The poor thermodynamic and thermal stability of self-healing glass sealants restrict their applications in planar solid oxide fuel cells (SOFCs). In this paper, a calcium borate crystalline is prepared by melting-quench and a subsequent crystallization. The crystalline phases include CaB4O7 and CaB2O4. The in situ observation reveals that the micro-indentation on the surface of such crystalline can be healed when heating from room temperature to 840 degrees C at a heating rate of 40 degrees C min(-1). Combining with the improved thermal stability, the crystalline sealant with desired self-healing property, at the operational temperature of SOFCs (e.g., 700-900 degrees C), provides additional solution for the sealing challenge of SOFCs. (C) 2010 Elsevier B.V. All rights reserved.