This standard applies to the measurement of low-frequency dielectric constant of pyroelectric materials. GB 11297.11-1989 Test method for dielectric constant of pyroelectric materials GB11297.11-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for the dielectric constant of pyraelectric materials Test method for the dielectric constant of pyraelectric materials This standard applies to the measurement of the low-frequency dielectric band number of pyroelectric materials. 1 Terminology
GB11297.11-89
The terminology used in this standard conforms to GB11294 "Common terminology of semiconductor optoelectronic materials and pyroelectric materials in infrared detection materials".
2 Measurement principle
For a parallel plate dielectric capacitor with infinite gap between the electrode plate and the dielectric, the capacitance is expressed as: C=
Where: E. - Dielectric constant of vacuum, = 8.854×10-10F/cm - Dielectric constant in the direction perpendicular to the electrode plate, a unitless physical quantity; electrode area.cm2:
d - Interval between the electrode plates, that is, the thickness of the dielectric sample, cm. If this capacitor is made of pyroelectric material, then according to formula (1), its dielectric constant can be expressed as: d
Using a capacitance bridge to measure the capacitance C, the dielectric constant of the pyroelectric material can be calculated according to formula (2). (1)wwW.bzxz.Net
During the measurement, there is a constant capacitance C between the measuring lead and the sample fixture. , which is in parallel with C, so the measured capacitance C should be:
C =C +C
Substitute the (: in (3) into (2), and the final expression of the dielectric constant is: -C
（4）
The dielectric constant of low-temperature thermoelectric materials is anisotropic, and the dielectric constant measured according to the principle of parallel plate capacitor should be the dielectric constant perpendicular to the direction of the plate, so the direction of the sample must be determined in advance. Pyroelectric materials are piezoelectric, and some are ferroelectric. Their dielectric constant is related to the test frequency, and is also related to temperature, pressure, humidity, test voltage and the aging process of the sample. Therefore, when measuring the low-temperature dielectric band number, the above-mentioned conditions should be clearly defined.
3 Test conditions
3.1 Test environment
3.1.1 The sample should be in a constant temperature state, and the temperature fluctuation range should be less than ±0.1℃. Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on October 9, 1988 and implemented on January 1, 1990
GB 11297.11--89
3.1.2 The temperature gradient around the sample is less than a.1℃/cm3.1.3 The humidity around the sample should be less than 60%. The air pressure is the local normal atmospheric pressure. 3.2 Test sample
3.2.1 The sample shape should be square or round, with an area A of 0.30.5cm and a thickness d of 0.05~0.10cm. 3.2.2 The thickness direction of the sample is parallel to the pyroelectric axis, and the allowable deviation is ±2°. 3.2.3 The surface of the sample must be finely ground or polished. For some cleavage If the cleavage surface of the material is flat, no processing is required. Then cover the metal electrode.
3.2.4 The average deviation of the sample thickness should be less than ±2%. 3.3 Sample clamp only
The connection between the electrode lead and the sample electrode adopts an elastic clamp, or conductive glue. The elastic clamp should ensure good electrical contact with the sample electrode, and should not produce a large local pressure on the sample. 3.4 Sample box
The sample box should be made of copper or its alloy, and properly grounded to shield the external electrical signal. 3. 5 / Measurement leads
The measurement leads should be shielded, and the screen wire must be well connected to the ground of the capacitance measuring instrument and the sample screen box. Capacitance measuring instrument requirements
4. 1 Test frequency
The test frequency is 1kHz±5%.
4.2 Test voltage
The output voltage of the measuring instrument is converted into the electric field strength applied to the sample, which should generally be less than 5V/cm. For extremely special ferroelectric materials, the test voltage should be as low as possible.
4.3 Capacitance measurement accuracy
The accuracy of the capacitance measuring instrument should not be less than 0.1%. 5 Measurement steps
5.1 Sample processing
5.1.1 Clean the unplated electrode part with alcohol or ether. 1.2 Use a measuring microscope to measure the electrode area. It should be measured at least 5 times, and then take the average value. The error should be less than 6. 5%, use a dry gauge to measure the thickness, select at least five points on the sample surface for measurement, and then average the values. The error should be less than 1%. 5.2 Sample aging and polarization treatment
Short-circuit the two electrodes of the sample and place them in dry air at room temperature for more than 24 hours. For pyroelectric materials with ferroelectricity, single polarization (polarization) treatment should be performed before short-circuiting.
5.3C. Determination
First separate the sample, with a spacing equivalent to the sample thickness, and then connect the measuring leads. The measured capacitance is the capacitance C of the fixture and the leads.
5.4C determination
Clamp the sample with a sample clamp, place it in a shielding box, adjust the temperature of the thermostat to reach the predetermined temperature, and measure the plate after 15 minutes of constant temperature. The measured capacitance is the C system at that temperature. 5.5 Calculation
Measure A, d, and C. Substituting the values ​​of θ and C into formula (4), the dielectric constant can be calculated. The test temperature must be specified when publishing the results. 6
Measurement error
GB 11297.11--89
The dielectric constant error measured by this standard is less than 2%. Additional notes:
This standard was drafted by the Institute of Crystal Materials of Shandong University. The main drafters of this standard are civilians.
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