Formation kinetic of RBa2Cu3Oy (R = rare earth)

• Main Authors: PoChing Lee, 李柏慶
• Other Authors: Huey-Chuen I.Kao
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/11455558863673794129

碩士 === 淡江大學 === 化學學系 === 90 === In this research, peak position of the DTA curve is employed for determining the formation temperature of RBa2Cu3Oy (R = rare earth, except Ce, Tb, Tm, Yb and Lu) under N2, Air and O2 atmosphere. For samples with average radius of 0.047 mm, the formation reaction temperatures under N2 and O2 atmosphere are 834 ±11 and 962 ±10 oC, respectively. The formation reaction temperature increases with increasing the heating rate and the oxygen partial pressure during the thermal analysis. Under the N2 atmosphere the reaction activation energy (Ea) are 200 ~ 300,200 ~ 350, 200 ~ 400 kJ/mole calculated from the Kissinger, Reich and Ozawa method, respectively. Nevertheless, the calculated Ea for Pr123 and Dy123 is relatively large, that should be reconfirmed. Under the O2 atmosphere, the calculated Ea by Kissinger and Reich methods is 1000 ~ 3000 kJ/mole. However, the calculated Ea by Ozawa method under O2 atmosphere is low, 400 ~ 700 kJ/mole, because the shape of the TG curve dose not satisfy the condition of the Ozawa method. The equilibrium temperature of the formation reaction the activation energy are not correlated to the radius of R3+ ion and the number of the 4f electrons. They are related to the oxygen partial pressure, particle size and the heating rate during the reaction.