(INVITED) Positron annihilation spectroscopy and third harmonic generation studies on MnO mixed lead zirconium silicate glass ceramics

Abstract

This work is intended to report pertinent studies covering several aspects viz., spectroscopic, higher order non-linear optical studies and positron annihilation spectroscopic studies on lead zirconium silicate glass ceramics admixed with different contents of MnO. Lead zirconium silicate glasses mixed with small contents (up to 1.0 mol%) of MnO were prepared and crystallized by subjecting them to the prolonged heat treatment at crystallization temperature ∼ 830 °C. The structural analysis of the samples carried out using XRD, TEM, EDS and differential scanning calorimetric techniques has suggested that the glass ceramics are entrenched with coagulated poly-crystallites viz., Mn2SiO4, Pb2MnO4 and Pb3Mn7O15 that contain manganese ions in multiple oxidation states. These studies have also suggested that Mn2+ ions occupy octahedral as well as tetrahedral positions and the tetrahedral occupancy is predominant in the glass ceramic sample mixed 0.6 mol% of MnO (M6). Infrared, Raman, optical absorption and photoluminescence spectral investigations have further supported the above conclusions and indicated an increasing rigidity of the glass network (attributed to the enhanced tetrahedral occupancy of manganese ions) with increasing concentration of MnO up to 0.6 mol%. Positron annihilation lifetime spectroscopic studies (carried out with 22Na isotope source of strength 0.1 MBq) suggested the sample M6 contains the lowest magnitude of free volume space. This is attributed to the participation of the maximal concentration of Mn2+ ions in the glass network forming. Non-linear optical (NLO) studies using NIR Er-glass laser (λ = 1540 nm) indicated the highest intensity third harmonic generation (THG) beam in the glass ceramics doped with small contents (∼0.2 mol%) of MnO. Overall analysis of these results suggested that the samples with lower concentrations of MnO possess highly disordered internal structure and facilitated the increase of intensity of THG beam; Hence, such samples may be considered as potential candidates for the applications in the fabrication of various micro sized opto-electronic devices, for example, optical switches, optical cross-connectors, microbolometers, photovoltaics, light sensors etc.