Significant enhancement in quality factor of Zn2TiO4 with Cu-substitution

Research highlights: → Cu-Substituted Zn2TiO4 as microwave dielectric resonator ceramic. → Sintering temperature reduced from 1180 deg. C to 1060 deg. C. → Sevenfold improvement in Quf from 2100 GHz (x = 0) to 15200 GHz (x = 0.10). → ε'r marginally reduced from 20 (x = 0) to 18 (x = 0.10). → Potential low cost alternative for few dielectric resonator applications. - Abstract: Zinc orthotitanate (Zn1-xCux)2TiO4, 0 ≤ x ≤ 0.20, spinel samples were prepared by solid state reaction and sintering. 1060 deg. C was the optimal sintering temperature for all the Cu-substituted samples which showed sintered density ≥94%, and maximum unloaded quality factor (Quf). SEM microphotographs revealed fairly uniform grains between 2 and 20 μm depending upon the composition. Microwave measurements at ∼7.1-7.5 GHz on these samples (as dielectric resonators) showed with Cu-substitution a steep increase in Quf value from 2100 GHz (for Zn2TiO4, x = 0) to 15,200 GHz (for x = 0.10), a significant jump of over 7 times, while ε'r was ∼20 (for x = 0) and ∼18 (x = 0.10). The jump in Quf in Cu-substituted samples was attributed partly to improved sintered density and partly to absence of paramagnetic Ti3+, as revealed by electron spin resonance spectra at 9.1 GHz.