Faculty Advisor: Khachatur Manukyan, Department of Physics and Astronomy
Research Area: Sustainable and Secure Nuclear

Ink-Jet Printing of CeO2 and Eu2O3 Thin Films for Nuclear Energy Applications and Nuclear Physics Measurements (Summer 2024)

My goal for this research project is to develop the capabilities to create uniform thin films using microdispensing ink jet printing. The ink jet printer will deposit picoliter sized droplets of metal nitrate solutions (0.0125 M cerium nitrate and 0.0125 M europium nitrate both with 2-methoxyethanol (solvent) and acetylacetone (fuel)) onto aluminum and silicon substrates, which will then be heat treated for combustion synthesis to turn the deposited solutions into thin films of metal oxides (cerium and europium oxide). Thin films of cerium and europium oxides, which are on the scale of 10s to 100s of nanometers thick, have numerous energy-related research applications. These materials are surrogates for nuclear fuel irradiation studies and targets for nuclear science measurements. In order to make the films, I will use an ink-jet micro dispensing printer to drop droplets onto the substrates. The droplet dispenser consists of a syringe to hold the solution, a glass tube for the droplets to pass through, and a piezoelectric crystal with electrodes on both ends to generate the droplets. Piezoelectricity is a feature of certain materials in which applying an electric field through the material causes the material to experience mechanical stress. The piezoelectric material in the printer, when no electric field is present, does not allow any fluid to flow through the glass tube. However, when a voltage differential is applied across the crystal from the two electrodes, an electric field is created, which causes a deformation in the crystal that allows fluid to flow. By making the voltage differential time dependent in the form of a wave, the electric field will fluctuate through time from its maximum value to zero and create droplets rather than a continuous stream of solution. These droplets are then dispensed onto the aluminum/silicon substrates.

There are numerous factors that affect the deposition of solutions using printing, such as the size of the droplets, the speed at which the droplets fall, and the step size in between droplets, which is the distance the printer tip moves in between dispensing. I can control and vary these factors by primarily changing the parameters involved with the voltage differential through the piezoelectric crystal. These parameters include changing the voltage used, changing the time in between pulses of the voltage waveform, and creating various multi waveforms with combinations of different voltages and pulse times. For this project, I am aiming to vary these parameters to reveal the optimal droplet size, speed, printer step size, etc. that can deposit solutions most consistently. After deposition, I will then use heat treatment to turn the deposited solutions into metal oxide thin films through combustion synthesis. Heat treating the deposited solutions at various temperatures and for various lengths of time will help reveal how combustion synthesis affects the characteristics of thin films. I will make thin films of cerium and europium oxides because I have previous experience in the lab characterizing the bulk combustion synthesis of cerium oxide, and the lab has already published a paper characterizing the bulk combustion synthesis of europium oxide. Ultimately, finding the optimal parameters for both printing and heat treatment will enable me to make the best and most uniform thin films. 

The first task I will need to complete is to investigate how varying the printer parameters affects solution deposition. The second task I will need to complete is to investigate how varying the heat treatment of deposited solutions affects combustion synthesis. The third task I will need to complete is to find the relationships between solution deposition, heat treatment, and the resulting thin films by observing the characteristics of films using electron microscopy.

Final Report