Ca for Er substitution in tetragonal ErPO4 · H2O crystallised from phosphoric acid solution
✍ Scribed by R. Kijkowska
- Book ID
- 102124366
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 150 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0232-1300
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✦ Synopsis
Abstract
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 HPO~4~^2‐^ for PO~4~^3‐^. Ca incorporation in erbium phosphate made expansion of tetragonal ErPO~4~ · H~2~O 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(PO~3~)~2~ formed as a separate phase. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)