Nanoscale Res Lett (2010) 5:1289–1294 DOI 10.1007/s11671-010-9640-z N A N O E X P R E S S Synthesis, Magnetic Anisotropy and Optical Properties of Preferred Oriented Zinc Ferrite Nanowire Arrays Daqiang Gao • Zhenhua Shi • Yan Xu • Jing Zhang • Guijin Yang • Jinlin Zhang • Xinhua Wang • Desheng Xue Received: 10 April 2010 / Accepted: 6 May 2010 / Published online: 22 May 2010 The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Preferred oriented ZnFe2O4 nanowire arrays with an average diameter of 16 nm were fabricated by post-annealing of ZnFe2 nanowires within anodic alumi- num oxide templates in atmosphere. Selected area electron diffraction and X-ray diffraction exhibit that the nanowires are in cubic spinel-type structure with a [110] preferred crystallite orientation. Magnetic measurement indicates that the as-prepared ZnFe2O4 nanowire arrays reveal uni- axial magnetic anisotropy, and the easy magnetization direction is parallel to the axis of nanowire. The optical properties show the ZnFe2O4 nanowire arrays give out 370–520 nm blue-violet light, and their UV absorption edge is around 700 nm. The estimated values of direct and indirect band gaps for the nanowires are 2.23 and 1.73 eV, respectively. Keywords ZnFe2O4 Nanowire arrays Preferred oriented Magnetic anisotropy Optical properties Introduction As an important member of ferrite family, nanometer-sized spinel ZnFe2O4 has received growing interest from the D. Gao Z. Shi J. Zhang G. Yang J. Zhang X. Wang D. Xue (&) Key Lab for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, 730000 Lanzhou, People’s Republic of China e-mail: xueds@lzu.edu.cn Y. Xu Department of Physics, Xinxiang University, 453003 Xinxiang, People’s Republic of China fundamental and experimental point of view because of its potential application in gas sensors with high sensitivity and low-energy consumption [1–4]. Besides, the nanome- ter-sized ZnFe2O4 is considered as a promising semicon- ductor photocatalyst for various photochemical processes, such as photoelectric conversion and photochemical hydrogen production from water, owing to its ability to absorb visible light, high efﬁciency, low cost, and excel- lently photochemical stability [5–7]. Meanwhile, the nanometer-sized ZnFe2O4 shows unusual magnetic prop- erties compared to the bulk form [8], such as high Curie temperature and large magnetization at room temperature (RT) have been observed in ZnFe2O4 nanoparticles and ﬁlms [9–12]. The issue has been extensively researched and ascribed to the dominant role of oxygen vacancies [13], surface effects [14], as well as cation random distri- bution of magnetic Fe3? ions and diamagnetic Zn2? ions among the interstitial octahedral (B) and tetrahedral (A) sites [15]. One-dimensional nanostructures can provide versatile building blocks for fabricating functional nanoscale elec- tronic, optoelectronic, biomedical devices, magnetic and optical properties based on the bottom-up paradigm [16– 20]. Recently, arrays of Ru, Pt, and PtRu nanowires and nanotubes were prepared by electrodeposition through the porous structure of an anodic aluminum oxide (AAO) membrane [21]. Iron-based 1D nanostructures have been successfully prepared using an electrospinning technique and varying the pyrolysis atmospheres [22]. Besides,1D magnetic MFe2O4 (M = Co, Ni and Mn) nanomaterials also have been fabricated owing to their unique application in mesoscopic physics and nanoscale devices excellent properties [23–25]. For zinc ferrite, Liu et al. fabricated ZnFe2O4 nanowires exhibiting unusual magnetic behavior by the thermal decomposition of the precursors inside silica 123