Crystal structure, electric and microwave dielectric properties of La2Mg(Mg1/3Sb2/3)O6 novel double-perovskite with non-stoichiometric 1:1 cationic ordering

In this contribution, the novel double-perovskite La2Mg(Mg1/3Sb2/3)O6 has been successfully prepared by solid-state reaction method, and its structure has been determined for the first time by a combination of X-ray and neutron powder diffraction data analysis. The novel material exhibits a thermal expansion of-9.1 ppm/degrees C and a large optical band gap (4.23 eV). The complex impedance data analysis indicates that La2Mg(Mg1/3Sb2/3)O6 features a Debye-like behaviour, with a bulk conductivity, & sigma;b, varying between 10-7-10-4 S ‧cm-1 within 500-900 degrees C temperature range, and activation energy (Ea) of -1.36 eV. In addition, the microwave dielectric properties of La2Mg(Mg1/3Sb2/3)O6 sintered at 1625 degrees C display optimized quality factor (Qxf) of -28,700 GHz (f = 9.65 GHz), a dielectric constant (& epsilon;r) of -20.2 and temperature coefficient of the resonant frequency (of) of - 89 ppm/degrees C. This work widen the reduced number of A3+( ) B2+ 2/3B5+ O3 compounds explored so far. 1/3

Automated summary

In this study, the novel double-perovskite La2Mg(Mg1/3Sb2/3)O6 was successfully synthesized by solid-state reaction method, and its structure was determined for the first time using a combination of X-ray and neutron powder diffraction analysis. The material showed a thermal expansion coefficient of -9.1 ppm/°C and a wide optical band gap of 4.23 eV. It exhibited Debye-like behavior in complex impedance analysis, with a bulk conductivity ranging from 10-7 to 10-4 S·cm-1 in the temperature range of 500-900 °C, and an activation energy of -1.36 eV. Additionally, the sintered La2Mg(Mg1/3Sb2/3)O6 exhibited optimized microwave dielectric properties with a quality factor (Qxf) of -28,700 GHz (f = 9.65 GHz), a dielectric constant (& epsilon;r) of -20.2, and a temperature coefficient of resonant frequency (of) of -89 ppm/°C.