Fig. 1 shows the schematic diagram of the experimental system
and the scanning electron microscope (SEM) image of a single
polyacrylonitrile (PAN) based carbon fiber, whose diameter is measured
as 4.3 lm. In our experience, the uniformity and graphitization
degree of thin carbon fibers could be higher than thick fibers.
So we chose thin carbon fibers for measurement in this work. In
the experiment, the carbon fiber is suspended between two heat
sinks which are maintained at environment temperature T0. Four
lead wires (100 lm diameter copper wire) are connected with
the carbon fiber using conductive silver paste. The resistance of a
12 mm long single carbon fiber is about 3300 X, while the contact
resistance is below 1 X which can be safely neglected. The resistance
of carbon fiber is measured using a four-probe method. A
high-precision DC voltage source (Advantest R6243) is used for
power supply. Two high-precision digital multimeters (Keitheley
2002, 8.5 digits) are used for measuring the voltage and current,
where a digital multimeter and a standard resistance (Yokogawa
2792) serve as a galvanometer.
A Spectra Physics model Stabilite 2018 ion laser (514.5 nm) is
used as an excitation source. The laser beam is focused at the center
of the test fiber through an Olympus 50 microscope objective.
The Raman spectra of sample are measured by Horiba T64000
Fig. 1 shows the schematic diagram of the experimental system
and the scanning electron microscope (SEM) image of a single
polyacrylonitrile (PAN) based carbon fiber, whose diameter is measured
as 4.3 lm. In our experience, the uniformity and graphitization
degree of thin carbon fibers could be higher than thick fibers.
So we chose thin carbon fibers for measurement in this work. In
the experiment, the carbon fiber is suspended between two heat
sinks which are maintained at environment temperature T0. Four
lead wires (100 lm diameter copper wire) are connected with
the carbon fiber using conductive silver paste. The resistance of a
12 mm long single carbon fiber is about 3300 X, while the contact
resistance is below 1 X which can be safely neglected. The resistance
of carbon fiber is measured using a four-probe method. A
high-precision DC voltage source (Advantest R6243) is used for
power supply. Two high-precision digital multimeters (Keitheley
2002, 8.5 digits) are used for measuring the voltage and current,
where a digital multimeter and a standard resistance (Yokogawa
2792) serve as a galvanometer.
A Spectra Physics model Stabilite 2018 ion laser (514.5 nm) is
used as an excitation source. The laser beam is focused at the center
of the test fiber through an Olympus 50 microscope objective.
The Raman spectra of sample are measured by Horiba T64000
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