Room-temperature fabrication of microwave dielectric Li2MoO4–TiO2 composite ceramics

Kähäri, Hanna; Teirikangas, Merja; Juuti, Jari; Jantunen, Heli

doi:10.1016/j.ceramint.2016.04.081

Cited by 51 publications

(53 citation statements)

References 12 publications

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“…The composition of the paste was experimentally optimized to give a smooth uniform flow during the extrusion by keeping the amount of the water and the aqueous phase as low as possible. A low water content is desirable since the evaporation of water during drying results in residual porosity 23 . A smooth sample surface was obtained after printing.…”

Section: Resultsmentioning

confidence: 99%

“…In this study, the water content was kept as low as possible because an excess amount during the drying causes porosity 23 . Furthermore, keeping the liquid content low was beneficial because it shortens the drying time and reduces the related shrinkage and cracking 31,38,39 .…”

Section: Discussionmentioning

confidence: 99%

“…Cracking can also be a sign of a too fast drying rate 40 . With further optimization of drying, for example in high humidity 40 , the porosity may be reduced but not totally removed as the evaporating water leaves some porosity behind 23 . However, the drying of the sample in this study was relatively successful because too fast a drying rate would also have resulted in warping and cracking 38,40 and these defects were not observed (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The dissolved Li 2 MoO 4 recrystallizes during drying due to water evaporation, which can be speeded up by heat treatment at 120 °C 21 . The RTF method has also been applied in the manufacture of Li 2 MoO 4 based composites to tailor the relative permittivity 22,23 and its thermal coefficient 23 , or to introduce magnetic properties 25 . As no sintering is required, the unwanted formation of extra phases or heat expansion mismatch between the materials are not observed.…”

Section: Introductionmentioning

confidence: 99%

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3D printed dielectric ceramic without a sintering stage

Väätäjä

Kähäri

Ohenoja

et al. 2018

Sci Rep

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This paper presents for the first time the fabrication of dielectric ceramic parts by 3D printing without sintering. The printable paste was prepared by mixing a carefully selected amount of water-soluble Li2MoO4 powder with water. A viscous mixture of solid ceramic particles and saturated aqueous phase was formed with a solid content of 60.0 vol.%. Printing of the sample discs was conducted with material extrusion using a low-cost syringe-style 3D printer. The consolidation and densification of the printed parts occurred during both printing and drying of the paste due to extrusion pressure, capillary forces, and recrystallization of the dissolved Li2MoO4. Complete drying of the paste was ensured by heating at 120 °C. The microstructure showed no delamination of the printed layers. Relatively high densities and good dielectric properties were obtained, especially when considering that no sintering and only pressure from the extrusion was employed. This approach is expected to be feasible for similar ceramics and ceramic composites.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

3D printed dielectric ceramic without a sintering stage

Väätäjä

Kähäri

Ohenoja

et al. 2018

Sci Rep

Self Cite

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“…Li 2 MoO 4 ceramics fabricated by this method exhibit an ε r of 5.1 and a tan δ value of 0.00035 at 9.6 GHz. It has also been found that the dielectric properties of Li 2 MoO 4 can be modified to provide, for example, a near‐zero temperature coefficient of frequency or permittivity.…”

Section: Introductionmentioning

confidence: 99%

Room‐temperature‐densified Li₂MoO₄ ceramic patch antenna and the effect of humidity

Kähäri

Ramachandran

Juuti

et al. 2016

Int J Applied Ceramic Tech

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A patch antenna was realized utilizing a Li2MoO4 disk fabricated by a room‐temperature densification method, where the densification takes place during pressing. Therefore, the size of the ceramic can easily be managed by controlling the mold dimensions, making this method advantageous for patch antenna design. The antenna showed reasonably good performance. A relative humidity of 80% lowered the resonant frequency and reduced the efficiency of the antenna. Use of a conformal coating reduced the changes and speeded up their reversibility. The results show that the room‐temperature densified Li2MoO4 ceramics are feasible for use under high humidity with a silicone coating.

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Cold‐Sintered C0G Multilayer Ceramic Capacitors

Wang

Zhou

Song

et al. 2019

Adv Elect Materials

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Multilayer ceramic capacitors (MLCCs) based on (Bi0.95Li0.05)(V0.9Mo0.1)O4‐Na2Mo2O7 (BLVMO‐NMO), with εr = 39, temperature coefficient of capacitance, TCC ≈ ±0.01%, and tan δ = 0.01 at 1 MHz, are successfully fabricated by a cold‐sintering process at 150 °C. Scanning electron microscopy of the MLCCs combined with EDS mapping, X‐ray diffraction, and Raman spectroscopy reveals well‐laminated and undistorted dielectric layers composed of BLVMO and NMO discrete phases separated by Ag internal electrodes. Prototypes show comparable properties to C0G MLCCs (TCC = ±30 ppm °C−1 from −55 to +125 °C) currently commercially fabricated at 1100 °C using CaZrO3‐based dielectrics with glass sintering aids and Ni internal electrodes.

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Room-temperature fabrication of microwave dielectric Li2MoO4–TiO2 composite ceramics

Cited by 51 publications

References 12 publications

3D printed dielectric ceramic without a sintering stage

3D printed dielectric ceramic without a sintering stage

Room‐temperature‐densified Li₂MoO₄ ceramic patch antenna and the effect of humidity

Cold‐Sintered C0G Multilayer Ceramic Capacitors

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Room-temperature fabrication of microwave dielectric Li2MoO4–TiO2 composite ceramics

Cited by 51 publications

References 12 publications

3D printed dielectric ceramic without a sintering stage

3D printed dielectric ceramic without a sintering stage

Room‐temperature‐densified Li2MoO4 ceramic patch antenna and the effect of humidity

Cold‐Sintered C0G Multilayer Ceramic Capacitors

Contact Info

Product

Resources

About

Room‐temperature‐densified Li₂MoO₄ ceramic patch antenna and the effect of humidity