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Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films / Xiaoxiao Guo in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10864–10869 Titre : Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films Type de document : texte imprimé Auteurs : Xiaoxiao Guo, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur Année de publication : 2010 Article en page(s) : pp. 10864–10869 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Effects--Varying--Preparation--Conditions--Dielectric--Constant--Mixed--Metal--Oxide--Films--Derived--Layered--Double--Hydroxide--Precursor  Films Résumé : Magnesium/aluminum layered double hydroxide (LDH) films have been prepared in situ by means of urea hydrolysis using aluminum metal as both the substrate and sole source of aluminum. Scanning electron microscopy (SEM) images showed that the LDH crystallites are almost perpendicular to the substrate and interlaced with each other forming a network of vacant pockets. The film showed outstanding mechanical strength and high adhesion with the substrate. After being calcined at 500 °C, MgAl mixed metal oxide (MMO) films were obtained which retained the morphology of the precursor films. The values of dielectric constant (k) of the MgAl-MMO films were measured and showed low values in the range 2.0−4.7 arising from the low density of the interlaced structure. The effect of varying the preparation conditions of the LDH precursor films on the microstructure and k-value of the corresponding MMO films was investigated by varying the metal ion concentration, crystallization time, and crystallization temperature. The MMO films became more compact with increasing metal ion concentration and crystallization time, which resulted in increased k-values. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900671b [article] Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films [texte imprimé] / Xiaoxiao Guo, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur . - 2010 . - pp. 10864–10869. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10864–10869 Mots-clés : Effects--Varying--Preparation--Conditions--Dielectric--Constant--Mixed--Metal--Oxide--Films--Derived--Layered--Double--Hydroxide--Precursor  Films Résumé : Magnesium/aluminum layered double hydroxide (LDH) films have been prepared in situ by means of urea hydrolysis using aluminum metal as both the substrate and sole source of aluminum. Scanning electron microscopy (SEM) images showed that the LDH crystallites are almost perpendicular to the substrate and interlaced with each other forming a network of vacant pockets. The film showed outstanding mechanical strength and high adhesion with the substrate. After being calcined at 500 °C, MgAl mixed metal oxide (MMO) films were obtained which retained the morphology of the precursor films. The values of dielectric constant (k) of the MgAl-MMO films were measured and showed low values in the range 2.0−4.7 arising from the low density of the interlaced structure. The effect of varying the preparation conditions of the LDH precursor films on the microstructure and k-value of the corresponding MMO films was investigated by varying the metal ion concentration, crystallization time, and crystallization temperature. The MMO films became more compact with increasing metal ion concentration and crystallization time, which resulted in increased k-values. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900671b

Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films / Xiaoxiao Guo in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10864–10869 Titre : Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films Type de document : texte imprimé Auteurs : Xiaoxiao Guo, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur Année de publication : 2010 Article en page(s) : pp. 10864–10869 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Layered  double  hydroxide  films  Scanning  electron  microscopy  images Résumé : Magnesium/aluminum layered double hydroxide (LDH) films have been prepared in situ by means of urea hydrolysis using aluminum metal as both the substrate and sole source of aluminum. Scanning electron microscopy (SEM) images showed that the LDH crystallites are almost perpendicular to the substrate and interlaced with each other forming a network of vacant pockets. The film showed outstanding mechanical strength and high adhesion with the substrate. After being calcined at 500 °C, MgAl mixed metal oxide (MMO) films were obtained which retained the morphology of the precursor films. The values of dielectric constant (k) of the MgAl-MMO films were measured and showed low values in the range 2.0−4.7 arising from the low density of the interlaced structure. The effect of varying the preparation conditions of the LDH precursor films on the microstructure and k-value of the corresponding MMO films was investigated by varying the metal ion concentration, crystallization time, and crystallization temperature. The MMO films became more compact with increasing metal ion concentration and crystallization time, which resulted in increased k-values. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900671b [article] Effects of varying the preparation conditions on the dielectric constant of mixed metal oxide films derived from layered double hydroxide precursor films [texte imprimé] / Xiaoxiao Guo, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur . - 2010 . - pp. 10864–10869. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10864–10869 Mots-clés : Layered  double  hydroxide  films  Scanning  electron  microscopy  images Résumé : Magnesium/aluminum layered double hydroxide (LDH) films have been prepared in situ by means of urea hydrolysis using aluminum metal as both the substrate and sole source of aluminum. Scanning electron microscopy (SEM) images showed that the LDH crystallites are almost perpendicular to the substrate and interlaced with each other forming a network of vacant pockets. The film showed outstanding mechanical strength and high adhesion with the substrate. After being calcined at 500 °C, MgAl mixed metal oxide (MMO) films were obtained which retained the morphology of the precursor films. The values of dielectric constant (k) of the MgAl-MMO films were measured and showed low values in the range 2.0−4.7 arising from the low density of the interlaced structure. The effect of varying the preparation conditions of the LDH precursor films on the microstructure and k-value of the corresponding MMO films was investigated by varying the metal ion concentration, crystallization time, and crystallization temperature. The MMO films became more compact with increasing metal ion concentration and crystallization time, which resulted in increased k-values. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900671b

Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors / Hongyun Chen in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6607–6611 Titre : Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors Type de document : texte imprimé Auteurs : Hongyun Chen, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur Année de publication : 2008 Article en page(s) : p. 6607–6611 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mixed  metal  oxide  films  Nestlike  microstructure  LDH  film  precursors  Scanning  electron  microscopy Résumé : Mixed metal oxide (MMO) films containing Ni2+ and Al3+ have been fabricated by a simple process involving calcination of layered double hydroxide (LDH) film precursors at 300−600 °C for 4 h in air. Scanning electron microscopy (SEM) reveals that the resulting Ni/Al−O thin films maintain the original nestlike morphology of the precursor films without any deformation of the microstructure during the thermal decomposition process. After surface treatment with an aqueous solution of sodium laurate, the wettability of the NiAl-LDH and Ni/Al−O thin film surfaces changes from hydrophilic to hydrophobic. Moreover, whereas the NiAl-LDH film exhibits a low adhesion for water (Cassie−Baxter behavior) after surface modification, the Ni/Al−O films exhibit a high adhesion for water (Wenzel behavior). A possible explanation for this phenomenon has been suggested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800388w [article] Facile fabrication and wettability of nestlike microstructure maintained mixed metal oxides films from layered double hydroxide films precursors [texte imprimé] / Hongyun Chen, Auteur ; Fazhi Zhang, Auteur ; Sailong Xu, Auteur . - 2008 . - p. 6607–6611. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6607–6611 Mots-clés : Mixed  metal  oxide  films  Nestlike  microstructure  LDH  film  precursors  Scanning  electron  microscopy Résumé : Mixed metal oxide (MMO) films containing Ni2+ and Al3+ have been fabricated by a simple process involving calcination of layered double hydroxide (LDH) film precursors at 300−600 °C for 4 h in air. Scanning electron microscopy (SEM) reveals that the resulting Ni/Al−O thin films maintain the original nestlike morphology of the precursor films without any deformation of the microstructure during the thermal decomposition process. After surface treatment with an aqueous solution of sodium laurate, the wettability of the NiAl-LDH and Ni/Al−O thin film surfaces changes from hydrophilic to hydrophobic. Moreover, whereas the NiAl-LDH film exhibits a low adhesion for water (Cassie−Baxter behavior) after surface modification, the Ni/Al−O films exhibit a high adhesion for water (Wenzel behavior). A possible explanation for this phenomenon has been suggested. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800388w

Facile preparation of pure CaAl-layered double hydroxides and their application as a hardening accelerator in concrete / Sailong Xu in Chemical engineering journal, Vol. 155 N° 3 (Decembre 2009) 

Public ISBD [article]  in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 881-885 Titre : Facile preparation of pure CaAl-layered double hydroxides and their application as a hardening accelerator in concrete Type de document : texte imprimé Auteurs : Sailong Xu, Auteur ; Zhanrui Chen, Auteur ; Bowen Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 881-885 Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : Layered  double  hydroxides  Separate  nucleation  and  aging  steps  Concrete  Hardening  accelerator  Compressive  and  flexural  strength Index. décimale : 660 Résumé : CaAl-layered double hydroxide (CaAl-LDH), one of anionic functional layered materials, has recently been proposed as potential concrete hardening accelerators. Previous laboratory synthesis shows the necessity of employing a protective nitrogen atmosphere to avoid the formation of large amounts of CaCO3 byproduct. Here, we present a preparation of pure CaAl-LDHs which are readily free of contamination by CaCO3. The CaAl-LDHs were prepared via a scalable method of separate nucleation and aging steps (SNAS) by facile introduction of a mixed ethanol/water media. The application of the as-prepared CaAl-LDHs was investigated as a hardening accelerator in concrete. Standard tests of the compressive and flexural strengths of the cement mortars showed that specimens containing CaAl-LDHs as a hardening accelerator exhibited a greatly enhanced performance in respect of early compressive strength and early flexural strength; and the values increased by 61% and 71%, respectively compared to the pristine concrete specimen. The enhanced performances were addressed in terms of the results in situ X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X1J78N-2&_user=6 [...] [article] Facile preparation of pure CaAl-layered double hydroxides and their application as a hardening accelerator in concrete [texte imprimé] / Sailong Xu, Auteur ; Zhanrui Chen, Auteur ; Bowen Zhang, Auteur . - 2010 . - pp. 881-885. Génie Chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 881-885 Mots-clés : Layered  double  hydroxides  Separate  nucleation  and  aging  steps  Concrete  Hardening  accelerator  Compressive  and  flexural  strength Index. décimale : 660 Résumé : CaAl-layered double hydroxide (CaAl-LDH), one of anionic functional layered materials, has recently been proposed as potential concrete hardening accelerators. Previous laboratory synthesis shows the necessity of employing a protective nitrogen atmosphere to avoid the formation of large amounts of CaCO3 byproduct. Here, we present a preparation of pure CaAl-LDHs which are readily free of contamination by CaCO3. The CaAl-LDHs were prepared via a scalable method of separate nucleation and aging steps (SNAS) by facile introduction of a mixed ethanol/water media. The application of the as-prepared CaAl-LDHs was investigated as a hardening accelerator in concrete. Standard tests of the compressive and flexural strengths of the cement mortars showed that specimens containing CaAl-LDHs as a hardening accelerator exhibited a greatly enhanced performance in respect of early compressive strength and early flexural strength; and the values increased by 61% and 71%, respectively compared to the pristine concrete specimen. The enhanced performances were addressed in terms of the results in situ X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X1J78N-2&_user=6 [...]

A General and scalable formulation of pure CaAl-layered double hydroxide via an organic/water solution route / Sailong Xu in Industrial & engineering chemistry research, Vol. 50 N° 11 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6567–6572 Titre : A General and scalable formulation of pure CaAl-layered double hydroxide via an organic/water solution route Type de document : texte imprimé Auteurs : Sailong Xu, Auteur ; Bowen Zhang, Auteur ; Zhanrui Chen, Auteur Année de publication : 2011 Article en page(s) : pp 6567–6572 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydroxide  Different  organic  Water  solution Résumé : CaAl-layered double hydroxide (CaAl-LDH) has recently been proposed as potential concrete hardening accelerators, because of the similarity in the AFm phase (a family of hydrated calcium aluminate phases) that occurs in hydrated cement. The applications of the promising materials require synthesis routes to be capable of producing large-scale, byproduct-free, and easy-to-handle CaAl-LDH. Herein, we report a general and scalable synthesis of pure CaAl-LDH via an organic/water solution. The possibility of the formation of CaAl-LDH is addressed in terms of the prevention of ethanol from the generation of CaCO3 byproduct. The morphology and crystallinity of CaAl-LDH are tuned by varying different pH value, ethanol/water volumetric content, crystallization time, and temperature. A proper synthesis condition (for example, an ethanol/water volume ratio of 4:1, a pH value of 10.5–11.5, an aging time of 24 h, and a crystallization temperature of 70 °C) are optimized, and further readily scaled up, by a factor of up to 20, with respect to the initial starting materials. Our results of pure CaAl-LDH in different organic/water solutions may open up a means to produce promising concrete hardening accelerators in large amounts. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102135k [article] A General and scalable formulation of pure CaAl-layered double hydroxide via an organic/water solution route [texte imprimé] / Sailong Xu, Auteur ; Bowen Zhang, Auteur ; Zhanrui Chen, Auteur . - 2011 . - pp 6567–6572. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6567–6572 Mots-clés : Hydroxide  Different  organic  Water  solution Résumé : CaAl-layered double hydroxide (CaAl-LDH) has recently been proposed as potential concrete hardening accelerators, because of the similarity in the AFm phase (a family of hydrated calcium aluminate phases) that occurs in hydrated cement. The applications of the promising materials require synthesis routes to be capable of producing large-scale, byproduct-free, and easy-to-handle CaAl-LDH. Herein, we report a general and scalable synthesis of pure CaAl-LDH via an organic/water solution. The possibility of the formation of CaAl-LDH is addressed in terms of the prevention of ethanol from the generation of CaCO3 byproduct. The morphology and crystallinity of CaAl-LDH are tuned by varying different pH value, ethanol/water volumetric content, crystallization time, and temperature. A proper synthesis condition (for example, an ethanol/water volume ratio of 4:1, a pH value of 10.5–11.5, an aging time of 24 h, and a crystallization temperature of 70 °C) are optimized, and further readily scaled up, by a factor of up to 20, with respect to the initial starting materials. Our results of pure CaAl-LDH in different organic/water solutions may open up a means to produce promising concrete hardening accelerators in large amounts. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102135k

Preparation of layered double hydroxide microspheres by spray drying / Yanchang Wang in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

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