THE EFFECT OF TEMPERATURE ON THE STRUCTURE OF AMORPHOUS HYDROGENATED CARBON

The results of a neutron diffraction study on the structure of amorpho us hydrogenated carbon alpha-C:H are presented up to a maximum tempera ture of 1000 degrees C. The data show clearly the effect on atomic cor relations of elevated temperatures, with the initial room-temperature amorphous network (a mixture of single bonds and olefinic double bonds ) becoming progressively aromatic, then graphitic as hydrogen is evolv ed. Complementary x-ray diffraction and infrared spectroscopy data are also presented, the infrared data enabling a more detailed discussion of the temperature-dependent hydrogen environment, and the x-ray data are used to highlight the change in the carbon network. Comparisons h ave been made with previous work on similar systems and a brief summar y of these results is given.