Modified Preparation And Physical Properties Of Multiferroic Material Gallium Ferrite

Multiferroic materials possess more than one type of ferroelectricity?ferroelectricity,ferromagnetism,ferroelasticity,and ferrotoroidicity?and there is coupling effect between them.Based on the improvement needs of storage:multifunction,miniaturization and high-performance circuits.Other than traditional semiconductor technology,multiferroic materials provide more possibilities for the technological improvement,such as magnetic heads for electric writing magnetic reading and multi-state magnetoelectric random access memory.As one of the single-phase multiferroic materials,Ga Fe O₃?GFO?has strong ferrimagnetism,and both ferroelectricity and ferromagnetism are derived from the ferric ions,which,therefore,step into the sight of scientific researchers gradually.The floating zone method is one kind of melt growth method.It owns many advantages like,fast growth rate,no pollution by using crucibles,and the crystals grown with high purity and good integrity.The most common heat source of the floating zone furnace is halogen lamp with ellipsoidal cavity reflecting and collecting heat.There is also laser as heat source called lasering-heating floating furnace,its heating temperature is up to 3000?,the temperature field is uniform,and the temperature gradient is large,it can be used to grow inconsistent molten compounds with a faster growth rate.In this paper,Ga Fe O₃ was treated as the main research object,using floating zone method and traditional solid-phase sintering method to prepare Ga_1-x/2Fe_1-x/2Ti_xO₃?0?x?0.15?crystal and Ga Fe_1-xCo_xO₃?0?x?0.10?ceramic,and we compared the laser-heating floating zone method and the light-heating floating zone Method to grow crystals.The specific research contents are as follows:?1?This paper compares the effects of different heat sources on crystal growth in the process of crystal growth.Compared with light heating,the advantages of laser heating are reflected in three aspects:higher temperature limit,uniform temperature field in the melting zone and large temperature gradient.This makes it possible to grow crystals with higher melting point and it is not easy for constitutional supercooling during crystal growth and faster growth rates can be used.However,when the crystal is actually grown,an excessively large temperature gradient will cause large strain energy inside the GFO crystal to crack.Therefore,the current light floating furnace is more suitable for the growth of GFO crystals.And the best growth conditions for GFO crystals are:a polycrystalline rod with a straight and uniform composition,a heating power of 55.8%,a growth rate of 3 mm/h,a rotational speed of 20 rpm opposite to the upper and lower rods,an oxygen-filled atmosphere and a pressure of 9 atm.?2?The GFO crystal with the composition of Ga_1-x/2Fe_1-x/2Ti_xO₃?0?x?0.12?was grown using the light floating zone method,and the quality of the crystal was determined to be good by Laue photo and rocking curve.XRD diffraction analysis showed that the maximum doping amount of Ti⁴⁺in GFO crystal was 12%,and the addition of titanium reduced the crystal lattice constant.The performance test of the crystal with the composition of Ga_1-x/2Fe_1-x/2Ti_xO₃?x=0,0.05,0.10?found that the magnetic properties of the crystal decreased with the increase amount of titanium doping,and the magnetic transition temperature also decreased.And the conductivity of the crystal increases.?3?The Ga Fe_1-xCo_xO₃?x=0,0.02,0.05,0.07,0.10?composition of ceramics was fabricated by solid-phase sintering method.The sintering system of GFCO-x was determined as:900?After 6h,the rod was sintered at 1350°C for 10h.XRD and Rietveld refinement of the samples showed that in addition to the main phase of Ga Fe_1-xCo_xO₃,there was second phase with space group Fd3?m.EDX indicated that the composition of the second phase in the GFCO-1 sample was Ga_0.9Fe_1.4Co_0.7O₄.Meanwhile,cobalt doping increased the degree of lattice distortion of GFO,and the average grain size decreased.Performance tests show that trace doping of cobalt could reduce the leakage current of GFO ceramics by 7 orders of magnitude,and Co²⁺enhance the magnetic properties of gallium ferrite ceramics and introduced a higher magnetic transition temperature due to the presence of the second phase.