First-principles study on oxygen ion conduction of La<sub>2</sub>GeO<sub>5</sub>based on the density functional theory

Sakaue, Mamoru; Cahyanto, Wahyu Tri; Kencana, W T D; Aspera, Susan Meñez; Miwa, Kuniyuki; Kishi, Hirofumi; Kunikata, Shinichi; Nakanishi, Hiroshi; Diño, Wilson Agerico; Kasai, Hitoshi; Ishihara, Takeshi

doi:10.1088/1742-6596/379/1/012012

Cited by 8 publications

(16 citation statements)

References 11 publications

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“…The lattice parameters are found to be

a\; =

4.2680 (7),

b\; =

4.2735 (6),

c\; =

14.404 (1) A with the germanium deficiency predominantly on one of two independent nonmetal sites. [ 17 ] Although the same crystal structure is observed compared to our results the reported lattice parameters are different due to the difference in the Ge content in both crystalline materials.…”

Section: Resultssupporting

confidence: 77%

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

Alkhamisi

Qasrawi

Khanfar

2023

Cryst. Res. Technol.

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Lanthanum germanide (La6Ge) thin films are successfully fabricated using the thermal evaporation technique under a vacuum pressure of 10−5 mbar. The resulting films display an orthorhombic structure, characterized by lattice parameters of a = 8.725 Å, b = 8.063 Å, and c = 5.569 Å. Optical analysis of the La6Ge thin films reveal their high transparency, with an energy bandgap of 3.75±0.04 eV. The bandgap exhibits indirect allowed transitions and featured energy band tails with widths measuring (1.64±0.14) eV. In addition, dielectric dispersion analyses indicate the presence of two dominant dielectric resonance peaks centered at 3.15 and 2.08 eV. Moreover, the La6Ge films demonstrate a terahertz (THz) cutoff frequency of 1.0 THz when illuminated with infrared and visible light. This cutoff frequency increases to 45.6 THz in the ultraviolet range. Furthermore, by utilizing the Drude–Lorentz method, the investigation of optical conductivity parameters reveals that the lanthanum germanide optical filters can achieve free hole density and drift mobility values of 14.44 cm2 V−1 s−1 and 2.8×1018 cm−3, respectively, under infrared light irradiation. The outstanding optical and dielectric properties exhibited by the La6Ge thin films make them excellent candidates for highly transparent optical filters suitable for terahertz technology.

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“…The lattice parameters are found to be

a\; =

4.2680 (7),

b\; =

4.2735 (6),

c\; =

Section: Resultssupporting

confidence: 77%

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

Alkhamisi

Qasrawi

Khanfar

2023

Cryst. Res. Technol.

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“…The occupied portion from -5 to -3.5 eV has the main contribution from p orbitals of oxygen O(1), O(2), O(3) and O(4), minor contributions from p orbitals of oxygen O(5), followed by d orbitals of germanium and lanthanum. In this region, we find strong hybridizations between p orbitals of oxygen O(1), O(2), O(3) and O(4) and germanium that indicates the covalent bond between Ge and O in GeO 4 substructure, as verified in[9,20]. In the regions from -3.5 to -1 eV,…”

supporting

confidence: 68%

“…Figure 6 shows the partial electronic distribution in the ranges from -5 to -3.5 eV and from -3 to 0 eV (Fermi energy) in the perfect undoped system. In the lower region (figures 6(a) and 6(b)), strong hybridizations between Ge and four oxygen atoms in tetrahedra substructures are found consistently with the TDOS analysis [9,20] . In the upper region (figures 6(c) and 6(d)), atomic orbitals of oxygen are predominant, followed by atomic orbitals of La(2) indicating an ionic interaction between La(2) and O(5).…”

Section: Electronic Structuresupporting

confidence: 55%

“…Here it is noted that the density height reflects the number of atoms contained in each group per unit cell: one for each dopant, three for La p orbitals of oxygen contribute primarily and d orbitals of lanthanum contribute in a small part. This reveals the p-d interaction accounting for La(2)-O(5) bonding [9,20]. The occupied states located just below the Fermi energy are mainly contributed from p orbitals of oxygen and slightly contributed from d orbitals of lanthanum.…”

Section: Electronic Structurementioning

confidence: 95%

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First-principles calculation on oxygen ion migration in alkaline-earth doped La₂GeO₅

Linh¹,

Sakaue²,

Aspera³

et al. 2014

J. Phys.: Condens. Matter

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By using first-principles calculations based on the density functional theory, we investigated the doping effects of alkaline-earth metals (Ba, Sr and Ca) in monoclinic lanthanum germanate La2GeO5 on its oxygen ion conduction. Although the lattice parameters of the doped systems changed due to the ionic radii mismatch, the crystal structures remained monoclinic. The contribution of each atomic orbital to electronic densities of states was evaluated from the partial densities of states and partial charge densities. It was confirmed that the materials behaved as ionic crystals comprising of cations of La and dopants and anions of oxygen and covalently formed GeO4. The doping effect on the activation barrier for oxygen hopping to the most stable oxygen vacancy site was investigated by the climbing-image nudged elastic band method. By tracing the charge density change during the hopping, it was confirmed that the oxygen motion is governed by covalent interactions. The obtained activation barriers showed excellent quantitative agreements with an experiment for the Ca- and Sr-doped systems in low temperatures as well as the qualitative trend, including the Ba-doped system.

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“…The operating temperature of SOFCs ranges from 1073 to 1273 K, which is still considered to be high for practical applications. Due to this, recent studies related to SOFC technology have involved materials design on electrodes and electrolyte with high O −2 ion conductivity even at lower operating temperatures [19] to improve problems with slow start up, and enable a wider area of practical application and variety of possible cost efficient materials to be used. Thus, an understanding of the detailed mechanism of O −2 ion conductivity in materials which are known to be good O −2 ion conductors is an important subject in materials design.…”

Section: Introductionmentioning

confidence: 99%

Analysis of structural and electronic properties of Pr₂NiO₄through first-principles calculations

Aspera¹,

Sakaue²,

Wungu³

et al. 2012

J. Phys.: Condens. Matter

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The structural and electronic properties of bulk Pr(2)NiO(4+δ) (δ = 0 and 0.031) were analyzed using first-principles calculations based on the density functional theory (DFT) for application to electrode materials in solid-oxide fuel cells (SOFCs). Two structures of Pr(2)NiO(4) were analyzed: one in space group I4/mmm associated with the high temperature tetragonal (HTT) structure, and the other in Bmab with the low temperature orthorhombic (LTO) structure. The main difference between the two structures is the pronounced tilting of the nickelate octahedra found in the Bmab structure. Here, we will show that the difference in the electronic properties between the two structures, i.e. half-metallic for the I4/mmm structure and metallic for the Bmab structure, is attributed to the tilting of the nickelate octahedra. Furthermore, we found that the presence of interstitial O atoms at the Pr(2)O(2) bilayers is responsible for the tilting of the octahedra and thus is a dominant factor in the transition from the I4/mmm structure to the Bmab structure. These results would be of great significance to materials design related to the enhancement of O diffusivity in this material.

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First-principles study on oxygen ion conduction of La₂GeO₅based on the density functional theory

Cited by 8 publications

References 11 publications

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

First-principles calculation on oxygen ion migration in alkaline-earth doped La₂GeO₅

Analysis of structural and electronic properties of Pr₂NiO₄through first-principles calculations

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First-principles study on oxygen ion conduction of La2GeO5based on the density functional theory

Cited by 8 publications

References 11 publications

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

Growth and Characterization of Lanthanum Germanide Thin Films by the Thermal Evaporation Technique

First-principles calculation on oxygen ion migration in alkaline-earth doped La2GeO5

Analysis of structural and electronic properties of Pr2NiO4through first-principles calculations

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Product

Resources

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First-principles study on oxygen ion conduction of La₂GeO₅based on the density functional theory

First-principles calculation on oxygen ion migration in alkaline-earth doped La₂GeO₅

Analysis of structural and electronic properties of Pr₂NiO₄through first-principles calculations