Нанокомпозити та наноматеріали

Dependence of the nanocomposite systems resistance on the initial materials dispersity
Ya.I. Lepikh, V.A. Borshchak, N.N. Sadova, N.P. Zatovskaya
Odesa I.I. Mechnikov National University, Dvoryanskaya str, Odesa-65082, Ukraine. 
E-mail: ndl_lepikh@onu.edu.ua

With the development of nanophysics and nanoelectronics, at present, widespread use is made of composite materials, which are a multiphase heterogeneous system consisting of components with various physical and chemical properties. It was found that a significant role in the reproduction and stability of the nanocomposites electrophysical parameters is played by the dispersion of the functional material and glass frit powders. At present, the dispersion of powders is not regulated; according to the design documentation, powders with particle sizes less than 25 microns are used. Our studies on samples made by standard technology showed a low level of the nanocomposites parameters reproducibility, which can be associated with a large glass particles spread in their geometric dimensions [1]. Studies of samples obtained from powders of lead-borosilicate glass (PbO, SiO2, B2O3, Al2O3) with fixed particle sizes (0.5 μm, 1 μm, 3 μm, 5 μm) and a functional material RuO2 with a particle size of 3 μm at a fixed annealing temperature (8700С ) showed the nanocomposites resistance dependence on the ratio of the glass and conductive phases concentration. It has been determined that for samples with a low content of ruthenium dioxide, the influence of the glass-frit particle sizes on the resistance is the largest. The resistance of the samples increases with increasing of the glass content, and the highest growth rate is observed for glass fiber with particle sizes of 0.5 μm. With an increase in the RuO2 concentration, the resistance approaches a constant value and does not depend on the glass fiber particle sizes. The resistance dependence on the particle sizes for high-resistance nanocomposites can be associated with the processes of sintering and the effect of the components dispersion on the conductive chains geometric dimensions. With a decrease in the glass particle sizes, the length increases and the cross-sectional area of the chains of the conducting phase decreases. In RuO2 – glass systems, a mixed character of conductivity is observed, which is a combination of processes occurring in the conductive and glass phases. In high-resistance nanocomposites, the main contribution to the conductivity is made by glass fiber, so the properties of this phase play a significant role in the process of current transfer.