Figure 3: Mechanisms in reversible temperature control of both electrical and thermal conductivities. | Nature Communications

Figure 3: Mechanisms in reversible temperature control of both electrical and thermal conductivities.

From: Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

Figure 3

(a) Schematic diagram of measurement of electrical resistance between two graphite flakes peeled from highly ordered pyrolytic graphite. The dimensions of the graphite flakes are ~1 μm×3 mm×3 mm. Graphite flakes are contacted by 30-μm diameter gold wires. (b) Measured variation of electrical resistance as a function of temperature, from 18.5 to 17.5 °C. The resistance of the circuit decreased about 460 times. Inset 1 is an optical image of graphite flakes submerged in solid hexadecane, and inset 2 shows the graphite flakes submerged in liquid hexadecane. (c) Stress distribution map in frozen hexadecane, showing that the stress is unevenly distributed from 74–400 p.s.i., with an average of ~160 p.s.i. (d) Conceptual illustration of the contact area variation between graphite flakes submerged in hexadecane through the process of hexadecane freezing and remelting. The anisotropic growth of hexadecane crystals generates pressure on the surface of the graphite flakes, which increases the contact area and reduces the flake separation. When the frozen hexadecane remelts, the pressure is released and the contact area decreases.

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