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Papers by Nathalie Jongen

Cdrom Collection Recents Progres En Genie Des Procedes N 91, 2004

J Colloid Interface Sci, 2001

Experiments have been performed to measure the effect of additives on the crystallization tempera... more Experiments have been performed to measure the effect of additives on the crystallization temperature of concentrated LiBr solutions cooled at a rate of 20°C/h. The measured crystallization temperatures correspond not to the temperatures of equilibrium solubility but to the critical temperature for heterogeneous nucleation of the hydrated LiBr salt on the glass wall of the test tube containing the sample solution. Various additives at concentrations from 250 to 1500 ppm have been investigated. Some soluble additives further decreased the experimental crystallization temperature by as much as 13°C, corresponding to 22°C below the equilibrium solubility. Large decreases in the crystallization temperature can be correlated with large values of complexation constants of the additive for either the Li+ or the Br− ion in solution. Solution complexation, however, is not sufficient to explain the magnitude of the decrease in the crystallization temperature. The only phenomenon capable of quantitatively explaining the magnitude of the decrease in the crystallization temperature is the change in the crystal/solution interfacial energy due to adsorption of the additive on the surface of the prenucleation embryos. A quantitative model of the crystal/solution interfacial energy due to adsorption has been developed using both the Langmuir and Gibbs adsorption equations, allowing the quantitative prediction of crystallization temperatures with additive concentration.

Journal of Materials Science Letters - J MATER SCI LETT, 2000

Journal of the European Ceramic Society, 1998

... 7. C. Faure, C. Delmas, M. Fouassier and P. Willmann, Preparation and characterization of cob... more ... 7. C. Faure, C. Delmas, M. Fouassier and P. Willmann, Preparation and characterization of cobalt-substituted αnickel hydroxides stable in KOH medium part I. α'-Hydroxide with an ordered packing. Journal of Power Sources 35 (1991), pp. 249–261. ...

Journal of Materials Science Letters, 1993

Figure 1 SEM micrograph of the mixed oxalate Y2Ba4 (C204)7 ° zH20 showing octahedral crystals. 02... more Figure 1 SEM micrograph of the mixed oxalate Y2Ba4 (C204)7 ° zH20 showing octahedral crystals. 0261-8028

Journal of Colloid and Interface Science, 2001

Experiments have been performed to measure the effect of additives on the crystallization tempera... more Experiments have been performed to measure the effect of additives on the crystallization temperature of concentrated LiBr solutions cooled at a rate of 20 • C/h. The measured crystallization temperatures correspond not to the temperatures of equilibrium solubility but to the critical temperature for heterogeneous nucleation of the hydrated LiBr salt on the glass wall of the test tube containing the sample solution. Various additives at concentrations from 250 to 1500 ppm have been investigated. Some soluble additives further decreased the experimental crystallization temperature by as much as 13 • C, corresponding to 22 • C below the equilibrium solubility. Large decreases in the crystallization temperature can be correlated with large values of complexation constants of the additive for either the Li + or the Br − ion in solution. Solution complexation, however, is not sufficient to explain the magnitude of the decrease in the crystallization temperature. The only phenomenon capable of quantitatively explaining the magnitude of the decrease in the crystallization temperature is the change in the crystal/solution interfacial energy due to adsorption of the additive on the surface of the prenucleation embryos. A quantitative model of the crystal/solution interfacial energy due to adsorption has been developed using both the Langmuir and Gibbs adsorption equations, allowing the quantitative prediction of crystallization temperatures with additive concentration. C 2001 Academic Press

Journal of Colloid and Interface Science, 2000

Copper oxalate particles precipitated from copper nitrate and sodium oxalate are aggregates of sm... more Copper oxalate particles precipitated from copper nitrate and sodium oxalate are aggregates of small crystallites. The crystallites seem to be self-organized such that they are very well aligned crystallographically within the volume of the aggregate. The addition of various cellulose derivatives induces different particle and crystallite morphologies. Without additives, particles with a cushion-like morphology are observed. Increasing the concentration of hydroxypropylmethylcellulose (HPMC) added to the precipitating agents induces a variation of the shape from low axial ratio forms such as cubes to higher axial ratio rods. The crystallites within these particles show a more elongated shape and smaller size as the HPMC concentration is increased. The polymer additive seems to influence the three steps of copper oxalate precipitation: nucleation, crystallite growth, and aggregation. The presence of HPMC affects the copper oxalate nucleation step whereby more nuclei are created and their sizes decrease as reflected by the crystallite volume (total number of crystallites increases while the precipitate yield is constant). In this paper we describe the characterization of these well-organized aggregates and propose a mechanism for the influence of the HPMC on the crystallite and aggregate shape. C 2000 Academic Press

Chemical Engineering & Technology, 2011

The successful scale-out and process intensification using a segmented flow tubular reactor (SFTR... more The successful scale-out and process intensification using a segmented flow tubular reactor (SFTR) for ultrafine CaCO 3 , BaTiO 3 , and nanosized ZnO from optimized minibatch (20 mL) conditions is presented. The capacity of the SFTR in process intensification was demonstrated by producing ∼ 5 kg batches of BaTiO 3 powders with excellent batch-to-batch reproducibility. The SFTR scale-out or numbering-up capacity was demonstrated for a nanostructured CaCO 3 in 500 g batches by scaling-out from one to six segmented flow tubular reactors run in parallel (scale-out/-up ratio of 5000 compared to lab batch experiments). The SFTR was then used to demonstrate its potential for nanosized ZnO powders producing 50 g lots of these nanopowders in a continuous process, a scale-out/up ratio of 250 compared to lab batch experiments without any loss of powder quality. The SFTR allows a precise control of precipitation conditions, leading to an excellent reproducibility in powder characteristics, and shows great promise as a simple production process of powders and advanced nanomaterials with highly controlled properties.

Powder technology, 2002

The measurement of particle size distributions (PSD) of model anisotropic particles with regular ... more The measurement of particle size distributions (PSD) of model anisotropic particles with regular cylindrical or platelet morphologies has been previously studied with several different instruments, and good correlations with image analysis were found for certain specific measurement methods. The correlation was found to be dependent on particle morphology. For cylindrical glass fibres, photocentrifuge data gave good correlations with image analysis, whereas for platelets the laser diffraction method gave the best correlation with image analysis. The study has been enlarged to investigate less regular-shaped particles found in real practical systems, namely, flake-like particles of mica and rod-like copper oxalate precipitates. The correlation between laser diffraction data and image analysis for the flake-like mica is very good and confirms the approach used with model platelets. The copper oxalate rod-like precipitates also confirm the applicability of the photocentrifuge particle size distribution measurement for such particle shapes. In both cases, there are, however, limitations on the interpretation of the particle size instrument data. Some shape information from microscopic images is needed to make some assumptions to simplify the deconvolution of size and shape from the data collected. D

Solid state ionics, 2004

High-quality nickel manganese oxalates have been prepared using an innovative approach for the pr... more High-quality nickel manganese oxalates have been prepared using an innovative approach for the production of homogeneous powders, the continuous Segmented Flow Tubular Reactor (SFTR). This new reactor is mainly composed of a mixer, a segmenter, a tubular section ...

Cdrom Collection Recents Progres En Genie Des Procedes N 91, 2004

J Colloid Interface Sci, 2001

Experiments have been performed to measure the effect of additives on the crystallization tempera... more Experiments have been performed to measure the effect of additives on the crystallization temperature of concentrated LiBr solutions cooled at a rate of 20°C/h. The measured crystallization temperatures correspond not to the temperatures of equilibrium solubility but to the critical temperature for heterogeneous nucleation of the hydrated LiBr salt on the glass wall of the test tube containing the sample solution. Various additives at concentrations from 250 to 1500 ppm have been investigated. Some soluble additives further decreased the experimental crystallization temperature by as much as 13°C, corresponding to 22°C below the equilibrium solubility. Large decreases in the crystallization temperature can be correlated with large values of complexation constants of the additive for either the Li+ or the Br− ion in solution. Solution complexation, however, is not sufficient to explain the magnitude of the decrease in the crystallization temperature. The only phenomenon capable of quantitatively explaining the magnitude of the decrease in the crystallization temperature is the change in the crystal/solution interfacial energy due to adsorption of the additive on the surface of the prenucleation embryos. A quantitative model of the crystal/solution interfacial energy due to adsorption has been developed using both the Langmuir and Gibbs adsorption equations, allowing the quantitative prediction of crystallization temperatures with additive concentration.

Journal of Materials Science Letters - J MATER SCI LETT, 2000

Journal of the European Ceramic Society, 1998

... 7. C. Faure, C. Delmas, M. Fouassier and P. Willmann, Preparation and characterization of cob... more ... 7. C. Faure, C. Delmas, M. Fouassier and P. Willmann, Preparation and characterization of cobalt-substituted αnickel hydroxides stable in KOH medium part I. α'-Hydroxide with an ordered packing. Journal of Power Sources 35 (1991), pp. 249–261. ...

Journal of Materials Science Letters, 1993

Figure 1 SEM micrograph of the mixed oxalate Y2Ba4 (C204)7 ° zH20 showing octahedral crystals. 02... more Figure 1 SEM micrograph of the mixed oxalate Y2Ba4 (C204)7 ° zH20 showing octahedral crystals. 0261-8028

Journal of Colloid and Interface Science, 2001

Experiments have been performed to measure the effect of additives on the crystallization tempera... more Experiments have been performed to measure the effect of additives on the crystallization temperature of concentrated LiBr solutions cooled at a rate of 20 • C/h. The measured crystallization temperatures correspond not to the temperatures of equilibrium solubility but to the critical temperature for heterogeneous nucleation of the hydrated LiBr salt on the glass wall of the test tube containing the sample solution. Various additives at concentrations from 250 to 1500 ppm have been investigated. Some soluble additives further decreased the experimental crystallization temperature by as much as 13 • C, corresponding to 22 • C below the equilibrium solubility. Large decreases in the crystallization temperature can be correlated with large values of complexation constants of the additive for either the Li + or the Br − ion in solution. Solution complexation, however, is not sufficient to explain the magnitude of the decrease in the crystallization temperature. The only phenomenon capable of quantitatively explaining the magnitude of the decrease in the crystallization temperature is the change in the crystal/solution interfacial energy due to adsorption of the additive on the surface of the prenucleation embryos. A quantitative model of the crystal/solution interfacial energy due to adsorption has been developed using both the Langmuir and Gibbs adsorption equations, allowing the quantitative prediction of crystallization temperatures with additive concentration. C 2001 Academic Press

Journal of Colloid and Interface Science, 2000

Copper oxalate particles precipitated from copper nitrate and sodium oxalate are aggregates of sm... more Copper oxalate particles precipitated from copper nitrate and sodium oxalate are aggregates of small crystallites. The crystallites seem to be self-organized such that they are very well aligned crystallographically within the volume of the aggregate. The addition of various cellulose derivatives induces different particle and crystallite morphologies. Without additives, particles with a cushion-like morphology are observed. Increasing the concentration of hydroxypropylmethylcellulose (HPMC) added to the precipitating agents induces a variation of the shape from low axial ratio forms such as cubes to higher axial ratio rods. The crystallites within these particles show a more elongated shape and smaller size as the HPMC concentration is increased. The polymer additive seems to influence the three steps of copper oxalate precipitation: nucleation, crystallite growth, and aggregation. The presence of HPMC affects the copper oxalate nucleation step whereby more nuclei are created and their sizes decrease as reflected by the crystallite volume (total number of crystallites increases while the precipitate yield is constant). In this paper we describe the characterization of these well-organized aggregates and propose a mechanism for the influence of the HPMC on the crystallite and aggregate shape. C 2000 Academic Press

Chemical Engineering & Technology, 2011

The successful scale-out and process intensification using a segmented flow tubular reactor (SFTR... more The successful scale-out and process intensification using a segmented flow tubular reactor (SFTR) for ultrafine CaCO 3 , BaTiO 3 , and nanosized ZnO from optimized minibatch (20 mL) conditions is presented. The capacity of the SFTR in process intensification was demonstrated by producing ∼ 5 kg batches of BaTiO 3 powders with excellent batch-to-batch reproducibility. The SFTR scale-out or numbering-up capacity was demonstrated for a nanostructured CaCO 3 in 500 g batches by scaling-out from one to six segmented flow tubular reactors run in parallel (scale-out/-up ratio of 5000 compared to lab batch experiments). The SFTR was then used to demonstrate its potential for nanosized ZnO powders producing 50 g lots of these nanopowders in a continuous process, a scale-out/up ratio of 250 compared to lab batch experiments without any loss of powder quality. The SFTR allows a precise control of precipitation conditions, leading to an excellent reproducibility in powder characteristics, and shows great promise as a simple production process of powders and advanced nanomaterials with highly controlled properties.

Powder technology, 2002

The measurement of particle size distributions (PSD) of model anisotropic particles with regular ... more The measurement of particle size distributions (PSD) of model anisotropic particles with regular cylindrical or platelet morphologies has been previously studied with several different instruments, and good correlations with image analysis were found for certain specific measurement methods. The correlation was found to be dependent on particle morphology. For cylindrical glass fibres, photocentrifuge data gave good correlations with image analysis, whereas for platelets the laser diffraction method gave the best correlation with image analysis. The study has been enlarged to investigate less regular-shaped particles found in real practical systems, namely, flake-like particles of mica and rod-like copper oxalate precipitates. The correlation between laser diffraction data and image analysis for the flake-like mica is very good and confirms the approach used with model platelets. The copper oxalate rod-like precipitates also confirm the applicability of the photocentrifuge particle size distribution measurement for such particle shapes. In both cases, there are, however, limitations on the interpretation of the particle size instrument data. Some shape information from microscopic images is needed to make some assumptions to simplify the deconvolution of size and shape from the data collected. D

Solid state ionics, 2004

High-quality nickel manganese oxalates have been prepared using an innovative approach for the pr... more High-quality nickel manganese oxalates have been prepared using an innovative approach for the production of homogeneous powders, the continuous Segmented Flow Tubular Reactor (SFTR). This new reactor is mainly composed of a mixer, a segmenter, a tubular section ...