Influence of Ce, Nd, Sm and Gd oxides on the properties of alkaline-earth borosilicate glass sealant

Peer review under responsibility of The Ceramic Society of Japan and the Korean Ceramic Society.

Abstract

In this study, the influence of CeO₂, Nd₂O₃, Sm₂O₃ and Gd₂O₃ on various properties of the melt-quench route derived SrO–CaO–ZnO–B₂O₃–SiO₂ glass have been investigated. Both the precursor glasses and heat treated glasses are characterized by dilatometry, differential scanning calorimetry (DSC), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The density and coefficient of thermal expansion of the glasses varies in the range 3.557–3.804 g cm⁻³ and 10.5–11.2 × 10⁻⁶ K⁻¹ (50–800 °C) respectively. Decrease in crystallization tendency with increase in cationic field strength of the ions is well supported by the increasing crystallization activation energy of the glasses calculated by Kissinger, Augis–Bennett and Ozawa models. XPS study revealed the presence of both Ce³⁺ and Ce⁴⁺ ions and an increase in characteristic binding energy of the respective rare earth elements from their core level studies. The Knoop hardness of the glasses varies in the range 6.03–6.28 GPa. The glass transition, glass softening and crystallization temperature; density and hardness of the glasses increased with increase in cationic field strength of the incorporated ions. The thermomechanical properties of the Gd₂O₃ containing glass advocate its applicability as the most promising sealant in solid oxide fuel cell.

Keywords:

• Solid oxide fuel cell
• Sealant
• Thermal expansion coefficient
• Infrared spectroscopy
• Rare earth oxide
• XPS

Acknowledgments

The authors thank Mr. Kamal Dasgupta, Acting Director and Dr. R. Sen, Head, Glass Division of CSIR-CGCRI for their encouragement to carry out this work. They are also thankful to Dr. R.N. Basu, Head, FuelCell and Battery Division for financial support under CSIR-NMITLI project on SOFC. Dr. Atiar Rahman Molla is sincerely thanked for carrying out the crystallization kinetics experiments. The technical support provided by the Material Characterization Division for recording XRD patterns, FESEM photomicrographs and XPS are also thankfully acknowledged.

Notes

Peer review under responsibility of The Ceramic Society of Japan and the Korean Ceramic Society.