GB/T 37255-2018 in English

1. Standard Overview

The National Standard of the People's Republic of China GB/T 37255-2018 "Test Method for Pyroelectric Coefficient of Materials under Biased Electric Field" specifies the terms and definitions, principles, test conditions and data processing methods for measuring the pyroelectric coefficient of materials under a DC biased electric field. This standard is applicable to the performance test of pyroelectric materials such as barium strontium titanate and lead chrysogenate.

2. Background of Standard Formulation

With the increasing application of pyroelectric materials in the fields of electronics, ceramics and sensors, it is crucial to accurately measure their pyroelectric coefficient under a DC biased electric field. The GB/T 37255-2018 standard is based on the many years of research by the Shanghai Institute of Ceramics, Chinese Academy of Sciences, and aims to provide unified technical specifications for scientific research and industrial production in related fields.

3. Test principle and device

The pyroelectric coefficient under bias electric field refers to the rate of change of the material polarization intensity with temperature under the action of DC bias electric field. The measuring device is shown in FIG1. The pyroelectric coefficient is calculated by measuring the voltage, temperature and time changes at both ends of the sampling resistor:

Wherein, $(\phi_{\mathrm{m}})_{\mathrm{E}}$ is the pyroelectric coefficient, with the unit of C/(m²·°C), and $P_{\mathrm{~m~}}$ is the polarization intensity, with the unit of C/m².

4. Test conditions and instruments

The test environment should meet the standard atmospheric conditions (15°C~35°C, relative humidity 25%~75%, atmospheric pressure 75kPa~106kPa) or arbitration atmospheric conditions (25±2°C, relative humidity 45%~55%). The main instruments and equipment include:

• Micrometer: graduation value is 0.01mm;
• Current limiting resistor: 10MΩ is recommended, power is 2W;
• Temperature measuring element: platinum resistance is recommended;

5. Sample requirements and test steps

The sample should be a square or round sheet with an area between 10mm²~100mm² and a thickness of 0.20mm~1.00mm. The surface needs to be coated with a metal full electrode and meet the following conditions:

1. Measure the sample size and calculate the main surface area A;
2. Dry the sample;
3. Place the sample in a high and low temperature test chamber with uniform temperature and no moisture interference;
4. Slowly apply the DC bias voltage to the required value and control the temperature change rate within the range of 2°C/min~4°C/min.

6. Implementation Suggestions

To ensure the accuracy of the test results:

• The instrument needs to be calibrated regularly;
• The sample surface should be free of defects or contamination;
• The operator needs to undergo professional training and be familiar with the measurement principle and data processing method of pyroelectric coefficient.