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Start Over Author "Aldao A" Journal journal of the european ceramic society
16 results on '"Aldao A"'

5. Influence of particle size on the conductance of SnO2 thick films

Author

Celso Manuel Aldao, Miguel Adolfo Ponce, and Miriam Susana Castro

Subjects
Recubrimientos y Películas, Diffusion transport, Materials science, Otras Ingenierías y Tecnologías, Semiconductor materials, Diffusion, Analytical chemistry, Conductance, Mineralogy, DEFECTS, ELECTRICAL PROPERTIES, INGENIERÍAS Y TECNOLOGÍAS, FILMS, DIFFUSION, Grain size, GRAIN SIZE, Ingeniería de los Materiales, SENSORS, Materials Chemistry, Ceramics and Composites, SNO 2, Particle size
Abstract

The electrical response of SnO2 thick films was found to be highly dependent on the grain size. This result can be explained as the consequence of the type of intergranular potential barriers developed at intergrains. Specifically, samples with smaller particle size have overlapped potential barriers and samples with higher particle size have separated potential barriers. Also, the influence of gas transport phenomena on the resistance of the gas sensor was investigated. From an analysis of the possible mechanisms involved in the oxygen diffusion, the Knudsen diffusion is suggested as the controlling step. Fil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Published
2003

6. Effects of thermal treatments on the conductance of tin oxide

Author

Miriam Susana Castro and Celso Manuel Aldao

Subjects
Recubrimientos y Películas, Materials science, Sensors, Físico-Química, Ciencia de los Polímeros, Electroquímica, Ciencias Químicas, Pellets, Analytical chemistry, Conductance, INGENIERÍAS Y TECNOLOGÍAS, Conductivity, Tin oxide, Isothermal process, Electrical resistivity and conductivity, Grain boundaries, Ingeniería de los Materiales, Thermal, Electrical conductivity, Materials Chemistry, Ceramics and Composites, Sample preparation, SnO2, CIENCIAS NATURALES Y EXACTAS
Abstract

Temperature dependence of electrical conductivity during heating and cooling under different atmospheres and resistivity transients at step isothermal changes in oxygen pressure of SnO2 sintered pellets are investigated. It is found that different thermal treatments in sample preparation give rise to diverse conductivity behaviors as a function of temperature and transient responses. These results indicate that grain sizes and widths of the depletion layers are responsible for the observed results. Also, oxygen diffusion into the tin oxide grain plays a significant role accounting for the observed conductance changes. Fil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Published
2000

7. Effects of the Sintering Temperature on the Oxygen Adsorption in ZnO Ceramics

Author

Celso Manuel Aldao and Miriam Susana Castro

Subjects
Materials science, technology, industry, and agriculture, Sintering, Mineralogy, chemistry.chemical_element, equipment and supplies, Microstructure, Oxygen, Adsorption, chemistry, Chemical engineering, Electrical resistivity and conductivity, visual_art, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Grain boundary, Ceramic, Electroceramics
Abstract

Changes in electrical resistivity due to oxygen adsorption for samples prepared at different sintering temperature are presented. It was found that samples cooled in steps from the sintering temperature show a higher resistivity and that oxygen indiffusion is faster in quenched samples and in samples sintered at low temperatures. Two mechanisms were determined to be responsible for an increase in the sample resistivity. First, oxygen adsorption at grains surfaces produces a rapid increase in resistivity and then a slow change in the response due to oxygen diffusion into the grains.

Published
1999

8. Advances in the study of the conduction modes in SnO2 varistors

Author

Rodrigo Parra, Celso Manuel Aldao, Miriam Susana Castro, and Miguel Adolfo Ponce

Subjects
VARISTORS, Materials science, Ingeniería de los Materiales, TUNNELLING, Materials Chemistry, Ceramics and Composites, Mineralogy, INGENIERÍAS Y TECNOLOGÍAS, Cerámicos, Humanities, ELECTRICAL CONDUCTIVITY
Abstract

The microstructure and electrical properties of the SnO2Co3O4Nb2O5La2O3 varistor system prepared through the conventional mixed oxides route were characterised. The electrical breakdown field (Er) and the non-linear coefficient (α) were determined from current density versus electric field curves. The barrier height and the concentration of donors were calculated by fitting the experimental data from impedance spectroscopy measurements assuming the formation of Schottky barriers at the grain boundaries and electrical conduction to occur due to tunnelling and thermionic emission. A model that takes into account the tunnelling contribution yielded more accurate results than a model based only on thermionic emission. Fil: Parra, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Published
2007

9. Thermionic, tunnelling, and polarization currents in zinc oxide varistors

Author

Miriam Susana Castro and Celso Manuel Aldao

Subjects
Materials science, Condensed matter physics, Conductance, Mineralogy, Varistor, Thermionic emission, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Thermal conduction, Polarization (waves), Capacitance, Materials Chemistry, Ceramics and Composites, Quantum tunnelling, Voltage
Abstract

We report an analysis of time, voltage, and temperature dependencies for ZnO varistors conductance. The conduction mechanisms proposed to interpret experiments include thermionic, tunnelling, and polarization currents. We analyse here the contributions of these mechanisms to conduction in order to identify their roles. We conclude that a tunnelling current shows the correct trends in the current-temperature curve. Also, capacitance measurements as a function of time and temperature are presented to discuss the influence of interface and deep bulk traps.

Published
1997

13. Influence of particle size on the conductance of SnO2 thick films

Author

Ponce, M.A., Aldao, C.M., and Castro, M.S.

Subjects
*THICK films, *DIFFUSION, *NUCLEAR physics, *SEMICONDUCTOR doping, *SURFACES (Technology)
Abstract

The electrical response of SnO2 thick films was found to be highly dependent on the grain size. This result can be explained as the consequence of the type of intergranular potential barriers developed at intergrains. Specifically, samples with smaller particle size have overlapped potential barriers and samples with higher particle size have separated potential barriers. Also, the influence of gas transport phenomena on the resistance of the gas sensor was investigated. From an analysis of the possible mechanisms involved in the oxygen diffusion, the Knudsen diffusion is suggested as the controlling step. [Copyright &y& Elsevier]

Published
2003
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16. Advances in the study of the conduction modes in SnO2 varistors

Author

Parra, R., Ponce, M.A., Aldao, C.M., and Castro, M.S.

Subjects
*MICROSTRUCTURE, *ELECTRICITY, *VARISTORS, *OXIDES, *ELECTRIC fields
Abstract

Abstract: The microstructure and electrical properties of the SnO2Co3O4Nb2O5La2O3 varistor system prepared through the conventional mixed oxides route were characterised. The electrical breakdown field (E r) and the non-linear coefficient (α) were determined from current density versus electric field curves. The barrier height and the concentration of donors were calculated by fitting the experimental data from impedance spectroscopy measurements assuming the formation of Schottky barriers at the grain boundaries and electrical conduction to occur due to tunnelling and thermionic emission. A model that takes into account the tunnelling contribution yielded more accurate results than a model based only on thermionic emission. [Copyright &y& Elsevier]

Published
2007
Full Text
View/download PDF

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