High room-temperature magnetization in Co-doped TiO_(2) nanoparticles promoted by vacuum annealing for different durations

To clarify the contribution of oxygen vacancies to room-temperature ferromagnetism(RTFM)in cobalt doped TiO_(2)(Co-TiO_(2)),and in order to obtain the high level of magnetization suitable for spintronic devices,in this work,Co-TiO_(2) nano-particles are prepared via the sol-gel route,followed by vacuum annealing for different durations,and the influence of vacu-um annealing duration on the structure and room-temperature magnetism of the compounds is examined.The results reveal that with an increase in annealing duration,the concentration of oxygen vacancies rises steadily,while the saturation magnetiza-tion(Ms)shows an initial gradual increase,followed by a sharp decline,and even disappearance.The maximum Ms is as high as 1.19 emu/g,which is promising with respect to the development of spintronic devices.Further analysis reveals that oxygen va-cancies,modulated by annealing duration,play a critical role in tuning room-temperature magnetism.An appropriate concentra-tion of oxygen vacancies is beneficial in terms of promoting RTFM in Co-TiO_(2).However,excessive oxygen vacancies will result in a negative impact on RTFM,due to antiferromagnetic superexchange interactions originating from nearest-neighbor Co^(2+)ions.

Relations of intensity just noticeable difference to intensity of tonal bursts with various durations

The relations of intensity Just Noticeable Difference (JND) to intensity for tone bursts maybe,depend on signal durations according to Jont B.Allen's [J. Acoust. Soc. Am. 102 3, 1997, 3628--3646.]. The intensity just noticeable differences for tone bursts with durations of 1 ms, 10 ms, 100 ms, 1000 ms, 5000 ms and 10000 ms were measured at different intensity levels of 20 dB, 30 dB, 40 dB, 50 dB, 60 dB, 70 dB, 80 dB, 90 dB, 100 dB. The data show that variance of Weber fraction (△I/I) with intensity is distinct from Riesz's result and SPIN theory, and that the relations between Weber fraction and intensity for signals of different durations are similar in spite of Weber fraction decreasing to asymptote with signal duration increasing. This means the difference of pulse measurement of intensity JND from Riesz's result and SPIN theory does not arise from the limited signal duration of pulse method and provides new cue for hearing research.