Double-frequency multichannel synchronization detection method for electric domain imaging

Abstract

The invention belongs to the technical field of ferroelectric or piezoelectric material electric domain testing, and relates to a double-frequency multichannel synchronization detection method for achieving electric domain imaging through an inverse piezoelectric effect. The method employs two phase locking amplifiers to achieve the real-time synchronous detection of out-plane and in-plane piezoelectric signals of a to-be-tested sample. Reference signals of the two phase locking amplifiers are provided by two independent frequency sources, and the frequency sources also provide AC signals which are the same as the reference signals, wherein the AC signals serve as excitation signals. The excitation signals provided by the two frequency sources are superposed through an adder and then serve as AC excitation signals located between a conductive probe and the to-be-tested sample. The method can detect the amplitude and phase signals of the out-plane and in-plane piezoelectric vibration of the to-be-tested sample through one-time scanning, achieves multichannel synchronous output in a real-time mode, and greatly improves the detection efficiency. Meanwhile, the method can improve the resolution of electric domain imaging, and effectively improves 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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