Magnetron Sputtering Properties Of Ni-mn-ga Films

Ni-Mn-Ga alloy has heating and magnetic induction shape memory, alsohas magnetic field induced strain and high frequency response. Ni-Mn-Ga alloyis becoming very popular material of shape memory, which has very broadapplication prospects in the microelectro-mechanical areas. At present, theresearch of Ni-Mn-Ga alloy focuses on deposition techniques, chemicalcomposition, surface morphology, mechanical properties, magnetic propertiesand martensitic phase transformation.Ni-Mn-Ga shape memory thin films were prepared by radio-frequencymagnetron sputtering at different substrate negative bias voltage of5V,10V,20V and30V, and using EDS, SEM, X-ray diffraction, AFM and VSMinstruments to study the chemical composition, structure, surface morphologyand magnetic properties of the substrate negative bias, to reveal the mechanismresponsible for its internal analysis of the formation of the reasons, the level ofheat treatment temperature on the film chemical composition, surfacemorphology and structure. In addition, under the same sputtering parameters, aseries of different thickness of Ni-Mn-Ga thin films were prepared by changingthe sputtering time, to research the different thickness of the film deposition rateand magnetic properties.The study found that the substrate negative bias has a significant impact onthe chemical composition of the film. with the rise of the negative bias, thecontent of Ni in the film firstly increases and then decreases,while the content ofthe Ga and Mn in the film firstly decrease and then increase.The size of film particle shows a decreasing trend with the increase ofsubstrate negative bias. The size of average particle is25-83nm. With theincrease of substrate negative bias the roughness of the film surface shows adecreasing trend, and is less than3.1nm, indicating the film is smooth.The films with substrate negative bias voltage of5V,10V,20V showstetragonal structure at room temperature. The bias voltage of30V the films iscubic austenitic structure at room temperature. Because the partial pressure is 10V, the films of remanence is minimum, the film Curie temperature is about340K.When the films heat treated at different temperatures, it found that the filmheated at1073K for60min can be completely crystallization. But the film cannot be completely crystallization when the temperature is below1073K. Heattreatment can make the particle size of the surface film larger,and the filmsurface is more smooth.With the increase of the thickness of the film coercivity of the films firstincreases and then decreases. When thickness of the film is1.2μm, thecoercivity is up to65Oe. The Curie temperature of the film is about350K; It isshows that the1.2μm thick of the film has a larger atomic exchange capacitythan0.4μm,0.8μm and2.3μm.