ESR STUDIES ON RADIATION-INDUCED DEFECTS IN HIGH-PRESSURE PHASE SIO2

An ESR (electron spin resonance) study was made on radiation induced d efects in synthetic coesite and stishovite, high pressure phases Of Si O2. Samples were synthesized in a static condition from SiO2 glass wit h high purity, and was irradiated with gamma-rays. In coesite, an axia l signal with g(perpendicular-to) = 2.0027 and g(parallel-to) = 1.9993 and an orthorhombic one with g(zz) = 2.0004, g(yy) = 1.9993 and g(xx) = 2.0048 are compared with those of defects in ZrSiO4. Two nonequival ent oxygen sites in coesite would be associated with these signals. In stishovite, only an axial signal with g(perpendicular-to) = 2.0052 an d g(parallel-to) = 2.0023 is detected, probably due to oxygen vacancy centers.