Ca for Er substitution in tetragonal ErPO4.H2O crystallised from phosphoric acid solution by R. Kijkowska

Crystal Research and Technology

Cryst. Res. Technol. 39, 111 (2004) - Abstract -

Ca for Er substitution in tetragonal ErPO4.H2O crystallised from phosphoric acid solution

R. Kijkowska

Institute of Inorganic Chemistry and Technology, Cracow University of Technology, Warszawska 24, 31-155 Kraków, Poland

Keywords	erbium phosphate, Ca-substitution, X-ray diffraction, IR-spectra
PACS	81.10.-h
DOI	10.1002/crat.200310157

Erbium phosphate monohydrate with limited Ca for Er substitution, obtained through crystallisation from boiling phosphoric acid solution has been characterised by X-ray diffraction, Ir-spectroscopy and thermal analysis (TGA-DTA) methods. The difference in the electric charge between di-valent calcium and tri-valent erbium in the solid crystallised was compensated by simultaneous substitution of HPO₄^2- for PO₄^3-. Ca incorporation in erbium phosphate made expansion of tetragonal ErPO₄^.H₂O unit cell. After ignition at 900°C the tetragonal crystal modification was maintained but the unit cell parameters of all the investigated phosphates, whether Ca-substituted or Ca-free, contracted to the same level. The unique contraction of the unit cell was resulted from recrystallisation of Ca-substituted into Ca-free erbium phosphate, while Ca was transferred into Ca(PO₃)₂ formed as a separate phase.

The full text of this paper in pdf-Format:

If you have come directly to this page, click this symbol

to go to the CRT homepage.