ELECTRICAL RESISTIVITY. Four Probe Method
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Four Probe Method
Electrical resistivity (ρ) measurements are carried out by the standard four-probe method over the temperature 8-300 K. Four platinum (Pt) electric leads are attached with silver paint/indium soldering on rectangular bar of specimens cut from sintered pellets with uniform cross section, as shown in Figure right side.
ρis obtained from ρ= RA/L, where R is resistance, A is area of cross section, and L is length between voltage leads.
Schematic diagram of
Closed cycle refrigerator (CCR) systems provide a convenient means of cooling samples to temperatures below 10 K. CCR systems require no liquid nitrogen as a source of cooling. Instead, a closed loop of helium gas is compressed and expanded.
The electrical resistivity system include the following components : cold head, gas lines, optional temperature controller, and compressor.
Diagram of the Setup of Resistivity Measurement
CJ-LR 400 GPIB
PC AT Program
AC Resistance Bridge
Electrical resistivity as a function of temperature for La2-xSrxCuO4
Electrical resistance as a function of temperature for LiTi2O4