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

Abstract Thephase transition, sinterability, and microwave dielectric properties of Zn(Mn 1- x Al x ) 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 °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 er value decreased gradually along with an inflection point of a sharp drop at x=0.7. The Q×f value significantly increased initially and reached the maximum value of 14460 GHz at x=0.8;it decreased thereafter. Meanwhile, the τf value was near the typical value of about ‒60 ppm/°C to ‒80 ppm/°C. TiO 2 and ZnO–B 2 O 3 (ZB) glass co-doping can effectively adjust the τf value of Zn(Mn 0.2 Al 0.8 ) 2 O 4 composition, with the highest Q×f value near zero, and can reduce its sintering temperature to 950 °C.The (1- y )Zn(Mn 0.2 Al 0.8 ) 2 O 4 - y TiO 2 (y=0.26)ceramics with 5 wt%ZB glass exhibited microwave dielectric properties (er=12.71,Q×f=8126 GHz, and τf=1.02 ppm/°C) appropriate for application in low-temperature co-fired ceramics (LTCC).