Abstract
| Original language | English |
|---|---|
| Journal | Materials Chemistry and Physics |
| Volume | 209 |
| Pages (from-to) | 121-133 |
| ISSN | 0254-0584 |
| DOIs | |
| Publication status | Published - 2018 |
Keywords
- Cerium oxide nanopowders
- Ce - propionate
- Ce2 O2 CO3
- Ferromagnetism
- Photoluminescence
Cite this
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Defect states and room temperature ferromagnetism in cerium oxide nanopowders prepared by decomposition of Ce-propionate. / Mihalache, V. ; Grivel, J. C.; Secu, M.
In: Materials Chemistry and Physics, Vol. 209, 2018, p. 121-133.Research output: Contribution to journal › Journal article › Research › peer-review
TY - JOUR
T1 - Defect states and room temperature ferromagnetism in cerium oxide nanopowders prepared by decomposition of Ce-propionate
AU - Mihalache, V.
AU - Grivel, J. C.
AU - Secu, M.
PY - 2018
Y1 - 2018
N2 - Four batches of cerium oxide powders (with nanocrystallite size of 6.9 nm–572 nm) were prepared from four precursor nanopowders by thermal decomposition of Ce-propionate and annealing in air between 250 °C–1200 °C for 10 min–240 min. Ceria formation reactions, structure, vibrational, luminescence and magnetic properties were investigated by differential scanning calorimetry, x-ray diffraction, electron microscopy, infrared spectroscopy, photoluminescence and SQUID. All the samples exhibit room temperature ferromagnetism, RTFM, (with coercivity, Hc, of 8 Oe - 121 Oe and saturation magnetization, Ms, of up to 6.7*10−3 emu/g) and a broad defect-related photoluminescence, PL, emission in the visible range. The samples derived from the same precursor show Ms proportional to the peak area of defect-related PL emission whereas this is not valid for the samples derived from the different precursors. An improvement of ferromagnetism and intensity of defect-related PL emission was observed when annealing the products in which nanocrystalline cerium oxide coexists with Ce - oxicarbonate traces, Ce2O2CO3. The experimental results were explained based on the following considerations: room temperature ferromagnetism was induced by the defective ceria with high concentration of oxygen vacancies generated by decomposition of Ce-propionate; oxygen vacancies of the starting precursor nanopowders could be redistributed (at the surfaces/grain boundaries, GBs) upon heating under conditions that promote an inert local environment; the decomposition of Ce2O2CO3 residues can provide an excess of oxygen vacancies at the nanoparticles surfaces or GBs, which can induce or enhance ferromagnetism; surfaces/GBs rather than bulk defects appear responsible for RTFM – this can explain the (often reported in literature) inconsistency between oxygen vacancies concentration and Ms.
AB - Four batches of cerium oxide powders (with nanocrystallite size of 6.9 nm–572 nm) were prepared from four precursor nanopowders by thermal decomposition of Ce-propionate and annealing in air between 250 °C–1200 °C for 10 min–240 min. Ceria formation reactions, structure, vibrational, luminescence and magnetic properties were investigated by differential scanning calorimetry, x-ray diffraction, electron microscopy, infrared spectroscopy, photoluminescence and SQUID. All the samples exhibit room temperature ferromagnetism, RTFM, (with coercivity, Hc, of 8 Oe - 121 Oe and saturation magnetization, Ms, of up to 6.7*10−3 emu/g) and a broad defect-related photoluminescence, PL, emission in the visible range. The samples derived from the same precursor show Ms proportional to the peak area of defect-related PL emission whereas this is not valid for the samples derived from the different precursors. An improvement of ferromagnetism and intensity of defect-related PL emission was observed when annealing the products in which nanocrystalline cerium oxide coexists with Ce - oxicarbonate traces, Ce2O2CO3. The experimental results were explained based on the following considerations: room temperature ferromagnetism was induced by the defective ceria with high concentration of oxygen vacancies generated by decomposition of Ce-propionate; oxygen vacancies of the starting precursor nanopowders could be redistributed (at the surfaces/grain boundaries, GBs) upon heating under conditions that promote an inert local environment; the decomposition of Ce2O2CO3 residues can provide an excess of oxygen vacancies at the nanoparticles surfaces or GBs, which can induce or enhance ferromagnetism; surfaces/GBs rather than bulk defects appear responsible for RTFM – this can explain the (often reported in literature) inconsistency between oxygen vacancies concentration and Ms.
KW - Cerium oxide nanopowders
KW - Ce - propionate
KW - Ce2 O2 CO3
KW - Ferromagnetism
KW - Photoluminescence
U2 - 10.1016/j.matchemphys.2018.01.053
DO - 10.1016/j.matchemphys.2018.01.053
M3 - Journal article
VL - 209
SP - 121
EP - 133
JO - Materials Chemistry and Physics
JF - Materials Chemistry and Physics
SN - 0254-0584
ER -