Design And Development For System Of Characterization Of Magnetoelectric Composites And Devices

The magnetoelectric composite is a new kind of functional material, magnetoelectric effect of which is achieved by the product of magnetostrictive effect of ferromagnetic material and piezoelectric effect of ferroelectric material. Its widely applications can be prospected and will attract much attentions as their high magnetoelectricity coefficient, stability in a large temperature range and simple processing technology, therefore, an auto-test system with high-accuracy is desirably needed to be established.In the present project thesis, several key properties parameters were researched by the theoretical derivation. According to the basic test laws, a test system for materials and devices was established. The test system can measure the magnetostrictive coefficient of magnetostrictive materials, the magnetoelectric coefficient of magnetoelectric composites and the performance of magnetic-sensitive sensor. It have meet the needs of science investigations and application tests as its high sensitivity and resolution. The Lab VIEW software was applied to speed the measurements and reduce the error.In the measurements of magnetoelectric coefficient, the ohms table was used, and the deformation resolution of0.5ppm was obtained by the method of four-needle electrodes. Matching way of reposed circuit was confirmed based on the analyzing electrical properties of magnetoelectric composites, which could increase the accuracy by depressing the disturbances. For the performances measurements of magnetic-sensitive sensor, magnetic shielding device was used to get sensitivity and noises. The disturbance of magnetic field outside decrease greatly.In this test system, many performance indexes are up to good standard. For example, the direct magnetic field and sensitivity reach up to0-600Oe and0.025Oe respectively. For the alternating magnetic field, the sensitivity achieves10pT, and the frequency is20Hz-100kHz with the resolution of1mHz. It is enough to characterize the performances of material and devices. Many kinds of materials were investigated using this test system, the results are the same as or better than the data that have been reported.