(Mg(1-x)Srx)2Al4Si5O(18)陶瓷的显微结构与微波介电性能研究

Microstructures and Microwave Dielectric Properties of (Mg_(1-x)Sr_x)_2Al_4Si_5O_(18) Ceramics

采用固相烧结反应法制备(Mg1-xSrx)2Al4Si5O18陶瓷.Sr掺杂促进低温相β-Mg2Al4Si5O18向高温相α-Mg2Al4Si5O18转变,并拓宽了(Mg1-xSrx)2Al4Si5O18陶瓷的致密化烧结温度范围.X射线衍射结果表明在0≤x<0.2范围内,(Mg1-xSrx)2Al4Si5O18陶瓷以(Mg,Sr)2Al4Si5O18堇青石固溶体形式存在;在0.6<x≤1.0范围内,以(Sr,Mg)Al2Si2O8固溶体存在.用扫描电子显微镜观察表明Sr掺杂可以有效地降低Mg2Al4Si5O18陶瓷的气孔率与微裂纹,促进SrAl2Si2O8锶长石晶粒生长与均匀分布.在0≤x≤0.4范围内,(Mg1-xSrx)2Al4Si5O18陶瓷介电常数基本保持在7.0左右.在0.6≤x≤1.0范围内从7.0增加到8.5.Qf值在0≤x≤0.2范围内从24100 GHz显著地提高到38900 GHz,然后逐渐降低至SrAl2Si2O8的14500 GHz.

（Mg1-xSrx）2Al4Si5O18 ceramics were fabricated by traditional ceramic sintering method.The phase transformation from β-Mg2Al4Si5O18 to α-Mg2Al4Si5O18 was accelerated and the width of sihtering range was boarded due to Sr ions doping.The XRD patterns show that the cordierite solid solution of（Mg,Sr）2Al4Si5O18 is kept in the range of 0≤x0.2,and the feldspar solid solution of（Sr,Mg）Al2Si2O8 is kept in the range of 0.6x≤ 1.0.Meanwhile,the change of feldspar’s crystal cell volumes complies with Vegard’s rules.SEM images show that the porosity and microcracks of cordierite ceramics are well suppressed due to Sr doping.The growth and distribution of feldspar particles are promoted.The dielectric constants of（Mg1-xSrx）2Al4Si5O18 ceramics keep at vicinity of 7.0 in the range of 0≤x≤0.4,then increase to 8.5 at the range of 0.6≤x≤1.0.The quality factors（Qf values） evidently increase from 24100 GHz at x=0 to 38900 GHz at x=0.2,then decrease continually to 14500 GHz at x=1.0.