An FTIR and ESR study of iron doped calcium borophosphate glass-ceramics

• Effect of iron on the Ca–B–P glasses has been studied by XRD, FTIR and ESR.
• IR spectra indicate some variations in the glass network with Fe2O3 addition.
• ESR spectra reveal resonance signals at g ∼ 2.0 and g ∼ 4.3 for as casted samples.
• Effects of heat treatment and iron addition on ESR spectra are discussed.
• The main crystalline phases observed are BPO4, CaBPO5, Ca(PO3) and B0.57Fe0.43PO4.

A series of glasses in the xFe2O3-(100-x) [42B2O3–24CaO–34P2O5] system has been prepared for x = 0–10. Structure of as casted glasses and their heat treated counterparts have been studied by X-ray diffraction, infrared and electron spin resonance spectroscopies. Amorphous nature of all of the compositions studied is confirmed by the XRPD spectra. After the heat treatment, besides the main BPO4 phase, CaBPO5 and Ca(PO3) crystalline phases were identified in the iron free glass while B0.57Fe0.43PO4 phase was also observed in the XRD pattern of iron containing samples. FTIR spectra indicate changes in the glass network upon iron addition. X-band ESR spectra exhibits resonance signals at g ∼ 2.0 and g ∼ 4.3 for all analyzed samples. A supplementary line centered at g ∼ 6 appears after the thermal treatment. The nature of ESR absorption signals and influence of iron content on the evolution of ESR parameters are discussed.

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