Effect of Ceramic Crucibles on Magneto-Optical PbO-Bi₂O₃-B₂O₃Glasses Properties

Abstract

Heavy-metal-oxide (HMO) glasses attract much interest in many applications such as Faraday rotators, current sensors, etc., in the area of magneto-optic effects due to their unique magnetic-optical property, high refractive index and other interesting properties. However, during the melt-quenching process of these glasses, the high corrosive nature of the melt to the crucibles makes the fabrication of HMO glasses complicated and the properties of the obtained glasses show strong dependence on the crucible materials. Literatures reported that the gold and platinum crucibles are not suitable due to their contamination to the melt glasses, ceramic crucible was considered suitable for the melting of HMO glasses. In this work, magnetic-optical glasses within the system of PbO-Bi 2 O 3 -B 2 O 3 have been prepared using different kinds of ceramic crucibles for the aim of finding the most suitable crucible for melting HMO glasses. The glass properties in terms of Verdet constant, thermal stability and UV-Vis-IR transmittance in function of different crucibles were studied and reported. It was found that the same batch of glasses prepared under same conditions (melting temperature, melting time and annealing process), but in different ceramic crucibles (coded as C1, C2 and C3) showed significant difference in properties such as glass forming ability, thermal stability, optical absorption in UV-Vis-IR and Verdet constant (0.0812 - 0.1483 min/G.cm). The ceramic crucible made of 25%Al2O3 and 75%SiO2 (C2) was found to be the most suitable for PbO-Bi 2 O 3 -B 2 O 3 glass preparation, compared with platinum, gold, C1 and C3. Glasses melted with C2 exhibit good performance in magneto and optical property, as well as good thermal stability.