| Dielectric materials,as the core materials of ceramic capacitors,are a kind of key materials for the development of new energy storage materials.They are widely used in the fields of microelectronic devices,memorizers,capacitors and so on.How to improve the dielectric properties of dielectric capacitors is a hot topic and frontier in the field of capacitors.ACu3Ti4O12（ACTO）ceramic material is a new type high dielectric constant material which has been discovered and studied in recent years,and this kind of material has high dielectric constant.Because of its excellent dielectric constant frequency and temperature stability,it has potential application value in energy storage capacitors.As a member of ACTO ceramic materials,Y2/3Cu3Ti4O12（YCTO）ceramic material exhibits excellent dielectric properties and the dielectric constant temperature stability which meets the requirements of X7R.However,in order to be applied in practical engineering,the bottleneck problems such as high loss and low breakdown electric field must be solved in order to be applied in practical engineering,despite the outstanding advantages of the YCTO ceramic material.Therefore,it is valuable to improve the dielectric constant,reduce the dielectric loss and improve the breakdown electric field of the YCTO material.In this study,the preparation process of YCTO ceramics was optimized and the properties of YCTO ceramics were improved.In addition,it is expected that the grain boundary resistance can be controlled by Zn,Mg and A1 ions substitution in the A’ site（Cu site）so as to reduce the dielectric loss.The relationship between grain boundary resistance and electric properties was also analyzed.Finally,the effects of ion substitution on the temperature stability and time stability of the materials were analyzed.The main conclusions of this study are as follows:1.Pure phase YCTO ceramics were successfully prepared by traditional solid state method.The effects of raw material selection and sintering process on the phase structure,surface morphology and dielectric properties of YCTO ceramics were systematically analyzed.The optimum preparation process of YCTO ceramic material was obtained:Mengtai titanium dioxide,sintering temperature of 1080 ℃,soaking time of 25 h.The prepared sample showed good surface morphology,homogeneous grain size,high dielectric constant（8350 at 10 kHz）and low dielectric loss（0.047 at 10 kHz）.2.Using the traditional solid state method,pure phase Y2/3Cu3-xZnxTi4O12,Y2/3Cu3-xMgxTi4O12 and Y2/3Cu3-xAlxTi4O12 ceramic material（x = 0,0.03,0.05,0.07,0.1）were successfully prepared.Systematic analysis of the effect of the three ion substitution on material phase structure,surface morphology,dielectric properties,impedance,and current density-electric field was carried out.The results showed that the introduction of three kinds of ions can effectively increase the grain boundary resistance of the material and thus reduced the dielectric loss and maintained the giant dielectric constant.Under the condition of 10kHz measurement frequency,when Zn ion substitution amount was 0.07,tanδ=0.033 and εr=8651;when Mg ion substitution amount was 0.05,tanδ=0.027 and εr=12370;and when Al ion substitution amount was 0.05,tanδ=0.028 and εr=9540.Among these three kind of ion substitution,Mg ion substitution induced the best dielectric properties,and Zn substitution induced the highest breakdown electric field and energy storage density.3.The time stability and temperature stability of three kinds of YCTO ceramics were measured.The results showed that all the substituted YCTO ceramic samples had good time stability and temperature stability.The temperature stability of the material increased gradually with the increasing of substitution content,and the temperature coefficient of each dielectric constants（TCK）was in accordance with X7R standard.The temperature stability of the A10.1 sample was the best（-7.9%～8.1%）,which was significantly higher than that of the base system（-21%～26%）. |
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