High-pressure Electrical Resistivity Studies Research Articles

High-pressure electrical resistivity studies for Ba1-xCsxFe2Se3

High-pressure electrical resistance measurements were performed for iron-based ladder material Ba1-xCsxFe2Se3 (x = 0.25 and 0.65) using a diamond anvil cell (DAC). Recent high-pressure study revealed that iron-based ladder material BaFe2S3 exhibits an insulator- metal transition and superconductivity, and this discovery would provide important insight for understanding the mechanism of iron-based superconductors. Therefore, it is intriguing to investigate the high-pressure properties for the iron-based ladder material Ba1-xCsxFe2Se3 system. The parent compounds BaFe2Se3 and CsFe2Se3 show insulating and magnetic ordering features. For Ba1-xCsxFe2Se3 system, no magnetic ordering is observed for x = 0.25 and minimum charge gap was estimated for x = 0.65. The insulator-metal transitions are observed in both materials.

High-pressure electrical resistivity studies for Ba1-xCsxFe2Se3

High-pressure electrical resistance measurements were performed for iron-based ladder material Ba1-xCsxFe2Se3 (x = 0.25 and 0.65) using a diamond anvil cell (DAC). Recent high-pressure study revealed that iron-based ladder material BaFe2S3 exhibits an insulator-metal transition and superconductivity, and this discovery would provide important insight for understanding the mechanism of iron-based superconductors. Therefore, it is intriguing to investigate the high-pressure properties for the iron-based ladder material Ba1-xCsxFe2Se3 system. The parent compounds BaFe2Se3 and CsFe2Se3 show insulating and magnetic ordering features. For Ba1-xCsxFe2Se3 system, no magnetic ordering is observed for x = 0.25 and minimum charge gap was estimated for x = 0.65. The insulator-metal transitions are observed in both materials.

Structural, optical and high pressure electrical resistivity studies of pure NiO and Cu-doped NiO nanoparticles

In this paper, pure NiO and Cu-doped NiO nanoparticles are prepared by co-precipitation method. The electrical resistivity measurements by applying high pressure on pure NiO and Cu-doped NiO nanoparticles were reported. The Bridgman anvil set up is used to measure high pressures up to 8 GPa. These measurements show that there is no phase transformation in the samples till the high pressure is reached. The samples show a rapid decrease in electrical resistivity up to 5 GPa and it remains constant beyond 5 GPa. The electrical resistivity and the transport activation energy of the samples under high pressure up to 8 GPa have been studied in the temperature range of 273–433 K using diamond anvil cell. The temperature versus electrical resistivity studies reveal that the samples behave like a semiconductor. The activation energies of the charge carriers depend on the size of the samples.

Unification of the pressure and composition dependence of superconductivity in Ru substituted BaFe2As2

Temperature dependent high pressure electrical resistivity studies have been carried out on Ba(Fe1−x Rux)2As2 single crystals with x=0.12, 0.26 and 0.35, which correspond to under-doped, optimally doped and over-doped composition regimes, respectively. The evolution of structural/magnetic (TS–M) and superconducting transition (Tc) temperatures, with pressure for various compositions has been obtained. The normal state resistivity has been analyzed in terms of a model that incorporates both spin fluctuations and the opening of the gap in the spin density wave (SDW) phase. It is shown that Tc scales with the strength of the spin fluctuation, B, and TS–M scales with the SDW gap parameter, Δ. This provides a prescription for the unification of the composition and pressure induced superconductivity in BaFe2As2.

High pressure electrical resistivity studies on Ni-doped TiO 2 nanoparticles

Electrical resistivity measurement of Ni-doped TiO 2 nanoparticles were performed under high pressure using a Bridgman opposed anvil setup. It is observed that, anatase phase nanoparticles shows a sudden increase in resistivity below the pressure limit of 4 GPa and is attributed to the transition from anatase to rutile phase. In addition, the transition limit is shifted towards lower pressure region with increase in dopant concentration. But, Ni-doped TiO 2 nanoparticles with rutile phase shows a rapid decrease in resistivity up to 5 GPa and thereafter it becomes constant. Samples with constant resistivity behavior are mainly ascribed to the semiconductor-metallic transformation.

57Fe Mossbauer spectroscopy and electrical resistivity studies on naturally occurring native iron under high pressures up to 9.1 GPa

We report the pressure dependence of the Mössbauer spectra and the electrical resistivity up to 9.1 GPa at room temperature for a native iron sample collected from the Precambrian Chaibasa shales, Singhbhum Craton, Eastern India. The Mössbauer spectroscopy of the sample at ambient conditions yields isomer shifts and magnetic hyperfine field values that confirm the presence of Fe0 oxidation state. Many theories have been put forward to explain the origin of this native iron including a Precambrian meteoritic impact. High-pressure Mössbauer spectroscopic measurements using diamond anvil cell (DAC) showed a constant isomer shift up to 5.6 GPa with a subtle variation of -1.07 × 10-3 mm/s/GPa followed by sharper change -4.3 × 10-3 mm/s/GPa above 6.3 GPa, a pressure much lower than the usual value reported for metallic iron. Further increase of pressure to 9.1 GPa results in the emergence of a tiny peak at ~0 isomer shift indicating the onset of the martensitic phase transition of iron from the body-centered-cubic (bcc) to hexagonal-close-packed (hcp) transition 4 GPa lower than the transition pressure normally observed for pure iron. This phase transition in the native iron is confirmed by high-pressure electrical resistivity study. Lowering of the transition pressure could be due to nucleation of hcp by stacking faults caused by shock metamorphism resulting from the Precambrian impact in the region.

Pressure-Induced Superconductivity inCaLi2

A search for superconductivity has been carried out on the hexagonal polymorph of Laves-phase CaLi(2), a compound for which Feng, Ashcroft, and Hoffmann predict highly anomalous behavior under pressure. No superconductivity is observed above 1.10 K at ambient pressure. However, high-pressure ac susceptibility and electrical resistivity studies to 81 GPa reveal bulk superconductivity in CaLi(2) at temperatures as high as 13 K. The normal-state resistivity displays a dramatic increase with pressure.

HIGH PRESSURE ELECTRICAL RESISTIVITY STUDY ON NONLINEAR SINGLE CRYSTAL ZINC THIOUREA CHLORIDE

Zinc thiourea chloride (ZTC) crystals were crystallized by slow evaporation technique. The lattice parameters of the grown crystals were determined by angle dispersive X-ray powder diffraction technique (XRD) and the structure was confirmed. High pressure electrical resistivity study was carried out on this crystal and the results are reported here.

High pressure electrical resistivity study on nonlinear bis thiourea cadmium chloride (BTCC) single crystal

AbstractThe Bis Thiourea Cadmium Chloride (BTCC) crystals have been crystallized by slow evaporation technique. The lattice parameters of the grown crystals have been determined by the Energy dispersive x‐ray diffraction technique (EDXRD) and the structure has been confirmed. The high pressure electrical resistivity study have been carried out on this crystal and the results have been reported here. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High pressure electrical resistivity study on nonlinear single crystal zinc thiourea sulphate (ZTS)

The Tris Zinc Thiourea Sulphate (ZTS) crystals have been crystallized by slow evaporation technique. The lattice parameters of the grown crystals have been determined by the Energy dispersive x-ray diffraction technique (EDXRD) and the structure has been confirmed. And, the high pressure electrical resistivity study have been carried out on this crystal and the results have been reported here. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of high-pressures on the electrical resistivity of natural zeolites from Deccan Trap, Maharashtra, India

We report here the electrical resistivity measurements on two natural zeolites–natrolite and scolecite (from the Killari borehole, Maharashtra, India) as a function of pressure up to 8 GPa at room temperature. High-pressure electrical resistivity studies on hydrous alumino-silicate minerals are very helpful in understanding the role of water in deep crustal conductivities obtained from geophysical models. The results obtained by magneto-telluric (MT) soundings and direct current resistivity surveys, along with the laboratory data on the electrical resistivity of minerals and rocks at high-pressure–temperature are used to determine the electrical conductivity distribution in continental lithosphere. The electrical resistivity of natural natrolite decreases continuously from 2.9 × 10 9 Ω cm at ambient condition to 7.64 × 10 2 Ω cm at 8 GPa, at room temperature. There is no pressure-induced first order structural phase transitions in natrolite, when it is compressed in non-penetrating pressure transmitting medium up to 8 GPa. On the other hand scolecite exhibits a pressure-induced transition, with a discontinuous decrease of the electrical resistivity from 2.6 × 10 6 to 4.79 × 10 5 Ω cm at 4.2 to 4.3 GPa. The observed phase transition in scolecite is found to be irreversible. Vibrational spectroscopic and X-ray diffraction studies confirm the amorphous nature of the high-pressure phase. The results of the present high-pressure studies on scolecite are in good agreement with the high-pressure Raman spectroscopic data on scolecite. The thermo gravimetric studies on the pressure-quenched samples show that the samples underwent a pressure-induced partial dehydration. Such a pressure-induced partial dehydration, which has been observed in natural scolecite could explain the presence of high conductive layers in the earth's deep-crust.

High-pressure and high-temperature electrical resistivity studies on Nd-123

High-pressure, high-temperature electrical resistivity measurements are carried out on NdBa 2Cu 3O 7− δ high T c superconductor (HTSC). The electrical resistivity is measured by four-probe method using Bridgmann Opposed Anvil High-Pressure Device (OAHPD). The high-temperature measurement is done using heating coil arrangement in OAHPD. The electrical resistivity is found to decrease with the increase of pressure up to 8 GPa. The sample shows a decrease in the resistivity up to the maximum pressure and temperature of 8 GPa and 523 K, respectively.

Synthesis and high-pressure electrical resistivity studies of Ti 3Al

Titanium aluminide (Ti 3Al) has been synthesized by a powder metallurgical method. X-ray diffraction studies show the formation of a single phase with hexagonal structure. Electrical resistivity studies were carried out by a four-probe technique both at high pressure and high temperature using a Bridgman Opposed Anvil High Pressure Device (OAHPD). The sample was studied up to a pressure and temperature of 10 GPa and 250 °C, respectively. The electrical resistivity is found to decrease with increasing pressure. The temperature effect causes an upward shift in the electrical resistivity in the range of pressure considered.

Pressure and temperature effect on the electrical resistivity of Nd 0.94Ca 0.06Ba 2Cu 3O 7−δ

High-pressure and high-temperature electrical resistivity studies on composition controlled Nd 0.94Ca 0.06Ba 2Cu 3O 7− δ superconductor have been done by four-probe technique using Opposed Anvil High-Pressure Device (OAHPD). The electrical resistivity measurements were carried out up to a maximum pressure of 8 GPa and at various temperatures up to a maximum of 523 K in steps of 50 K using the heating coil arrangement. Simulation of the X-ray diffraction pattern confirms the structure of the sample. A gradual decrease in the electrical resistivity with increase of pressure was observed. The observed decrease in the electrical resistivity on application of pressure is discussed with respect to the structural changes under pressure. Measurements were performed up to a pressure and temperature of 8 GPa and 523 K, respectively. Improved electrical resistivity is observed under pressure. The temperature effect causes an upward shift in the electrical resistivity in the observed range of pressure.

HIGH PRESSURE ELECTRICAL RESISTIVITY OF COMPOSITION CONTROLLED Nd-123 BASED BULK MATERIAL

High pressure electrical resistivity studies were carried out on the high temperature superconductor Nd 1-x Ca x Ba 2 Cu 3 O 7-δ for various calcium concentrations x=0.00, 0.03, 0.06 and 0.10 obtained by the solid-state reaction method. The electrical resistivity study was performed using the four-probe technique with a Bridgman opposed anvil device. All four samples show an initial drastic fall in electrical resistivity up to a pressure of around 3 GPa that remains almost constant up to 8 GPa.

High pressure electrical resistivity study on cubic SnTe1−xSx

High pressure electrical resistivity study on cubic SnTe1−xSx

High pressure electrical resistivity study on orthorhombic SnTe 1− xSe x

We report the results of the X-ray powder diffraction and high pressure electrical resistivity studies on SnTe 1− x Se x with 0.5≤ x≤1. The electrical resistivity is found to be decreasing with increase of pressure and also with the selenium concentration.

High pressure electrical resistivity study on cubic SnTe1−xSex

High pressure electrical resistivity study on cubic SnTe_1−xSe_x

SYNTHESIS, CHARACTERISATION AND HIGH PRESSURE STUDIES OF Yb0.8Sr0.2Ba2Cu3O7−y SUPERCONDUCTOR

The superconducting compound Yb 0.8 Sr 0.2 Ba 2 Cu 3O7−y is synthesised, characterised and Tc measurements are made. It crystallises in a tetragonal cell with the lattice parameters a=3.813(6) Å, b=3.813(6) Å and c=11.705(4) Å. The compound exhibits superconductivity with a transition temperature of 68 K. High pressure electrical resistivity studies are performed upto 80 kbar using Bridgman opposed anvil high pressure device. The compound exhibits metallic behaviour and no phase transition is observed upto 80 kbar.

HIGH PRESSURE ELECTRICAL RESISTIVITY STUDY ON ORTHORHOMBIC SnTe1−xSx

Electrical resistivity measurements under pressure and lattice parameter study on SnTe 1–xSx(0.5≤x≤1) are reported here. The structure of these samples is confirmed by the theoretical calculation of X ray intensities using Lazy-Pulverix programme. The electrical resistivity decreases with the increase of pressure and also with the decrease of sulphur concentration. High pressure electrical resistivity study has produced more evidence that the compounds are layered material.