Electrical resistivity of amorphous Fe90-xCoxZr10 alloys: Weak localization and spin fluctuation effects

The results of electrical resistivity () measurements performed on amorphous Fe_90-xCo_xZr₁₀ alloys in the temperature range 77 K to 350 K are presented and discussed in the light of existing theoretical models. Besides unambiguously identifying weak localization, electron-phonon scattering, electron-magnon scattering and scattering of conduction electrons from spin fluctuations as main mechanisms governing the temperature dependence of within the temperature range covered in this work, the present results demonstrate that inelastic scattering of electrons from longitudinal phonons provides the most effective dephasing mechanism. Weak localization effects basically account for the negative temperature coefficient of observed for temperatures below the minimum and the inelastic scattering time or dephasing time increases rapidly with Co concentration. Spin fluctuation effects show up clearly for temperatures in the vicinity of the Curie temperature through a contribution to (T) which varies with temperature as . That spin fluctuations get suppressed by Co substitution is strongly indicated by a continuous decline of the coefficient of the term with increasing Co concentration.     

Comparative studies of volatile oil composition of Rhododendron anthopogon by hydrodistillation, supercritical carbon dioxide extraction and head space analysis

Volatile oil composition of the leaves of Rhododendron anthopogon (Ericaceae) growing wild in alpine Western Himalaya was studied using different extraction techniques including SC-CO(2) extraction and hydrodistillation (HD). Results from different extraction methodologies were compared with headspace analysis (HS) and evaluated for the effectiveness of techniques in characterisation of various terpene categories and to assess their influence on the yield and composition of volatiles. Variability in constituents and in quantitative yields was observed. The results varied with different extraction methods. A total of 27 constituents in SC-CO(2) extraction, 31 in HD and 17 in HS analysis were identified. Constituents in SC-CO(2) and HD oils were identified by gas chromatography mass spectrometry analysis. SC-CO(2) extraction was carried out at 40°C and 140 bar pressure and the oil represented by major constituents as β-caryophyllene (5.96%), α-humulene (4.06%) and p-menthadiene-2,9-diol (7.28%); in HD, oil limonene (11.26%), β-caryophyllene (11.62%), α-humulene (7.22%), and E-nerolidol (5.83%) dominated the oil and in HS analysis, limonene (24.14%), γ-terpinene (40.73%), α-terpinene (4.92%), β-phellandrene (3.44%) and β-ocimene (7.15%) were present as major constituents.     

Effect of Hydrostatic Pressure on the Resistivity of La0.8Ag0.1MnO3 Ceramic near TC

JETP Letters - The effect of hydrostatic pressure up to 8.5 GPa on the transport characteristics of granular ceramic manganite La0.8Ag0.1MnO3 near the temperature corresponding to the...     

Effect of Frequency of the Alternating Electric Field on Temperature Impedance Spectra of LuFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Ceramic Multiferroic

Temperature impedance spectra are measured on LuFe₂O₄ ceramic multiferroics over a temperature range of 100–400 K, upon applying a sinusoidal voltage with a frequency varying between 20 Hz and 120MHz. At signal frequencies of 30–70 MHz, spectra exhibit features such as an abnormal positive temperature resistance coefficient within the temperature range of 200–260 K, which are interpreted in the context of the generalized barrier model.