LEADER 00000nam  2200421   4500 
001    AAI3478736 
005    20111219092150.5 
008    111219s2011    ||||||||||||||||| ||eng d 
020    9781124965673 
035    (UMI)AAI3478736 
040    UMI|cUMI 
100 1  Khurshid, Hafsa 
245 10 Synthesis and characterization of iron based nanoparticles
       for novel applications 
300    229 p 
500    Source: Dissertation Abstracts International, Volume: 73-
       02, Section: B, page:  
500    Adviser: George C. Hadjipanayis 
502    Thesis (Ph.D.)--University of Delaware, 2011 
520    The work in this thesis has been focused on the 
       fabrication and characterization of iron based 
       nanoparticles with controlled size and morphology with the
       aim: (i) to investigate their properties for potential 
       applications in MICR toners and biomedical field and (ii) 
       to study finite size effects on the magnetic properties of
       the nanoparticles 
520    For the biomedical applications, core/shell structured 
       iron/iron-oxide and hollow shell nanoparticles were 
       synthesized by thermal decomposition of iron 
       organometallic compounds [Fe(CO)5] at high temperature. 
       Core/shell structured iron/iron-oxide nanoparticles have 
       been prepared in the presence of oleic acid and 
       oleylamine. Particle size and composition was controlled 
       by varying the reaction parameters during synthesis. The 
       as-made particles are hydrophobic and not dispersible in 
       water. Water dispersibility was achieved by ligand 
       exchange a with double hydrophilic diblock copolymer. 
       Relaxometery measurements of the transverse relaxation 
       time T2 of the nanoparticles solution at 3 Tesla confirm 
       that the core/shell nanoparticles are an excellent MRI 
       contrast agent using T2 weighted imaging sequences. In 
       comparison to conventionally used iron oxide nanoparticles,
       iron/iron-oxide core/shell nanoparticles offer four times 
       stronger  T2 shortening effect at comparable core size due
       to their higher magnetization. The magnetic properties 
       were studied as a function of particle size, composition 
       and morphology 
520    Hollow nanostructures are composed of randomly oriented 
       grains arranged together to make a shell layer and make an
       interesting class of materials. The hollow morphology can 
       be used as an extra degree of freedom to control the 
       magnetic properties. Owing to their hollow morphology, 
       they can be used for the targeted drug delivery 
       applications by filling the drug inside their cavity 
520    For the magnetic toners applications, particles were 
       synthesized by chemically reducing iron salt using sodium 
       borohydride and then coated with polyethylene glycol. 
       Parameters such as the reactant concentrations and their 
       flow rate were varied to study the effect of particle size,
       structure and crystallinity on the magnetic nanoparticles.
       Many different hydrophilic surfactants and polymers 
       electrolytes were investigated for the particles' 
       stability in water. PSSNa was found to be the best coating
       agent among all the other investigated polymer and 
       surfactants for particles stability in water. Particles 
       have an average size of 50 nm and magnetization above 150 
       emu/g. It is anticipated that owing to their high 
       saturation magnetization and magneto crystalline 
       anisotropy, the incorporations of PSSNa coated 
       nanoparticles into the MICR toner can reduce the pigment 
       loading and hence optimize the toner quality 
520    The magnetic properties were studied as a function of 
       particle size, composition and morphology. The saturation 
       magnetization and coercivity was found to be strongly 
       dependent on the particle size and morphology. The 
       estimated effective anisotropy of the particles was found 
       to be much higher than their bulk values because of their 
       morphology and finite size effects. Core/shell particles 
       below an average size of 12 nm display superparamagnetism 
       and exchange bias phenomenon. The hollow morphology can be
       used as an extra degree of freedom to control magnetic 
       properties. The enormously large number of pinned spins at
       the inner and outer surface and at the interface between 
       the grain boundaries in hollow nanoparticles, gives rise 
       to a very large value of effective anisotropy in these 
       nanoparticles and measured hyteresis loops are minor 
       loops. The surface spin disorder contribution to magnetic 
       behavior is strongly influenced by the cooling field 
590    School code: 0060 
650  4 Physics, Condensed Matter 
650  4 Nanotechnology 
690    0611 
690    0652 
710 2  University of Delaware.|bDepartment of Physics and 
773 0  |tDissertation Abstracts International|g73-02B 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/