The modeling of magnetocaloric effect (MCE) based on quasiparticle formalism was used to show a possibility to increase our
knowledge of diffusion and phase transitions by a transdisciplinary scientific approach. Generalized understanding of diffusion
and of some phase transitions was suggested. New relations between MCE and elastic parameters of materials, obtained from
modeling procedure, were presented. The paper contains also the short discussion of a necessity to use hypercomplex mathematics
in modeling of magnetic processes and specifically in a modeling of MCE. Some remarks concerning nanomaterials are added.
A thermogravimetric method has been used for the determination of the oxygen chemical diffusion coefficients in La1–xSrxMnO3+δ; x=0; 0.05; 0.10; 0.15 (LSM).
A temperature range of 700–1000C was studied.
The chemical diffusion coefficient varies between 1.6⋅10–13 and 1.8⋅10–10cm2s–1 for the samples in the temperature range studied. The activation energy for oxygen chemical diffusion was determined to be
190–280 kJ mol–1 for the LSM samples. The magnitude of the chemical diffusion coefficients of the LSM samples does not depend on the strontium
site occupation factor.
A consecutive model of surface reaction, consisting of two steps (desorption and diffusion) was applied. It was concluded that diffusion modifies the temperature programmed desorption spectra, although the single peak curves appear. The differential method for calculation of kinetic parameters based on thesTM shift give values close to predicted ones only in the cases when particular steps are rate limiting. Generally, the desorption process have to be considered as a complex reaction, with the overall kinetic parameters. As a consequence of diffusion influence, the overall kinetic parameters are smaller than those for desorption step was obtained.
Authors:D. Berkün, D. Balköse, F. Tıhmınlıoǧlu, and S. Altınkaya
Two types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film
forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were
The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of
water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore
dimensions of the NaCMC films.
Authors:E. Kemnitz, A. A. Galkin, T. Olesch, S. Scheurell, A. P. Mozhaev, and G. N. Mazo
The oxygen diffusion and exchange behaviour of NdBa2Cu3O7−x is investigated by means of isothermal and dynamic-thermal analytical techniques. From the results it is concluded that oxygen anions move along vacancies in the CuO2-layers of the perovskite-like structure. In temperature regions where the diffusion rate is low (665 K<T<773 K) heterogeneous oxygen exchange reactions take place on the phase boundary. The higher the exchange rate the more the partially heterogeneous exchange is favoured in comparison to the completely heterogeneous isotope exchange. Depending on the oxygen deficiency of NdBa2Cu3O7−x the out-diffusion of oxygen becomes dominating at higher temperatures.
Authors:K. Nassr, M. Lübbers, Vera Šestákova, and J. Mimkes
Diffusion of Cu, Ag, Au, Ge and Zn in single crystal gallium antimonide has been carried out by measuring Hall effect according
to van der Pauw, conductivity, energy dispersive X-ray (EDX) and surface electron microscopy. The best results have been obtained
in excess of antimony. The resulting diffusion data in GaSb are diffusivity Do, activation enthalpy Q, carrier density p and mobility µ at 300 K:
Ag: Do=1.8·10−4 cm2 s−1, Q=1.2 eV, p=6·1018 cm−3, µ=550 cm2 (Vs)−1
Au: Do=6.6·10+3 cm2 s−1, Q=2.7 eV, p=5·1018 cm−3, µ=500 cm2 (Vs)−1
Cu: Do=3.2·10+8 cm2 s−1, Q=2.7 eV, p=2·1018 cm−3, µ=150 cm2 (Vs)−1
Zn: Do=9.2·10−2 cm2 s−1, Q=1.8 eV, p=2·1020 cm−3, µ=80 cm2 (Vs)−1
Ge: Do=1.0·10−1 cm2 s−1, Q=1.7 eV, p=1·1019 cm−3, µ=320 cm2 (Vs)−1.
The adsorption kinetics of H2O in a clinoptilolite rich zeolitic tuff was experimentally investigated at 18°C. In the identification of the diffusion mechanism
the isothermal adsorption model equation was used. It was found out that the intraparticle mass transfer becomes more dominant
over the heat transfer with increase in particle size and the adsorptive dose pressure. Although initially intraparticle mass
transfer was the controlling resistance later external heat transfer also contributes to the transfer mechanism.
Knowledge diffusion is the adaptation of knowledge in a broad range of scientific and engineering research and development. It can be defined as the adaptations and applications of knowledge documented in