The Study of Physical Properties for CePt2+x(X=0, 0.5, 1) nanoparticle and bulk

• Main Authors: Huang Po Han, 黃柏翰
• Other Authors: Y. D. Yao
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/22996363922564711103

碩士 === 輔仁大學 === 物理學系 === 89 === The specific heats, magnetic susceptibility, lattice constants and microstructures of CePt2+x(X=0,0.5,1) are reported in this article. In CePt2 Ce is a magnetic ion with J=5/2, based on the magnetic entropy of specific heat and Curie constants of magnetic susceptibility, we observed that the mixed valence of Ce is induced in CePt2.5 and CePt3 due to extra amount of Pt. The antiferromagnetic ordering temperature TN of CePt2+x is suppressed from 1.4K to 0.6K as x increases from 0 to 1. In nanoparticles of CePt2+x (X=0,0.5,1) no antiferromagnetic order was observed, instead a Kondo anomaly was seen at very low temperatures. It is conjectured that the long-range antiferromagnetic order of RKKY can not be sustained as the size of specimens decreases to a critical value. The magnetic entropy of CePt2+x nanoparticles deduced from low-temperature specific heat are much smaller than that of the CePt2+x bulk, the possible reason was attributed to the formation of non-magnetic surface Ce ions. This consequence is consistent with the result of magnetic susceptibility measurements, in which the Curie constants become very small as compared with the bulk specimens.