A Study Of The Positive Temperature Coefficient Of Resistivity Of Lanthanum Doped Barium Titanate Prepared By Combustion Synthesis PDF Download

The search for low-cost technologies that reduces our energy consumption is a priority in our struggle for the well-being of our environment. This project had two objectives : (1) Synthesizing BaTiO3 nanoparticles of a controlled size and structure for an electroluminescent device (ELD) (2) Analyzing the effect of doping barium titanate with lanthanum and optimizing the concentration for our application. The BaTiO3 particles created for this project will enable a more efficient use of the necessary electric energy for the emission of light in ELDs. They can also reduce the thickness of the overall device, which would result in lower production costs and increased brightness. The BaTiO3 was synthesized using a sol-gel method, which allows for the control of particle size and dopant concentration in 6 different powders. The material was characterized using scanning electron microscopy, X-ray diffraction analysis and X-Ray photoelectron spectroscopy (XPS). The XPS results showed a large split in the lanthanum's binding energy which was never discussed in the litterature. Following this, a hypothesis was advanced related to the interaction between the Ti-O strong bond and the lanthanum. The ELDs were screen-printed by hand using inks made from the experimental BaTiO3 and a ZnS commercial powder. The optimal concentration of dopant (0,5 mol% La) was obtained by using impedancte spectroscopy and photometry to determine, respectively, the electric permittivity of the BaTiO3 layer and the luminescence of the ELDs. One of the luminescent samples was found to be 600% brighter than the others. Although an anomaly among the samples, it is a real result and could reveal to be of great importance for the field of ELD research if it can be reproduced using a commercial printer.