首页 | 本学科首页   官方微博 | 高级检索  
     


Heat capacity of vanadium-oxygen alloy
Authors:Hideaki Inaba  Seiichi Tsujimura  Keiji Naito
Affiliation:Department of Nuclear Engineering, Faculty of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan
Abstract:Heat capacities of vanadium-oxygen alloys with various compositions, VO0.0834, VO0.1127, VO0.1245, and VO0.1296, were measured from 320 to 920K by adiabatic scanning calorimetry. A heat capacity anomaly due to order-disorder rearrangement of oxygen atoms was observed for all the compositions. The transition temperatures from α′ to β phase were found to be 780, 791, 786, and 768K for VO0.0839, VO0.1127, VO0.1245, and VO0.1296, respectively. The transition temperatures from β′ to β were also observed to be 665 and 660K for VO0.1245 and VO0.1296, respectively, but they shifted to lower temperatures in repeated measurements. The excess heat capacity due to order-disorder transition was obtained by assuming that the heat capacity can be expressed as the sum of a harmonic term of lattice vibration, a dilational term, an electronic term, and an anharmonic term of lattice vibration. The entropy changes due to the transition for VO0.0834, VO0.1127, VO0.1245, VO0.1296 were determined from the excess heat capacities to be 1.90, 2.88, 2.82, and 2.88 J K?1 mole?1, respectively, values which were explained by calculating the entropy changes due to the order-disorder rearrangement of oxygen atoms in the superstructures of VOx alloys. From the O/V dependence of the transition temperature and entropy change, the most stable composition of the α′ phase was thought to be V48O5.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号