Genesis of nanocrystalline Ho2O3 via thermal decomposition of holmium acetate: Structure evolution and electrical conductivity properties

This study focuses on the preparation of nanostructured holmium oxide via the decomposition of holmium acetate precursor utilizing the non-isothermal strategy. Thermogravimetric analysis (TGA) was used to follow up the various thermal events involved in the decomposition process. Dehydration completes approximately at 150 °C, which is followed by the decomposition of the anhydrous acetate leading to the formation of holmium oxide. Based on the TGA results the acetate precursor was heated non-isothermally at the temperature range of 150–700 °C. The obtained solids were characterized using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). It is found that nanocrystalline Ho₂O₃ starts to form at 500 °C and presents the only phase detected at the 500–700 °C range. The electrical conductivity of the solids that form at the temperature range of 300–700 °C was investigated. The obtained values were correlated with the observed structural modifications accompanying the heat treatment. The electrical conductivity of the Ho₂O₃ samples prepared at 500, 600 and 700 °C reaches the values of 1.92 × 10^?7, 1.61 × 10^?7 and 8.33 × 10^?8 Ω^?1·cm^?1 at a measuring temperature of 500 °C, respectively. These values are potentially advantageous for high-resistivity devices.