Ispitivanje proizvoda od elektrokeramike elektrokemijskom impedancijskom spektroskopijom

master's thesis

• Title (english): Probing of electrocheramic products by electrochemical impedance spectroscopy
• Author: Hrvoje Trinki
• Mentor: Sanja Martinez (mentor)
• Committee member: Sanja Martinez (predsjednik povjerenstva)
• Committee member: Jozefina Katić (član povjerenstva)
• Committee member: Elvira Vidović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2020-07-17, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Cilj ovog rada bio je ispitati metodom elektrokemijske impedancijske spektroskopije utjecaje različitih uvjeta proizvodnje i uporabe na električne karakteristike komercijalnih termistora – proizvoda od elektrokeramike. Snimanjem elektrokemijskih impedancijskih spektara na sobnoj temperaturi i temperaturi od 120 °C određene su frekvencije na kojima će se pobliže promatrati proces zagrijavanja prilikom kojeg dolazi do eksponencijalnog porasta otpora termistora. Elektrokemijskim impedancijskim spektrima snimanim na sobnoj temperaturi i 120 °C zajedno s elektrokemijskim impedancijskim mjerenjima provedenim prilikom zagrijavanja uzoraka na frekvencijama od 10 Hz, 1000 Hz i 100000 Hz dokazano je kako različiti procesni parametri prilikom elektrodepozicije nikla ne utječu na električna svojstva termistora. Dopiranje termistora vodikom provedeno je u spajanjem termistora na negativan pol izvora struje prilikom elektrolize vodovodne vode. Snimanjem elektrokemijskih impedancijskih spektara dopiranih uzoraka i modeliranjem dobivenih podataka utvrđeno je kako uslijed dopiranja termistora vodikom ne dolazi do smanjena visine Schottkyjeve barijere koje bi se očitovalo padom otpora granice zrna, već da su razlike u iznosima impedancije posljedica različite unutarnje strukture termistora. Metodama pretražne elektronske mikroskopije (SEM) i emisijske disperzivne rendgenske analize (EDS) potvrđeno je kako su razlike u električnim karakteristikama termistora posljedica strukturnih razlika u elektrokeramičkom materijalu.

Abstract (english)

The goal of this research was to determine the influence of different process parameters and application conditions on commercially available thermistors – electroceramic products – by electrochemical impedance spectroscopy. Electrochemical impedance spectra recorded on ambient temperature and 120 °C pointed to the specific frequencies on which the heating process, during which the resistance of the thermistor increases exponentially, was to be further analyzed. Electrochemical impedance spectra recorded on ambient temperature and 120 °C together with electrochemical impedance measurements conducted on fixed frequencies of 10 Hz, 1000 Hz and 100000 Hz proved that different process parameters during the electrodeposition of nickel do not affect the electrical properties of thermistors. Hydrogen doping of thermistors was performed by connecting the thermistors to the negative pole of the power source during the electrolysis of tap water. The recorded electrochemical impedance spectra of hydrogen doped thermistors and modeling of the acquired data suggest that hydrogen doping does not lead to the lowering of the Schottky barrier, which would be indicated by lower values of grain boundary resistance, but rather that the differences in impedance values are the result of different internal structures of thermistors. SEM and EDS analysis results confirmed that the differences in electrical properties are cause by structural differences in the electroceramic material.

• Keywords: elektrokeramika; PTC efekt; termistor; barijev titanat; EIS
• Keywords (english): electroceramics; PTC effect; thermistor; barium titanate; EIS
• Language: croatian
• URN:NBN: urn:nbn:hr:149:999273
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2022-04-21 10:13:19