A novel (1-x)MgZr0.85Sn0.15Nb2O8-xBa3Ti4Nb4O21 microwave dielectric composite ceramic with near-zero temperature coefficient

A novel temperature stable (1-x)MgZr0.85Sn0.15Nb2O8-xBa3Ti4Nb4O21-2 wt% BaCu(B2O5) (MZSN-BTN-BCB, x = 0.12, 0.14, 0.15, 0.16, 0.18 in molar) composite ceramic was fabricated via a conventional solid-state reaction method. MZSN and BTN phase can coexist in the sintered ceramics due to the different crystal structures from the results of X-Ray diffraction and scanning electron microscopy. The sintering temperature and phase composition are especially relevant to the microwave dielectric properties. The optimal sintering temperature of MZSN-BTN ceramics was successfully reduced to 1125 degrees C due to the formation of BCB liquid phase. The temperature coefficient of the resonant frequency was successfully adjusted to near zero by adding an appropriate amount of BTN due to its opposite-sign tau f value. Excellent microwave dielectric properties of epsilon r = 33, Qxf = 53,950 GHz (at 6.079 GHz), tau f = -4.3 ppm/degrees C were obtained in 0.88MZSN0.12BTN-2 wt% BCB composite ceramics when sintered at 1125 degrees C for 4 h. (c) 2021 Elsevier B.V. All rights reserved.