Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3
The effects of laser irradiation on γ-Fe2O3 4 ± 1 nm diameter maghemite nanocrystals synthesized by co-precipitation and dispersed into an amorphous silica matrix by sol-gel methods have been investigated as function of iron oxide mass fraction. The structural properties of γ-Fe2O3 phase were carefu...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Taylor & Francis Group
2016-01-01
|
| Series: | Science and Technology of Advanced Materials |
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1080/14686996.2016.1222494 |
| _version_ | 1830357661117317120 |
|---|---|
| author | Yassine El Mendili Jean-François Bardeau Nirina Randrianantoandro Jean-Marc Greneche Fabien Grasset |
| author_facet | Yassine El Mendili Jean-François Bardeau Nirina Randrianantoandro Jean-Marc Greneche Fabien Grasset |
| author_sort | Yassine El Mendili |
| collection | DOAJ |
| description | The effects of laser irradiation on γ-Fe2O3 4 ± 1 nm diameter maghemite nanocrystals synthesized by co-precipitation and dispersed into an amorphous silica matrix by sol-gel methods have been investigated as function of iron oxide mass fraction. The structural properties of γ-Fe2O3 phase were carefully examined by X-ray diffraction and transmission electron microscopy. It has been shown that γ-Fe2O3 nanocrystals are isolated from each other and uniformly dispersed in silica matrix. The phase stability of maghemite nanocrystals was examined in situ under laser irradiation by Raman spectroscopy and compared with that resulting from heat treatment by X-ray diffraction. It was concluded that ε-Fe2O3 is an intermediate phase between γ-Fe2O3 and α-Fe2O3 and a series of distinct Raman vibrational bands were identified with the ε-Fe2O3 phase. The structural transformation of γ-Fe2O3 into α-Fe2O3 occurs either directly or via ε-Fe2O3, depending on the rate of nanocrystal agglomeration, the concentration of iron oxide in the nanocomposite and the properties of silica matrix. A phase diagram is established as a function of laser power density and concentration. |
| first_indexed | 2024-12-20T02:27:39Z |
| format | Article |
| id | doaj.art-3658cfeb9d1d4fd9957b9c4c9a9b180d |
| institution | Directory Open Access Journal |
| issn | 1468-6996 1878-5514 |
| language | English |
| last_indexed | 2024-12-20T02:27:39Z |
| publishDate | 2016-01-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | Science and Technology of Advanced Materials |
| spelling | doaj.art-3658cfeb9d1d4fd9957b9c4c9a9b180d2022-12-21T19:56:39ZengTaylor & Francis GroupScience and Technology of Advanced Materials1468-69961878-55142016-01-0117159760910.1080/14686996.2016.12224941222494Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3Yassine El Mendili0Jean-François Bardeau1Nirina Randrianantoandro2Jean-Marc Greneche3Fabien Grasset4Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, LUNAM UniversitéInstitut des Molécules et Matériaux du Mans, UMR CNRS 6283, LUNAM UniversitéInstitut des Molécules et Matériaux du Mans, UMR CNRS 6283, LUNAM UniversitéInstitut des Molécules et Matériaux du Mans, UMR CNRS 6283, LUNAM UniversitéInstitut des Sciences Chimiques de Rennes, CNRS UMR 6226, Université Rennes 1The effects of laser irradiation on γ-Fe2O3 4 ± 1 nm diameter maghemite nanocrystals synthesized by co-precipitation and dispersed into an amorphous silica matrix by sol-gel methods have been investigated as function of iron oxide mass fraction. The structural properties of γ-Fe2O3 phase were carefully examined by X-ray diffraction and transmission electron microscopy. It has been shown that γ-Fe2O3 nanocrystals are isolated from each other and uniformly dispersed in silica matrix. The phase stability of maghemite nanocrystals was examined in situ under laser irradiation by Raman spectroscopy and compared with that resulting from heat treatment by X-ray diffraction. It was concluded that ε-Fe2O3 is an intermediate phase between γ-Fe2O3 and α-Fe2O3 and a series of distinct Raman vibrational bands were identified with the ε-Fe2O3 phase. The structural transformation of γ-Fe2O3 into α-Fe2O3 occurs either directly or via ε-Fe2O3, depending on the rate of nanocrystal agglomeration, the concentration of iron oxide in the nanocomposite and the properties of silica matrix. A phase diagram is established as a function of laser power density and concentration.http://dx.doi.org/10.1080/14686996.2016.1222494nanocompositessol-gellaser irradiationramanphase transformationssilica matrixε-fe2o3 |
| spellingShingle | Yassine El Mendili Jean-François Bardeau Nirina Randrianantoandro Jean-Marc Greneche Fabien Grasset Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 Science and Technology of Advanced Materials nanocomposites sol-gel laser irradiation raman phase transformations silica matrix ε-fe2o3 |
| title | Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 |
| title_full | Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 |
| title_fullStr | Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 |
| title_full_unstemmed | Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 |
| title_short | Structural behavior of laser-irradiated γ-Fe2O3 nanocrystals dispersed in porous silica matrix : γ-Fe2O3 to α-Fe2O3 phase transition and formation of ε-Fe2O3 |
| title_sort | structural behavior of laser irradiated γ fe2o3 nanocrystals dispersed in porous silica matrix γ fe2o3 to α fe2o3 phase transition and formation of ε fe2o3 |
| topic | nanocomposites sol-gel laser irradiation raman phase transformations silica matrix ε-fe2o3 |
| url | http://dx.doi.org/10.1080/14686996.2016.1222494 |
| work_keys_str_mv | AT yassineelmendili structuralbehavioroflaserirradiatedgfe2o3nanocrystalsdispersedinporoussilicamatrixgfe2o3toafe2o3phasetransitionandformationofefe2o3 AT jeanfrancoisbardeau structuralbehavioroflaserirradiatedgfe2o3nanocrystalsdispersedinporoussilicamatrixgfe2o3toafe2o3phasetransitionandformationofefe2o3 AT nirinarandrianantoandro structuralbehavioroflaserirradiatedgfe2o3nanocrystalsdispersedinporoussilicamatrixgfe2o3toafe2o3phasetransitionandformationofefe2o3 AT jeanmarcgreneche structuralbehavioroflaserirradiatedgfe2o3nanocrystalsdispersedinporoussilicamatrixgfe2o3toafe2o3phasetransitionandformationofefe2o3 AT fabiengrasset structuralbehavioroflaserirradiatedgfe2o3nanocrystalsdispersedinporoussilicamatrixgfe2o3toafe2o3phasetransitionandformationofefe2o3 |