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Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno

Abstract

We present the theoretical and experimental developments made to study the desorption of hydrogen from metallic samples by Thermal Desorption Spectroscopy (TDS). With this technique gas desorption is stimulated by the programmed heating of the sample. To perform the study we set up a newly designed equipment and develop theoretical models of the kinetic processes involved. The equipment and the models are used to analyze the desorption process in a real system. We begin by analyzing the models developed to interpret the results of the experiments. These models considersimultaneously bulk diffusion and surface reaction processes in metal-hydrogen systems with one or two thermodynamic phases. We present numerical results, computer simulations and analytical approximations of the original models. Based on these results we analyze the main features of the spectra for the different relevant kinetic processes, and determine the changes induced in them when material parameters (activation energies, geometry) or experimental parameters (heating speed, initial concentration) are modified.We present the original equipment, designed and constructed during this work to perform the TDS experiments. We describe its main characteristics, its components, its range of operation and its sensibility. We also offer an analysis of the background spectrum. We use the Pd-H system  More>>
Authors:
Castro, F J [1] 
  1. Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)
Publication Date:
Jul 01, 2000
Product Type:
Thesis/Dissertation
Report Number:
INIS-AR-V-001
Reference Number:
EDB-00:112502
Resource Relation:
Other Information: TH: Thesis doctoral; PBD: 2000
Subject:
08 HYDROGEN; DESORPTION; HYDRIDES; HYDROGEN; KINETICS; LABORATORY EQUIPMENT; MATHEMATICAL MODELS; METALS; PALLADIUM HYDRIDES; SURFACES; THERMAL ANALYSIS
OSTI ID:
20066063
Research Organizations:
Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Dept. de Ingenieria Nuclear e Investigacion Aplicada
Country of Origin:
Argentina
Language:
Spanish
Other Identifying Numbers:
TRN: AR00V0001027809
Availability:
Available from INIS in electronic form
Submitting Site:
INIS
Size:
208 pages
Announcement Date:

Citation Formats

Castro, F J. Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno. Argentina: N. p., 2000. Web.
Castro, F J. Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno. Argentina.
Castro, F J. 2000. "Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno." Argentina.
@misc{etde_20066063,
title = {Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno}
author = {Castro, F J}
abstractNote = {We present the theoretical and experimental developments made to study the desorption of hydrogen from metallic samples by Thermal Desorption Spectroscopy (TDS). With this technique gas desorption is stimulated by the programmed heating of the sample. To perform the study we set up a newly designed equipment and develop theoretical models of the kinetic processes involved. The equipment and the models are used to analyze the desorption process in a real system. We begin by analyzing the models developed to interpret the results of the experiments. These models considersimultaneously bulk diffusion and surface reaction processes in metal-hydrogen systems with one or two thermodynamic phases. We present numerical results, computer simulations and analytical approximations of the original models. Based on these results we analyze the main features of the spectra for the different relevant kinetic processes, and determine the changes induced in them when material parameters (activation energies, geometry) or experimental parameters (heating speed, initial concentration) are modified.We present the original equipment, designed and constructed during this work to perform the TDS experiments. We describe its main characteristics, its components, its range of operation and its sensibility. We also offer an analysis of the background spectrum. We use the Pd-H system to test the equipment and the models. The samples chosen, powders, granules, foils and wires, were previously characterized to analyze their composition, their morphology and their characteristic size. We show the results of Scanning Electron Microscopy (SEM) observation, X ray diffraction (XRD) and Auger Electron Spectroscopy (AES) analysis.We then present and analyze in depth the experimental desorption spectra of the palladium powder. Based on the analysis we determine the rate limiting step for desorption and the characteristic activation energies. When the system is on the b phase (hydride) the rate limiting step is the recombination of two hydrogen atoms on the surface of the material. When the surface of the sample is in the a phase (solid solution) the rate limiting step is one of the processes that occurs on the surface of the material: the transfer of a hydrogen atom from the bulk to the surface or the recombination and desorption on the surface. By fitting the spectra we obtain an activation energy equal to 31 n 6 kJ/mol for the b phase, and equal to 35 n 3 kJ/mol for the a phase. We also compare the spectra of the powder with the spectra of the granules, foils and wires. Based on this comparison we analyze the effect on the desorption spectra of the characteristic size and geometry of the samples.Finally, we present a study of hydrogen desorption in the Pd-H system poisoned with sulfur. The poisoning produces as main effects a delay of the absorption and desorption processes without any appreciable loss in the storage capacity of the material.The experimental apparatus and theoretical models developed have been applied to the study of a MH system using samples with different morphology, characteristic size, geometry and surface state. The spectra were measured for different hydrogen concentrations and heating speeds. The results obtained encourage the utilization of TDS for the study and characterization of hydrogen desorption in MH systems. The technique is suited for the detailed analysis of the physical properties of the system and for the qualitative evaluation of the kinetic processes and their possible influence on technological devices.}
place = {Argentina}
year = {2000}
month = {Jul}
}