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.

A new glass-free low temperature sinterable CuMoO 4 ceramic was prepared by a solid state ceramic route. The structural, microstructural, electron dispersive spectrum, and X-ray photoelectron spectroscopy analysis revealed the quality of the material synthesized. The CuMoO 4 ceramic sintered at 650 °C exhibits densification of 96% and low coefficient of thermal expansion (CTE) of 4.6 ppm/°C in the temperature range of 25−500 °C. It has relative permittivity (ε r ) of 7.9, quality factor (Qf) of 53 000 GHz, and temperature coefficient of resonant frequency (τ f ) of −36 ppm/°C (25−85 °C) at 12.7 GHz. The sintered ceramic also shows ε r of 11 and low dielectric loss (tan δ) of 2.7 × 10 −4 at the frequency of 1 MHz. The full width half-maximum (fwhm) of A 1g Raman mode of CuMoO 4 ceramic at different sintering temperatures correlate well with the Qf values. The low sintering temperature, low relative permittivity, high-quality factor, and matching coefficient of thermal expansion to that of Si make CuMoO 4 a suitable candidate for ultralow temperature cofired ceramic (ULTCC) applications.

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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 new glass with ultralow glass transition temperature based on 10Li2O–10Na2O–20K2O–60MoO3 (LNKM) has been developed by conventional glass melting and quenching process. The glass has ultralow glass transition and melting temperatures being 198 and 350 °C respectively. The glass exhibits a coefficient of thermal expansion of 17 ppm/°C in the temperature range of 25–300 °C. X-ray diffraction and Raman spectroscopic studies indicate that the glass is partially crystallized. The chemical and elemental composition of the glass is confirmed by X-ray photoelectron spectroscopy. The glass pellet heat treated at 300 °C has a relative permittivity of 5.07 and dielectric loss tangent of 0.006 at 1 MHz. At 9.97 GHz, it shows a relative permittivity of 4.85 and dielectric loss tangent of 0.0009. The temperature dependence of the relative permittivity at 1 MHz and 9.97 GHz of the glass is 307 ppm/°C (temperature range 20–100 °C) and 291 ppm/°C (temperature range 25–85 °C), respectively.

The present paper presents ceramic composites with ultralow sintering temperature of 500 ̊C with densification of 96 % by adding small amount (0.5, 1 and 2 wt.%) of Ag2O to CuMoO4 by simple mixing method. The effect of Ag2O addition on the structure, microstructure, sintering and thermal as well as microwave dielectric properties of CuMoO4 is also studied. The reduction in the sintering temperature is due to the formation of trace amount (1.4%) of copper silver molybdate (Cu2Ag2(MoO4)3) as observed from Rietveld refinement analysis as well as backscattered SEM image. Doping has very little influence on the structure and coefficient of thermal expansion that is about 4.7-5.2 ppm/C. The composites sintered at 500 ̊C exhibit relative permittivity of about 8-9, quality factor (Qf) of 26000-37000 GHz at 12 GHz, temperature coefficient of resonant frequency of-31-33 ppm/C and are compatible with Al electrode. The present work results in obtaining welldensified ultralow temperature cofired ceramic composites at low sintering temperature without much structural change and good thermal properties but with different dielectric properties by small doping. These composites can be used as low cost candidates for wide range of microwave applications like multilayer packages and substrates owing to the low energy required during processing and hence can pave way to the advancement of electronic materials.

A facile formulation of room temperature curable and screen printable zirconium silicate (ZrSiO 4 ) ink has been developed. The ZrSiO 4 ink printed on flexible BoPET (biaxially-oriented polyethylene terephthalate) substrate showed a surface roughness of ~160 nm for a printed layer thickness of 25 µm. The screen printed ZrSiO 4 layer on BoPET substrate has relative permittivity of 3.01 and dielectric loss of 10 0.006 at 10 GHz. It showed a temperature coefficient of relative permittivity of 55 ppm/ o C in the temperature range of 30-60 o C at 15 GHz. The room temperature curability, low dielectric loss, low relative permittivity, mechanical and temperature stability of microwave dielectric properties of printed ZrSiO 4 layer make it suitable for printed microwave applications. 15 70

Smart temperature responsive inorganic materials in accessible temperature ranges open up new positions in the technology. Herein, we present for the first time a CuMoO4 polymorph mixture preparedby a simple cryogenic quenching approach, which offers a fast temperature response close towater boiling temperaturefor use asa permanent temperature recorder. The new cryogenic quenching technique initiates the formation of a unique polymorph mixture of a deep brown color with a non-uniform combination of -CuMoO4, with the outer region -CuMoO4, which has been prepared by conventional solid-state synthesis. Insitu structural analysis and refinement results confirmthe presence of CuMoO4 amount polymorph decreases and that of the phase increases with temperature, accounting for the irreversible thermochromic behavior. The thermal analysis reveals that the polymorph mixture exhibits a fast response with the color changing from deep brown to bright green with intermediate colors of light brown, yellowish green and light green depending on the exposure temperature as observed from reflectance measurements.