ELECTRICAL RESISTIVITY

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ELECTRICAL RESISTIVITY
Four Probe Method Electrical resistivity
(?) 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. ?is obtained from ? RA/L, where R
is resistance, A is area of cross section, and L
is length between voltage leads.
Schematic diagram of resistivity measurement
General Description 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
Pump
RMC-Cryosystems Thermometer
System Interconnections
Prepare the sample
Sample space
CJ-LR 400 GPIB Adapter
PC AT Program Control
Data Output
LR-400 Fore-Wire AC Resistance Bridge
7001 Switch System
CTI-Cryogenics (MODEL 22)
Experimental Results
Electrical resistivity as a function of
temperature for La2-xSrxCuO4
Electrical resistance as a function of
temperature for LiTi2O4