Oxidative degradation of CVD diamond

Studies of the short-time oxidative degradation of diamond have been conducted to better define the limits of application at high temperature. The infrared (IR) and visible optical performance of polished chemical vapor deposition (CVD) diamond windows were degraded after heating in a furnace at 800 degree(s)C in air for 75 s, while heating at 700 degree(s)C for 75 s produced little change. The 800 degree(s)C heating resulted in increased light scatter visually, and microscopic etched features were revealed by optical microscopy, scanning electron microscopy, and Talystep surface profiles. Many of the etched features are concentrated at grain boundaries while some features appear to reflect residual damage from mechanical polishing that could not be seen before the heat treatment. The IR transmission of samples heated in air at 800 degree(s)C was reduced due to scatter. The scatter at 10.6 micrometers increased from 0.8% for unheated material to 2.8% for material heated at 800 degree(s)C for 75 s and 6.2% for material heated at 800 degree(s)C for 255 s. Single crystal (110) natural diamond was also heated in air. Heating for 4 min at 800 degree(s)C caused little change in IR transmission, while heating for 9 min at 800 degree(s)C caused a significant loss in IR transmission.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.