The Magnetoelectric Effect In Single Phase Trinuclear Iron Cluster And Tetrachlorogallate Composite Materials

Molecule-based materials are rich in chemical structures,and have the advantages of flexibility,easy preparation and easy processing.Therefore,molecule-based materials have their unique advantages both in the design and synthesis of single-phase magnetoelectric materials and in the processing and preparation of magnetoelectric composites.At present,the research on the magnetoelectric effect of molecule-based materials has just started.Further research on molecule-based magnetoelectric materials is expected to be complementary to the traditional oxide ceramic magnetoelectric materials in terms of performance.In this dissertation,the single-phase magnetoelectric effect of molecule-based materials was discussed,and the construction of magnetoelectric composites was made by using molecule-based ferroelectric materials for the first time,which expanded the types of magnetoelectric composites.It has mainly carried out the following four aspects of work:1.Based on the design idea of spin-and charge-frustration,the magnetoelectric effect at near room temperature was realized in the metal iron cluster of[Fe3O(CH3COO)6(C5H5N)3]·(C5H5N)(1).The structure analysis of 1 at different temperatures and electrical polarization test proved that 1 was an electronic ferroelectric.On this basis,the results of the magnetic fitting calculations and the constraint density function theory(CDFT)calculations of 1 indicate that the two magnetodielectric peaks in 1 are derived from the coexistence of spin-and charge-frustration,and spin-frustration and the order-disorder of the electron.2.The uniaxial molecule-based ferroelectric[C3N2H5][ClO4](2)and the magnetostrictive material Terfenol-D were used to construct the magnetoelectric composites,demonstrating the feasibility of construction of magnetoelectric composites by using molecule-based ferroelectrics.3.The molecule-based multiaxial ferroelectric[N(CH3)4][GaCl4](3)was designed and synthesized.The polarized thin film of 3 could be easily obtained and exhibited good piezoelectric performance when comparing with the uniaxial ferroelectrics.Furthermore,3/Terfenol-D,an example of a magnetoelectric composite based on the multiaxial molecule-based ferroelectric,was firstly prepared.Investigation of the magnetoelectric effect of 3/Terfenol-D indicated that its room temperature magnetoelectric voltage coefficient was as high as 186 mV cm-1 Oe-1 at the resonance frequency.This work successfully exhibits the advantages of multiaxial ferroelectrics in the preparation of magnetoelectric materials.4.On the basis of molecular solid solution strategy,the multiaxial molecule-based ferroelectric[N(CH3)4][GaCl4](3)was doped and modified.The solid solution[N(CH3)4][GaBrCl3](4)with better piezoelectric property than 3 was obtained.4 was chosen as the piezoelectric phase.On the other hand,amorphous FeBSi alloy(Metglas)with a larger effective piezomagnetic coefficient than Terfenol-D was chosen as the ferromagnetic phase.The laminated magnetoelectric composites 4/Metglas were successfully constructed.The measurement of 4/Metglas revealed a giant room-temperature magnetoelectric effect of up to 8.74 V cm-1 Oe-1,which lays a solid foundation for the applications of this system.