Influence of manganese ions in calcium silicate glass–ceramics on optical, mechanical, and magnetic properties

Abstract

Nanocrystalline calcium silicate powder was synthesized by adding different ratios of MnO2 ranging from 0.00 to 2.00 wt% to detect its effect on the structure and physical properties. The pseudowollastonite triclinic and low combeite of hexagonal phase with nanocrystallite size less than 85.0 nm were confirmed by the XRD technique and average particle size ranging from 7.8 to 27.9 nm as detected by HR-TEM micrograph images. Stretching and bending vibration of the O–Si–O band were shifted to higher values upon the addition of MnO2 were verified by FT-IR. Increasing both the density and ultimate strength with a reduction in the porosity leads to an improvement in the mechanical properties with the addition of MnO2. Additionally, the increasing MnO2 content showed an improvement in magnetic and optical properties, which exhibited a decrement in the optical band gap Eg from 3.9 to 1.6 eV. Hence, the MnO2 acts as a structural network modifier of calcium silicate glass–ceramics. Furthermore, the estimated values of the Lande g-factor (2.01534–2.01731) for the d5 system of the Mn2+ displayed a negative shift from the free electron (2.0023), and the hyperfine splitting constant A value was 87 × 10−4 cm−1, indicating that the Mn2+ ions are in an ionic environment.