Evaluation of a.c. conductivity of rubber ferrite composites from dielectric measurements

Abstract

The effect of frequency, composition and temperature on the a.c. electrical conductivity were studied for the ceramic, Ni 1-x Zn x Fe 2 O 4 , as well as the filler (Ni 1-x Zn x Fe 2 O 4) incorporated rubber ferrite composites (RFCs). Ni 1-x Zn x Fe 2 O 4 (where x varies from 0 to 1 in steps of 0⋅ ⋅2) were prepared by usual ceramic techniques. They were then incorporated into a butyl rubber matrix according to a specific recipe. The a.c. electrical conductivity (σ σ a.c.) calculations were carried out by using the data available from dielectric measurements and by employing a simple relationship. The a.c. conductivity values were found to be of the order of 10-3 S/m. Analysis of the results shows that σ σ a.c. increases with increase of frequency and the change is same for both ceramic Ni 1-x Zn x Fe 2 O 4 and RFCs. σ σ a.c. increases initially with the increase of zinc content and then decreases with increase of zinc. Same behaviour is observed for RFCs too. The dependence of σ σ a.c. on the volume fraction of the magnetic filler was also studied and it was found that the a.c. conductivity of RFCs increases with increase of volume fraction of the magnetic filler. Temperature dependence of conductivity was studied for both ceramic and rubber ferrite composites. Conductivity shows a linear dependence with temperature in the case of ceramic samples.

Electrical transport measurements of highly conductive carbon nanotube/poly(bisphenol A carbonate) composite

“…This frequency independent conductivity is indicative of nonzero dc conductivity and a clear deviation from the classical dielectric behavior characterized by = Љ 0 , where is the conductivity, is the angular frequency, Љ is the imaginary part of the dielectric constant, and 0 is the vacuum permittivity. 31,32,38,39 The frequency independent ac conductivity shown in Figs. 2͑a͒ and 2͑b͒ of the composites can also be best described by the scaling law ͓Eq.…”

Synthesis of nickel–rubber nanocomposites and evaluation of their dielectric properties

“…With this 20,000 data points can be acquired in a matter of 5 min and transported to a file. The dielectric permittivity of the sample was calculated using the relation [7]:…”

“…The insulating host material can in turn be made conducting or semi-conducting, depending on the amount of filler particles dispersed in the medium [5]. Magnetic fillers are incorporated in rubber matrices to impart magnetic property to the host and such fillers can be metal particles or magnetic oxides like ferrites [6][7][8]. When magnetic oxides are used, very high volume fraction of the filler is necessary to get the required magnetization because of the low density of oxides in comparison to metals.…”

“…Natural rubber is a commonly available elastomer and there exist reports on the studies on electrical properties of composites based on natural rubber with ferrite particles as fillers [7,8]. However reports on the synthesis of composites of natural rubber dispersed with metal particles are not very abundant in the literature.…”

Synthesis, growth, optical, mechanical and electrical properties of L-lysine L-lysinium dichloride nitrate (L-LLDN) single crystal

“…The temperature variation of a.c. electrical conductivity decreases with increasing temperature due to thermal expansion of the crystal shown in figure 7c. When increasing the temperature the density of the crystal is reduced by thermal expansion (Sindhu et al 2002) and thus decreases the conductivity.…”