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Structural elucidation and iron oxidation states in situ formed β‐Ca 3 (PO 4 ) 2 /α‐Fe 2 O 3 composites
Author(s) -
Nandha Kumar Ponnusamy,
Mishra Sandeep K.,
Kannan Sanjeevi
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14889
Subject(s) - isostructural , raman spectroscopy , oxidation state , x ray photoelectron spectroscopy , materials science , x ray crystallography , iron phosphate , crystal structure , crystallography , diffraction , analytical chemistry (journal) , chemistry , mineralogy , composite material , metallurgy , phosphate , metal , chemical engineering , physics , organic chemistry , optics , engineering , chromatography
A detailed structural analysis on the in situ synthesized β‐Ca 3 (PO 4 ) 2 /α‐Fe 2 O 3 composites is demonstrated. Compositional ratios, the influence and occupancy of iron at the β‐Ca 3 (PO 4 ) 2 lattice, oxidation state of iron in the composites are derived from analytical techniques involving XRD, FT‐IR, Raman, refinement of the powder X‐ray diffraction and X‐ray photoelectron spectroscopy. Iron exists in the Fe 3+ state throughout the investigated systems and favors its occupancy at the Ca 2+ (5) site of β‐Ca 3 (PO 4 ) 2 until critical limit, and thereafter crystallizes as α‐Fe 2 O 3 at ambient conditions. Fe 3+ occupancy at the β‐Ca 3 (PO 4 ) 2 lattice yields a Ca 9 Fe(PO 4 ) 7 structure that is isostructural with its counterpart. A strong rise in the soft ferromagnetic behavior of β‐Ca 3 (PO 4 ) 2 /α‐Fe 2 O 3 composites is obvious that depends on the content of α‐Fe 2 O 3 in the composites. Overall, the diverse level of iron inclusions at the calcium phosphate system with a Ca/P ratio of 1.5 yields a structurally stable β‐Ca 3 (PO 4 ) 2 /α‐Fe 2 O 3 composites with assorted compositional ratios.