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Author: search.filters.author.Titiroongraung, WisutSubject: search.filters.subject.Large Diamond

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    Development of Large Diamond Synthesis by Double Test Tubes Hot Filament Chemical Vapor Deposition
    (2017-01-01)
    Sodngam, Piyachat
    ;
    Meekluab, Prapassorn
    ;
    Siriwongrungson, Vilailuck
    ;
    Neamchalern, Surasak
    ;
    Titiroongraung, Wisut
    In this research, “diamond” synthesis device by double test tubes hot filament chemical vapor deposition (HFCVD) was developed and proposed. Remaining hydrogen was reused for the maximum utilization of resources. In addition, this diamond synthesis device is capable to synthesis diamond continuously of up to 60 h per time. As a result, large diamond as large as 1.85 mm and 1.73 mm can be produced from the synthesis of three times with 180 h in total. Moreover, after each synthesis, the quality of diamond crystal was improved by annealing in hydrogen atmosphere. The crystal size was measured and physical characteristics of diamond were analyzed using scanning electron microscopy (SEM). The increasing rate of diamond crystal size after each synthesis was also examined. In addition, electrical properties of the synthetic diamond was compared with natural diamond from room temperature (25°C) to 200°C. The synthetic diamond has the resistance of 1337.28 M?, which the natural diamond has the resistance of 1428.67 M?. Temperature changes has no effect on the resistance of the diamond crystal. Moreover, the synthetic diamond was confirmed to be diamond using Raman spectroscopy. It has the same peak as the natural diamond at the Raman shift of 1332 cm<sup>-1</sup>.