Observation Method of Ion Migration Behavior in Zinc Oxide Grain Boundary Aging Process

A technology of aging process and ion migration, applied in the direction of material analysis, measuring devices, instruments, etc. by electromagnetic means, can solve the lack of convincing experimental basis and the inability to further accurately reveal the microscopic aging mechanism of zinc oxide varistors, ion migration Problems such as lack of direct experimental evidence of behavior

Active Publication Date: 2021-08-17
TSINGHUA UNIV +4
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Problems solved by technology

However, so far, there is no direct experimental evidence to support this aging model, which also leads to the lack of a solid experimental basis and convincingness for subsequent identification of aging migration ions and research on improving the aging characteristics of piezoresistors based on th

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  • Observation Method of Ion Migration Behavior in Zinc Oxide Grain Boundary Aging Process
  • Observation Method of Ion Migration Behavior in Zinc Oxide Grain Boundary Aging Process
  • Observation Method of Ion Migration Behavior in Zinc Oxide Grain Boundary Aging Process

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Embodiment 1

[0110] Bi-based ZnO quasi-twin samples were prepared, and the typical microstructure inside them is as follows: Figure 5 As shown, it has a uniform grain boundary layer of less than 1 μm, which is equivalent to a single grain boundary structure inside a conventional zinc oxide varistor. Figure 5 At the same time, based on the grain boundary microstructure, a theoretical model of double Schottky barriers in the grain boundary region was constructed to facilitate the understanding of the subsequent PEA measurement results. The two interfaces of the grain boundary layer are negatively charged interface state ions, and it is generally believed that the interface state ions are relatively stable in space and will not migrate under the action of an external electric field; while the depletion layers of the grains on both sides Inside are positively charged donor ions, which can be divided into stable ions that are relatively stable in space and metastable ions that can be activate...

Embodiment 2

[0116] Example 1 Using the PEA method to measure the Bi-based zinc oxide quasi-twin samples during the aging process, the space charge change characteristics of the double Schottky barrier region on the grain boundary inside the sample were studied, and the reverse bias side during the aging process was observed. The ion migration and neutralization process of the potential barrier. Researchers generally believe that the width of the depletion layer in the grain on both sides of the grain boundary should be in the range of several hundred nm for the theoretical modeling of the double Schottky barrier at the grain boundary inside the zinc oxide varistor. And the measurement result of PEA method shows (such as Image 6 ), the waveform width representing the concentration of donor ions in the grain depletion layer is at the level of 100 μm, which is somewhat different from the estimation in the theoretical model, which is related to the principle of the PEA method itself.

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Embodiment 3

[0121] Here, based on the differential scheme of equations, the simple case of rectangular wave acoustic wave propagation in a lossy medium is further discussed in order to obtain a more specific understanding of the acoustic loss phenomenon. Figure 7 The attenuation process of rectangular wave propagating in lossy medium is given. Such as Figure 7 As shown, after the sound wave whose initial waveform is a rectangular wave propagates from the origin in a lossy medium, its waveform will become more and more like a Gaussian function waveform as the propagation distance increases. The amplitude of the waveform decreases as the propagation time increases. For example, the peak value of a rectangular wave with an amplitude of 1 decays to about 0.6 after a propagation distance of about 1.8 mm; and the waveform width expands as the propagation time increases. Figure 8 In addition, the waveform loss of the rectangular wave after propagating the same distance in the lossy medium wi...

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Abstract

A method for observing the ion migration behavior during the aging process of zinc oxide grain boundaries. Continuously apply +3V DC voltage bias to the Bi-based quasi-twin crystal sample, and perform DC aging at 320K temperature. During the aging period, every 10 minutes, the positive polarity is applied The ns-level pulse is used to carry out the PEA measurement, obtain the measurement result of the space charge distribution inside the sample at the corresponding time, and analyze the measurement result. Its beneficial effect is: Aiming at the loss phenomenon of the sound wave containing the space charge distribution information inside the sample in the measurement of the PEA method when it propagates in the lossy medium, a corresponding sound wave loss model is established, and the lossy sound wave propagation equation proposed in it is revised. , and further perfected the theoretical system of the PEA method. The acoustic wave loss model proposed by the invention has universality and can be applied to the discussion of the acoustic wave signal loss phenomenon in the PEA method measurement of various material samples.

Description

technical field [0001] The invention relates to the field of zinc oxide grain boundary structure research, in particular to a method for observing ion migration behavior in the zinc oxide grain boundary aging process. Background technique [0002] For ZnO varistors, the aging model of "depletion layer ion migration and neutralization leads to a decrease in the height of the double Schottky barrier" has been recognized by most scholars due to the support of a series of indirect experimental evidence. However, so far, there is no direct experimental evidence to support this aging model, which also leads to the lack of a solid experimental basis and convincingness for subsequent identification of aging migration ions and research on improving the aging characteristics of piezoresistors based on this aging model. . [0003] In fact, the lack of direct experimental evidence of ion migration behavior during the aging process prevents researchers from further accurately revealing ...

Claims

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Application Information

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IPC IPC(8): G01N27/622
CPCG01N27/622
Inventor 何金良孟鹏飞胡军程晨璐谢清云曹伟谷山强万帅刘宇舜
Owner TSINGHUA UNIV
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