Role of Dopant Incorporation on the Magnetic Properties of Ce1−xNixO2 Nanoparticles: An Electron Paramagnetic Resonance Study

S. K. Misra; S. I. Andronenko; M. H. Engelhard; Aaron Thurber; K. M. Reddy; Alex Punnoose

Role of Dopant Incorporation on the Magnetic Properties of Ce_1−xNi_xO₂ Nanoparticles: An Electron Paramagnetic Resonance Study

S. K. Misra, S. I. Andronenko, M. H. Engelhard, Aaron Thurber, K. M. Reddy, Alex Punnoose

Physics Department

Research output: Contribution to journal › Article › peer-review

Abstract

Nickel doping has been found to produce weak room-temperature ferromagnetism (FM) in CeO 2 . The saturation magnetization ( M s ) of the chemically synthesized Ce 1− x Ni x O 2 samples showed a maximum for x = 0.04, above which the magnetization decreased gradually. For Ce 1− x Ni x O 2 samples with x ≥ 0.04, an activation process involving slow annealing of the sample to 500 °C increased the M s by more than two orders of magnitude. However, no such activation effect was observed in samples with x x for x >0.04, and (ii) the dramatic increase in M s in the activated Ce 1− x Ni x O 2 samples with x ≥ 0.04 and the absence of this behavior in samples with x 1− x Ni x O 2 samples with 0.01 &les; x &les; 0.10 at 5 and 300&emsp13;K indicates the presence of several paramagnetic species: (i) two magnetically inequivalent Ni 2+ ions with the ionic spin S = 1, (ii) one Ce 3+ ion with spin S = 1/2, and (iii) three O 2 − defects with S = 1/2. The spectra of the samples with x 2+ EPR line ascribed to dopant ions in substitutional sites, whereas in samples with x ≥ 0.04, there is an additional EPR line attributed to Ni 2+ ions occupying interstitial sites. In the activated sample with x = 0.08, the EPR line due to the interstitial Ni 2+ ions is completely absent, and only the line due to substitutional Ni 2+ ions is present, suggesting that the enhanced FM arises from migration of Ni 2+ ions from interstitial to substitutional sites.

Original language	American English
Journal	Journal of Applied Physics
State	Published - 15 Feb 2008

Keywords

cerium compounds
ferromagnetic materials
impurity distribution
interstitials
magnetic particles

EGS Disciplines

Physics

Access to Document

http://dx.doi.org/10.1063/1.2833291

Cite this

@article{e84f83407536421d8d23c615fdc578a3,

title = "Role of Dopant Incorporation on the Magnetic Properties of Ce1−xNixO2 Nanoparticles: An Electron Paramagnetic Resonance Study",

abstract = " Nickel doping has been found to produce weak room-temperature ferromagnetism (FM) in CeO 2 . The saturation magnetization ( M s ) of the chemically synthesized Ce 1− x Ni x O 2 samples showed a maximum for x = 0.04, above which the magnetization decreased gradually. For Ce 1− x Ni x O 2 samples with x ≥ 0.04, an activation process involving slow annealing of the sample to 500 °C increased the M s by more than two orders of magnitude. However, no such activation effect was observed in samples with x x for x >0.04, and (ii) the dramatic increase in M s in the activated Ce 1− x Ni x O 2 samples with x ≥ 0.04 and the absence of this behavior in samples with x 1− x Ni x O 2 samples with 0.01 &les; x &les; 0.10 at 5 and 300&emsp13;K indicates the presence of several paramagnetic species: (i) two magnetically inequivalent Ni 2+ ions with the ionic spin S = 1, (ii) one Ce 3+ ion with spin S = 1/2, and (iii) three O 2 − defects with S = 1/2. The spectra of the samples with x 2+ EPR line ascribed to dopant ions in substitutional sites, whereas in samples with x ≥ 0.04, there is an additional EPR line attributed to Ni 2+ ions occupying interstitial sites. In the activated sample with x = 0.08, the EPR line due to the interstitial Ni 2+ ions is completely absent, and only the line due to substitutional Ni 2+ ions is present, suggesting that the enhanced FM arises from migration of Ni 2+ ions from interstitial to substitutional sites.",

keywords = "cerium compounds, ferromagnetic materials, impurity distribution, interstitials, magnetic particles",

author = "Misra, {S. K.} and Andronenko, {S. I.} and Engelhard, {M. H.} and Aaron Thurber and Reddy, {K. M.} and Alex Punnoose",

year = "2008",

month = feb,

day = "15",

language = "American English",

}

TY - JOUR

T1 - Role of Dopant Incorporation on the Magnetic Properties of Ce1−xNixO2 Nanoparticles: An Electron Paramagnetic Resonance Study

AU - Misra, S. K.

AU - Andronenko, S. I.

AU - Engelhard, M. H.

AU - Thurber, Aaron

AU - Reddy, K. M.

AU - Punnoose, Alex

PY - 2008/2/15

Y1 - 2008/2/15

N2 - Nickel doping has been found to produce weak room-temperature ferromagnetism (FM) in CeO 2 . The saturation magnetization ( M s ) of the chemically synthesized Ce 1− x Ni x O 2 samples showed a maximum for x = 0.04, above which the magnetization decreased gradually. For Ce 1− x Ni x O 2 samples with x ≥ 0.04, an activation process involving slow annealing of the sample to 500 °C increased the M s by more than two orders of magnitude. However, no such activation effect was observed in samples with x x for x >0.04, and (ii) the dramatic increase in M s in the activated Ce 1− x Ni x O 2 samples with x ≥ 0.04 and the absence of this behavior in samples with x 1− x Ni x O 2 samples with 0.01 &les; x &les; 0.10 at 5 and 300&emsp13;K indicates the presence of several paramagnetic species: (i) two magnetically inequivalent Ni 2+ ions with the ionic spin S = 1, (ii) one Ce 3+ ion with spin S = 1/2, and (iii) three O 2 − defects with S = 1/2. The spectra of the samples with x 2+ EPR line ascribed to dopant ions in substitutional sites, whereas in samples with x ≥ 0.04, there is an additional EPR line attributed to Ni 2+ ions occupying interstitial sites. In the activated sample with x = 0.08, the EPR line due to the interstitial Ni 2+ ions is completely absent, and only the line due to substitutional Ni 2+ ions is present, suggesting that the enhanced FM arises from migration of Ni 2+ ions from interstitial to substitutional sites.

AB - Nickel doping has been found to produce weak room-temperature ferromagnetism (FM) in CeO 2 . The saturation magnetization ( M s ) of the chemically synthesized Ce 1− x Ni x O 2 samples showed a maximum for x = 0.04, above which the magnetization decreased gradually. For Ce 1− x Ni x O 2 samples with x ≥ 0.04, an activation process involving slow annealing of the sample to 500 °C increased the M s by more than two orders of magnitude. However, no such activation effect was observed in samples with x x for x >0.04, and (ii) the dramatic increase in M s in the activated Ce 1− x Ni x O 2 samples with x ≥ 0.04 and the absence of this behavior in samples with x 1− x Ni x O 2 samples with 0.01 &les; x &les; 0.10 at 5 and 300&emsp13;K indicates the presence of several paramagnetic species: (i) two magnetically inequivalent Ni 2+ ions with the ionic spin S = 1, (ii) one Ce 3+ ion with spin S = 1/2, and (iii) three O 2 − defects with S = 1/2. The spectra of the samples with x 2+ EPR line ascribed to dopant ions in substitutional sites, whereas in samples with x ≥ 0.04, there is an additional EPR line attributed to Ni 2+ ions occupying interstitial sites. In the activated sample with x = 0.08, the EPR line due to the interstitial Ni 2+ ions is completely absent, and only the line due to substitutional Ni 2+ ions is present, suggesting that the enhanced FM arises from migration of Ni 2+ ions from interstitial to substitutional sites.

KW - cerium compounds

KW - ferromagnetic materials

KW - impurity distribution

KW - interstitials

KW - magnetic particles

UR - https://scholarworks.boisestate.edu/physics_facpubs/58

UR - http://dx.doi.org/10.1063/1.2833291

M3 - Article

JO - Journal of Applied Physics

JF - Journal of Applied Physics

ER -