The absorption peak was detected in this range due to the washing of nanoparticles with alcohol in the final stage. It is well known that the characteristic vibration bands corresponding to (M−O) metal-oxygen bonds will be in the range of 400–800 cm−1. The very strong bands related to Ti−O and Ti−O−Ti stretching vibrations appeared at 400–600 cm−1 and 525–700 cm−1, respectively [37]. Meanwhile the absorption at 536 cm−1 is attributed to Ni–O bond. Therefore, it can be said that the absorption at 536 cm−1 corresponding to the formation of nickel titanate phases is in agreement with XRD diffraction pattern. FT-IR is known as a sensitive technique for carbonate phase identification. With characteristic bands of the carbonates (867, 1067, 1440 cm−1) not appearing in the spectrum, it can be stated that the synthesized nanocrystals are carbonate-free [31]. Therefore FT-IR spectrum confirms the formation of pure NTO nanoparticles, these nanoparticles are then dried at very low temperature (50 °C) with complete removal of other by-products.