PdPtAu alloys for low-temperature precision resistors

Area of Science:

• Condensed Matter Physics
• Materials Science
• Low-Temperature Physics

Background:

• Palladium-rich alloys (PdPt, PdAu) show unusual resistance-temperature behavior with flat minima, even after impurity oxidation removes the Kondo effect.
• Thermoelectric potentials of PdPt and PdAu alloys have opposite signs against superconductors, enabling novel alloy design.

Purpose of the Study:

• To investigate the thermoelectric properties of palladium-based alloys.
• To develop ternary PdPtAu alloys with suppressed thermoelectric power.
• To create a tool for precise alloy composition determination for specific temperature ranges.

Main Methods:

• Fabrication of palladium-rich PdPt and PdAu alloys.
• Oxidation of impurities to eliminate the Kondo effect.
• Measurement of resistance-temperature behavior and thermoelectric potentials against a superconductor.
• Development of a nomogram for alloy composition based on desired resistivity minimum temperature.

Main Results:

• Palladium-rich PdPt and PdAu alloys exhibit flat resistance minima independent of the Kondo effect.
• Ternary PdPtAu alloys were successfully prepared with negligible thermoelectric power against a superconductor.
• A nomogram was developed to determine alloy composition for resistivity minima between 1.5 and 4.2 K.
• Manufactured alloys demonstrated a temperature coefficient of resistivity < 10(-6)/K and thermoelectric power < 1 nV/K.

Conclusions:

• Ternary PdPtAu alloys can be engineered to possess near-zero thermoelectric power.
• The developed nomogram provides a practical method for creating alloys with specific low-temperature resistance characteristics.
• These alloys are promising for applications requiring stable resistance and minimal thermoelectric effects at cryogenic temperatures.