Study On Preparation And Properties Of Ni-Mn-In Heusler Alloy Films

In recent years,Ni-Mn-In Heusler alloys have attracted extensive attention and research due to its multifunctional characteristics,such as large magnetothermal effect,magnetoresistance,and magnetic shape memory effect.In addition,because there are lots of possible combinations of elements and the crystal structure can be adjusted by element substitution,Heusler alloys have been explored in the field of electrocatalysis.In order to develop Heusler alloys in micro devices and explore the application of Heusler alloys in the field of electrocatalytic hydrogen evolution(HER).In this paper,Ni-Mn-In alloy targets were synthesized by arc melting.Ni-Mn-In alloy thin films were prepared by pulsed laser deposition(PLD).The structure,magnetic properties and hydrogen catalysis of the sample were studied by Atomic force microscope(AFM),X-ray diffraction(XRD),Quantum interference device(SQUID),electrochemical testing and other equipments.The main contents are as following:(1)The large volume change of ferromagnetic shape memory alloy films is strictly limited by the rigid substrate.However,because of the high growth temperature(>673K),it is difficult to grow Heusler alloys with high crystallization quality on flexible polymers.We successfully synthesized high quality 100 nm thick Ni_51.6Mn_33.5In_14.9(Ni-Mn-In)thin films on transparent flexible mica substrates by PLD,and their crystal structure,morphology and magnetic properties were compared with those grown on Si(100)substrates.As the interlayer interaction in mica substrates is van der Waals force,the thickness of the substrates can be reduced by simple mechanical stripping method,so that the samples of Ni-Mn-In films grown on ultra-thin mica substrates have extremely high flexibility.The mechanical properties of the flexible Ni-Mn-In films were tested by repeated bending at a radius of curvature of 0.745 cm,and it was found that the sample resistance increased by only 8%after more than 10,000 cycles'bending.These results show that flexible ferromagnetic shape memory alloy films can be obtained by using mica substrates and have great potential applications in flexible electronics.(2)In the past few decades,Heusler alloys have attracted much attention as functional magnetic materials,considering that Heusler alloys contain a variety of transition metal elements with catalytic activity,the crystal structure can be adjusted by elemental substitution,and then the catalytic effect can be modified.Ni-Mn-In alloy was prepared on nickel foam by PLD as a cathode electrode for electrocatalytic hydrogen evolution(HER)reaction.It was shown that the catalyst had good catalytic performance(the electrode produced an overpotential of-114 m V(1.50V vs.RHE)at a current density of 10 m A/cm²),the initial catalytic performance was better than that of pure Ni electrode and Ni-Mn electrode.In addition,the stability of the Ni-Mn-In electrode was increased by covering the surface with a thin layer of 10 nm thick Pt atoms,the electrode potential change of 110 m V in 5 h decreased to only 10 m V in 20h.The catalytic stability has been effectively improved.