Garfinkel David A, Pakeltis Grace, Tang Nan, Ivanov Ilia N, Fowlkes Jason D, Gilbert Dustin A, Rack Philip D
Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
ACS Omega. 2020 Jul 21;5(30):19285-19292. doi: 10.1021/acsomega.0c02894. eCollection 2020 Aug 4.
Pulsed laser-induced dewetting (PLiD) of AgNi thin films results in phase-separated bimetallic nanoparticles with size distributions that depend on the initial thin film thickness. Co-sputtering of Ag and Ni is used to generate the as-deposited (AD) nanogranular supersaturated thin films. The magnetic and optical properties of the AD thin films and PLiD nanoparticles are characterized using a vibrating sample magnetometer, optical absorption spectroscopy, and electron energy loss spectroscopy (EELS). Magnetic measurements demonstrate that AgNi nanoparticles are ferromagnetic at room temperature when the nanoparticle diameters are >20 nm and superparamagnetic <20 nm. Optical measurements show that all nanoparticle size distributions possess a local surface plasmon resonance (LSPR) peak that red-shifts with increasing diameter. Following PLiD, a Janus nanoparticle morphology is observed in scanning transmission electron microscopy, and low-loss EELS reveals size-dependent Ag and Ni LSPR dipole modes, while higher order modes appear only in the Ag hemisphere. PLiD of Ag-Ni thin films is shown to be a viable technique to generate bimetallic nanoparticles with both magnetic and plasmonic functionality.
脉冲激光诱导的AgNi薄膜去湿（PLiD）会产生相分离的双金属纳米颗粒，其尺寸分布取决于初始薄膜厚度。通过共溅射Ag和Ni来制备沉积态（AD）纳米颗粒过饱和薄膜。利用振动样品磁强计、光吸收光谱和电子能量损失谱（EELS）对AD薄膜和PLiD纳米颗粒的磁性和光学性质进行了表征。磁性测量表明，当纳米颗粒直径>20 nm时，AgNi纳米颗粒在室温下呈铁磁性，而直径<20 nm时呈超顺磁性。光学测量表明，所有纳米颗粒尺寸分布都具有一个局域表面等离子体共振（LSPR）峰，该峰随直径增加而红移。PLiD之后，在扫描透射电子显微镜中观察到了Janus纳米颗粒形态，低损耗EELS揭示了尺寸依赖的Ag和Ni LSPR偶极模式，而高阶模式仅出现在Ag半球。结果表明，Ag-Ni薄膜的PLiD是一种生成具有磁性和等离子体功能的双金属纳米颗粒的可行技术。
