Density Functional Theory applied to magnetic materials: Mn3O4 at different hybrid functionals

Ribeiro, Rosane Aparecida; Lázaro, Sérgio Ricardo de; Pianaro, S. A.

doi:10.1016/j.jmmm.2015.04.091

Cited by 65 publications

(48 citation statements)

References 53 publications

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“…The peak position shifts toward high (2 θ ) angle this shift may be caused by the nonuniform strain developed due to the influence of different ionic radii Mn 2+ ( r = 0.93

\overset{'}{normalÅ}

) and Ba 2+ ( r = 1.38

\overset{'}{normalÅ}

), whereas the interplanar spacing shifts to lower values due to the increase in lattice parameters as Ba concentration increases. The lattice parameters, unit cell volume and bond length are calculated using VESTA software and are summarized in Table , the values are in good agreement with the work reported in literature, the crystallite size is calculated using Debye–Scherrer formula,

D = \frac{0.94 λ}{β \cos θ}

where D , λ , and β are the crystallite size, the wavelength of the X‐ray (0.154056 nm) and the full width half maximum; respectively, it is clearly seen that the crystallite size varies with Ba concentration in Mn 3 O 4 lattice (see Table ).…”

Section: Resultssupporting

confidence: 79%

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application

Najim

Darwoysh

Dawood

et al. 2018

Physica Status Solidi (a)

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The fabrication of reliable and cost‐effective gas sensor for low concentrations of toxic gases such as ammonia is still a challenging task, in this work the authors report structural, topography, and optical properties of pure and Ba‐doped Mn3O4 thin films prepared by chemical spray pyrolysis (CSP) as well as its gas sensing performance toward low concentrations of ammonia gas. XRD analyses prove the films have tetragonal spinel structure with a preferred orientation along the direction (103). AFM and SEM measurements show the films have homogeneous with rough surfaces and porous structures. EDS measurement confirms the presence of Mn, O, and Ba elements according to a doping concentration ratio. Optical measurements show the optical band gap redshifts and the bond length expands as Ba concentration increases. The optimal results are achieved in Mn3O4:Ba1% thin films where porous structure, rough surface, high crystallinity, and maximum response toward (20, 30, 40, and 50 ppm) of ammonia gas with great stability. Empirical equations are suggested to evaluate the sensitivity in terms of relative bond length and RMS roughness. These results show the films are good candidates in p‐type MOS gas sensors.

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“…The peak position shifts toward high (2 θ ) angle this shift may be caused by the nonuniform strain developed due to the influence of different ionic radii Mn 2+ ( r = 0.93

\overset{'}{normalÅ}

) and Ba 2+ ( r = 1.38

\overset{'}{normalÅ}

D = \frac{0.94 λ}{β \cos θ}

Section: Resultssupporting

confidence: 79%

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application

Najim

Darwoysh

Dawood

et al. 2018

Physica Status Solidi (a)

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“…Mn 3 O 4 has a tetragonally distorted spinel structure (space group I4 1 , see Fig.1 of Ref. [69]). The [68] experimental band gap in this oxide has been reported for thin films, E g = 2.51 eV and nanoparticles, E g = 2.07 eV [70].…”

Section: Resultsmentioning

confidence: 99%

“…A more detailed comparison using the B3LYP, B3PW hybrid functionals were done in Ref. [69]. Within ACBN0, the U values were calculated for the FiM6 configuration for the two different Mn atoms separately and these values were then used to calculate the total energies of all other configurations (Table 8).…”

Section: Resultsmentioning

confidence: 99%

Improved electronic structure and magnetic exchange interactions in transition metal oxides

Gopal¹,

Gennaro²,

Gusmão³

et al. 2017

J. Phys.: Condens. Matter

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Abstract. We discuss the application of the Agapito Curtarolo and Buongiorno Nardelli (ACBN0) pseudo-hybrid Hubbard density functional to several transition metal oxides. ACBN0 is a fast, accurate and parameter-free alternative to traditional DFT+U and hybrid exact exchange methods. In ACBN0, the Hubbard energy of DFT+U is calculated via the direct evaluation of the local Coulomb and exchange integrals in which the screening of the bare Coulomb potential is accounted for by a renormalization of the density matrix. We demonstrate the success of the ACBN0 approach for the electronic properties of a series technologically relevant mono-oxides (MnO, CoO, NiO, FeO, both at equilibrium and under pressure). We also present results on two mixed valence compounds, Co 3 O 4 and Mn 3 O 4 . Our results, obtained at the computational cost of a standard LDA/PBE calculation, are in excellent agreement with hybrid functionals, the GW approximation and experimental measurements.

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“…Among these, Mn 3 O 4 is the most stable of oxides with a magnetic moment of 5.27 μB. Also, Mn 3 O 4 is a material with normal spinal structure containing a tetrahedral site occupied by Mn 3+ cations (Ribeiro et al 2015). Our previous work indicates that Mn 3 O 4 is distributed over the entire surface of the granules as points in the nano-sized range.…”

Section: Dielectric Studies Of Doped Ybco Samplesmentioning

confidence: 99%

YBCO as a transition metal oxide ceramic material for energy storage

et al. 2019

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Background: Dielectric properties and ac conductivity were studied and correlated with the structure of a series of YBCO ceramic, doped with different doping levels ranging from 0.1 to 0.5 wt.% of magnetic nano-metal oxides, namely Mn 3 O 4 , Co 3 O 4 , and Cr 2 O 3. The most important feature of this study was the ultrahigh values of dielectric constants at a low frequency, exactly 50 Hz. We found that the undoped YBCO has a value of ε′ equal to 6.99 × 10 6 at 50 Hz at room temperature which was increased to 1.09 × 10 8 at 120°C, higher than any other ferroelectric material. Moreover, the value of ε′ depends on the nature and the value of the magnetic moment of the doped metal oxides. The value of ε′ is at least three orders of magnitude greater than any previously studied composites which suggest that this perovskite ceramic material can be used to create electrostatic capacitors with energy far better than the best electrode doublelayer capacitors (EDLC). Additionally, ac electrical conductivity has two frequency-dependent regions, the low frequency, where σ ac is independent of frequency, and the high-frequency region where dispersion occurs. The ac conductivity measurement with frequency leads us to conclude that the conduction mechanism in the studied samples can be correlated barrier hopping (CBH) model. Results: The dielectric properties of undoped YBCO ceramics at 50 Hz in temperature ranging from room temperature to 120°C were studied. It is obvious that the dielectric constant and dielectric loss of YBCO decrease with increase in frequency and temperature. It can be noticed that dielectric constant of YBCO increases at 50 Hz from 6.99 × 10 6 at room temperature to 1.09 × 10 8 at 120°C. The high values of ε′ recorded for YBCO doped with Mn 3 O 4 varied from 9.45 × 10 5 to 15.5 at room temperature and 1.34 × 10 5 to 9.242 at 1 MHz at 120°C. For doped YBCO with Co 3 O 4, the values of ε\ varied from 9.5 × 10 5 at 50 Hz to 13.24 at 1 MHz at room temperature, with changes from7.8 × 10 4 at 50 Hz to 53.42 at 1 MHz. For YBCO ceramic samples doped with Cr 2 O 3, ε′ varied from 1.138 × 10 6 at 50 Hz to 8.38 × 10 3 at 1 MHz at room temperature and from 5.935 × 10 5 at 50 Hz to 3.53 × 10 3 at 1 MHz at 120°C. The ac conductivity was further studied for undoped YBCO and doped YBCO with 0.1 wt.% of nano-metal oxide of Cr 2 O 3 , Co 3 O 4 , and Mn 3 O 4 samples. For all the studied samples, we found σ ac is typically specified to the hopping conduction and ac conductivity has a power law behavior in terms of frequency (ω). In general, there are two frequency-dependent regions for all the studied ceramic samples; in the low-frequency region, σ ac is independent of frequency whereas in the high-frequency region, dispersion occurs. The change in microwave conductivity of the studied samples with frequency (1-5 MHz) is shown in Fig. 5. It is observed that for all samples, the conductivity increases with temperatures and depends on the doped metal oxide. The values of σ ac at 5 MHz varied from − 0.4 to 1.2 for undoped YBC...

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Density Functional Theory applied to magnetic materials: Mn3O4 at different hybrid functionals

Cited by 65 publications

References 53 publications

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application

Improved electronic structure and magnetic exchange interactions in transition metal oxides

YBCO as a transition metal oxide ceramic material for energy storage

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Density Functional Theory applied to magnetic materials: Mn3O4 at different hybrid functionals

Cited by 65 publications

References 53 publications

Structural, Topography, and Optical Properties of Ba‐Doped Mn3O4 Thin Films for Ammonia Gas Sensing Application

Structural, Topography, and Optical Properties of Ba‐Doped Mn3O4 Thin Films for Ammonia Gas Sensing Application

Improved electronic structure and magnetic exchange interactions in transition metal oxides

YBCO as a transition metal oxide ceramic material for energy storage

Contact Info

Product

Resources

About

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application

Structural, Topography, and Optical Properties of Ba‐Doped Mn₃O₄ Thin Films for Ammonia Gas Sensing Application