A study of a material with zero thermal expansion

2014 Fiscal Year Final Research Report

• Project/Area Number: 24656534
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Naval and maritime engineering
• Research Institution: Kobe University
• Principal Investigator: IWAMOTO Yuji 神戸大学, 海事科学研究科(研究院), 准教授 (80244680)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: ゼロ熱膨張 / 核磁気共鳴

Outline of Final Research Achievements

Yb based intermetallic compounds reveal variable physical properties by the valence of the Yb site. The intermetallic compound YbGaGe was reported as a zero thermal expansion (ZTE) material from 10 to 300 K by Salvador et al. They suggested that the ZTE behavior is due to the valence transition in the Yb atom.
We have carried out 171Yb nuclear magnetic resonance (NMR) and 69, 71Ga-NMR and nuclear quadrupole resonance (NQR) measurements on YbGaGe to understand the unusual thermal expansion of this system from a microscopic point of view. In the 171Yb NMR measurement, two signals corresponding to two crystallographically non-equivalent Yb sites in YbGaGe were observed. The temperature (T) dependence of the nuclear spin-lattice relaxation rate in the both 171Yb-NMR signals was proportional to T in the measured T range. In the 69, 71Ga NQR measurements, two distinctive NQR signals were observed in the both 69Ga and 71Ga nuclei, although the Ga site is crystallographically one in YbGaGe.

Free Research Field

低温物理学