Abstract: The techniques of orientation mapping based on electron back-scattering diffraction, scanning electron microscopy and X ray diffraction were used to investigate macro-texture,
microstructure and orientation evolution of grains. The preparation atmosphere with lower purity is one of the important reasons, which
induces twins in large quantity in the diamond films investigated. The impurity atoms reduce the stack fault energy in diamond, lower the
obstacles to the formation of twin boundaries, and therefore accelerate the appearance of twins. Frequent twining results in the texture
transformation from {100} to {122}, a weakened film texture as well as the tendency leading to isotropic properties. The {110} oriented
grains keep their orientation after twinning, and therefore indicate certain orientation stability against the repeatedly twinning effects.

Key words: diamond film, texture, microstructure, twins