Research On The Uniformity Of BST-based Ferroelectric Material Used For Phase Shifter

As a key component of phased array radar, the performance of phase shifter plays acrucial role in the normal performance of the device. Ferroclectric phase shifter, as a typicalmedium phase shifter, because of its excellent advantages, has earned lots of attention. Inorder to meet the requirence of the design of the phase shifter, moderate dielectric constant,low dielectric loss and high tenability are necessary for the ferroelectric material. Becauseof its excellent dielectric properties, BSTM is a hot research area. However, as thelimitation of the traditional ceramic process，the uniformity of BSTM is usually relativelypoor. Based on Ba_0.55Sr_0.45TiO₃and Ba0.6Sr0.4TiO3, some research activities interrelated tothe uniformity had been done, and the main works are as follows:Large scale BSTM ceramics had been made with different moulding process （Dry Press,Isopressing and Gel-casting）, and the uniformity of BSTM with different process had beencompared. The results showed that, the moulding process plays an important part in theuniformity of BSTM and each moulding process has its own advantages and disadvantages.The dopant of Manganese compound is crucial in the improvement of the BSTMdielectric properties. In the former works, the Manganese was doped in solid state （MnCO3or MnO2）, the granularity and distribution were limited. This paper discussed the effect ofliquid state Mn（NO3）2dopant on the uniformity and dielectric properties of BSTM, and acontrast with solid state MnCO3was done. The results showed that, the ceramic samplesdoped with gained higher density, lower dielectric loss and relatively better uniformity.In order to avoid the ununiformity caused by the density difference between BST andMgO, it is necessary to find a new two-phase compound system of BST. As a microwaveceramic, ZnNb₂O₆has a low dielectric constant and sintering temperature. In this paper,high performance ZnNb₂O₆ceramics were made by the traditional solid-state reaction andthe dielectric properties of BST+xwt%ZnNb₂O₆（x=10,20,30,40） were studied.