Frustrated Metastable Behavior of Magnetic and Transport Properties in Charge Ordered La1-xCaxMnO3+d Manganites

We have studied the effect of metastable, irreversibility induced by repeated thermal cycles on the electric transport and magnetization of polycrystalline samples of La1-xCaxMnO3 (0.48\leq x \leq 0.55) close to charge ordering. With time and thermal cycling (T<300 K) there is an irreversible transformation of the low-temperature phase from a partially ferromagnetic and metallic to one that is less ferromagnetic and highly resistive for the composition close to charge ordering (x=050 and 0.52). Irrespective of the actual ground state of the compound, the effect of thermal cycling is towards an increase of the amount of the insulating phase. We have observed the magnetic relaxation in the metastable state and also the revival of the metastable state (in a relaxed sample) due to high temperature thermal treatment. We observed changes in the resistivity and magnetization as the revived metastable state is cycled. The time changes in the magnetization are logarithmic in general and activation energies are consistent with those expected for electron transfer between Mn ions. Changes induced by thermal cycling can be inhibited by applying magnetic field. These results suggest that oxygen non-stoichiometry results in mechanical strains in this two-phase system, leading to the development of frustrated metastable states which relax towards the more stable charge-ordered and antiferromagnetic microdomains. Our results also suggest that the growth and coexistence of phases gives rise to microstructural tracks and strain accommodation, producing the observed irreversibility.Comment: 13 Pages, 10 Figure

Thermoelectric Properties of Chalcogenide System

We will discuss the development of a new ternary and quaternary tellurium telluride chalcogenide nanoparticles used for efficient thermo-electric waste heat energy convertor called thermo-electric generator. Nanoparticles-based tellurium telluride chalcogenide nanoparticles, which will be used for thermoelectric generator, will eventually solve an important issue of the energy crises, that is, conversion of waste heat into useful electrical energy. By injecting charge carriers in the host matrix of Tl10-x-yAxByTe6 nanomaterials system, different types of dopants (A = Pb, Sn, Ca and B = Pb, Sb Sr, etc.), with x = 0–2.5 and y = 0–2.5 on tellurium telluride has been introduced to synthesize new materials by Co-precipitation techniques and also by solid state reaction techniques followed by Ball-Milling for the fabrication of nanomaterials. We will study the effect of reduction of charge carriers in thermal and transport properties using different dopants contents by replacing host atoms. The charge carrier’s concentration will affect the ratio of electron-hole concentration which in turns increases the electron scattering in these chalcogenide nanoparticles, which will affect the electrical conductivity and thermo-power. The prime purpose of doping with different ionic radii and different concentration is to enhance the power factor for the tellurium telluride nanosystem. At the end one will be able to control different physical parameters such as, thermally assisted electrical conductivity, and thermopower. Different characterization technique will be applied, for example, X-Ray diffraction techniques will be used for structural analysis, SEM will shows the morphological structure of the particles at 100 nm and energy dispersive x-rays spectroscopy will be used for elemental analysis. The electrical conductivity will be measured by four-probe resistivity measurement techniques, and Seebeck coefficient will be measured by standard temperature gradient techniques

Hybrid Nature Properties of Tl_10-xATe₆ (A = Pb and Sn) Used as Batteries in Chalcogenide System

In future, the most common batteries will be the thallium. As there is many types of batteries but the thallium batteries are better from them. In here, we have made the compound which is more positive work than the other batteries. The different elements are doping in the tellurium telluride to determine the different properties like electrical and thermal properties of nanoparticles. The chalcogenide nanoparticles can be characteristics by the doping of the different metals which are like the holes. We present the effects of Pb and Sn doping on the electrical and thermoelectric properties of Tellurium Telluride Tl10-xPbxTe6 and Tl10-xSnxTe6 (x = 1.00, 1.25, 1.50, 1.75, 2.00) respectively, which were prepared by solid state reactions in an evacuated sealed silica tubes. Structurally, all these compounds were found to be phase pure as confirmed by the x-rays diffractometery (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis. The thermo-power or Seebeck co-efficient (S) was measured for all these compounds which show that S increases with increasing temperature from 295 to 550 K. The Seebeck coefficient is positive for the whole temperature range, showing p-type semiconductor characteristics. Similarly the electrical conductivity (σ) and the power factors have also complex behavior with Pb and Sn concentrations. The power factor (PF = S2σ) observed for Tl10-xPbxTe6 and Tl10-xSnxTe6 compounds are increases with increase in the whole temperature range (290 K–550 K) studied here. Telluride’s are narrow band-gap semiconductors, with all elements in common oxidation states, according to (Tl+)9(Pb3+)(Te2−)6 and (Tl+)9(Sn3+)(Te2−)6. Phases range were investigated and determined with different concentration of Pb and Sn with consequents effects on electrical and thermal properties

Thermoelectricity Properties of Tl_10-x ATe₆ (A = Pb) in Chalcogenide System

The different elements are doping in the tellurium telluride to determine the different properties like electrical and thermal properties of nanoparticles. The chalcogenide nanoparticles can be characteristics by the doping of the different metals which are like the holes. We present the effects of Pb doping on the electrical and thermoelectric properties of Tellurium Telluride Tl10-xPbxTe6 (x = 1.000, 1.250, 1.500, 1.750, 2.000) respectively, which were prepared by solid state reactions in an evacuated sealed silica tubes. Structurally, all these compounds were found to be phase pure as confirmed by the x-rays diffractometery (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis. The thermo-power or Seebeck co-efficient (S) was measured for all these compounds which show that S increases with increasing temperature from 295 to 550 K. The Seebeck coefficient is positive for the whole temperature range, showing p-type semiconductor characteristics. Similarly, the electrical conductivity (σ) and the power factors have also complex behavior with Pb and Sn concentrations. The power factor (PF=S2σ) observed for Tl10-xPbxTe6 compounds are increases with increase in the whole temperature range (290 K-550 K) studied here. Telluride’s are narrow band-gap semiconductors, with all elements in common oxidation states, according to (Tl+) 9 (Pb3+)(Te2−)6. Phases range were investigated and determined with different concentration of Pb and Sn with consequents effects on electrical and thermal properties