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Open AccessArticle

A Positron Implantation Profile Estimation Approach for the PALS Study of Battery Materials

and

Condens. Matter 2023, 8(2), 48; https://doi.org/10.3390/condmat8020048 - 22 May 2023

Viewed by 816

Abstract

Positron annihilation spectroscopy is a powerful probe to investigate the interfaces in materials relevant for energy storage such as Li-ion batteries. The key to the interpretation of the results is the positron implantation profile, which is a spatial function related to the characteristics of the materials forming the battery. We provide models for the positron implantation profile in a cathode of a Li-ion battery coin cell. These models are the basis for a reliable visualization of multilayer geometries and their interfaces in thin cathodes of lithium-ion batteries. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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Open AccessArticle

Study of Interacting Heisenberg Antiferromagnet Spin-1/2 and 1 Chains

Debasmita Maiti

Dayasindhu Dey

and

Manoranjan Kumar

Condens. Matter 2023, 8(1), 17; https://doi.org/10.3390/condmat8010017 - 29 Jan 2023

Viewed by 1180

Abstract

Haldane conjectures the fundamental difference in the energy spectrum of the Heisenberg antiferromagnetic (HAF) of the spin S chain is that the half-integer and the integer S chain have gapless and gapped energy spectrums, respectively. The ground state (gs) of the HAF spin-1/2 and spin-1 chains have a quasi-long-range and short-range correlation, respectively. We study the effect of the exchange interaction between an HAF spin-1/2 and an HAF spin-1 chain forming a normal ladder system and its gs properties. The inter-chain exchange interaction

J_{⊥}

can be either ferromagnetic (FM) or antiferromagnetic (AFM). Using the density matrix renormalization group method, we show that in the weak AFM/FM coupling limit of

J_{⊥}

, the system behaves like two decoupled chains. However, in the large AFM

J_{⊥}

limit, the whole system can be visualized as weakly coupled spin-1/2 and spin-1 pairs which behave like an effective spin-1/2 HAF chain. In the large FM

J_{⊥}

limit, coupled spin-1/2 and spin-1 pairs can form pseudo spin-3/2 and the whole system behaves like an effective spin-3/2 HAF chain. We also derive the effective model Hamiltonian in both strong FM and AFM rung exchange coupling limits. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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Open AccessArticle

Physicochemical Properties of Ti³⁺ Self-Doped TiO₂ Loaded on Recycled Fly-Ash Based Zeolites for Degradation of Methyl Orange

Iván Supelano García

Carlos Andrés Palacio Gómez

Marc H. Weber

Indry Milena Saavedra Gaona

Claudia Patricia Castañeda Martínez

José Jobanny Martínez Zambrano

Hugo Alfonso Rojas Sarmiento

Julian Andrés Munevar Cagigas

Marcos A. Avila

Carlos Rettori

Carlos Arturo Parra Vargas

and

Julieth Alexandra Mejía Gómez

Condens. Matter 2022, 7(4), 69; https://doi.org/10.3390/condmat7040069 - 18 Nov 2022

Cited by 1 | Viewed by 1335

Abstract

The extensive production of coal fly ash by coal combustion is an issue of concern due to its environmental impact. TiO₂-zeolite composites were synthesized, at low cost, using recycled coal fly ash from a local thermoelectric power plant to produce the zeolite using the hydrothermal method. TiO₂ was loaded by means of the impregnation method using ethanol and titanium isopropoxide between 8.7 and 49.45 wt% TiO₂. The samples were characterized by X-ray diffraction, Raman, electron spin resonance, high-resolution transmission electron microscopy, N₂ adsorption-desorption, doppler broadening of annihilation radiation, and diffuse reflectance techniques, and the photocatalytic activity of the composites was evaluated according to the degradation of methyl orange under UV light. The results show that TiO₂ crystallizes in the anatase phase with a Ti³⁺ oxidation state, without post-treatment. TiO₂ particles were located within the pores of the substrate and on its surface, increasing the surface area of the composites in comparison with that of the substrates. Samples with TiO₂ at 8.7 and 25 wt% immobilized on hydroxysodalite show the highest degradation of methyl orange among all studied materials, including the commercial TiO₂ Degussa P25 under UV light. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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Open AccessArticle

On Three “Anomalous” Measurements of Nonlinear QPC Conductance

Mukunda P. Das

and

Frederick Green

Condens. Matter 2022, 7(3), 49; https://doi.org/10.3390/condmat7030049 - 10 Aug 2022

Cited by 1 | Viewed by 1080

Abstract

Practical mesoscopic devices based on quantum point contacts (QPCs) must function at operating point involving large internal driving fields. Experimental evidence has accumulated to display anomalous nonlinear features of QPC response beyond the capacities of accepted tunnelling-based models of nonlinear quantum transport. Here, we recall the physical setting of three anomalous QPC experiments and review how, for two of them, a microscopically based nonequilibrium quantum kinetic description—the correct physical boundary conditions being crucial—has already overcome the predictive limitations of standard nonequilibrium mesoscopic models. The third experiment remains a significant challenge to all theorists. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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