A quantitative study of the calcination and sintering of nanocrystalline titanium dioxide and its flexural strength properties

We performed a quantitative study of the calcination and sintering of nanocrystalline titanium dioxide (TiO2) using the Rietveld refinement technique. Previously, we developed a sol–gel technique to synthesize 5–15 nm anatase powder. Here, we performed a quantitative analysis to study the phase evolution during calcination (400 and 800 °C) and the crystal structure after sintering (1400 and 1500 °C). TiO2 nanopowder was obtained by hydrolyzing titanium tetraisopropoxide in a mixture of isopropanol and deionized water, after calcination at 400 °C. Additionally, the powder was cold die compacted and sintered at 1200–1600 °C, to study the biaxial flexural strength and microstructure as a function of sintering temperature. Powder X-ray diffraction technique was used for phase analysis. Scanning electron microscopy was used for microstructural analysis. Rietveld refinement, performed using GSAS software, provided accurate quantitative analysis. Grain size and density increased with increasing sintering temperature. Biaxial flexural tests, performed as per ASTM F-394 with some adaptation, demonstrated a maximum strength of 127.6 MPa in specimens sintered at 1500 °C.