Lithium molybdate disks were fabricated by moistening watersoluble Li 2 MoO 4 powder with deionized water and compressing it under a pressure of 130 MPa. Disks were postprocessed at room temperature, at 120°C, and at 540°C, which is a common sintering temperature for Li 2 MoO 4 . Regardless of the postprocessing temperature, densities as high as 87%-93% of the theoretical value were achieved. The X-ray diffraction patterns of processed disks were all the same with no signs of hydrates or constitutional water. The samples also exhibited very similar microstructures and microwave dielectric properties with a relative permittivity of 4.6-5.2 and a Q 3 f value of 10 200-18 500 at 9.6 GHz, depending on the postprocessing temperature.
Dielectric properties of lithium molybdate disks fabricated by moistening water-soluble Li 2 MoO 4 powder, compressing it, and postprocessing the samples at 120°C, were improved by the optimization of powder particle size, sample pressing pressure, and postprocessing time. It appeared that the postprocessing temperature of the Li 2 MoO 4 ceramics could be chosen so as to be applicable to the associated integrated materials as long as the postprocessing time was adequately adjusted to ensure the removal of the residual water. In addition, the dielectric properties of Li 2 MoO 4 ceramic were modified with an inclusion of suitable additives. For example, at 1 GHz the relative permittivity of Li 2 MoO 4 disks fabricated at room temperature and postprocessed at 120°C was increased from 6.4 to 8.8 with an addition of 10 vol% of rutile TiO 2 and to 9.7 with an addition of 10 vol% of BaTiO 3 . At the same time the loss tangent value increased from 0.0006 to 0.0014 and to 0.011, respectively.
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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