Documents disponibles écrits par cet auteur

Continuous Hydrothermal Synthesis of Nickel Ferrite Nanoparticles Using a Central Collision-Type Micromixer / Kiwamu Sue in Industrial & engineering chemistry research, Vol. 50 N° 16 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9625-9631 Titre : Continuous Hydrothermal Synthesis of Nickel Ferrite Nanoparticles Using a Central Collision-Type Micromixer : effects of temperature, residence time, metal salt molality, and NaOH addition on conversion, particle size, and crystal phase Type de document : texte imprimé Auteurs : Kiwamu Sue, Auteur ; Mitsuko Aoki, Auteur ; Takafumi Sato, Auteur Année de publication : 2011 Article en page(s) : pp. 9625-9631 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Particle  size  Temperature  effect  Micromixing  Collision  Nanoparticle Résumé : Continuous hydrothermal synthesis of nickel ferrite nanopartides from Fe(NO3)3 and Ni(NO3)2 was performed using a central collision-type micromixer developed for rapid heating of a starting solution to the reaction temperature and homogeneous nucleation. Temperature, residence time, and nitrate molality were varied in the ranges 573―673 K, 0.02―2.00 s, and 0.05―0.50 mol/kg, respectively. The effects of temperature, residence time, nitrate molality, and NaOH addition on conversion, Ni/Fe molar ratio, particle size, and crystal phase were examined using ICP spectroscopy, EDX spectroscopy, TEM, and XRD. In the cases without NaOH, the Ni conversion was less than 2% at temperatures up to 623 K and increased dramatically to around 50% at 673 K, whereas the Fe conversion was more than 94% at all temperatures. In terms of conversion, the Ni/Fe molar ratio was less than 0.01 at temperatures up to 623 K, and stable nickel ferrite was not produced. By contrast, at 673 K, the Ni/Fe molar ratio increased sharply to more than 0.2, and stable nickel ferrite could be obtained. With increasing residence time at 673 K, the Ni conversion and Ni/Fe ratio increased, and the lattice parameter decreased from 8.35 to 8.34 Å. These results indicate that the products at an early stage of the reaction are similar in structure to γ-Fe2O3 and can be considered as a Ni-deficient NiFe2O4 whereas the products at a later stage have a structure dose to that of NiFe2O4. In addition, the average particle size increased slightly from 5.2 to 7.4 nm at 0.05 mol/kg and increased markedly from 5.8 to 12.3 nm at 0.50 mol/kg with increasing temperature despite the high Fe conversion of >97% at the shortest residence time of 0.02 s. In the cases with NaOH, smaller nanoparticles of less than 5.0 nm with a stoichiometric Ni/Fe molar ratio of 0.5 were produced at 673 K. On the basis of these results, the mechanisms of nucleation and growth in the nickel ferrite synthesis are discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425206 [article] Continuous Hydrothermal Synthesis of Nickel Ferrite Nanoparticles Using a Central Collision-Type Micromixer : effects of temperature, residence time, metal salt molality, and NaOH addition on conversion, particle size, and crystal phase [texte imprimé] / Kiwamu Sue, Auteur ; Mitsuko Aoki, Auteur ; Takafumi Sato, Auteur . - 2011 . - pp. 9625-9631. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9625-9631 Mots-clés : Particle  size  Temperature  effect  Micromixing  Collision  Nanoparticle Résumé : Continuous hydrothermal synthesis of nickel ferrite nanopartides from Fe(NO3)3 and Ni(NO3)2 was performed using a central collision-type micromixer developed for rapid heating of a starting solution to the reaction temperature and homogeneous nucleation. Temperature, residence time, and nitrate molality were varied in the ranges 573―673 K, 0.02―2.00 s, and 0.05―0.50 mol/kg, respectively. The effects of temperature, residence time, nitrate molality, and NaOH addition on conversion, Ni/Fe molar ratio, particle size, and crystal phase were examined using ICP spectroscopy, EDX spectroscopy, TEM, and XRD. In the cases without NaOH, the Ni conversion was less than 2% at temperatures up to 623 K and increased dramatically to around 50% at 673 K, whereas the Fe conversion was more than 94% at all temperatures. In terms of conversion, the Ni/Fe molar ratio was less than 0.01 at temperatures up to 623 K, and stable nickel ferrite was not produced. By contrast, at 673 K, the Ni/Fe molar ratio increased sharply to more than 0.2, and stable nickel ferrite could be obtained. With increasing residence time at 673 K, the Ni conversion and Ni/Fe ratio increased, and the lattice parameter decreased from 8.35 to 8.34 Å. These results indicate that the products at an early stage of the reaction are similar in structure to γ-Fe2O3 and can be considered as a Ni-deficient NiFe2O4 whereas the products at a later stage have a structure dose to that of NiFe2O4. In addition, the average particle size increased slightly from 5.2 to 7.4 nm at 0.05 mol/kg and increased markedly from 5.8 to 12.3 nm at 0.50 mol/kg with increasing temperature despite the high Fe conversion of >97% at the shortest residence time of 0.02 s. In the cases with NaOH, smaller nanoparticles of less than 5.0 nm with a stoichiometric Ni/Fe molar ratio of 0.5 were produced at 673 K. On the basis of these results, the mechanisms of nucleation and growth in the nickel ferrite synthesis are discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425206