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Mahmood Q, Hassan M, Noor NA. Systematic study of room-temperature ferromagnetism and the optical response of Zn 1-x TM x S/Se (TM = Mn, Fe, Co, Ni) ferromagnets: first-principle approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:506001. [PMID: 27758981 DOI: 10.1088/0953-8984/28/50/506001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The structural, magnetic and optical characteristics of Zn1-x TM x S/Se (TM = Mn, Fe, Co, Ni and x = 6.25%) have been investigated through the full-potential linearized augmented plane wave method within the framework of density functional theory. The optimized structures have been used to calculate the ferromagnetic and the antiferromagnetic ground-state energies. The stability of the ferromagnetic phase has been confirmed from the formation and the cohesive energies. The Heisenberg model is used to elucidate the Curie temperature (T c) of these alloys. From the band structures and density of states plots, it has been observed that TM-doped ZnS/Se alloys appear to be semiconductors and exhibit ferromagnetism. In addition, the observed ferromagnetism has also been explained in terms of direct exchange energy Δ x (d), exchange splitting energy Δ x (pd), crystal-field energy (E crys), exchange constants (N 0 α and N 0 β) and magnetic moments that shows potential spintronic applications. The optical behaviors of these alloys have been explained in terms of real and imaginary parts of the dielectric constant ε(ω), refractive index n(ω), extinction coefficient K(ω), reflectivity R(ω) and absorption coefficient σ(ω), in the energy range 0-25 eV. The calculated static limits of the band gaps and real part of the dielectric constants satisfy the Penn model. The critical limits of the imaginary part of the dielectric constants and absorption coefficients indicate that these alloys can be operated in the visible and the ultraviolet region of the electromagnetic spectrum; therefore, make them important for optoelectronic applications.
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Affiliation(s)
- Q Mahmood
- Department of Physics, University of the Punjab, Quaid-e-Azam Campus, Lahore 54590, Pakistan
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Fabbro MT, Saliby C, Rios LR, La Porta FA, Gracia L, Li MS, Andrés J, Santos LPS, Longo E. Identifying and rationalizing the morphological, structural, and optical properties of [Formula: see text]-Ag 2MoO 4 microcrystals, and the formation process of Ag nanoparticles on their surfaces: combining experimental data and first-principles calculations. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:065002. [PMID: 27877844 PMCID: PMC5069988 DOI: 10.1088/1468-6996/16/6/065002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 06/01/2023]
Abstract
We present a combined theoretical and experimental study on the morphological, structural, and optical properties of β-Ag2MoO4 microcrystals. β-Ag2MoO4 samples were prepared by a co-precipitation method. The nucleation and formation of Ag nanoparticles on β-Ag2MoO4 during electron beam irradiation were also analyzed as a function of electron beam dose. These events were directly monitored in real-time using in situ field emission scanning electron microscopy (FE-SEM). The thermodynamic equilibrium shape of the β-Ag2MoO4 crystals was built with low-index surfaces (001), (011), and (111) through a Wulff construction. This shape suggests that the (011) face is the dominating surface in the ideal morphology. A significant increase in the values of the surface energy for the (011) face versus those of the other surfaces was observed, which allowed us to find agreement between the experimental and theoretical morphologies. Our investigation of the different morphologies and structures of the β-Ag2MoO4 crystals provided insight into how the crystal morphology can be controlled so that the surface chemistry of β-Ag2MoO4 can be tuned for specific applications. The presence of structural disorder in the tetrahedral [MoO4] and octahedral [AgO6] clusters, the building blocks of β-Ag2MoO4, was used to explain the experimentally measured optical properties.
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Affiliation(s)
- Maria T Fabbro
- Department of Chemistry, CDMF, Universidade Federal de São Carlos, 13565-905, São Carlos, Brazil
- Department of Inorganic and Organic Chemistry, Universitat Jaume I, Campus Riu Sec, E-12071, Castellón, Spain
| | - Carla Saliby
- Department of Chemistry, CDMF, Universidade Federal de São Carlos, 13565-905, São Carlos, Brazil
| | - Larissa R Rios
- Department of Chemistry, CDMF, Universidade Federal de São Carlos, 13565-905, São Carlos, Brazil
| | - Felipe A La Porta
- Department of Chemistry, Universidade Tecnológica Federal do Paraná, 86036-370, Londrina, Brazil
| | - Lourdes Gracia
- Department of Physic and Analytical Chemistry, Universitat Jaume I, Campus Riu Sec, E-12071, Castellón, Spain
| | - Máximo S Li
- Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970, São Carlos, Brazil
| | - Juan Andrés
- Department of Physic and Analytical Chemistry, Universitat Jaume I, Campus Riu Sec, E-12071, Castellón, Spain
| | - Luís P S Santos
- Department of Chemistry, INCTMN, Instituto Federal do Maranhão, Monte Castelo, 65030-005, São Luís, Brazil
| | - Elson Longo
- CDMF, INCTMN, Instituto de Química, Universidade Estadual Paulista, Araraquara, 14801-907, Brazil
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