A multiferroic material [NH2-CH+-NH2]Co(HCOO)3 of metal-organic frameworks with weak ferromagnetism and dielectric relaxation

Jiangqi Luo,Dongmei Zhao,Haiyun Wang,Qiong Fu,Weiping Li,Laihui Luo

doi:10.1063/1.4993508

Abstract

In order to seek for the single-phase multiferroic metal-organic frameworks (MOFs) materials, we prepared a multiferroic material [NH2-CH+-NH2]Co(HCOO)3 (FMDCo) by solvothermal method. We found that it had weak ferromagnetism below 12.5 K with the coercive fields (Hc) of 560 Oe, remnant magnetization (Mr) of 7.67 emu/g and saturation magnetization (Ms) of 10.3 emu/g and exhibited obvious dielectric relaxation. The octahedral metal ions (Co2+) were linked by formate (HCOO-) ligands. The AmineH+ cation (NH2-CH+-NH2) were located within the cube-like cavities of the framework and formed extensive hydrogen bonds with the framework. This improved the phase transition temperature and thermal stability. This finding helps to understand the nature of magnetic and electric ordering in the MOFs.

Highlights

ABX3 metal-organic frameworks (MOFs) (A=protonated AmineH+, B=metal ion M, and X=HCOO-) exhibit a perovskite architecture, where the octahedral metal ions are linked by anti-anti formate ligands and the AmineH+ cations are located within the cube-like cavities of the framework.[7,8]
In perovskite MOFs compounds, the electronic and magnetic properties associated with order/disorder transitions of the [AmineH]+ cations and the framework [M(HCOO)3], respectively.[9,10,11]
It was proved by Xu, et al that the magnetic [NH4][M(HCOO)3] had electric ordering and could be a new type of MOF-based multiferroics.[21,22,23]

Summary

INTRODUCTION

Metal-organic frameworks (MOFs) materials have gathered a lot of scientific attention owing to their variety of structural characteristics and extensive applications in gas storage, catalysis, sensor, nonlinear optics, solar cells, and so forth.[1,2,3,4,5,6] ABX3 MOFs (A=protonated AmineH+, B=metal ion M, and X=HCOO-) exhibit a perovskite architecture, where the octahedral metal ions are linked by anti-anti formate ligands and the AmineH+ cations are located within the cube-like cavities of the framework.[7,8] In perovskite MOFs compounds, the electronic and magnetic properties associated with order/disorder transitions of the [AmineH]+ cations and the framework [M(HCOO)3]-, respectively.[9,10,11] So the perovskite MOFs materials can be suitable candidates, as single-phase multiferroic materials with excellent electronic and magnetic properties.[12,13,14,15,16]. It has been reported that the MOFs materials with different A (different size, type) exhibit different physical properties.[17,18,19,20] It was proved by Xu, et al that the magnetic [NH4][M(HCOO)3] had electric ordering and could be a new type of MOF-based multiferroics.[21,22,23] The property of ferroelectricity induced by magnetic order was found in the metal-organic framework magnet [CH3NH3][Co(HCOO)3].9,24. FMD was chosen to synthesize the metal-formate frameworks material [NH2-CH+-NH2]Co(HCOO)[3] (FMDCo here after) and the magnetic and electrical properties were interrogated. The crystalline structures of the crystals were measured by X-ray diffraction (XRD) apparatus (Bruker D8 Advance) with Cu Kα1 radiation at room temperature. The IR measurement was carried out by a FTIR spectrometer (Bruker Tensor 27) with the wave number range of 4000-400 cm-1

RESULTS AND DISCUSSION

Hydrogen bonding contacts

CONCLUSIONS