ZnO–B2O3–P2O5–RnOm glasses containing different concentrations of Fe2O3 (ranging from 0 to 5 mol %) were prepared. A number of studies viz., glass transition temperature (Tg), density (α), thermal expansion coefficient (a), chemical durability, infrared spectroscopic and X-ray diffraction (XRD) patterns of these glasses had been carried out. The results of these studies have been analyzed in the light of different oxidation states of iron ions. The physical properties coupled with infrared spectroscopic and XRD indicates that the iron ions (when present in the concentration range, 0–2 mol %) exist mostly in trivalent state and occupy both tetrahedral and octahedral substitutional positions and are found to increase the rigidity of the glass network. However, in the concentration range of 2–5 mol %, the iron ions in the glass network seem to be existing by and large in Fe2+ state, occupying predominantly octahedral positions and are acting as modifiers.

Structure and crystalline behavior of the ternary system ZnO-B2O3-P2O5 glasses were investigated by means of X-ray diffraction (XRD) and infrared Raman spectra. The research showed that number of the planar [BO3] units increases with the increase of B2O3 content. When the B2O3 content is above ≥10 mol %, the relative content of planar [BO3] units increases rapidly and causes weakening of the glass structure and decrease in the chemical stability. In the crystallized glasses the predominant crystal phase Zn2P2O7 decreases with the increase of B2O3 content, while the crystal phase BPO4 increases with it, which cause the declining of chemical stability and the decrease of thermal coefficients of expansion.