Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

Pressure-and temperature-dependent mechanical, elastic, and thermodynamical properties of rock salt to CsCl structures in semiconducting SrX (X = O, S, Se, and Te) chalcogenides are presented based on model interatomic interaction potential with emphasis on charge transfer interactions, covalency effect, and zero point energy effects apart from long-range Coulomb, short-range overlap repulsion extended and van der Waals interactions. The developed potential with non-central forces validates the Cauchy discrepancy among elastic constants. The volume collapse (V P /V 0 ) in terms of compressions in SrX at higher pressure indicates the mechanical stiffening of lattice. The expansion of SrX lattice is inferred from steep increase in V T /V 0 and is attributed to thermal softening of SrX lattice. We also present the results for the temperaturedependent behaviors of hardness, heat capacity, and thermal expansion coefficient. From the Pugh's ratio (/ = B T /G H ), the Poisson's ratio (m) and the Cauchy's pressure (C 12 -C 44 ), we classify SrO as ductile but SrS, SrSe, and SrTe are brittle material. To our knowledge these are the first quantitative theoretical prediction of the pressure and temperature dependence of mechanical stiffening, thermally softening, and brittle nature of SrX (X = O, S, Se, and Te) and still await experimental confirmations.

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“…We express the molecular force in the absence of the Lorentz effective field [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] …”

Section: Resultsmentioning

confidence: 99%

“…With these understanding of interatomic potential in SrX, we have four material parameters, namely, modified ionic charge; hardness, range, force parameter [Z m , b, q, f(r)]. Values of them can be deduced from equilibrium conditions [32][33][34][35][36][37].…”

Section: The Methodsmentioning

confidence: 99%

High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenides

et al. 2016

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“…Equation ( 4 ) is a generalised Bloch–Grüneisen expression where the exponent n depends on the dominant scattering mechanism at play 49 , 52 , 54 , 55 . While a n = 2 value is ascribed to a dominant electron–electron scattering mechanism 54 , 56 , a n = 3 value to s-d electron scattering (Bloch–Wilson mechanism) 55 , a n = 4.5 value to electron–magnon scattering 54 and a n = 5 value to electron-acoustic phonon scattering 5 , 49 , 52 , 54 , 55 . In a three-dimensional bulk metallic palladium, the temperature variation of resistance is known to be of T kind implying a dominant electron-acoustic phonon scattering mechanism.…”

Section: Resultsmentioning

confidence: 99%

Charge transport variation from Bloch–Grüneisen to Mott variable range hopping and transport change due to hydrogenation in Palladium thin films

Jayakumar

Dixit

Jose

et al. 2021

Sci Rep

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We report a systematic investigation of the differences in charge transport mechanism in ultra-thin nano-island like films of palladium with thickness varying between 5 nm and 3 nm. The thicker films were found to be metallic in a large temperature range with a dominant Bloch–Grüneisen mechanism of charge transport arising due to electron-acoustic phonon scattering. These films were also found to exhibit an additional electron–magnon scattering. At temperatures below 20 K, the two films displayed a metal-insulator transition which was explained using Al’tshuler’s model of increased scattering in disordered conductors. The thinner films were insulating and were found to exhibit Mott’s variable range hopping mechanism of charge transport. The thinnest film showed a linear decrease of resistance with an increase in temperature in the entire temperature range. The island-like thin films were found to display very different response to hydrogenation at room temperature where the metallic films were found to display a decrease of resistance while the insulating films were found to have an increase of resistance. The decrease of resistance was ascribed to a hydrogen induced lattice expansion in the thin films that were at the percolation threshold while the resistance increase to an increase in work function of the films due to an increased adsorption of the hydrogen atoms at the surface sites of palladium.

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“…31 The motion of charge carriers in the adiabatic region is considered to be faster than lattice vibrations. Using Eq.…”

Section: Electrical Propertiesmentioning

confidence: 99%

Crystalline and Electronic Structures and Magnetic and Electrical Properties of La-Doped Ca2Fe2O5 Compounds

Phan

Tho

Tran

et al. 2017

Journal of Elec Materi

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Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

Cited by 20 publications

References 71 publications

High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenides

High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenides

Charge transport variation from Bloch–Grüneisen to Mott variable range hopping and transport change due to hydrogenation in Palladium thin films

Crystalline and Electronic Structures and Magnetic and Electrical Properties of La-Doped Ca2Fe2O5 Compounds

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