Phase and Microstructure Evaluation and Microwave Dielectric Properties of Mg1−x Ni x SiO3 Ceramics

Abstract

The ceramics were prepared using the solid-state reaction method and their phase, microstructure and microwave dielectric properties were investigated. A single-phase clinoenstatite system with monoclinic structure (space group P2 1 /c) was confirmed through x-ray diffraction (XRD) analysis for the compositions with x £ 0.1. The compositions with x ‡ 0.15 contain SiO 2 and (Mg 1Àx Ni x ) 2 SiO 4 phases only as confirmed from the XRD data of their sintered samples. The unit cell volume was decreased while the theoretical density was increased with increase in x from 0 to 0.1. A decrease in dielectric constant (e r ) while an increase in unloaded quality factor multiplying the resonant frequency (Q u f o ) and temperature coefficient of resonant frequency (s f ) was observed with increase in Ni content from 0 to x = 0.1. In the present study, e r $ 6.10, Q u f o $ 118,702 GHz and s f $ À10 ppm/°C was achieved for the composition with x = 0.1 sintered at 1425°C for 9 h. The material is a good candidate for millimeter wave applications.

Accelerated Osteogenic Response of Electrodynamically Stimulated Mg1–xCaxSi1–xZrxO3 (x = 0–0.4) Bioelectrets

“…19-0239) was observed during phase analyses. The development of secondary-phase Mg 2 SiO 3 complicates the synthesis of single-phase MgSiO 3 . , On increasing the concentration of Ca and Zr from 0.3 to 0.4, minor phases (CaSiO 3 , Ca 2 MgSiO 7 , Mg 2 SiO 4 , and CaMg­(SiO 3 ) 2 ) started to form.…”

“…This was the result of lattice expansion that occurred within MgSiO 3 . − However, as the value of x increases from 0.3 to 0.4, the peak shifts toward a higher angle. Because of the presence of more Ca 2+ at the Mg 2+ site, the lattice contraction in MCSZO- X bioceramics occurs. , − Also, for compositions x = 0.3 to 0.4, the presence of two additional minor phases of CaSiO 3 and CaMgSiO 3 (JCPDS no. 19-0239) was observed during phase analyses.…”

A comparison of syntheses approaches towards functional polycrystalline silicate ceramics

“…Prominent examples of ionic replacements for the tuning of material parameters are found in almost every materials science direction. In the ongoing search for materials with ever improved dielectric properties for high frequency wireless applications, cation substitutions are often introduced in the host material to reduce dielectric loss [49][50][51], achieve near zero temperature factor of resonant frequency [52,53], reduce secondary phase formation [54], improve densification and adjust its permittivity [1]. Bioactive glasses and ceramics are routinely substituted with a broad range of cations to harness their profound effects on the material properties.…”

The latest process and challenges of microwave dielectric ceramics based on pseudo phase diagrams

“…With a Q×f value larger than 100,000 GHz, another class of binary silicate can be written as A 2 SiO 4 (A = Ba, Sr, Ca, Mg, Zn) [20][21][22][23]. Forsterite Mg 2 SiO 4 is extensively explored because of its superior microwave dielectric properties (ε r ≈ 7.8, Q×f value ≈ 240,000 GHz, and τ f ≈ -67 ppm/ , sintered at 1450 ℃ -1500…”