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.
SebastianMT, UbicR, JantunenH.Low-loss dielectric ceramic materials and their properties. Int Mater Rev. 2015;60:392–412. doi: 10.1179/1743280415Y.0000000007
2.
MananA, UllahZ, AhmadAS, Phase microstructure evaluation and microwave dielectric properties of (1–x) Mg 0.95 Ni 0.05 Ti 0.98 Zr 0.02 O3–xCa 0.6 La 0.8/3 TiO3 ceramics. J Adv Ceram. 2018;7:72–78. doi: 10.1007/s40145-018-0258-4
3.
VargheseJ, SiponkoskiT, TeirikangasM, Structural, dielectric, and thermal properties of Pb free molybdate based ultralow temperature glass. ACS Sustainable Chem Eng. 2016;4:3897–3904. doi: 10.1021/acssuschemeng.6b00721
4.
GeorgeS, SebastianMT.Synthesis and microwave dielectric properties of novel temperature stable high Q, Li2ATi3O8 (A=Mg, Zn) ceramics. J Am Ceram Soc. 2010;93:2164–2166. doi: 10.1111/j.1551-2916.2010.03703.x
5.
LiCC, XiangHC, XuMY, Low-firing and temperature stable microwave dielectric ceramics: Ba2LnV3O11 (Ln= Nd, Sm). J Am Ceram Soc. 2018;101:773–781. doi: 10.1111/jace.15251
6.
ZhouD, GuoD, LiWB, Novel temperature stable high-ε r microwave dielectrics in the Bi2 O3–TiO2–V2O5 system. J Mater Chem C. 2016;4:5357–5362. doi: 10.1039/C6TC01431C
7.
LiCC, XiangHC, XuMY, Li2AGeO4 (A = Zn, Mg): Two novel low-permittivity microwave dielectric ceramics with olivine structure. J Eur Ceram Soc. 2018;38:1524–1528. doi: 10.1016/j.jeurceramsoc.2017.12.038
8.
SongXQ, DuK, ZhangXZ, Crystal structure, phase composition and microwave dielectric properties of Ca3MSi2O9 ceramics. J Alloys Compd. 2018;750:996–1002. doi: 10.1016/j.jallcom.2018.04.044
9.
LiCC, YinCZ, DengM, Tunable microwave dielectric properties in SrO-V2O5system through compositional modulation. J Am Ceram Soc. 2020;103:2315–2321. doi: 10.1111/jace.16955
LiCC, YinCZ, ChenJQ, Crystal structure and dielectric properties of germanate melilites Ba2MGe2O7 (M = Mg and Zn) with low permittivity. J Eur Ceram Soc. 2018;38:5246–5251. doi: 10.1016/j.jeurceramsoc.2018.07.020
12.
LanXK, ZouZY, LuWZ, Phase transition and low-temperature sintering of Zn(Mn1-Al5)2O4 ceramics for LTCC applications. Ceram Int. 2016;42:17731–17735. doi: 10.1016/j.ceramint.2016.08.098
13.
ZhouD, WangH, YaoX, Microwave dielectric properties of low temperature firing Bi2Mo2O9 ceramic. J Am Ceram Soc. 2010;91:3419–3422. doi: 10.1111/j.1551-2916.2008.02596.x
14.
LiCC, WenWX, XiangHC, Low temperature sintering and microwave dielectric properties of Zn3Mo2O9 ceramic. J Mater Sci: Mater Electron. 2018;29:1907–1913.
15.
XiangHC, LiCC, TangY, Two novel ultralow temperature firing microwave dielectric ceramics LiMVO6 (M = Mo, W) and their chemical compatibility with metal electrodes. J Eur Ceram Soc. 2017;37:3959–3963. doi: 10.1016/j.jeurceramsoc.2017.04.038
16.
LacorreP, GoutenoireF, BohnkeO, Designing fast oxide-ion conductors based on La2Mo2O9. Nature. 2000;404:856–858. doi: 10.1038/35009069
17.
GoutenoireF, IsnardO, RetouxR, Crystal structure of La2Mo2O9, a new fast oxide− ion conductor. Chem Mater. 2000;12:2575–2580. doi: 10.1021/cm991199l
18.
ArulrajA, GoutenoireF, TabelloutM, Synthesis and characterization of the anionic conductor system La2Mo2O9-0.5 x F x (x= 0.02−0.30). Chem Mater. 2002;14:2492–2498. doi: 10.1021/cm011239x
19.
HakkiBW, ColemanPD.A dielectric resonator method of measuring inductive capacities in the millimeter range. IEEE Trans Microwave Theor Tech. 1960;8:402–410. doi: 10.1109/TMTT.1960.1124749
20.
CourtneyWE.Analysis and evaluation of a method of measuring the complex permittivity and permeability microwave insulators. IEEE Trans Microwave Theor Tech. 1970;18:476–485. doi: 10.1109/TMTT.1970.1127271
21.
LiuW, PanW, LuoJ, Suppressed phase transition and giant ionic conductivity in La2Mo2O9 nanowires. Nat Commun. 2015;6:8354. doi: 10.1038/ncomms9354
22.
YuCY, ZengY, YangB, Titanium dioxide engineered for near-dispersionless high terahertz permittivity and ultra-low-loss. Sci Rep. 2017;7:6639. doi: 10.1038/s41598-017-07019-9
23.
XiangHC, LiCC, JantunenH, Ultralow loss CaMgGeO4 microwave dielectric ceramic and its chemical compatibility with silver electrodes for low-temperature cofired ceramic applications. ACS Sustainable Chem Eng. 2018;6:6458–6466. doi: 10.1021/acssuschemeng.8b00220
