Phase Diagram of 4He Film in 3D Nanopores of ZTC

• Published in: Journal of low temperature physics 2011-03, Vol.162 (5-6), p.565-572
• Main Authors: Nakashima, Yuna, Matsushita, Taku, Hieda, Mitsunori, Wada, Nobuo, Nishihara, Hirotomo, Kyotani, Takashi
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Fluid dynamics; Fluids; Heat capacity; Magnetic Materials; Magnetism; Nanomaterials; Nanostructure; Networks; Physics; Physics and Astronomy; Specific heat; Three dimensional
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-010-0321-1

In the study to examine effects of three-dimensional (3D) film connectivity on superfluid 4 He film in the pore network, we have measured heat capacities of 4 He film adsorbed in zeolite templated carbon (ZTC), which is an assembly of graphene fragments and has network of 1.2 nm pore with the 3D period of 1.4 nm, shorter than those of nanoporous materials studied so far. From the heat of desorption, the 4 He film adsorbed in ZTC was observed to be formed up to about 1.4 atomic layers. Heat capacities of the 4 He film are rather similar to those on SiO 2 -based porous materials than those on graphite, except for large heat capacities of monolayer 4 He film. At low coverages, the heat capacity rapidly decreases below a temperature T L , suggesting a localized state of 4 He at T < T L . The T L almost monotonically lowers with increasing the coverage. Heat capacity isotherms show maxima around 1.1 layers, which suggests quantum degenerate fluid (Bose fluid) above the coverage. From these results, the phase diagram of 4 He film adsorbed in ZTC has been determined.