BO_(2)-F^(+)Centers in the Radiation-damaged YCOB Crystals

An intense paramagnetic EPR signal generated from x-ray-irradiated,powdered YCOB crystals was observed at the liquid nitrogen temperature for the first time.Five peaks,located at the positions where the effective g factor equals to 1.992,1.986,1.980,1.974 and 1.965,labeled as A,B,C,D and E respectively,were observed.It is believed that the peaks A,B,C and D generated from the BO_(2)-F^(+)center which is a single electron trapped in an oxygen vacancy which was originally occupied by an O^(2-)ion bonded to a(BO3)^(3-)anion group.The peak E is thought of coming from Y2+ions that are formed by the Y^(3+) ions trapping electrons.The mechanism for the formation of the radiation-induced defects in the YCOB crystals is suggested.