Size effect on magnetic susceptibility of titanium monoxide nanocrystals

Abstract

For the first time a magnetic quantum-size effect is found in paramagnetic titanium monoxide nanocrystals with the sizes down to 30 nm. In situ measurements in the temperature range from 300 to 1200 K showed that the magnetic susceptibility of superstoichiometric titanium monoxide nanocrystals TiO y (y > 1) depends not only on the structural state of the sample, but also on the size of nanocrystals. The data analysis both for the ordered and disordered TiO y showed that the reason for inversely proportional dependence of Van-Vleck paramagnetism on the size of titanium monoxide nanocrystals is distortion of local symmetry of titanium and oxygen atoms near the nanocrystal surface. Van-Vleck contribution induced by the atomic-vacancy disordering in titanium monoxide is proportional to the deviation of the long-order parameter from its maximal value.

Influence of high energy milling on titanium oxide Ti3O5 crystal structure

“…One of the effective methods for obtaining nanoparticles is high-energy milling, which makes it possible to control the size of the resulting particles, dope the material during milling, and use various media for synthesis [19]. The milling of titanium oxides Ti 2 O 3 [20,21], TiO 2 (rutile) [22,23] by means of high-energy ball milling leads to a decrease of the particle size only, the milling of ordered titanium monoxide TiO y leads to a decrease of long-range order parameter of monoclinic TiO y [24,25], and phase transitions in TiO 2 from anatase to the high-pressure phase TiO 2 (II) occurs during milling [26,27].…”

Effect of Stoichiometry and Ordering on the Microstructure of Titanium Monoxide TiOy

“…It possesses a wide homogeneity region (0.8 > y > 1.3) and contains up to 16 at. % structural vacancies in both titanium and oxygen sublattices simultaneously. − Such considerable amount of vacancies results in significant differences in the properties of substoichiometric, stoichiometric, and superstoichiometric TiO y in both ordered and disordered states. − In addition, a size effect was detected in the properties of nonstoichiometric titanium monoxide nanocrystals. − Earlier in ref , mechanical and annealing twins, longitudinal and transverse cleavage steps due to intermittent motion of twin boundaries had been found in nonstoichiometric titanium monoxide. When the stoichiometry changed, the curvature of cleavage edges because of the effect of defects (vacancies) and elastic stress inhomogeneity was observed.…”

Effects of high mechanical treatment and long-term annealing on crystal structure and thermal stability of Ti2O3 nanocrystals

“…19,20 The CSR size was obtained by extrapolating the dependence b*(s) to the value s ¼ 0, and the magnitude of microstrain was determined from the slope of this dependence. 21,22 The microstructure of nanocrystals was studied with the high-resolution scanning electron microscopy (SEM) on a ZEISS Ultra 55 microscope. The working distance (WD) was 3.9-4.3 mm, the electron high tension (EHT) was 3-5 keV, and the beam width ranged from 2 to 6 mm depending on magnication.…”