Low temperature synthesis and dielectric characterisation of La₂Mo₂O₉ ceramic at RF and microwave frequencies

ABSTRACT

Using a simple solid-state mixed oxides method, dense La₂Mo₂O₉ ceramics with a relative density higher than 94% were prepared at relatively low sintering temperatures (<960°C) and the crystal structure, dielectric properties were studied in some details. Splitting peaks in XRD profiles evidenced the presence of monoclinic phase. Optimum dielectric properties at microwave frequency were achieved in the best-sintered sample at 920°C, with a moderate relative permittivity of 20.6, a temperature coefficient of the resonance frequency of −38 ppm/°C, but a relatively low quality factor Q×f ∼ 7,160 GHz (f = 9.7 GHz). Complex impedance analysis revealed a thermally activated process derived from the successive short-distance diffusion of oxygen vacancies in the present La₂Mo₂O₉ ceramics, accounting for the low quality factor.

KEYWORDS:

• Dielectrics
• ceramics
• dielectric properties
• Rietveld refinement

Acknowledgements

This work was supported by Natural Science Foundation of Guangxi Zhuang Autonomous Region (No 2018GXNSFAA281253), National Natural Science Foundation of Shaanxi (Grant No. 2019JQ-573 and 2017JQ2037), and Special Fund for high-level talents of Xijing University (No. XJ17T05).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Natural Science Foundation of Guangxi Zhuang Autonomous Region [grant number 2018GXNSFAA281253], National Natural Science Foundation of Shaanxi [grant number 2019JQ-573] and [grant number 2017JQ2037], and Special Fund for high-level talents of Xijing University [grant number XJ17T05 ].