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Effects of processing parameters on the morphology of precipitated manganese oxide powders / Zhao, Qiang in Industrial & engineering chemistry research, Vol. 48 N°3 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1490–1494 Titre : Effects of processing parameters on the morphology of precipitated manganese oxide powders Type de document : texte imprimé Auteurs : Zhao, Qiang, Auteur ; Shih, Wan Y., Auteur ; Shih, Wei-Heng, Auteur Année de publication : 2009 Article en page(s) : p. 1490–1494 Langues : Anglais (eng) Mots-clés : Manganese  oxide  powders Résumé : It is desirable that the surface area of catalytic materials can be controlled by adjusting the processing parameters. In this paper we report that the morphology of precipitated manganese oxide powders after 500 °C calcination is affected by the volume ratio between the manganese nitrate precursor and ammonium hydroxide and also by the concentration of the precursor solution. When a large amount of ammonium hydroxide (nominal concentration of NH4OH in the final suspension greater than 4 N) was used, the synthesized powder had plate-like particles with higher specific surface area compared to spherical particles made by a small amount of ammonium hydroxide (nominal concentration of NH4OH less than 1 N). Thinner plates were synthesized from the system with lower nominal concentration of Mn(NO3)2, resulting in even higher specific surface area. The surface area differences between these powders synthesized by different conditions decreased as the calcination temperatures increased from 500 to 900 °C because the high calcination temperatures eliminated the morphology difference among them. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801173e [article] Effects of processing parameters on the morphology of precipitated manganese oxide powders [texte imprimé] / Zhao, Qiang, Auteur ; Shih, Wan Y., Auteur ; Shih, Wei-Heng, Auteur . - 2009 . - p. 1490–1494. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1490–1494 Mots-clés : Manganese  oxide  powders Résumé : It is desirable that the surface area of catalytic materials can be controlled by adjusting the processing parameters. In this paper we report that the morphology of precipitated manganese oxide powders after 500 °C calcination is affected by the volume ratio between the manganese nitrate precursor and ammonium hydroxide and also by the concentration of the precursor solution. When a large amount of ammonium hydroxide (nominal concentration of NH4OH in the final suspension greater than 4 N) was used, the synthesized powder had plate-like particles with higher specific surface area compared to spherical particles made by a small amount of ammonium hydroxide (nominal concentration of NH4OH less than 1 N). Thinner plates were synthesized from the system with lower nominal concentration of Mn(NO3)2, resulting in even higher specific surface area. The surface area differences between these powders synthesized by different conditions decreased as the calcination temperatures increased from 500 to 900 °C because the high calcination temperatures eliminated the morphology difference among them. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801173e

Highly photoluminescent and stable aqueous ZnS quantum dots / Li, Hui in Industrial & engineering chemistry research, Vol. 49 N° 2 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 578–582 Titre : Highly photoluminescent and stable aqueous ZnS quantum dots Type de document : texte imprimé Auteurs : Li, Hui, Auteur ; Shih, Wan Y., Auteur ; Shih, Wei-Heng, Auteur Année de publication : 2010 Article en page(s) : pp 578–582 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Aqueous  photoluminescent  ZnS  quantum  Mercaptopropionic  acid. Résumé : We report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) with water as the medium. The method involves first synthesizing ZnS QDs with 3-mercaptopropionic acid (MPA) as the capping molecule and then replacing some of the MPA with (3-mercaptopropyl)trimethoxysilane (MPS). The resultant MPS-replaced ZnS QDs were about 5 nm in size with a cubic zinc blende crystalline structure, and they had both MPA and MPS on the surface as confirmed by Fourier transform infrared (FTIR) spectroscopy. They exhibited blue trap-state emissions around 415 nm and a quantum yield (QY) of 75% with rhodamine 101 as the reference, and they remained stable for more than 60 days under ambient conditions. Through the capping-molecule replacement procedure, the MPS-replaced ZnS QDs avoided the shortcomings of both MPA/ZnS QDs and MPS/ZnS QDs and acquired the advantages of strong photoluminescence and good stability, which are important to QD applications, especially for bioimaging. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901086d [article] Highly photoluminescent and stable aqueous ZnS quantum dots [texte imprimé] / Li, Hui, Auteur ; Shih, Wan Y., Auteur ; Shih, Wei-Heng, Auteur . - 2010 . - pp 578–582. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 578–582 Mots-clés : Aqueous  photoluminescent  ZnS  quantum  Mercaptopropionic  acid. Résumé : We report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) with water as the medium. The method involves first synthesizing ZnS QDs with 3-mercaptopropionic acid (MPA) as the capping molecule and then replacing some of the MPA with (3-mercaptopropyl)trimethoxysilane (MPS). The resultant MPS-replaced ZnS QDs were about 5 nm in size with a cubic zinc blende crystalline structure, and they had both MPA and MPS on the surface as confirmed by Fourier transform infrared (FTIR) spectroscopy. They exhibited blue trap-state emissions around 415 nm and a quantum yield (QY) of 75% with rhodamine 101 as the reference, and they remained stable for more than 60 days under ambient conditions. Through the capping-molecule replacement procedure, the MPS-replaced ZnS QDs avoided the shortcomings of both MPA/ZnS QDs and MPS/ZnS QDs and acquired the advantages of strong photoluminescence and good stability, which are important to QD applications, especially for bioimaging. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901086d