Formation and investigation of samarium doped cerium oxide thin films

Author, Institution: Mantas Sriubas, Kaunas University of Technology

Science Area, Field of Science: Technological Sciences, Materials Engineering – 08T

Scientific supervisor: Prof. Dr. Giedrius Laukaitis (Kaunas University of Technology, Physical Sciences, Physics – 02P)

Dissertation Defence Board of Material Engineering Science Field:
Prof. Dr. Habil. Arvaidas Galdikas (Kaunas University of Technology, Physical Sciences, Physics – 02P) – chairman;
Prof. Dr. Diana Adlienė (Kaunas University of Technology, Physical Sciences, Physics – 02P);
Prof. Dr. Habil. Maria Gazda (Gdansk University of Technology, Technological Sciences, Material Engineering – 08T);
Dr. Viktoras Grigaliūnas (Institute of Materials Science, Technological Sciences, Material Engineering – 08T);
Assoc. Prof. Dr. Tomas Šalkus (Vilnius University, Technological Sciences, Material Engineering – 08T).

The doctoral dissertation is available at the library of Kaunas University of Technology (K. Donelaičio g. 20,Kaunas)

Annotation:
Ionic conductors are the main component in O₂, CO_x, NO_x gas sensors and solid oxide fuel cells. One of the most promising conductors at intermediate temperatures (600 °C) is Sm_xCe_1-xO_2-δ (SDC). The electrical properties of SDC depend on the Sm dopant concentration, the working temperature, the oxygen pressure, the migration path of oxygen ions, and the microstructure. Microstructural properties depend on the formation method and its parameters. So, the objective of the theses was to evaluate the influence of the specific surface area of powders, the deposition rate, the substrate temperature and the substrate type on the properties of Sm_0.2Ce_0.8O_2-δ (SDC) thin films deposited by using the e-beam evaporation method. Therefore, SDC thin films were deposited on 50 °C – 600 °C temperature SiO₂, Alloy600, Si (100) Al₂O₃ substrates by using powders of 6.2 m²/g, 11.3 m²/g, 38.8 m²/g and 201.3 m²/g specific surface area and 0.2 nm/s – 1.6 nm/s deposition rate.
The reasons and processes determining the dependences of the microstructure, the surface morphology, the electrical and optical properties on the deposition parameters were analyzed and discussed after the investigation of thin films by means of X-ray diffractometer, scanning electron microscope, atomic force microscope, energy-dispersive X-ray spectroscope, X-ray photoelectron spectroscope, electrochemical impedance spectroscope, spectrophotometer.