不同退火温度镍注入二氧化钛的结构与磁性

为了证实铁磁性的来源,选用注入剂量相同、退火温度不同的镍注入二氧化钛的4种样品,用同步辐射X线衍射、卢瑟福背散射/沟道实验和超导量子干涉仪,对样品分别进行了θ-2θ扫描、随机谱和沟道谱以及磁性的测试.结果表明:镍注入二氧化钛在高温退火后的结构发生了变化,形成了镍-纳米粒子,其嵌入二氧化钛中的镍-纳米粒子的结构和样品的磁性可以通过退火来调节.随着退火温度的增加,镍-纳米粒子的尺度增加,并且退火温度稳定在1 073 K以上;镍注入二氧化钛中能够测量到铁磁性,其主要原因是金属镍-纳米粒子的形成;另外,其他因素对二氧化钛铁磁性也有贡献,像辐照产生的缺陷、镍原子替位等.

Structure and Magnetism of Ni-implanted TiO2 Annealed at Different Temperatures

To confirm the origin for the ferromagnetism,four kinds of samples in Ni-implanted TiO2 with the same implanted fluence and different annealing temperature are selected.The structural and magnetic properties are discussed.The θ-2θ scan,random spectra,channeling spectra and magnetic properties are performed by synchrotron radiation X-ray diffraction(SRXRD),Rutherford backscattering/channelling spectrometry(RBS/C) and SQUID.These testing results indicate that Ni NCs have been formed in TiO2 after ion implantation and annealing and the structure and magnetic properties of Ni NCs embedded inside TiO2 can be tuned by post-annealing.With increasing annealing temperature,the Ni NCs are growing in size and are stable up to 1 073 K.The Ni NCs are the main origin of the measured ferromagnetism.However,the SQUID results indicate other contributions for the observed magnetic properties,as irradiation induced defects or substituted Ni ions mediated by defects being the possible candidates.