A dual-frequency multi-channel simultaneous detection method for electrical domain imaging

Abstract

The invention belongs to the technical field of electric domain testing of ferroelectric or piezoelectric materials, and relates to the dual-frequency multi-channel synchronous detection of electric domain imaging by using the inverse piezoelectric effect. The method uses two lock-in amplifiers to measure the out-of-plane and in-plane pressure Real-time synchronous detection of electrical signals; wherein, the reference signals of the two phase-locked loop amplifiers are provided by two independent frequency sources respectively, and the frequency sources also provide an AC signal identical to the reference signal as an excitation signal, and the two frequency The excitation signal provided by the source is superimposed by the adder and loaded as an AC excitation voltage between the conductive probe and the sample to be tested. The present invention can detect the amplitude signal and phase signal of the out-of-plane and in-plane piezoelectric vibration of the sample to be tested through one scan, and output synchronously with multiple channels in a real-time manner, which greatly improves the detection efficiency; at the same time, the present invention can Improve the resolution of electric domain imaging and effectively improve the detection accuracy.

Description

technical field [0001] The invention belongs to the technical field of electric domain testing of ferroelectric or piezoelectric materials, and in particular relates to dual-frequency and multi-channel synchronous detection of electric domain imaging by utilizing the inverse piezoelectric effect. Background technique [0002] Ferroelectric material is a kind of dielectric material with spontaneous polarization behavior, its essential characteristic is to have spontaneous polarization, spontaneous polarization has two or more possible orientations, and spontaneous polarization can be turned under the action of external electric field. When the temperature is lower than the Curie temperature, the ferroelectric has a spontaneous polarization, and when the temperature is higher than the Curie temperature, the spontaneous polarization disappears. The spontaneous polarization in ferroelectric crystals, ferroelectric thin films, and ceramic grains is not uniformly distributed throu...

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Problems solved by technology

In particular, when DC bias is applied on the needle tip to induce polarization reversal to observe the electric domain movement, due to the effect of the depolarization field, the above scanning method will inevitably affect the accuracy and efficiency of electric domain imaging.

In addition, the amplitude and frequency of the AC voltage often need to be determined according to specific experimental conditions, because the vertical piezoelectric response signal and the horizontal piezoelectric response signal are not completely consistent in response to frequency, and the signal-to-noise ratio is optimal. Piezoelectric response signals need to be obtained at different frequencies, so it is difficult to achieve high-resolution imaging of out-of-plane and in-plane electrical domains at the same time by relying on the previous single-frequency excitation signal

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