Sol–gel synthesis of nanosized λ-Ti₃O₅ crystals

In this study, we show a synthesis of λ-Ti₃O₅ nanocrystals dispersed in silica by sol–gel method. The X-ray diffraction measurements, Rietveld analyses, and transmission electron microscope images of the obtained samples showed that tuning the sintering temperature in the synthesis process can control the size of the λ-Ti₃O₅ nanocrystals, i.e., 8±2 nm (1123°C; sample 1), 9±3 nm (1133°C; 2), 9±2 nm (1143°C; 3), 10±3 nm (1153°C; 4), 11±4 nm (1163°C; 5), 13±4 nm (1173°C; 6), 25±12 nm (1200°C; 7), and 36±15 nm (1250°C; 8), whereas adjusting the hydrogen flow rate can tune the oxidation-reduction state of the sample without apparent change in the crystal size. At the lowest sintering temperature of 1123°C, the smallest X-Ti₃O₅ nanocrystals of 8 nm in size were produced