Dilute impurities and growth conditions can drastically affect the transport properties of TiSe2, especially below the charge-density-wave transition. In this paper, we discuss the effects of cooling rate, annealing time, and annealing temperature on the transport properties of TiSe2: slow cooling polycrystalline TiSe2 postsynthesis drastically increases the low-temperature resistivity, which is in contrast to the metallic behavior of single-crystalline TiSe2 attributed to charge doping from the residual iodine transport agent. A logarithmic increase of resistivity upon cooling and negative magnetoresistance with a sharp cusp around zero field are observed for the first time for the polycrystalline TiSe2 samples, pointing to weak-localization effects due to low dimensionality. Annealing at low temperatures has a similar, but less drastic effect. Furthermore, rapid quenching of the polycrystalline samples from high temperatures freezes in disorder, leading to a decrease in the low-temperature resistivity.
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