The influence of Mm substitution (Mm = mischmetal) on structural, transport and magnetic properties of (Dy1-xMmx)Co2 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) alloys has been investigated by means of X-ray diffraction (XRD), temperature dependent electrical resistivity (ρ(T)), ac susceptibility (χ(T)) and thermopower (S(T)). XRD patterns show the formation of solid solutions crystallizing with cubic Laves (C15) type structure at room temperature. The pronounced discontinuities in the resistivity and thermopower at Curie temperature (TC) are explained based on the suppression of the spin-fluctuation contribution. The gradual decrease in TC and sharpness of discontinuities in ρ(T) and S(T) with increasing Mm substitution has been discussed. © 2008 Elsevier Ltd. All rights reserved.

Sankaranarayanan V

Department Of Physics

Sundara Ramaprabhu

Cerium alloys

Diffraction

Electric properties

Electric resistance

INTERMETALLICS

Magnetic materials

Magnetic properties

Magnetic susceptibility

Metallic compounds

Rare earth elements

Solid solutions

Transport properties

X ray analysis

X ray diffraction analysis

A. LAVES PHASES

A. Rare-earth intermetallics

B. ELECTRICAL RESISTANCE AND OTHER ELECTRICAL PROPERTIES

B. Magnetic properties

F. Diffraction

Curie temperature

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Intermetallics

The magnetic behaviour in Dy1-xMmxCo2 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5; Mm = mischmetal) compounds is reported using temperature and field dependence of magnetization (M-T and M-H respectively) measurements. A strong composition dependent irreversibility is observed in both the M-T and M-H scans below the magnetic ordering temperature (TC). A clear change of the first-order magnetic transition of DyCo2 to a second-order one in Dy0.5Mm0.5Co2 is evidenced by M-T and a series of Arrott (M2 versus H/M) plots, obtained from the M-H isotherms around TC. The variation in induced moments of the Co sublattice is estimated. It is found that the Mm substitution can only lead to a considerable reduction in the TC, saturation magnetization, and Co moment. The observed behaviour of M-T and M-H plots with increasing Mm content is discussed in detail. © 2010 IOP Publishing Ltd.

Journal of Physics Condensed Matter

Magnetic behaviour in Dy1-xMmxCo2 compounds

The structural and electrical transport properties of Ho1-x Mmx Co2 (x=0, 0.1, 0.2, 0.3, and 0.4 and Mm=mischmetal) alloys and their hydrides in the hydrogen concentration (y) range of 0≤y≤3.6 have been determined through the powder x-ray diffraction (XRD) and temperature dependence of electrical resistivity [ρ (T)] measurements. At room temperature, these compounds crystallize in Mg Cu2 -type (C15) structure. The crystalline nature and lattice expansion of hydrogenated alloys have been studied using the hydrogen concentration dependence of XRD peak analysis indicating the coexistence of two hydride phases at intermediate hydrogen concentrations. The temperature dependence of the electrical resistivity of alloys has been discussed based on the conduction electron scattering and spin fluctuation scattering mechanisms. The changes in magnetic ordering and transition temperature upon Mm substitution and at different concentrations of hydrogen loadings have been discussed. Furthermore, the transformation from metalliclike conductivity to thermally activated conduction mechanism and different conduction regimes of temperature dependent resistivity upon increasing H concentration have been well described by Kondo-type and electron-electron scattering effects. © 2007 American Institute of Physics.

Fulltext

Journal of Applied Physics

Influence of hydrogen absorption on structural and electrical transport properties of Ho1-xMmxCo2 alloys

Thermodynamic and hydrogen-induced structural properties of hydrogenated Ho1-xMmxCo2 (x ≤ 0, 0.1, 0.2, 0.3 and 0.4, Mm ≤ mischmetal) alloys have been investigated. The hydrogen absorption pressure-composition isotherms were studied in the temperature range 50-200 °C and pressure range 0.001-1 bar using a Sieverts-type apparatus. The effect of Mm on the equilibrium plateau pressure and hydride stability has been discussed. Structural analyses and hydrogen-induced amorphization of Ho 1-xMmxCo2hydrides were performed using powder x-ray diffraction. The structural stability of these alloys upon repeated hydrogenation and dehydrogenation cycles has been investigated. At lower hydriding pressure and temperatures, Ho1-xMmxCo 2-hydrides retain their Laves C15 structure; however, the large lattice volume expansion about 24% is observed in the β-phase. The effect of hydrogenation pressure and temperature and Mm concentration on the hydrogen-induced transformation from crystalline Ho1-xMm xCo2-H to amorphous Ho1-xMmxCo 2-H and recrystallization into elemental hydrides have been studied and discussed. © 2007 IOP Publishing Ltd.

Journal of Physics D: Applied Physics

Thermodynamic and hydrogen-induced structural properties of Ho 1-xMmxCo2-hydrides

Journal of Alloys and Compounds

Transport properties of (, Ho) in magnetic field

Physica B: Condensed Matter

AC susceptibility in Y1−xTbxCo2 compounds

Physical Review B

Anomalous magnetotransport in(Y1−xGdx)Co2alloys: Interplay of disorder and itinerant metamagnetism

Magnetic and transport properties of Laves phase Dy1-xMmxCo2 (x = 0-0.5) alloys

Journal	Intermetallics
ISSN	09669795
Open Access	No