Hydrothermal synthesis, structure characterization and antiferromagnetic properties of thortveitite-type β-Mn2V2O7

Abstract

β-Mn2V2O7 powder is successefully prepared at 200—220℃ under pH=6—9 by a novel hydrothermal synthesis technology. The phase, the morphology and the microstructure of the prepared sample are investigated by XRD, SEM, EDS, TEM, HRTEM and SAED. The results show that β-Mn2V2O7 powder has a thortveitite structure with monoclinic system. The powder synthesized at 200 ℃ under pH=6—7 has a rod morphology, while that at 200 ℃ under pH=8—9 has coexistent petal and rod morphologies. HRTEM and SAED measurements indicate that β-Mn2V2O7 grows anisotropically and has crystalline integrality. Magnetic properties are measured by superconducting quantum interference device (SQUID) in a temperature range of 2—300 K under a magnetic field of 1T. The magnetic measurement results indicate that β-Mn2V2O7 undergoes a transition from antiferromagnetic to paramagnetic with a Néel temperature of 24 K. Above 100K, the inverse susceptibility is fitted well to the Curie-Weiss law and paramagnetic Weiss temperature θ=-24.6 K, and the Curie constant C=9.846 K emu mol-f.u.-1 can be caculated, which means that there exists an obvious antiferromagnetic interaction in thortveitite-type β-Mn2V2O7, the antiferromagnetic behavior is caused by the superchange of Mn2+-O2--Mn2+.