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Spray pyrolysis of (super) conductors
J. AemsolSci. Vol. 29, Suppl. I, pp. S915-S916, 1998 8 1998 Published by Elsevier Science Ltd. All rights resewed printed in Great Britain OOZI-8502/98 $19.00 + 0.00
Pergamon
SPRAY PYROLYSIS
YKAMLAG,
OF (SUPER) CONDUCTORS
I. COLBECK, C.H. CHEN* AND J. SCHOONMAN*
Institute for Environmental Research, Department of Biological Sciences University of Essex, Colchester CO4 3SQ, United Kingdom *Laboratory for Inorganic Chemistry Delft University of Technology, Julianalaan 136 2628 BL Delft, The Netherlands KEYWORDS
nanoparticles, electrostatic spray deposition, spray pyrolysis In recent years aerosol generation has seen many new developments. Aerosol routes are now routinely used to generate nanophase materials. Nanostructured materials show improved or even new properties as compared to microstructured materials. Aerosol routes in material synthesis can be classified into two categories, i.e. gas-to-particle and droplet-to-particle conversion, depending on the starting precursors. The disadvantage of the gas-to-particle conversion is that multi-component materials cannot easily be produced. For droplet-to-particle conversion, spray pyrolysis has been used to synthesise powders of a wide variety of materials. The process involves the atomisation of a precursor solution into droplets which are subsequently heated. The solvent evaporates and intra-particle reactions occur to form the desired material. Spray pyrolysis is a relatively simple process and multi-component materials can easily be synthesised. A modification of spray pyrolysis is Electrostatic Spray Pyrolysis (ESP). ESP is easily modified to form thin films. Here the aerosol is collected on a substrate to form a thin film. This technique is referred to as Electrostatic Spray Deposition (ESD) and has been developed at DelR University of Technology. Besides nanosized powders ESP and ESD can be used to form nanostructured materials with morphologies ranging from dense and porous to reticular. A high -temperature- bismuth oxide superconductor powder has been produced by spray pyrolysis under various conditions. An aqueous solution of (Bi-Pb-Sr-Ca-Cu-0) nitrate was atomised using different carrier gases and temperatures, the aerosol was then dried in a tube furnace and collected by a cold finger. The powder was examined by XRD, SEM and EDX. Unagglomerated spherical particles were obtained at 700 “C and 800 “C with nitrogen or air as the carrier gas (Figure 1). At a temperature of 900 “C agglomerated particles were produced. With oxygen as the carrier gas the particles were not entirely spherical. The size of the particles was in the range of 100 mn to 1 pm. The powder produced consists of different phases. These phases are characterised using High Resolution Electron Microscope (HREM) and electron diffraction. s915
S916
Abstracts
of the 5th International
Fig. 1 Bi-Pb-Sr-Ca-Cu-0,
Aerosol
Conference
1998
powder at 800 “C, carrier gas: air.
Ti02 is a multi-functional material used in the fields of catalysis, dye-synthesised solar cells, lithium-insertion-based devices, integrated circuits, gas sensors, and the paint industry. Most of these applications are realised with micro- or nano-structured TiO, powders or thin films. Thin films of TiO, were prepared on metal or glass substrates by ESD. Two precursor liquids consisting of an alcoholic solution of Ti(i-CsH,O), and a sol of TiO, were used for comparison. From the precursor solution, different morphologies ranging from relatively dense to highly porous including a reticular structure (Figure 2) were obtained depending on the deposition conditions (mainly substrate temperature and solvent composition). The particle size was of the order of a micron. Very dense smooth nanostructured TiO, films (Figure 3) were obtained between 100 and 2OO’C.
Fig. 2 Reticular Ti02 film from a precursor solution of Ti(i-C,H70),
Fig. 3 Dense smooth TiO, film from a precursor of a sol of TiO,
Acknowledgement: The authors are grateful to the European Science Foundation (NAN0 program) for providing a fellowship for Y. Kamlag which made it possible to establish a co-operation between the two Universities
Pergamon
SPRAY PYROLYSIS
YKAMLAG,
OF (SUPER) CONDUCTORS
I. COLBECK, C.H. CHEN* AND J. SCHOONMAN*
Institute for Environmental Research, Department of Biological Sciences University of Essex, Colchester CO4 3SQ, United Kingdom *Laboratory for Inorganic Chemistry Delft University of Technology, Julianalaan 136 2628 BL Delft, The Netherlands KEYWORDS
nanoparticles, electrostatic spray deposition, spray pyrolysis In recent years aerosol generation has seen many new developments. Aerosol routes are now routinely used to generate nanophase materials. Nanostructured materials show improved or even new properties as compared to microstructured materials. Aerosol routes in material synthesis can be classified into two categories, i.e. gas-to-particle and droplet-to-particle conversion, depending on the starting precursors. The disadvantage of the gas-to-particle conversion is that multi-component materials cannot easily be produced. For droplet-to-particle conversion, spray pyrolysis has been used to synthesise powders of a wide variety of materials. The process involves the atomisation of a precursor solution into droplets which are subsequently heated. The solvent evaporates and intra-particle reactions occur to form the desired material. Spray pyrolysis is a relatively simple process and multi-component materials can easily be synthesised. A modification of spray pyrolysis is Electrostatic Spray Pyrolysis (ESP). ESP is easily modified to form thin films. Here the aerosol is collected on a substrate to form a thin film. This technique is referred to as Electrostatic Spray Deposition (ESD) and has been developed at DelR University of Technology. Besides nanosized powders ESP and ESD can be used to form nanostructured materials with morphologies ranging from dense and porous to reticular. A high -temperature- bismuth oxide superconductor powder has been produced by spray pyrolysis under various conditions. An aqueous solution of (Bi-Pb-Sr-Ca-Cu-0) nitrate was atomised using different carrier gases and temperatures, the aerosol was then dried in a tube furnace and collected by a cold finger. The powder was examined by XRD, SEM and EDX. Unagglomerated spherical particles were obtained at 700 “C and 800 “C with nitrogen or air as the carrier gas (Figure 1). At a temperature of 900 “C agglomerated particles were produced. With oxygen as the carrier gas the particles were not entirely spherical. The size of the particles was in the range of 100 mn to 1 pm. The powder produced consists of different phases. These phases are characterised using High Resolution Electron Microscope (HREM) and electron diffraction. s915
S916
Abstracts
of the 5th International
Fig. 1 Bi-Pb-Sr-Ca-Cu-0,
Aerosol
Conference
1998
powder at 800 “C, carrier gas: air.
Ti02 is a multi-functional material used in the fields of catalysis, dye-synthesised solar cells, lithium-insertion-based devices, integrated circuits, gas sensors, and the paint industry. Most of these applications are realised with micro- or nano-structured TiO, powders or thin films. Thin films of TiO, were prepared on metal or glass substrates by ESD. Two precursor liquids consisting of an alcoholic solution of Ti(i-CsH,O), and a sol of TiO, were used for comparison. From the precursor solution, different morphologies ranging from relatively dense to highly porous including a reticular structure (Figure 2) were obtained depending on the deposition conditions (mainly substrate temperature and solvent composition). The particle size was of the order of a micron. Very dense smooth nanostructured TiO, films (Figure 3) were obtained between 100 and 2OO’C.
Fig. 2 Reticular Ti02 film from a precursor solution of Ti(i-C,H70),
Fig. 3 Dense smooth TiO, film from a precursor of a sol of TiO,
Acknowledgement: The authors are grateful to the European Science Foundation (NAN0 program) for providing a fellowship for Y. Kamlag which made it possible to establish a co-operation between the two Universities