Overview
ISO 21819-1:2018 specifies a standardized measurement method for assessing piezoelectric properties of fine (advanced) ceramics and devices under high‑temperature conditions. The standard defines how to determine the electromechanical coupling coefficient by measuring resonance and antiresonance frequencies with an impedance analyser while the specimen is held at elevated temperatures. It addresses test setup, measurement conditions, procedures, calculations and required test reporting.
Key Topics and Requirements
- Scope: Applies to piezoelectric fine ceramics and piezoelectric devices intended for high‑temperature operation (test temperature ≥ 100 °C and below Curie point).
- Measurement principle: Resonant‑antiresonant method - determine coupling via resonance/antiresonance frequency measurements using an impedance analyser.
- Equipment:
- Impedance analyser capable of frequency scans and admittance/impedance measurement.
- Thermostatic chamber suitable from ambient to test temperature with ±5 °C (or better) stability and internal circulation recommended.
- Thermocouples complying with IEC 60584‑1/2 and continuous temperature recorder.
- Test piece holder that does not affect the target vibration mode.
- Measurement conditions & procedure:
- Start at ambient (25 ± 5 °C), raise to test temperature at ≤ ±10 °C/min.
- Record temperature when specimen reaches test temperature ±2 °C, measure after 1 min, and at further intervals (examples: 1, 10, 100, 1 000 min).
- Calibrate to remove lead/fixture impedance effects; use short leads to minimize artefacts.
- After hold period, cool back to ambient and record final values and elapsed times.
- Data handling & calculations:
- Round resonance/antiresonance frequencies to three decimal places; electromechanical coupling coefficient and admittance values to two decimals; relative permittivity to integer.
- Compute rate of change of coupling coefficient over time and include in report.
- Reporting: Must include standard reference, specimen details (type, material, geometry), apparatus models, temperature sensor details and full measurement timeline/results.
Applications and Users
Who benefits:
- Materials scientists and R&D teams developing high‑temperature piezoelectric ceramics.
- Quality assurance and testing laboratories verifying high‑temperature stability of piezoelectric sensors, actuators and transducers.
- Manufacturers of aerospace, automotive, energy and industrial sensors where piezoelectric components operate at elevated temperatures.
Practical uses:
- Validate long‑term retention of piezoelectric performance at operating temperatures.
- Compare material grades or processing conditions for thermal stability.
- Provide traceable test data for product qualification and design margins.
Related Standards
- IEC 60584‑1 / IEC 60584‑2 (thermocouples)
- EN 50324‑1, EN 50324‑2, EN 50324‑3 (terms and measurement methods for piezoelectric ceramics)
Keywords: ISO 21819-1:2018, piezoelectric, fine ceramics, high‑temperature testing, resonant‑antiresonant method, impedance analyser, electromechanical coupling coefficient, measurement procedure.