http://192.168.1.40:8080/xmlui/handle/123456789/1114 2026-05-31T14:25:04Z 2026-05-31T14:25:04Z Saha, S. Sinha, Tripurari Prasad http://192.168.1.40:8080/xmlui/handle/123456789/2296 2018-11-27T11:50:34Z 2006-01-01T00:00:00Z

Dielectric relaxation in SrFe 1/2Nb 1/2O 3 Saha, S.; Sinha, Tripurari Prasad The strontium iron niobate Sr Fe12 Nb12 O3 ceramic is synthesized by a solid-state reaction technique. The x-ray diffraction of the sample at room temperature shows a monoclinic phase. The dielectric permittivity and the loss tangent of the sample are measured in a frequency range from 50 Hz to 2 MHz and in a temperature range from 143 to 473 K. The frequency dependence of the loss peak is found to obey an Arrhenius law with an activation energy of 0.272 eV. An analysis of the loss factor with frequency is performed by using the scaling behavior of the dielectric loss spectra. The scaling behavior of the dielectric loss spectra shows its temperature-independent nature. The relaxation mechanism is discussed in the framework of conductivity and impedance spectroscopy. The variation of dielectric constant with temperature is explained considering the space-charge polarization. DOI: 10.1063/1.2160712

2006-01-01T00:00:00Z Kumar, A. Prasad, K. Choudhary, S. N. Sinha, Tripurari Prasad http://192.168.1.40:8080/xmlui/handle/123456789/2295 2018-11-27T11:50:37Z 2005-12-01T00:00:00Z

Phase transition in Ph[(Mg3/4Cu1/4) 1/3Nb2/3]O3 ceramic Kumar, A.; Prasad, K.; Choudhary, S. N.; Sinha, Tripurari Prasad Single phase perovskite-type cubic ceramics of Pb[(M3/4Cu1/4)(1/3)Nb-2/3]O-3 (PMCN) were synthesized by high temperature double step solid state reaction technique. Dielectric studies show relaxor behaviour with diffuse phase transition. The phase transition (T-m) occurs at -22 degrees C at 10 kHz. The frequency dependence of T-m has been modeled using Vogel-Fulcher relation. The dielectric relaxation in PMCN is found analogous to the magnetic relaxation in spin-glass system. The relaxor behaviour in PMCN has also been examined through admittance spectroscopy.

2005-12-01T00:00:00Z Ray, D. K. Himanshu, A.K. Sinha, Tripurari Prasad http://192.168.1.40:8080/xmlui/handle/123456789/2294 2018-11-27T11:50:36Z 2005-10-01T00:00:00Z

Study of impedance spectroscopy conducting polymer prepared with the use of water soluble support polymer Ray, D. K.; Himanshu, A.K.; Sinha, Tripurari Prasad The intrinsically conducting polymer (ICP), polyaniline (PANI) is synthesized by chemical oxidative polymerization process with the help of water soluble support polymer poly-vinyl alcohol (PVA). The field dependence of the dielectric response is measured in the frequency range 50 Hz-1 MHz and temperature range 140-318 K. The frequency dependence of the imaginary impedance (Z") is found to obey an Arrhenius law with the activation energy of 0.0176 eV. An analysis of real and imaginary parts of dielectric permittivity, conductivity formalism and impedance (Z) with frequency and temperature is performed, showing the polydispersive nature of the sample as confirmed by Cole-Cole plot as well as the scaling behaviour of the Z". The frequency dependent electrical data are discussed in the context of models for dc and ac transport in PANI-PVA composite, with the results supporting hopping of charges among positively charged polaron and bipolaron states. These results elucidate that there is an increased coupling among the local dipolar motions (short-range order localized motion).

2005-10-01T00:00:00Z Prasad, S. Prasad, K. Choudhary, S. N. Sinha, Tripurari Prasad http://192.168.1.40:8080/xmlui/handle/123456789/2293 2013-03-20T05:56:40Z 2005-07-15T00:00:00Z

Electrical behaviour of 0.80Pb[(Mg,Zn)1/3Ta2/3]O 3-0.20PbTiO3 relaxor Prasad, S.; Prasad, K.; Choudhary, S. N.; Sinha, Tripurari Prasad Polycrystalline 0.80Pb[(Mg2/3Zn1/3)(1/3)Ta-2/3]O-3-0.20PbTiO(3) (PMZT-PT) having a tetragonal perovskite type structure was prepared by the high temperature solid-state reaction method. Dielectric studies showed the relaxor behaviour with diffuse phase transition. High value of epsilon(m) > 8000 was realized with T-m (phase transition temperature) at 57 degrees C at 1 kHz. The frequency dependence of T-m has been modeled using Vogel Fulcher relation. The dielectric relaxation in the present system was found analogous to the magnetic relaxation in spin-glass system. Complex impedance analysis indicated the system undergoing a polydispersive non-Debye type dielectric relaxation. The relaxation behaviour in PMZT-PT was also probed through admittance spectroscopy. DOI: 10.1016/j.physb.2005.04.014

2005-07-15T00:00:00Z