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A Spectroscopic and Structural Study of M(3d) 2+ ‐Doped β‐Tricalcium Phosphate – the Binding Properties of Ni 2+ and Cu 2+ in the Pseudo‐Octahedral Ca(5)O 6 Host‐Sites
Author(s) -
Mayer Isaac,
Gdalya Sarit,
Burghaus Olaf,
Reinen Dirk
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900236
Subject(s) - octahedron , crystallography , electron paramagnetic resonance , steric effects , chemistry , ionic bonding , bond length , spectroscopy , ion , ground state , crystal structure , stereochemistry , nuclear magnetic resonance , atomic physics , physics , organic chemistry , quantum mechanics
The pseudo‐octahedral Ca(5) 2+ position in β‐Ca 3 (PO 4 ) 2 is a highly interesting host site with unexpectedly short Ca–O bond lengths, which can be easily substituted by small 3d‐cations, such as Ni 2+ . Also Cu 2+ may fully replace Ca(5) 2+ , leading to remarkably large energetic and steric distortion effects due to E g ⊗ ϵ g Jahn–Teller coupling – with a ground‐state splitting of about 1.25 eV. The Cu(Ni)–O bond is strongly ionic according to a 3d‐mixing coefficient of the e g ‐electrons above 0.90, as revealed by EPR‐ and d–d spectroscopy. It is suggested that the flexibility of the Ca(5)O 6 host polyhedra, which lie isolated in the lattice, in respect to deformations and to substitutions by smaller cations is one reason that β‐TCP is a useful biomaterial.