Extended operating temperature window of giant negative thermal expansion in Sn-doped Ca_2RuO_4

摘要

Colossal negative thermal expansion (NTE) recently discovered in layered ruthenate Ca2RuO4 is achieved by microstructural effects because of the crystal grains showing highly anisotropic thermal distortion and the pores in the sintered body. To improve the NTE properties, we have investigated element-substitution effects. We discovered that Sn doping expanded the operating-temperature window toward higher temperatures up to 700 K and improved the temperature linearity of NTE without decreasing the total volume change related to NTE. We discuss changes in NTE properties caused by Sn doping in terms of the electronic states and the structural transformation. Published by AIP Publishing.