Peculiarities of coexistence of phases with different electric conductivities under the influence of an electric current

1998 ◽  
Vol 58 (6) ◽  
pp. 3008-3014 ◽  
Author(s):  
Yu. Dolinsky ◽  
T. Elperin
Author(s):  
Ian M. Anderson ◽  
Arnulf Muan ◽  
C. Barry Carter

Oxide mixtures which feature a coexistence of phases with the wüstite and spinel structures are considered model systems for the study of solid-state reaction kinetics, phase boundaries, and thin-film growth, and such systems are especially suited to TEM studies. (In this paper, the terms “wüstite” and “spinel” will refer to phases of those structure types.) The study of wüstite-spinel coexistence has been limited mostly to systems near their equilibrium condition, where the assumptions of local thermodynamic equilibrium are valid. The cation-excess spinels of the type Ni2(1+x)Ti1-xO4, which reportedly exist only above 1375°C4, provide an excellent system for the study of wüstite-spinel coexistence under highly nonequilibrium conditions. The nature of these compounds has been debated in the literature. X-ray and neutron powder diffraction patterns have been used to advocate the existence of a single-phase, non- stoichiometric spinel. TEM studies of the microstructure have been used to suggest equilibrium coexistence of a stoichiometric spinel, Ni2TiO4, and a wüstite phase; this latter study has shown a coexistence of wüstite and spinel phases in specimens thought to have been composed of a single, non- stoichiometric spinel phase. The microstructure and nature of this phase coexistence is the focus of this study. Specimens were prepared by ball-milling a mixture of NiO and TiO2 powders with 10 wt.% TiO2. The mixture was fired in air at 1483°C for 5 days, and then quenched to room temperature. The aggregate thus produced was highly porous, and needed to be infiltrated prior to TEM sample preparation, which was performed using the standard techniques of lapping, dimpling, and ion milling.


2018 ◽  
Author(s):  
T.A. Konev ◽  
V.A. Kuzmin ◽  
E. Yu. Mutovina ◽  
R.D. Puzhaykin ◽  
Vladimir Salomatov

Chemical sources of current are investigated as lines with distributed parameters. Analytical expressions are obtained for the voltage and active power values of the source at different distances from the beginning of the cell as well as dependences of the working voltage and active power on the source length. Effects of a reduction in the operating voltage and active power are due to the flow of electric current along the source during operation. The magnitude of these effects depends not only on the length of the source, but also on the ratio of characteristic resistance to the load resistance.<br>


Author(s):  
Leonardo José Cavalcante Vasconcelos ◽  
ARLESON KENNEDI FRANÇA DOS SANTOS ◽  
Dalton Valadares ◽  
Alexander Sena

Sign in / Sign up

Export Citation Format

Share Document