Novel magnetic nanomaterial Co0.7Zn0.3Fe2−xGdxO4 for nanotechnology applications: experimental and theoretical investigations
01 Oct 2021-Journal of Materials Science: Materials in Electronics (Springer US)-Vol. 32, Iss: 20, pp 24748-24765
TL;DR: In this article, a spinel with a high crystallinity was synthesized by the co-precipitation method for the first time, and the analysis of the magnetic properties indicated that the coercivity (Hc) and Curie temperature (Tc) values increase while the saturation magnetization (Ms) value decreases upon doping with Gd.
Abstract: Co0.7Zn0.3Fe2−xGdxO4 (x = 0.02) ferrite nanoparticles with average size of 32 nm is synthesized by the co-precipitation method for the first time. X-ray diffraction spectra revealed the formation of single-phase spinel with a high crystallinity. Fourier transform infra-red spectra confirmed the formation of spinel matrix crystallographic sites and Scanning Electron Microscopy images confirmed the formation of agglomerated spherical particles with nanometric sizes. The analysis of the magnetic properties indicates that the coercivity (Hc) and Curie temperature (Tc) values increase while the saturation magnetization (Ms) value decreases upon doping with Gd. These results can be seen as a significant improvement of the magnetic properties compared to the undoped material, which could be beneficial for nanotechnology applications. The material is also studied from a theoretical perspective using first-principles calculations. The used PBE-HF method based on the GGA method with the implication of the onsite-exact-exchange proved to be very accurate in describing the system, giving rise to a semi-conducting behavior for the inverse spinel CoFe2O4 and a metallic electronic structure for Gd-doped Co0.7Zn0.3Fe2O4.
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TL;DR: In this paper , the magnetic properties of Ni-Co spinel ferrite with oleic acid were studied using a co-precipitation method using magnetic properties measurement system.
Abstract: In this paper, the magnetic properties of Ni_0.5Co_0.5Fe_1.59Mo_0.1Gd_0.2Sm_0.1Tb_0.01O_4 nanoparticles coated with oleic acid and prepared for the first time by the co-precipitation method were studied using magnetic property measurement system. TGA analysis was used to analyze the thermal behavior of the obtained precipitate. The formation of a pure phase of spinel nanoparticles with a mixed structure coated with oleic acid was confirmed by X-ray diffraction. The formation of crystallographic sites of spinel structure and the presence of oleic acid on the surface of nanoparticles was confirmed by infrared spectroscopy (FTIR). Transmission electron microscopy shows that the nanoparticles have a spherical shape morphology. The magnetic properties were determined at three different temperatures (5, 80, and 300 K) and revealed that the synthesized material has a superparamagnetic behavior. DFT calculations were performed to study the effect of doping the Ni–Co spinel ferrite with Mo, Sm, Tb, and Gd. Graphical abstract
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TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
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TL;DR: In this article, a method for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector is given, where the integration can be over the entire zone or over specified portions thereof.
Abstract: A method is given for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector. The integration can be over the entire Brillouin zone or over specified portions thereof. This method also has applications in spectral and density-of-state calculations. The relationships to the Chadi-Cohen and Gilat-Raubenheimer methods are indicated.
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University of Udine1, National Research Council2, International School for Advanced Studies3, Massachusetts Institute of Technology4, University of Paris5, Princeton University6, University of Minnesota7, ParisTech8, University of Milan9, International Centre for Theoretical Physics10, University of Paderborn11, ETH Zurich12, École Polytechnique Fédérale de Lausanne13
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Abstract: QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.
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TL;DR: Quantum ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Abstract: Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.
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