Application Cases

Experiment Name: Study on Polarization of Ferroelectric Ceramics under Biaxial Stress

Research Direction: In novel ferroelectric ceramics, the low Curie temperature of barium titanate piezoelectric ceramics prevents the enhancement of the polarization process through increased temperature. For new high-temperature ferroelectric ceramics, the high coercive electric field exceeds the material's breakdown electric field, making it difficult to achieve saturated polarization. As a result, polarization through pure electric fields is limited in the polarization processes of these advanced ferroelectric ceramics. In reality, besides electric fields, stress fields can also alter the texture of ferroelectric materials. Previous studies have demonstrated that stress can assist the polarization process in ferroelectric materials.

Based on this background, this chapter investigates the polarization process of ferroelectric materials under biaxial stress. An experimental setup was independently designed and constructed. By testing the residual polarization and piezoelectric constants under different polarization loading methods, the polarization process under various loading conditions was studied, enabling ferroelectric ceramics to achieve excellent piezoelectric performance under low electric fields.

Test Equipment: High-voltage amplifier, Signal generator, Electrometer, etc.

Experimental Process:

Figure 1: (a) Schematic diagram of the force distribution on the sample during the loading process of biaxial transverse stress in ferroelectric ceramics; (b) Schematic diagram of the loading device.

The experimental setup, as shown in Figure (b), is a self-designed and developed loading device for biaxial force-electric coupling effects. The test specimen measures 4 × 4 × 4 mm³. Biaxial transverse stress is applied through four insulated alumina ceramic block elements, as illustrated in Figure 1(a). The electric field is applied perpendicular to the biaxial transverse stress through through-holes in the upper and lower parts of the device. Before the experiment begins, the device shown in Figure 1(b) is filled with oil and sealed using sealing rings placed at all contact surfaces. When the testing machine acts on the compression rod, the sealed oil in the container converts the uniaxial pressure into pressure applied to the aforementioned insulated alumina ceramic block elements.

Experimental Results:

Figure 2: Curves of material polarization under different methods as a function of electric field and stress. The figures show the polarization results of the material under electric field amplitudes of (a) 0.5Ec, (b) 0.75Ec, (c) 1.0Ec, and (d) 1.25Ec.

Figure 2 depicts the polarization results of the samples under four different polarization methods, showing the changes in material polarization throughout the entire polarization process rather than only the residual polarization values after polarization. From the figures, it can be observed that under Loading Method 1 (traditional pure electric field polarization), the residual polarization values of the material under polarization electric fields of 0.5, 0.75, 1.0, and 1.25 times the coercive electric field are 0.02, 0.05, 0.115, and 0.12 C/m², respectively. This indicates that polarization increases with the increase in the electric field.

High-Voltage Amplifier Recommendation: ATA-7030

Figure: ATA-7030 High-Voltage Amplifier Specifications

This document has been compiled and released by Aigtek. For more application cases and detailed product information, please follow us continuously. Xi'an Aigtek has become an instrument and equipment supplier with a wide range of product lines and considerable scale in the industry. Demo units are available for free trial.