Kongfang Wei

The study of damage produced by H-ion and He-ion implantation in Lithium tantalate crystal

LiTaO3 single crystals were implanted by 100keV H-ion or He-ion. The results indicate that H-ion implantation creates a lower damage level than the He-ion implantation does, but the yield of oxygen vacancy produced by H-ion implantation is far higher than by He-ion implantation.

Structural Distortion and Defects in Ti

Ti3AlC2 samples are irradiated in advance by 3.5MeV Fe-ion to the fluence of 1.0×10 16 ion/cm 2 , and then are implanted by 500 keV He-ion with the fluence of 1.0×10 17 ion/cm 2 at room temperature. The irradiated samples are investigated by grazing incidence x-ray diffraction (GIXRD) and transmission electron microscopy (TEM). GIXRD results show serious structural distortion, but without amorphization in the irradiated samples. Fe-ion irradiation and He-ion implantation create much more serious structural distortion than single Fe-ion irradiation. TEM results reveal that there are a large number of defect clusters in the damage region, and dense spherical He bubbles appear in the He depositional region. It seems that the pre-damage does not influence the growth of He bubbles, but He-ion implantation influences the pre-created defect configurations.

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The effects of high energy Kr26+ ions bombardment in polycrystalline Fe3O4 thin films are reported. The magnetic and electrical transport properties of the Fe3O4 thin films, are sensitive to Kr26+ ions bombardment and exhibit diverse behaviors with different fluence. The modifications could be interpreted by an effects related to the stress and damage induced by bombardment. In addtion, possible mechanism of modifications of Fe3O4 ferrite thin films was discussed briefly by using the variable-range hopping (VRH) model.

AlC

Two kinds of Fe/Cu multilayers with different modulation wavelength were deposited on cleaved Si(100) substrates and then irradiated at room temperature using 400 keV Xe20+ in a wide range of irradiation fluences. As a comparison, thermal annealing at 300-900 degrees C was also carried out in vacuum. Then the samples were analyzed by XRD and the evolution of crystallite structures induced by irradiation was investigated. The obtained XRD patterns showed that, with increase of the irradiation fluence, the peaks of Fe became weaker, the peaks related to Cu-based fcc solid solution and Fe-based bcc solid solution phase became visible and the former became strong gradually. This implied that the intermixing at the Fe/Cu interface induced by ion irradiation resulted in the formation of the new phases which could not be achieved by thermal annealing. The possible intermixing mechanism of Fe/Cu multilayers induced by energetic ion irradiation was briefly discussed.