Authors:Y. Ichiyanagi, T. Uehashi, S. Yamada, Y. Kanazawa, and T. Yamada
Summary Ni1-xZnxFe2O4 (0≤x≤1) mixed ferrite nanoparticles encapsulated with amorphous-SiO2 were prepared by a wet chemical method. Particle sizes were controlled to range from 2.6 to 33.7 nm by heat treatment, and the particle size dependence of saturation magnetization Ms was investigated for the x=0.5 region. The Ms value decreased abruptly for particle sizes below about 6 nm. From the temperature dependence of the magnetization under field-cooled and zero-field-cooled conditions, blocking temperatures Tb were observed to be between 28 and 245 K depending on the particle size. At the blocking temperature, the superparamagnetic spins in the particle are supposed to be blocked against the thermal fluctuation energy. A smaller particle volume causes a lower blocking temperature; so an extremely small particle would be strongly affected by thermal fluctuation.
Fuzzy inference approach was applied to select the control input for the precision water bath of the heat exchange calorimeter used at a non-air-conditioned laboratory. The thermal fluctuation of the bath water was necessary to be kept within a narrow range. The cooling water or coolant kept at a temperature lower than the set temperature was circulated in the bath. The deviation corresponding to the difference between the set temperature and the observed temperature was observed as the input signal. The output or control input to be given to the heather element in the water bath was calculated by the fuzzy modus. The output function was simplified by means of circulating the cooling water. The contribution of each membership function was changed according to the thermal progress of the observed temperature of the water. The whole system including the control programs was examined by a practical water bath, and fairly good results were obtained. Reasonable recoveries were also shown for external thermal disturbances given to the controlled system.
Authors:Cristian Vasile Grigoras and Anca Giorgiana Grigoras
” refers to a thermalfluctuation of CRR in glass transition range. Mean thermalfluctuation (noted as δ T ) could also be considered as an intrinsic parameter of glass transition that is responsible for changes in CRR volume due to changes of
Authors:Shree Mishra, Prafulla K. Jha, and Arun Pratap
statistical limit, any size effect due to thermalfluctuation above 3% (i.e., below 4 nm) are not addressed in this study and other method such as density functional theoretical calculation can be considered for such small nanostructures.
Authors:S. K. Arya, Tanvi Vats, Shailesh N. Sharma, Kulvir Singh, and A. K. Narula
materials, it is believed to be due to band tailing associated with disorder produced by thermalfluctuations in crystal lattice. For small absorption coefficients, there is usually an Urbach tail where α ( υ ) depends exponentially on the photon energy hυ