The role of sodium nickelate in the metastable recrystallization of diamond

• Published in: Diamond and related materials 1994-12, Vol.4 (1), p.20-25
• Main Authors: Komath, Manoj, Cherian, Kuruvilla A., Kulkarni, S.K., Ray, Arabinda
• Format: Article
• Language: English
• Subjects: Chemical characterization; Cross-disciplinary physics: materials science; rheology; Etching; Exact sciences and technology; Materials science; Metastable carbon; Methods of crystal growth; physics of crystal growth; Physics; Solution growth; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Theory and models of film growth
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/0925-9635(94)90064-7

Diamond has been observed to recrystallize from an NiNaOHC system at atmospheric pressure. The basic procedure of the experiment involves the dissolution of diamond carbon and nickel in hot NaOH melt (at about 850 °C) and fast cooling of the system to room temperature. In this paper the physicochemical studies done to understand the mechanism of the metastable recrystallization of diamond are reported. The various observations and analyses proved that the product of the NiNaOH reaction, NaNiO 2, plays a critical role in the diamond recrystallization. Evidence points towards a process in which a co-crystallization of carbon (in the form of diamond) and NaNiO 2 (as thin, small platelets) takes place. The crystallization of NaNiO 2 in the form of platelets while cooling is thought to create favourable conditions locally for the growth of diamond crystallites.