| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 103 === Abstract
This research is to synthesize barium zirconate (BaZrO3) films on ZrN-coated Si substrate at 90oC by hydrothermal-galvanic couple method (HT-GC) using fixed 0.5 M Ba(OH)2 with 2 M-4 M NaOH as electrolyte. The influences of the OH- ions concentration on the growth of BaZrO3 films are discussed. ZrN/Si substrate was prepared by unbalance megnetron sputtering technique at sputter power 300 W and 400 W. In the literature, except for our research, no research has been reported on the BaZrO3 film synthesis by using such a method. Traditionally, hydrothermal method and hydrothermal-electrochemical method in synthesizing BaZrO3 films usually require bulk-Zr as seeding layers. ZrN/Si substrate has never been used in the literature before. No complete mechanism has been proposed for synthesizing BaZrO3 films by hydrothermal-galvanic couple method in the past.
The influences of voltage and current at different reaction times on growth of BaZrO3 films was investigated. The growth mechanisms of BaZrO3 films were studied by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), field-emission scanning electron microscope (FE-SEM) and energy dispersive spectrometers (EDS). Crystalline BaZrO3 films could be obtained in 0.5 M Ba(OH)2 mixed with 4 M NaOH electrolyte for 12 hours by using ZrN/Si substrate with various sputter powers. The morphology of films turned from nanolayered structure into dense microstructure and crystallinity became better with increasing of the OH- concentration. After analyzing of the experimental data, the films were at first single layer with many pores and microcracks that allows electrolytes penetruting into the ZrN and reacting continuilly. Finally, multilayer structure was obtained. We found the films prepared at low concentration of OH- condition were mutilayer structure which contained mostly oxide. With increasing the concentration of OH-, morphology turned into dense microstructure and the content of BaZrO3 increased.
In this work, crystalline BaZrO3 films were successfully prepared on ZrN/Si by hydrothermal-galvanic couple method without further annealing. The process was one-step which prone to green processing and synthesis. The growth of films could be tailored by controlling the voltage and current versus time behavior. The thickness of BaZrO3 films could be controlled by the thickness of seeding-layer ZrN.
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