Sintering behaviour and microwave dielectric properties of MgO-2B2O3-xwt%BaCu(B2O5)-ywt%H3BO3 ceramics

Abstract

This study investigates the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 series ceramics synthesised by solid-state reaction. According to the X-ray diffraction and microstructural analyses, the as-prepared MgO-2B2O3 ceramics possess a single-phase structure with a rod-like morphology. The effects of different quantities of H3BO3 and BaCu(B2O5) (BCB) on the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 ceramics were investigated. Accordingly, the optimal sintering temperature was obtained by adding 30 wt% H3BO3 and 8 wt% BCB. We also reduced the sintering temperature to 825 °C. Furthermore, the addition of 40 wt% H3BO3 and 4 wt% BCB increased the quality factor, permittivity, and temperature coefficient of resonance frequency of MgO-2B2O3 to 44,306 GHz (at 15 GHz), 5.1, and −32 ppm/°C, respectively. These properties make MgO-2B2O3 a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.

Mg3B2O6 microwave dielectric ceramics fabricated by combining cold sintering with post‐annealing process

“…Excess H 3 BO 3 was added to the MBO formula to compensate for the volatilization of B 2 O 3 , 15–17 and the XRD patterns of MgO‐(1 + x )H 3 BO 3 ( x = 18%, 20%, 22%, 24%) calcined at 1150°C for 4 h are shown in Figure 1A. It can be seen that the main diffraction peaks belong to the orthorhombic MBO phase, corresponding to the standard PDF card (PDF#38‐1475) with a space group of Pbnm (No.58).…”

B2O3‐modified geopolymer and its liquid‐phase sintered products for immobilization of strontium

“…Similarly, the ceramic products of (Na, Sr)‐GP with the addition of B 2 O 3 also performed better anti‐leaching abilities than the ones not incorporating B 2 O 3 . The reasons for this can be described as liquid‐phase sintering accelerating the atomic rearrangement during the phase transitions, leading to a compact microstructure of the loading substrate 42,43 . When treated at the temperature of 1000°C, the product with the addition of 2.0 wt% B 2 O 3 possesses the best immobilization property of leaching rate of 1.29%.…”

Phase transition mechanism and long‐term stability of LiF‐assisted sintered Li2MgxZrO3+x microwave dielectric ceramics

“…Therefore, it is necessary to use sintering additives to promote the sinterability of ceramic samples and reduce the sintering temperature to realize low-temperature sintering. There are a variety of additives that can facilitate the sintering of ceramics as well as lower the sintering temperature, such as BaCu(B 2 O 5 ), 20 CuO, 21 H 3 BO 3 , 22 and low-melting glassy materials. 23 However, these sintering aids may produce small amounts of impurities which may deteriorate the MDPs.…”