Electrical Properties of Rutile Single Crystal Irradiated by High-Fluence-Reactor-Neutron
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Electrical Properties of Rutile Single Crystal Irradiated by High-Fluence-Reactor-Neutron Tiecheng Lu1,3, Libin Lin1, Gang Cheng1, Xuechun Xu1, Chunpei Zhao2, Yunfei Tian2 1 Department of Physics, Sichuan University, Chengdu 610064, P. R. China Key Lab of Irradiation Physics and Technology (Sichuan University), Ministry of Education, P. R. China 2 Analytic and Testing Center, Sichuan University, Chengdu 610064, P. R. China 3 International Center for Material Physics, Chinese Academy of Sciences, Shenyang110015, P.R.China ABSTRACT Electrical properties of rutile (TiO2) single crystals irradiated by high-fluence-reactor neutrons have been investigated for the first time. In this paper, the colorless rutile single crystal turns into dark blue after being irradiated by high-fluence-reactor neutrons of 1019/cm2 and its electrical properties change, from high insulator to normal semiconductor. The relationship of sample resistance to temperature (at low temperature, room temperature and high temperature, respectively) and the effect of annealing atmosphere ( in air or in vacuum) on the electrical property of the sample have been studied. The results show that the sample has semiconductor properties at low temperature. At high temperature, however, it is oxidized into colorless insulator in air and the activation energy gradual changes due to slow oxidization process. In 10-4 Pa vacuum condition, TiO2 becomes a semiconductor due to the presence of ion defects. The electrical conductance mechanism is also discussed. INTRODUCTION As a good insulator, pure stoichiometric TiO2 rutile has varied physical properties and unique photochemical characteristics. It has already been extensively studied for a long time due to practical or potential application in a variety of fields, such as photochemical cell, water electrolysis, etc. Especially in practical application, the reduced or defective TiO2 is preferred due to its semiconductor physical properties. When TiO2 loses some oxygen ions, magneli phase[1], i.e. TiO2-X construction, appears. Meanwhile, the color is changed to dark blue from originally colorless. As a result, its electrical conductivity increases quickly, and it is changed into n-type semiconductor from originally insulator [2]. According to the studies of the reduced rutile crystal, rutile can be reduced by three essential methods, i.e. annealing under a reducing atmosphere like hydrogen or high vacuum etc[3], irradiation by Ar+ or implanting by W, Cr etc[4], and irradiation by pulsed laser[5]. After being annealed under an oxidizing atmosphere, the reduced rutile crystal can be changed into the insulator because of the replenishment of oxygen ions or removal of the oxygen-vacancy defects. All of these studies focus on the surface-defect effect of rutile. In this paper, body-defect effect induced by neutron irradiation has been paid much attention, and the electrical property of neutron irradiated rutile single crystal has been investigated.
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EXPERIMENTAL DETAILS Five rutile single crystal specime
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