| [NH2?CH3?2]Mn?HCOO?3 is a multiferroic metal organic framework materials,not only has ferroelectric,ferromagnetic and ferroelastic and other properties,but also has the advantages of its large surface area,high porosity,structure and function easy to cut and so on,it has great application value in the light of the device,magnetic field.In recent years,it has caused a research upsurge.Whether the magnetic properties of [NH2?CH3?2]Mn?HCOO?3 are caused by their framework structure or determined by metal ions have been debated by researchers for a long time.Therefore,the structure and magnetic properties of the compounds were studied by doping with [NH2?CH3?2]Mn?HCOO?3.In this paper,a series of doping multiferroic materials [NH2?CH3?2]Mn?HCOO?3 compounds have been synthesized,including Co,Mg,Ca,the physical properties of these three systems have been studied,and get the following conclusions:[NH2?CH3?2]Mn1-xCox?HCOO?3?0 ? x ? 1?series compounds have been synthesized through the hydrothermal.Compounds are orthogonal structure with space group R-3C?167?.After adding Co2+,because the effective ionic radius of Co2+ is smaller than the effective ionic radius of Mn2+,XRD spectrum peak overall shift to the right,demonstrated that the doping ions have been random solid solution to [NH2?CH3?2]Mn?HCOO?3 matrix material,it also can be demonstrated by the two elements of the peak area in XPS;Based on the analysis of Rietveld XRD spectra,with the doping of Co2+,crystal cell parameters are reduced.With the addition of ions,the band gap increases gradually,and the thermal stability of the series compounds is better.At low temperature?5Kroom temperature?,the M-T curves of the samples have antiferromagnetic paramagnetic transition.The magnetic properties of the samples are related to the exchange coupling between Mn2+ and Co2+.The magnetization of the samples increased obviously with the increase of doping concentration x,and the temperature of the TN increased with the increase of the lattice symmetry.The M-T curves show that the magnetization of these compounds are strongly related to the incorporation of metal ions.In the case of cold/zero field cooling,it is found that the total magnetic field direction is opposite to the applied magnetic field.[NH2?CH3?2]Mn1-xMgx?HCOO?3?0 ? x ? 0.5?,[NH2?CH3?2]Mn1-xCax?HCOO?3?0 ? x ?0.3?compounds have been synthesized by hydrothermal,and their structure and magneticproperties also have been studied.The results show that the samples are orthogonal and the space group are R-3C?167?.With the increase of doping concentration,the change of the unit cell parameters is not very regular,because the ionic spin state of manganese ions changes with the incorporation of new metal ions.Thermogravimetric analysis showed that the thermal stability of the compound doped with calcium was better than that of the compound doped with magnesium.At low temperature,the antiferromagnetic paramagnetic phase is also present in the samples.The doping of Mg2+ and Ca2+ ions results in the change of Nair temperature,and the TN temperature of Mg doped compound decreases with the increase of concentration,and the doping concentration of calcium doped compound is small,which can not draw a certain conclusion.The M-T cold/zero field cooling curves show that the total magnetic field direction of[NH2?CH3?2]Mn1-xMgx?HCOO?3 compound is opposite to the applied magnetic field,the total magnetic field direction of [NH2?CH3?2]Mn1-xCax?HCOO?3 compound is not affected by external magnetic field. |
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