Estudos das propriedades físicas de nanocristais de tio2 dopados com íons nd3+

Abstract

This work analyzes the structural and optical properties of titanium dioxide nanocrystals doped with different concentrations of Neodymium, as a function of temperature, to obtain efficient luminescent markers for use in biological assays. These structural and optical properties were studied using Raman spectroscopy, lifetime and photoluminescence (PL). At first, a structural analysis was carried out as a function of the Neodymium concentration, to verify if there was a phase change with the addition of the dopant. When analyzing the optical properties as a function of temperature, in the range from room temperature to 670K, it was verified by the luminescence spectrum that the integrated area of the Neodymium emission spectrum is low at the first temperatures, and increases with increasing temperature. The same behavior is observed in the lifetime, under the same conditions. Thus, the results suggest that the low emission at lower temperatures is due to the intrinsic defects of Titanium Dioxide. In the second part, an analysis was performed as a function of the heat treatment in the samples, three heat treatment were made: one at 500ºC, another at 750ºC, and finally at 1000ºC for 1h. Through Raman spectroscopy, it was verified that there was an influence of heat treatment on the proportion of the crystalline phases of rutile, anatase, and brookite this behavior is temperature dependent. From this, it was observed that in the temperature region between the thermal baths of 500 and 750ºC, the predominant phase is anatase, which affects the emission spectrum, since it presents with narrow emission bands, with more defined peaks. , characteristic of a more crystalline medium. The same occurs in the lifetime, at room temperature, it is not possible to obtain it and as the temperature increases its value also increases. Therefore, the results suggest that samples with a heat treatment at 750 °C are the best results since it is in this temperature range that the medium is more crystalline and stable.