J Supercond Nov Magn (2015) 28:1199–1206 DOI 10.1007/s10948-014-2890-8 LETTER TEM Image Analysis of FePt Based Nanoparticles Synthesized by Using Fe(hfac) 3 and Fe(tmhd) 3 Komkrich Chokprasombat · Yaowarat Sirisathitkul · Chitnarong Sirisathitkul · Pharunee Sarmphim · Phimphaka Harding Received: 9 October 2014 / Accepted: 14 November 2014 / Published online: 21 January 2015 © Springer Science+Business Media New York 2015 Abstract By implementing transmission electron micro- scope (TEM) image processing, effects of a reducing agent and surfactant concentrations on the reactions between Pt(acac) 2 and alternative Fe(β -diketonate) 3 , i.e., Fe(tmhd) 3 and Fe(hfac) 3 , can be determined. The oleic acid and oley- lamine of 0.5 mmol give rise to the FePt-based nanoparticles as small as 3 nm. Larger particles up to 5 nm in diam- eter with better self-assembled patterns are obtained by increasing each surfactant to 5 mmol. With such excessive surfactants in the synthesis, the reducing agent such as 1,2- hexadecanediol may not be required since it does not signif- icantly influence the particle size and assembly. Moreover, it accelerates the reduction of Pt(acac) 2 , resulting in larger size distribution. This work demonstrates that image pro- cessing allows the size analysis from statistically sufficient number of nanoparticles. This intensity-based analysis is, K. Chokprasombat Department of Physics, Faculty of Liberal Arts, Rajamangala University of Technology Rattanakosin, Nakhon Pathom, 73170, Thailand Y. Sirisathitkul () School of Informatics, Walailak University, Nakhon Si Thammarat, 80161, Thailand e-mail: kinsywu@gmail.com C. Sirisathitkul · P. Harding Molecular Technology Research Unit, School of Science, Walailak University, Nakhon Si Thammarat, 80161, Thailand P. Sarmphim Science Program, Faculty of Liberal Arts, Rajamangala University of Technology Srivijaya, Songkhla, 90000, Thailand however, susceptible to the error arising from a low contrast between the nanoparticle and the background. The magni- fication of TEM images should therefore be optimized to minimize systematic errors. Keywords TEM image processing · Magnetic nanoparticles · FePt · Fe(β -diketonate) 3 · Surfactant 1 Introduction The synthesis of iron-platinum (FePt) nanoparticles has been under research and development for more than a decade owing to its future applications in ultrahigh den- sity recording [1] and energy storage [2]. Traditionally, FePt nanoparticles have been synthesized by the thermal decom- position of iron pentacarbonyl (Fe(CO) 5 ) and the reduction of platinum acetylacetonate (Pt(acac) 2 ) in a high boiling point organic solvent [3]. Organic molecules such as oleic acid and oleylamine are commonly used as stabilizing sur- factants. Oleylamine tends to surround Pt-rich cores in the nucleation stage of nanoparticle formations, whereas oleic acid attaches to Fe atoms. It follows that their concentrations also affect the particle morphology and composition [4]. Since Fe(CO) 5 is very toxic, volatile, and highly flammable, iron acetylacetonate (Fe(acac) 3 ) has been stud- ied in subsequent works as a green alternative [5]. However, by using Fe(acac) 3 as the Fe source, the size of the obtained FePt nanoparticles was found to be around 2 nm which is smaller than the superparamagnetic limit of fct FePt [5, 6]. To prepare the FePt nanoparticles with size of around 5 nm, the excessive surfactants were employed [7, 8]. Although the particles in [8] were quite uniform in size and shape, the