Electrolytic synthesis of diamond in molten salts

• Project/Area Number: 24655192
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Single-year Grants
• Research Field: Inorganic industrial materials
• Research Institution: Kyoto University
• Principal Investigator: NOHIRA Toshiyuki 京都大学, エネルギー科学研究科, 准教授 (00303876)
• Project Period (FY): 2012-04-01 – 2014-03-31
• Project Status: Completed (Fiscal Year 2013)
• Budget Amount: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000); Fiscal Year 2012: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
• Keywords: ダイヤモンド / 溶融塩 / 電解合成

Research Abstract

This study was conducted aiming at the electrochemical synthesis of diamond in high temperature molten salt under ambient pressure. Molten LiCl-KCl containing various amounts of KOH and K2CO3 was used as an electrolysis bath at 923 K. The effects of the added amounts of KOH and K2CO3 and the electrolysis potential on the formation of sp3 carbon were investigated. It was suggested that the deposition of carbon occurs at more negative than 1.0 V (vs. Li+/Li), and that the evolution of hydrogen proceeds at more negative than 1.3 V. From the analysis of the samples prepared at 0.8-1.2 V, though the formation of diamond was not confirmed, the optimum condition to synthesize the samples containing larger amount of sp3 carbon was indicated.