Synthesis and sintering
The first phase involved synthesizing CaMgSi2O₆ (CMS) based ceramics (Pure CaMgSi2O6 and Ca1-xAxMgSi2O6 (A= Ba and Sr) and CaMg1-xBxSi2O6 (B= Co, Ni, Mn, Cu)) through solid-state reaction methods. Precursors such as high purity CaCO₃, MgO, SiO2, BaCO3, SrCO3, CoO, NiO, MnO and CuO were mixed in stoichiometric ratios. The mixtures were calcined at various temperatures (900 °C to 1200 °C) to determine optimal synthesize conditions. The synthesized powders were ball milled and dried again and were sieved after being pelleted with the 5 wt% PVA solution. The as-prepared powders were pressed into cylinders of 12.7 mm in diameter and 6.5 mm in thickness and disks of 12.7 mm in diameter and 3 mm in thickness under a pressure of 200 MPa. These cylinders and disks were sintered at 1180 - 1310 ℃ for 4 hours.
Characterization
• X-ray Diffraction (XRD) was employed to confirm the crystallographic structure, revealing that the CMS phase is stable in the targeted temperature range.
• Scanning Electron Microscopy (SEM) provided insights into the microstructural features, showing uniform grain distribution and minimal porosity, which are crucial for dielectric performance.
• Dielectric Measurements were conducted using a network analyzer to assess the dielectric constant (ε) and quality factor (Q×f) at microwave frequencies.
Main Achievements
1. Improved Densification: By optimizing the synthesis temperature and doping various cations into the crystal structure, we achieved a density exceeding 98% of the theoretical Density.
2. Enhanced Dielectric Properties: The optimized pure CMS ceramics, as well as those doped with various cations, exhibited exceptional dielectric properties, making them ideal for applications in microwave communications and devices.
3. Reduce sintering temperature
The optimal sintering temperature of the samples decreased by up to 100 degrees with the doping of various cations, while the dielectric properties improved compared to the undoped ceramics.
