On the structural and magnetic properties of K3CrTe3O12, Na3CrTe3O12 and NaCrTe2O8

1983 ◽  
Vol 48 (8) ◽  
pp. 2197-2204 ◽  
Author(s):  
Pavel Danihelka

K3CrTe3O12, Na3CrTe3O12, and NaCrTe2O8 were obtained by reacting telluric acid or amorphous potassium tellurate with molten alkali dichromates, and their structural and magnetic properties were studied. The three substances are paramagnetic, with magnetic moments corresponding to the chromium oxidation state III. The sodium compounds obey the Curie-Weiss law up to the temperature of decomposition, the potassium compound follows this law up to a temperature of 800 K, above which the magnetic moment of chromium decreases probably on account of a partial reversible oxidation of chromium by the tellurium(VI) present. The three substances investigated were indexed in the tetragonal system and their lattice parameters were calculated. The two sodium salts involve the same basic structure motiv, viz. Te12O4824-.

2021 ◽  
Vol 63 (9) ◽  
pp. 1306
Author(s):  
Е.М. Якунина ◽  
Е.А. Кравцов ◽  
Yu.N. Khaydukov ◽  
Н.О. Антропов ◽  
В.В. Проглядо

Layered nanoheterostructures Fe | MgO | Cr | MgO | Fe is an artificial ferromagnetic material in which the exchange interaction of the magnetic moments of Fe layers through intermediate dielectric and metal layers can lead to magnetic configurations that are not realized in the well-studied Fe | MgO | Fe and Fe | Cr | Fe. In this work, we investigated the correlations of the structural and magnetic properties of layered nanoheterostructures Fe (10 nm) | MgO (1.5 nm) | Cr (t nm) | MgO (1.5 nm) | Fe (7 nm) (thickness t = 0.9 and 1.8 nm). Structural studies performed using X-ray diffractometry and high-resolution reflectometry confirmed the formation of a textured structure and revealed its well-defined layered character with sharp interlayer boundaries.


2004 ◽  
Vol 11 (01) ◽  
pp. 15-20 ◽  
Author(s):  
BAOLIN WANG ◽  
XIAOSHUANG CHEN ◽  
GUIBIN CHEN ◽  
GUANGHOU WANG ◽  
JIJUN ZHAO

The structural and magnetic properties of Cu -coated Co clusters are investigated with empirical genetic algorithm simulation and a spin-polarized spd tight-binding model Hamiltonian. In some specific stoichiometric compositions, icosahedral Co n (n=1, 2, 4, 7, 13, 19, 55) clusters perfectly coated with A Cu monolayer or dual layer are obtained. The outer Cu layers lead to significant modification of the magnetic moment of the Co core, depending on the structure and thickness of the Cu layers. The interaction between Cu and Co atoms induces a nonzero magnetic moment for Cu atoms.


2011 ◽  
Vol 170 ◽  
pp. 74-77 ◽  
Author(s):  
Kazimierz Łątka ◽  
Jacek Gurgul ◽  
Andrzej W. Pacyna ◽  
Rainer Pöttgen

The results of magnetic studies and Mössbauer investigations made with 119Sn source are reviewed for the series of RERhSn (RE = Tb, Dy and Ho) compounds crystallizing in the same hexagonal ZrNiAl-type of structure. The role of crystalline electric field effects in the establishing of magnetic moment orientations observed in these compounds and their influence on the observed magnitudes of magnetic moments are discussed.


2022 ◽  
Vol 12 (2) ◽  
pp. 695
Author(s):  
Alessandra Geddo Lehmann ◽  
Giuseppe Muscas ◽  
Maurizio Ferretti ◽  
Emanuela Pusceddu ◽  
Davide Peddis ◽  
...  

We investigated the structural and magnetic properties of 20 nm-sized nanoparticles of the half-doped manganite Ho0.5Ca0.5MnO3 prepared by sol-gel approach. Neutron powder diffraction patterns show Pbnm orthorhombic symmetry for 10 K < T < 290 K, with lattice parameters a, b, and c in the relationship c/√2 < a < b, indicating a cooperative Jahn–Teller effect, i.e., orbital ordering OO, from below room temperature. In contrast with the bulk samples, in the interval 250 < T < 300 K, the fingerprint of charge ordering (CO) does not manifest itself in the temperature dependence of lattice parameters. However, there are signs of CO in the temperature dependence of magnetization. Accordingly, below 100 K superlattice magnetic Bragg reflections arise, which are consistent with an antiferromagnetic phase strictly related to the bulk Mn ordering of a charge exchange-type (CE-type), but characterized by an increased fraction of ferromagnetic couplings between manganese species themselves. Our results show that in this narrow band half-doped manganite, size reduction only modifies the balance between the Anderson superexchange and Zener double exchange interactions, without destabilizing an overall very robust antiferromagnetic state.


2010 ◽  
Vol 24 (08) ◽  
pp. 967-978 ◽  
Author(s):  
JINGSHAN QI ◽  
HAILIN YU ◽  
XUEFAN JIANG ◽  
DANING SHI

We present a comprehensive investigation of the equilibrium structural, electronic and magnetic properties of C o2 MnSi and C o2 FeSi by density-functional theory (DFT) within the generalized gradient approximation (GGA) using the projected augmented wave (PAW) method. The on-site Coulomb interaction has also taken into account ( GGA +U) approach to unravel the correlation effects on the electronic structure. The change of the energy gap, "spin gap", Fermi energy level and magnetic moments with the lattice parameters is investigated. We found that the on-site correlation interaction in C o2 FeSi is stronger than in C o2 MnSi . So on-site electronic correlation is necessary for C o2 FeSi and the magnetic moments reproduce experimental results well by GGA +U. Further we also found that a moderate change of the lattice parameters does not change the half-metallic ferromagnet (HMF) behavior for both materials. Appearance of half-metallicity is consistent with the integral magnetic moments, which also agrees with the experiment measurements.


2021 ◽  
Vol 35 (05) ◽  
pp. 2150088
Author(s):  
G. Kasprzak ◽  
J. Rzacki

This paper presents results of density functional theory (DFT) studies on structural, electronic, and magnetic properties of novel Y2FeSi Heusler material characterized by spin polarization at Fermi level of [Formula: see text] and magnetic moment of 1.56 [Formula: see text]. The total magnetic moment of investigated material is dominated by Iron sites, while magnetic moments coming from Yttrium sites are aligned antiparallel to the Iron. Here, we introduced Co and Mn substitutions to alter the magnetic and electronic properties of the studied material. The Heusler alloys are very sensitive to electronic structure changes induced by ionic substitutions, which allowing to specifically modulate their properties. The Co-substitution lowered the total magnetic moment to [Formula: see text][Formula: see text]1.20 [Formula: see text] and Mn caused a rise to [Formula: see text][Formula: see text]1.93 [Formula: see text]. Introduction of Mn resulted in [Formula: see text] spin polarization. We hope that this study will promote further theoretical as well as experimental interest in these types of compounds.


2010 ◽  
Vol 168-169 ◽  
pp. 149-152 ◽  
Author(s):  
A.V. Korolyov ◽  
N.I. Kourov ◽  
S.Z. Nazarova ◽  
Y.A. Dorofeev ◽  
N.V. Volkova ◽  
...  

Magnetic properties of Ni3Al1-yMny alloys at y≤0.6 were investigated at T≤400 K in magnetic fields H≤4 MA/m. The concentration y dependencies of the spontaneous magnetic moment s, the effective magnetic moment eff, the Curie temperature ТС, the Weiss constant , and the temperature independent part of the magnetic susceptibility 0 were determined. The behavior of the Rhodes-Wohlfarth parameter р(y) in the transition region from the itinerant electron magnetism to the spin localized one is related to the increase in the spontaneous magnetic moment of Ni atoms inversely proportional to the average distance between Mn atoms with the highly localized magnetic moments.


2016 ◽  
Vol 845 ◽  
pp. 138-141 ◽  
Author(s):  
Oksana Pavlukhina ◽  
Vasiliy D. Buchelnikov ◽  
Vladimir V. Sokolovskiy

In this work, the structural and magnetic properties of Cr – doped Ni1.75Co0.25Mn1.5In0.5 Heusler alloys are investigated by using the density functional theory calculations. The chemical disorder is treated by the 16-atom supercell approach. Three compositions with substitution of 6.25 %, 12.5 %, and 18.75% Cr for Mn are taken into consideration. The formation energy, magnetic moments and lattice parameters depending on the Cr content are found. It is shown that compositions with 6.25% and 12.5% of Cr are energetically stable in austenite.


2013 ◽  
Vol 710 ◽  
pp. 174-177
Author(s):  
Lei Feng ◽  
Fei Wang ◽  
Ju Gao ◽  
Jin Zhi Yin ◽  
Xiu Yan Luo

A new Heusler alloyV2NiGawith Hg2CuTi-type structure was investigated by first-principles calculations. The band structures and magnetic properties have been studied. The alloy has a total magnetic moment of 1.05μBper unit cell on first-principles calculations which is in agreement with theSlaterPauling(SP) rule. The magnetic moments ofV(1) atom andV(2) atom are 1.28μBand-0.44μBrespectively, so the alloy is a ferrimagnetism.


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