Cu0.1 OHy
Sr5 (PO4 )3 Cu0.05 OHy
Ca5 (PO 4)3Cu0.3OHy
5000 10000 15000 20000 25000 30000
5000 10000 15000 20000 25000 30000
-1
Wave number, cm
Wave number, cm
-1
Magnetic Properties of Sr 5(PO 4)3CuxOHy
1. Ceramic samples
5 MCO3 (M = Ca, Sr, Ba) + 3 NH4H2PO4 + x Cu(NO3)2
0,20
0,014
0,012
χ, emu/mol
M5(PO4)3CuxOHy; 0≤x≤0.85, 0≤y≤1
M=Ba
x=0.3
M=Sr
x=0.3
Sr5 (PO4 )3Cu0.3 OHy , oxidized
Sr5 (PO4 )3Cu0.1 OHy , oxidized
Sr5 (PO4 )3Cu0.3 OHy
Sr5 (PO4 )3Cu0.1 OHy
Sr5 (PO4 )3Cu0.85OHy , reduced
0,010
?u(+2) air
?u(+2) argon
?u(+2) O2
0,15
x ´ (Cu+2)
600°C + 1100°C, 30h, air
M=Ca
x=0.3
Paramagnetic copper vs. total copper
contents
Temperature dependence of magnetic
susceptibility
0,008
0,006
redoxidized
rot: oxidized
oxidized
blue: reduced
0,10
0,05
0,004
0,002
0,00
0,000
0
50
100 150 200 250 300 350 400
0,0
0,2
0,4
Temperature, ?
0,6
0,8
x(Cutot.)
Infrared Spectra
2. Growth of single crystals
M5(PO4)3CuxOHy
Cu-O vibrations
1300°C, 2h, slow cooling
transparent needles of
M5(PO4)3Cu1/3OHy
Cu-Obridged -O
Crystal Structure
Sr5 (PO4 )3 (CuO2 )1/3
Cu-Otherminal
Ba 5 (PO 4 ) 3 Cu0.3 OHy
Transmission, a.u.
+ 3 M2Bi2Cu2Oz
Influence of copper content on Cu-O
vibrations
Sr5 (PO4 )3 Cu0.85OHy
Sr5 (PO4 )3 Cu0.6 OHy
Sr 5 (PO 4 ) 3 Cu0.3 OHy
Sr5 (PO4 )3 Cu0.4 OHy
Ca 5 (PO 4 ) 3 Cu0.3 OHy
Sr5 (PO4 )3 Cu0.2 OHy
Sr5 (PO4 )3 Cu0.1 OHy
b
Sr5 (PO4 )3 Cu0.01OHy
a
4000
3000
O split
2000
Wave number, cm
850 800 750 700 650
-1
Wave number, cm
1000
-1
Cu
Substitution of Hydroxyl Groups by Copper Ions
1) Hydroxyl groups in the channels
PO4
Ca1
c
PO4
Cu/O
2) Some of hydroxyl groups replaced by oxocuprates(I) ions
Ca2
3) Oxocuprate ions build oligomeric chains
Ca2
Dependence of cell parameters and cell volume on copper content in Sr5 (PO4) 3 Cu xOHy
612
7,30
9,84
4) Formation of vacancies by oxidation of copper(I) to copper(II)
O
Cu
Vacancy
OH
610
9,82
References
3
V, Å
a, Å
9,80
c, Å
608
7,29
606
[1] P.E. Kazin, A.S. Karpov, M. Jansen, J. Nuss, Y.D. Tretyakov, Z. Anorg.
Allg. Chem. 629 (2003) 344
604
9,78
a
c
9,76
0,0
0,2
0,4
0,6
x
0,8
7,28
1,0
602
600
0,0
0,2
0,4
0,6
x
0,8
1,0
[2] A.S. Karpov, J. Nuss, M. Jansen, P.E. Kazin, Y.D. Tretyakov, Solid State
Sci. in press
[3] P.E. Kazin, A.S. Karpov, M. Jansen, EP No 02014451, Ceramic pigments
on apatite basis