钇掺杂浓度梯度对BST薄膜介电特性的影响

Effect of Gradient of Doped Concentration on Dielectric Performance of Y-BST Films

用改进的溶胶-凝胶(sol-gel)法制备光滑致密的相邻两层钇(Y)掺杂浓度之差即掺杂浓度梯度分别为0、0.1%和0.3%摩尔比的6层钛酸锶钡(Ba0.6Sr0.4TiO3)薄膜,分别表示为0YBST、1YBST和3YBST,研究掺杂浓度梯度对薄膜介电特性的影响。X射线衍射(XRD)表明,薄膜为沿(110)晶面生长的立方钙钛矿多晶结构,其中,0YBST显示最强的晶化,1YBST显示最弱的晶化。0YBST具有最差的介电特性,而3YBST具有最佳的介电特性,介电损耗小于1%,优质因子大于40,可满足微波调谐需要。还讨论了介电损耗减小的机理。

Six-layer yttrium (Y) graded doped Ba0.6Sr0.4TiO3 films orderly with doping concentrations of 1%/1%/1%/1%/1%/1%, 1%/1.1%/1.2%/1.3%/1.4%/1.5% and 1%/1.3%/1.6%/1.9%/2.2%/2.5%, have been prepared by an improved sol-gel method, which were denoted as 0YBST, 1YBST and 3YBST, where 0, 1 and 3 was orderly denoted as the gradients of Y doped concentration of 0, 1% and 3% mol ratios, and the effect of the gradient of Y doped concentration on dielectric performance of three films has been studied. X-ray diffraction (XRD) shows that three films mainly grow along (110) orientation and they exhibit cubic perovskite polycrystalline structure. 0YBST reveals the strongest crystallization and the worst morphology, 1YBST exhibits the weakest crystallization, and 3YBST exhibits the best morphology. However, 0YBST shows the worst dielectric properties, while 3YBST reveals the best dielectric properties with less than 1% dielectric loss and more than 40 figure of merit, meeting the needs of microwave applications. The mechanism of the low dielectric losses of the graded doped BST films was also discussed.