Study On The Preparation And Properties Of Ternary Solid Solution Multiferroics Materials

Multiferroic materials,as one important kind of functional materials,it has two or more than two kinds of ferroics in order.Because of this property,it provides a good foundation for new function materials and is one popular material in research.Among single-phase multiferroic materials,BiFeO3 is the only one who has both weak ferromagnetic and ferroelectric properties at room temperature while its Curie(Tc-1103K),Neel(TN-643K)temperature are both above room temperature,so it can be used in various practical applications.Nowadays,there are still two obstacles about BiFeO3 in its scientific research and practical applications all over the world.On the one hand,BiFeO3 doesn't get good ferroelectric and exists big leakage,meanwhile,Fe's valence change and oxygen vacancy of it will appear when it was fabricated(Bismuth can volatile easily and will form a intermediate phase Bi2Fe4O9 and Bi25FeO40),because of this,its resistivity value is very small and its application in Piezoelectricity and ferroelectric function materials is limited.On the other hand,spiral magnetic structure of BiFeO3 devotes a week magnetic property at low magnetic field.In this paper,we did a lot research on how to fabricate ternary multiferroic materials by studying its component,processing,structure and properties.Specifically,we use BaTiO3 and BiFeO3 to prepare binary solid solutions to modify its ferroelectric and leakage and mixed LaFeO3 with BaTiO3-BiFeO3 to prepare ternary solid solutions.We added citric acid whose molar amount is 1.2 times to the cation's amount to the solution which was mixed with ethylene glycol and ethanol,then calcined at 750 ?,so the pure phase 0.97BiFeO3-0.03BaTiO3 will be obtained.The solid solution ceramic will be obtained after sintered at 750?-830? when the pure phase powder was pressed into disks,three stacked and covered with the original powder at the same time.Then we measured the ceramics' density,dielectric properties,ferroelectric properties and magnetic properties.All the ceramics' dielectric constant is small,and their dielectric loss is strong among 20-2MHz.Among 10M-1GHz,the result is opposite.When sintered at 770 ? the 0.97BiFeO3-0.03BaTiO3 ceramic sample will get a good ferroelectric properties,its Pr is 0.28?C/cm2and Ec is 4.34kV/cm.We didn't get saturated hysteresis loop because the ceramic sample' leakage is big when the higher sintered temperature was used.When sintered at 750? the ceramic sample will get a good magnetic properties,its Mr is 0.033emu/g and He is 2256.71 Oe.The ceramic sample' Mr and HC will be smaller when the sintered temperature gets higher.We prepared 0.9603BiFeO3-0.0297BaTiO3-0.01LaFeO3 powders with the same way.The solid solution ceramic will be obtained after sintered at 750?-830? when the pure phase powder was pressed into disks,three stacked and covered with the original powder at the same time.Then we measured the ceramics' density,dielectric properties,ferroelectric properties and magnetic properties.All the ceramics' dielectric constant is small,and their dielectric loss is strong among 20-2MHz.Among 10M-1GHz,the result is opposite.When sintered at 750? the 0.9603BiFeO3-0.0297BaTiO3-0.01LaFeO3 ceramic sample will get a good ferroelectric properties,its Pr is 0.54?C/cm2and Ec is 5.25kV/cm.We didn't get saturated hysteresis loop because the ceramic sample' leakage is big when the higher sintered temperature was used.When sintered at 750 ? the ceramic sample will get a good magnetic properties,its Mr is 0.21 emu/g and HC is 2927.40e.The ceramic sample' Mr and HC will be smaller when the sintered temperature gets higher.We fabricated 0.9603BiFeO3-0.0297BaTiO3-0.01LaFeO3 ternary solid solutions ceramic with the second non-magnetic phase BaTiO3 and the third magnetic phase LaFeO3.The measured result indicates that ternary solid solutions ceramic has a well dielectric properties,ferroelectric properties and magnetic properties.