Synthesis of BaTiO3 thin films at low Ba+2 concentrations by hydrothermal-galvanic couple method

• Main Authors: Chi- Han Chen, 陳祺涵
• Other Authors: Fu-Hsing Lu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/qc86v9

碩士 === 國立中興大學 === 材料科學與工程學系所 === 102 === This research is to synthesize BaTiO3 films on TiN/Si substrate by the hydrothermal-galvanic couple method. Investigated BaTiO3 films with different [Ba2+] concentration compared with those synthesized by hydrothermal-galvanic couple method. BaTiO3 films were fabricated by using various concentrations of Ba(CH3COO)2 mixed with 2 M NaOH reaction solutions at 80°C for 60 minutes. According to different Ba(CH3COO)2 concentrations, characteristics of voltage and current , the relative intensity, the average grain size were discussed. The influence of [Sr2+] in SrTiO3 were also be compared. While Ba(CH3COO)2 concentration is higher than 0.04 M, spontaneous voltage and current between TiN and platinum electrodes were observed apparently which confirmed the existence of galvanic couple in this system. XRD identify the cubic phase crystalline BaTiO3 films. The BaTiO3 relative intensity at different concentration [Ba2+] from hydrothermal-galvanic couple is higher than a single hydrothermal method. FE-SEM observed morphology and cross-sectional structure of as-deposited TiN /Si. The continuous dense BaTiO3 covered over TiN / Si at [Ba2+] concentration above 0.04 M by hydrothermal-galvanic couple method. Grain size and thickness of the BaTiO3 film was decreased with [Ba2+]concentrations decreased significantly. When the concentration of Ba(CH3COO)2 increased from 0.04 M to 0.5 M, the die-lectric constant of BaTiO3 films decreased. The dielectric constant of BaTiO3 films at 10 kHz obtained at 0.04 M Ba(CH3COO)2 was 179 and dielectric loss was 3.18. Another part of this study, the experimental results and SrTiO3 with different strontium ions concentration were compared. BaTiO3, and SrTiO3 have the same structure. However, the maximum current, the quantity of electric charge, energy den-sity, and relative intensity and the data analysis of different concentrations of [Ba2+] is much lower than [Sr2+] under the same basic conditions. SrTO3 film can be prepared at low [Sr2+] concentration of 0.0001 M, but [Ba2+] is at least 0.04 M.