Vibrational spectra of α‐CaNa₂P₂O₇ · 4H₂O, CaNH₄NaP₂O₇ · 3H₂O and CdNH₄NaP₂O₇ · 3H₂O

Abstract

Abstract The IR and Raman spectra of polycrystalline samples of α‐CaNa 2 P 2 O 7 · 4H 2 O, CaNH 4 NaP 2 O 7 · 3H 2 O and CdNH 4 NaP 2 O 7 · 3H 2 O were recorded and analysed. Vibrational bands due to NH 4 + , P 2 O 7 4− and H 2 O are identified. The POP bridge angle is found to be about 129° and the pyrophosphate ion is non‐centrosymmetric. The NH 4 + ion is likely to be rotating freely in the componds XNH 4 NaP 2 O 7 · 3H 2 O (X = Ca, Cd).