Seebeck Coefficient and Resistivity¶
Seebeck coefficient measurement is an electrical characterization method that records the voltage generated by a temperature gradient across a sample, together with four-terminal electrical resistivity, usually versus temperature. The two numbers describe a thermoelectric material. Thermal conductivity, and therefore ZT, is a separate measurement unless a dedicated option is fitted.
How Seebeck and resistivity measurement works¶
The sample is clamped between electrodes. A heater sets a gradient. Two thermocouples measure temperatures and the voltage between them. The slope of voltage versus ΔT is the Seebeck coefficient (static DC / slope method). Resistivity is a DC four-terminal measurement with a current source specified at 0–160 mA, optional 220 mA.
LINSEIS specifies atmospheres of inert, oxidizing, reducing, or vacuum, water cooling, and sample sizes of bars or cylinders up to 23 mm long and discs of 10, 12.7, or 25.4 mm. Published Seebeck accuracy is about ±7% with ±3.5% repeatability; resistivity about ±10% with ±5% repeatability. Those are manufacturer figures, not in-house measurements.
Which of the three furnaces is installed is not asserted. The catalogue leads with approximately −100 °C to 500 °C and names 1500 °C as a furnace option.
When to use Seebeck and resistivity measurement¶
- Bulk thermoelectric legs, bars, and discs
- Tracking S and ρ versus temperature in a chosen atmosphere
- Comparing doped samples on the same geometry
- Feeding a ZT calculation once thermal conductivity is known from another method
What Seebeck and resistivity measurement cannot do¶
- It does not measure thermal conductivity. No κ, no ZT, unless a Harman option is actually installed.
- Thin films need an adapter that may not be fitted. Default geometry is bulk.
- Accuracy bands are manufacturer typical, not a certificate for your contact.
- 1500 °C is an option, not a promise. Confirm the furnace.
The LSR-3 at MPaCT Lab, Flagstaff, Arizona¶
The MPaCT Lab at Northern Arizona University operates a LINSEIS LSR-3 Seebeck and resistivity system in Flagstaff, Arizona. The catalogue specifies approximately −100 °C to 500 °C with furnace options to 1500 °C; bars and cylinders 6–23 mm long; discs 10, 12.7, or 25.4 mm; static gradient / slope Seebeck with dual thermocouples; DC four-terminal resistivity; and inert, oxidizing, reducing, or vacuum atmospheres. The instrument is listed as available. It is open to NAU researchers, external academic users, and industry partners, on a fee-for-service basis or as a trained hands-on user.
| Specification | Value |
|---|---|
| Temperature | Approx. −100 °C to 500 °C; up to 1500 °C with furnace options |
| Bar / cylinder samples | Length up to 23 mm |
| Disc samples | 10, 12.7, or 25.4 mm |
| Seebeck method | Static gradient / slope, dual thermocouples |
| Resistivity | DC four-terminal, 0–160 mA (optional 220 mA) |
| Atmospheres | Inert, oxidizing, reducing, or vacuum |
Figures follow the equipment catalogue and LINSEIS LSR-3 published specifications.
Full LSR-3 specifications and booking →
Sample requirements¶
- Geometry. A bar, cylinder, or disc that matches the table. Parallel faces and known length between thermocouple contacts.
- Contacts. Say if the material is difficult to contact. Oxide skins wreck both S and ρ.
- Atmosphere. Inert is the usual request. Oxidizing or reducing must be stated.
- Temperature. State the maximum. Do not assume 1500 °C.
Frequently asked questions¶
What is the Seebeck coefficient?¶
The Seebeck coefficient is the voltage generated per kelvin of temperature difference across a material. Together with electrical resistivity and thermal conductivity it determines the thermoelectric figure of merit ZT. The LSR-3 measures Seebeck and resistivity on the same bulk sample; thermal conductivity is a different instrument.
What sample size does the LSR-3 take?¶
LINSEIS specifies bars or cylinders with a small footprint and length up to 23 mm, and discs of 10, 12.7, or 25.4 mm. The catalogue lists bars and cylinders 6 to 23 mm in length and the same disc diameters. Thin-film adapters exist as an option; do not assume one is installed.
How hot or cold can the measurement go?¶
LINSEIS sells three furnaces: a low-temperature furnace from -100 C to 500 C, infrared furnaces to 800 C or 1100 C, and a resistance furnace to 1500 C. The catalogue quotes approximately -100 C to 500 C, with 1500 C as a furnace option. Which furnace is fitted is not asserted here; ask staff before planning a 1500 C run.
Can the LSR-3 measure ZT by itself?¶
Not in the base configuration. ZT needs thermal conductivity as well as Seebeck and resistivity. LINSEIS offers a Harman option for a direct ZT on thermoelectric legs; that option is not claimed as installed. A full ZT usually combines this instrument with a thermal-conductivity measurement.
Why is my Seebeck coefficient noisier than the resistivity?¶
Seebeck is a small voltage on a small gradient. Poor thermal contact, a gradient that is not steady, or thermocouple placement that is not the electrical contact will scatter S while four-wire resistivity still looks clean. LINSEIS states Seebeck accuracy of about plus or minus 7 percent and resistivity about plus or minus 10 percent; contact quality is how you get inside those bands.
Request time on this instrument¶
MPaCT Lab - Building 98E, South Engineering Lab
561 E Pine Knoll Dr, Flagstaff, AZ 86001
Phone: 928-523-2343 · Email: mpct.nano@nau.edu