A detailed study of the substitution mechanism for improved zinc-borate: High-performance and its crystal structure variation

The substitution properties of Mn2+ to Zn2+ for Zn3B2O6 ceramic was probed at the atomic scale using the first principle calculation, involving the bond properties, electron density, and formation energy. All samples were synthesized through the solid–state reaction method, and the variation of macro performance, like sintering and dielectric properties, was discussed in detail. The sintering property was characterized by the differential-thermal & thermo-mechanical analyzer and scanning electron microscopy, the dielectric property was characterized by the Network Analyzer, and the phase formation was verified by the X-ray dispersive spectroscopy. Three sites in the Zn3B2O6 crystal are available for Mn2+ to be occupied, and the substitution process for the Zn3 site has the lowest formation energy. The ion-substitution in ZnO4 tetrahedron results in the change of the electron distribution and bond property. The dielectric performance of Zn3B2O6 ceramic has been improved, and the microstructure has been densified at 900 °C, yielding values of εr = 6.58, Q×f = 88,100 GHz (15 GHz), relative density = 96.7%, and τf = −56.5 ppm/°C as x = 0.04. Additionally, the activation energy has been decreased and the densification window shifts forward slightly.