Structure–property relationships of low sintering temperature scheelite-structured (1 − x)BiVO4–xLaNbO4 microwave dielectric ceramics. Issue 10 (28th February 2017)

• Record Type: Journal Article
• Authors: Pang, Li-Xia; Zhou, Di; Qi, Ze-Ming; Liu, Wei-Guo; Yue, Zhen-Xing; Reaney, Ian M.
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 10(2017)
• Page Start: 2695
• Page End: 2701
• Publication Date: 2017-02-28
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6tc05670a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A permittivity of ∼76.3 ± 0.5 and a quality factor >10 000 GHz were obtained in 0.94BiVO4 –0.06LaNbO4 ceramic sintered at 800 °C. Abstract : A series of (1 − x )BiVO4 – x LaNbO4 (0.0 ≤ x ≤ 1.0) ceramics were prepared via a solid state reaction method. A scheelite-structured solid solution was formed for x ≤ 0.5 but for x > 0.5, tetragonal scheelite, monoclinic LaNbO4 -type and La1/3 NbO3 phases co-existed. As x increased from 0 to 0.1, the room temperature crystal structure gradually changed from monoclinic to tetragonal scheelite, associated with a decrease in the ferroelastic phase transition temperature from 255 °C (BiVO4 ) to room temperature or even below. High sintering temperatures were also found to accelerate this phase transition for compositions with x ≤ 0.08. Temperature independent high quality factor Q f >10 000 GHz in a wide temperature range 25–140 °C and high microwave permittivity ε r ∼76.3 ± 0.5 was obtained for the x = 0.06 ceramic sintered at 800 °C. However, small changes in composition resulted in a change in the sign and magnitude of the temperature coefficient of resonant frequency (TCF) due to the proximity of the ferroelastic transition to room temperature. If TCF can be controlled and tuned through zero, then (1 − x )BiVO4 – x LaNbO4 (0.0 ≤ x ≤ 1.0) is a strong candidate for microwave device applications.