No abstract

In this paper, ceramic upside-down lithium molybdate-strontium titanate (LMO-ST) composites fabricated at room temperature are described. Room temperature fabrication (RTF) is a promising alternative to the time- and energy-consuming high-temperature sintering of electroceramics, which involves mixing of the initial phases, molding with a steel dye, pressing, and drying, while in the last two phases the action of densification takes place. The LMO-ST composites are based on a high ratio of filler ST, coupled with the corresponding LMO binder. Part of the binder is admixed to the ceramic particles and additional part is added as a saturated aqueous solution, which crystallizes during pressing and drying, leading to its deposition on the surface of the filler particles. As a result, sufficient binding with 76–84% relative density was achieved. The deeper insight into the method was provided by various processing aspects and corresponding microstructural investigations. The particle size distribution, pressure, pressing time, ultrasonic treatment, drying time and processing conditions were optimized to obtain improved functional properties of the LMO-ST composites. The results of this study with relative permittivity in the range of 65–78 and dielectric loss tangent values of 0.002–0.05 can attract considerable attention for the use of LMO-ST composites in the industry of electroceramics.

Author Contributions: NK, MS, SŠ and HJ agreed about the research content. HJ and MN conceptualized the experimental method developed by Hanna Kähäri and demonstrated all the knowledge and details to NK. NK, MN and HJ developed the LMO-ST composition and processing conditions. NK, MS, HJ, MN and SŠ conceived the idea and course of the experiments. NK, SŠ synthesized the initial strontium titanate. NK conducted the RTF sample preparation and characterization, along with the optimization of processing parameters. SŠ operated the scanning electron microscope and provided the imaging of the composite samples. SŠ conducted XRD characterization of samples. NK, SŠ, MS analyzed the dielectric measurements, SEM micrographs and other results supporting the findings of the study. Findings were discussed and confirmed from NK, SŠ, MS, HJ, MN. All authors reviewed the manuscript.