Composition-structure-property relationships in CeZr(1.14)Bi(0.045)A(0.045)Mo(4.5)O(18) (A = Nb, Ta and Sb) microwave dielectric ceramics revealed by Raman, far-infrared and terahertz spectra

Understanding composition-structure-property relationships is critical to developments and applications of novel microwave dielectric ceramics used in the field of wireless communications. Herein, a series of CeZr1.14Bi0.045A0.045Mo4.5O18 (abbreviated as CZA, A = Nb, Ta and Sb) ceramics were prepared through a solid-state reaction method. Density and scanning electron microscope results revealed dense and homogeneous microstruc-tures. X-ray diffraction analysis indicated the formation of solid solutions. Accordingly, the effects of extrinsic factors were negligible and thus composition-structure-property re-lationships were systematically investigated by the combination of the chemical bond theory, Raman spectroscopy, far-infrared (FIR) spectroscopy and terahertz time-domain spectroscopy (THz-TDS) from an intrinsic perspective. Interestingly, the measured dielectric constants (& epsilon;r) and quality factors (Q x f) are quite close to the extrapolated values from FIR and THz-TDS, and these values show a similar trend with varying components. In addition, Mo-O bonds play an important role in the coefficient of thermal expansion (a) and bond energy (E), and the composition dependent temperature coefficient of the reso-nance frequency (tf) can be well explained by variations of mean a and E of Mo-O bonds. Typically, excellent properties of Q x f = 116,485 GHz (at 9.58 GHz), & epsilon;r = 9.91 and tf = -19.20 ppm & DEG;C-1 were achieved for the CZSb ceramic sintered at 700 & DEG;C. Notably, Q x f values of CZSb and CZTa ceramics are 6.13 and 4.16 times larger than that of the matrix, respectively. Ultra-high Q x f, low sintering temperatures (600 -700 & DEG;C) and low & epsilon;r make them potential candidates for low temperature co-fired ceramics (LTCC) applications. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).