Course detail
Non-destructive diagnostics and physics of dielectrics
FEKT-LNDDAcad. year: 2011/2012
The objective of the course is to provide a survey of methods dealing on one side with the localisation and description of defects and their experimental investigation and on another side with the behaviour of dielectrics in electric fields and with their applications. Main topics cover transport and stochastic processes, noise non-destructive spectroscopy, non-destructive diagnostics, reliability tests, physical nature of polarisation in dielectrics, polarisation mechanisms at the microscopic level, mathematical and physical description of dielectric polarisation, overview of dielectric systems currnetly used in electrical engineering.
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Planned learning activities and teaching methods
Assesment methods and criteria linked to learning outcomes
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Specification of controlled education, way of implementation and compensation for absences
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Type of course unit
Lecture
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Syllabus
Identification of defects from transport characteristics, V-A characteristics v in forward and reverse direction, excess current, generation-recombination process, degradation
Fluctuation processes, noise spectral power density and its correlation with the type of defect, low-frequency noise as reliability and quality indicator, lambda parameter - mean time to failure and its quantification
Noise density in semiconductor devices, noise in homogenous structures and in thin-layer and thick-layer resistors
Partial discharges and noise in insulators and dielectrics, noise in capacitors
Noise in semiconductor lasers, alloy and FET transistors
RTS noise of semiconductor diodes with quantum holes and dots
Theory for the design of a concept of a non-destructive diagnostic test
Phenomenological description of the polarisation
Types of relaxation mechanisms in polymers, glasses and ceramic systems
Mathematical methods for the evaluation of dielectric data
Degradation processes and their observation and monitoring by dielectric methods
Major types of dielectric materials
Main fields of application of dielectric materials and criteria for the selection of dielectrics for individual applications
Fundamentals seminar
Teacher / Lecturer
Syllabus
Calculation of noise magnitude in individual circuit components, transformation of noise during the transmission of a signal through an electronic system
Elements of diagnostics - size of ensembles and credibility of results, determination of the noise type, calculation of the excess current and of the reliability parameters
Dipol moments of elementary structural units (chemical bonds, molecules) and their calculation, polarisability alfa for atomic and dipole polarisation
Calculation of the local field and trabsition to the ferroelectric state, calculation of the permittivity of dielectric materials from their structure
Transformation from the time domain to the frequency domain and vice versa, Debye model, calculation of the distribution of relaxation times, both analytically and numerically, Hamon approximation, fitting
Ionic polarizations and the calculation of ionic polarizability
Laboratory exercise
Teacher / Lecturer
Syllabus
Measurements of the spectral density of a fluctuation (a stochastic process) by both analogue and digital methods
Analysis of noise types from the experimentally found curves
Experimental determination of the dipole moment of nitrobenzene
Measurement of charge and discharge currents of dielectrics and transformation of the time-domain results to the frequency domain via Hamon approximation
Measurement of frequency and temperature dependence of complex permittivity and analysis of the results, determination of the activation energy and co-operativity of the relaxation process