Overview
ISO 24687:2023 - Fine ceramics (advanced ceramics, advanced technical ceramics) - specifies methods to measure the Seebeck coefficient and electrical conductivity of bulk-type thermoelectric materials from 300 K to 1 200 K. The standard defines a simultaneous measurement approach (off‑axis four‑terminal method) that yields high-accuracy electronic transport data used for material development, characterization and quality control in thermoelectric power generation, energy harvesting, cooling and heating applications.
Key topics and technical requirements
- Measurement principle
- Simultaneous determination of Seebeck coefficient (S = E / ΔT) and electrical conductivity (σ) using a combined off‑axis four‑terminal arrangement.
- Seebeck measurement requires thermoelectric voltage between two points and the temperature difference measured by thermocouples; conductivity is obtained from four‑probe resistivity measurements and specimen geometry.
- Temperature range
- Applicable between 300 K and 1 200 K, with specimen and electrode heating controlled in a test chamber.
- Apparatus and accuracy
- Stable current source (specified accuracy ±0.5% over ±1 A range).
- High‑resolution electronic voltmeter for small thermoelectric voltages.
- Conducting metal blocks (e.g., Pt or W) that also serve as electrodes for high temperatures.
- Thermocouple probes with small diameter (≤ 0.5 mm) and resolution of at least 0.01 K.
- Test chamber capable of reaching 1 200 K, maintaining temperature within ±1 K, and providing vacuum (below ~3 Pa) and controlled backfill gases (He, Ar, N2, O2) as required.
- Specimen preparation
- Rectangular bar specimens preferred for stable contact.
- End faces parallel within 0.01 mm and surface roughness Ra ≤ 10 μm.
- Quality assurance
- Periodic checks using certified reference materials (Annex B).
- Interlaboratory evaluation data provided (Annex A).
- Alignment with laboratory competence (ISO/IEC 17025) and related electrical conductivity test methods (ISO 23331).
Practical applications and users
- Materials scientists and R&D teams developing thermoelectric ceramics and bulk thermoelectric materials.
- Quality control laboratories in the fine ceramics and advanced materials industries.
- Device designers and engineers modelling thermoelectric modules for power generation, energy harvesting, cooling and heating.
- Testing and calibration labs performing certified measurements for material datasheets and performance benchmarking.
Related standards
- ISO/IEC 17025 - laboratory competence and calibration.
- ISO 23331 - test method for total electrical conductivity of conductive fine ceramics.
- Annex A (interlaboratory evaluation) and Annex B (periodic apparatus checks) support traceability and reproducibility.
Keywords: ISO 24687:2023, Seebeck coefficient, electrical conductivity, thermoelectric materials, fine ceramics, four‑terminal method, 300 K–1200 K, power factor, zT, material characterization.