Phase transition and low-temperature sintering of Zn(Mn1-xAlx)2O4 ceramics for LTCC applications

Thephase transition, sinterability, and microwave dielectric properties of Zn(Mn1-xAlx)(2)O-4 (0.2 <= x <= 0.9) solid solutions synthesized through a solid-state reaction were investigated. The densification temperature of the solid solutions decreased to 1250 degrees C, which is much lower than that of the end members. All compositions showed a single phase with a tetragonal structure at x <= 0.6and a cubic structure at 0.7 <= x <= 0.9. As the x value increased, the epsilon r value decreased gradually along with an inflection point of a sharp drop at x=0.7. The Q x f value significantly increased initially and reached the maximum value of 14460 GHz at x=0.8;it decreased thereafter. Meanwhile, the tau f value was near the typical value of about -60 ppm/degrees C to -80 pprn/degrees C. TiO(2)and ZnO-B2O3(ZB) glass co-doping can effectively adjust the tau f value of Zn(Mn0.2Al0.8)(2)O(4)composition, with the highest Q x f value near zero, and can reduce its sintering temperature to 950 degrees C.The (1-y)Zn(Mn0.2Al0.8)(2)O-4-yTiO(2)(y=0.26)ceramics with 5 wt%ZB glass exhibited microwave dielectric properties (epsilon r= 12.71,Q x f=8126 GHz, and tau f=1.02 ppm/degrees C) appropriate for application in low-temperature co-fired ceramics (LTCC). (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.