A study on the origin of room temperature ferromagnetism in Ni1−Gd O nanoparticles

Gokul, B.; Saravanan, P.; Vinod, V.T.P.; Černík, Miroslav; Ramakrishnan, S.

doi:10.1016/j.jmmm.2015.06.060

Cited by 19 publications

(6 citation statements)

References 27 publications

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“…One can see from Figure a that there are two Gaussian peaks locating at 932.5 and 952.2 eV, which belong to Cu 2p 3/2 and Cu 2p 1/2 binding state, respectively, which agrees well with the reported binding energies for Cu 1+ . , The core-level spectrum of Gd 3d is given in Figure b. One can see that the peak locates at 1186.6 eV, which is in line with the reported value for Gd 3+ . The XPS results provide direct evidence that the valence state of Cu is +1 and that of Gd is +3.…”

Section: Resultssupporting

confidence: 85%

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Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Zhu

Chen

Ming

et al. 2021

ACS Appl. Mater. Interfaces

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Cu12Sb4S13 has aroused great interest because of its earth-abundant constituents and intrinsic low thermal conductivity. However, the applications of Cu12Sb4S13 are hindered by its poor thermoelectric performance. Herein, it is shown that Gd substitution not only causes a significant increase in both electrical conductivity σ and thermopower S but also leads to dramatic drop in lattice thermal conductivity κ L. Consequently, large ZT reaches 0.94 at 749 K for Cu11.7Gd0.3Sb4S13, which is ∼41% higher than the ZT value of undoped sample. Rietveld refinements of XRD results show that accompanying inhibition of impurity phase Cu3SbS4, the number of Cu vacancies increases substantially with substituted content x (x ≤ 0.3), which leads to reduced κ L owing to intensive phonon scattering by the point defects and increased σ arising from the charged defects (V Cu ’ ). Crucially, synchrotron radiation photoelectron spectroscopy reveals substantial increment of electronic density of states at Fermi level upon Gd substitution, which is proven, by our first-principle calculations, to originate from contribution of Gd 4f orbit, resulting in enhancement of S. Our study provides us with a new path to enhance thermoelectric performance of Cu12Sb4S13.

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Section: Resultssupporting

confidence: 85%

“…One can see that the peak locates at 1186.6 eV, which is in line with the reported value for Gd 3+ . 34 The XPS results provide direct evidence that the valence state of Cu is +1 and that of Gd is +3. 3.2.…”

Section: Resultsmentioning

confidence: 95%

Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Zhu

Chen

Ming

et al. 2021

ACS Appl. Mater. Interfaces

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show abstract

“…These peaks are in agreement with the one reported by Michalska et al [29], implying the only one kind of Ni ion such as Ni 2+ exist in A0 ceramic. In the Sr 2+ doped ceramics, the Ni 2+ ion can also be detected, although the related peaks have about 0.3 eV shift towards lower binding energies compared with sample A0 [30]. The area of each peaks have changed minutly, indicating the constant Ni ion content.…”

Section: Electrical Characterization Xps and Impedance Analysismentioning

confidence: 93%

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

Zhang

Thayil

et al. 2020

Preprint

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Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2053.6 Ω·cm, 3654-3709 K, 0.3149-0.3197 eV and -4.111--4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. Furthermore, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with <1.3% of resistance shift after 100 thermal shock cycles.

show abstract

Section: Electrical Characterization Xps and Complex Impedance Analysismentioning

confidence: 93%

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

Zhang

Thayil

et al. 2020

Preprint

View full text Add to dashboard Cite

Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2053.6 Ω·cm, 3654-3709 K, 0.3149-0.3197 eV and -4.111--4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. The impedance data analysis also discussed the conduction mechanism of the MCNS ceramic, while grain resistance dominates the whole resistance of the samples. Furthermore, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with <1.3% of resistance shift after 100 thermal shock cycles.

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A study on the origin of room temperature ferromagnetism in Ni1−Gd O nanoparticles

Cited by 19 publications

References 27 publications

Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

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A study on the origin of room temperature ferromagnetism in Ni1−Gd O nanoparticles

Cited by 19 publications

References 27 publications

Improved Thermoelectric Performance of Cu12Sb4S13 through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Improved Thermoelectric Performance of Cu12Sb4S13 through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

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Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering

Improved Thermoelectric Performance of Cu₁₂Sb₄S₁₃ through Gd-Substitution Induced Enhancement of Electronic Density of States and Phonon Scattering