Kunal Pubby

Comparative Dielectric Analysis of Co-Zr Doped M-Type Barium Hexaferrites BaCoxZrxFe(12-2x)O19 Prepared by Different Wet Chemical Routes

Samples of barium hexaferrites (BaCoxZrxFe(12-2x)O19) with varying molar concentration of Cobalt and Zirconium were synthesized successfully by three different wet chemical routes: Sol gel, Citrate and self-combustion. Dielectric constant, dielectric loss tangent and AC Conductivity measurements were carried out in the frequency range 20Hz–1MHz over Impedance analyzer. Dielectric constant and loss tangent variations are explained on the basis of Maxwell-Wagner interfacial polarization in accordance with Koops phenomenological theory. AC Conductivity varies in accordance to Jonscher law (σac = σdc + Aωn) and shows normal behavior shown by other ferrites. The observed behavior of these samples suggests that the materials are suitable for applications in microwave devices. Three wet chemical routes are compared and it can be concluded that samples synthesized by citrate method are showing higher dielectric constant, low loss and low conductivity, hence are better.

Frequency and temperature dependence of dielectric and electric properties of Ba2-xSm4+2x/3Ti8O24 with structural analysis

Abstract Dielectric ceramics samples of barium titanium oxide doped with samarium, having a complex structural formula of Ba2-xSm4+2x/3Ti8O24 (referred to as BST), were fabricated by a high temperature solid-state reaction technique with varying x (0.0, 0.2, 0.4, 0.6). X-ray diffraction technique was used to check the formation of particular phases. Scanning electron microscope technique was used to study the surface morphology of the samples. The samples were studied in a temperature range of 298 K to 623 K and frequency range of 10 KHz to 1 MHz. The dielectric constant (εr), loss tangent (tan δ), and AC conductivity (σAC) were measured on sintered disks of BST samples. The DC resistivity of different compositions was measured at room temperature. Detailed studies of dielectric and electrical properties showed that these properties are strongly dependent on composition, frequency and temperature. The compounds showed stable behavior in lower temperature range (up to 523 K), therefore, they can be used in practical applications in this temperature range.

Effect of Substitution of Samarium and Lanthanum on Dielectric and Electrical Properties of Barium Titanate

In this research paper, we report the dielectric and electric investigation of series of dielectric ceramics samples with structural formula Ba2-xRe4+2x/3Ti8O24 (where Re = Sm and La and x = 0.0, 0.2, 0.4 and 0.6). The dielectric parameters (i.e. dielectric constant and loss tangent) and ac conductivity are measured with impedance analyzer. This paper is presented to compare the effect of samarium and lanthanum doping on the properties of barium titanate. The research work concludes that lanthanum doping has more favorable effect on the properties. This paper also presents impedance analysis and V-I characteristics of all the samples. This is concluded that these properties are strongly dependent on frequency, temperature and composition. The investigation reports almost constant value of dielectric constant and very low loss tangent at lower temperatures.

Energy harvesting using piezoelectric materials

ABSTRACT This paper is presented to achieve the objective of energy harvesting from vibrational sources through piezoelectric materials. In this analysis, two piezoelectric buzzers: 35 mm buzzer and 27 mm buzzer were used to carry out the experiment. The experimental set-up includes an electro-dynamic shaker, function generator and a power amplifier. Buzzer of thickness 35 mm gave maximum output at resonant frequency of 23 Hz and 57 g of mechanical stress while buzzer of thickness 27 mm gave maximum output at resonant frequency of 25 Hz and 27 g of weight. The paper also presents some important applications of piezoelectricity in day-to-day life.

Effect of precursors on dielectric properties of Co-Zr doped strontium hexaferrites in 20 Hz – 120 MHz frequency range

ABSTRACT Cobalt and zirconium doped ferrite pellets of composition are synthesized successfully using the sol-gel method with two different precursors: Citric Acid and Tartaric Acid. Dielectric constant and dielectric loss tangent measurements are performed in the frequency range 20 Hz − 120 MHz over Impedance analyzer. A.C. conductivity is calculated from Debyes equation of complex permittivity. Dielectric constant and loss tangent are found to be varying in accordance to Maxwell-Wagner theory of interfacial polarization. A.C. conductivity is found to increase with increase in frequency as well as doping amount. Dielectric analysis of two series concludes that ferrites prepared using tartaric acid have higher values of dielectric properties at lower frequencies in comparison to those prepared with citric acid, while at higher frequencies, the effect of precursors seems to be insignificant. The enhancement of dielectric constant and dielectric loss with increase in dopant concentration suggests that these samples are promising materials for applications in microwave devices.

Fabrication and microwave absorption properties of hexaferrite composites in Ku-band

In this research, M-type hexaferrites doped with Co,Ti, Sr(CoTi)xFe(12-2x)O19 (x=0.0, 0.2, 0.4, 0.8, 1.0) have been synthesized using normal ceramic technique. Properties like complex permittivity, complex permeability and reflection loss of composites of these hexaferrites with epoxy resin have been measured in Ku-band i.e. 12.4-18 GHz.