Synthesis of High Quality Zinc Blende CdSe Nanocrystals

Mohamed, Mona; Tonti, Dino; Al-Salman, † Awos; Chemseddine, A.; Chergui, Majed

doi:10.1021/jp051123e

Cited by 150 publications

(133 citation statements)

References 36 publications

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“…There have also been several reports of non-equilibrium phases in semiconductor NPs. [4][5][6][7] For multicomponent metal NPs, metastable phases [8][9][10][11] are well known. In some instances, metastable phases frustrate efforts to obtain equilibrium phases.…”

mentioning

confidence: 99%

Composition‐Mediated Order‐Disorder Transformation in FePt Nanoparticles

Johnston‐Peck

Cullen

Tracy

2013

Part & Part Syst Charact

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While great progress has been made in the synthesis, property optimization, and applications of chemically synthesized functional nanoparticles (NPs), a signifi cant remaining challenge is to uniformly control the composition and phase of multicomponent NPs. Phase equilibria for NPs may be altered from bulk behavior due to the higher proportion of surface atoms and contributions from surface chemistry, such as ligand monolayers, resulting in altered thermodynamic and metastable phases for NPs. For Co [ 1,2 ] and Ag, [ 3 ] new phases have been observed in NPs and nanowires, respectively. There have also been several reports of non-equilibrium phases in semiconductor NPs. [4][5][6][7] For multicomponent metal NPs, metastable phases [8][9][10][11] are well known. In some instances, metastable phases frustrate efforts to obtain equilibrium phases. FePt NPs are such a system, wherein an undesired metastable alloy phase and multiple intermetallic phases have hindered the preparation of intermetallic, phase-pure, chemically synthesized FePt NPs with a monodisperse size distribution. [ 12 ] New insights about these challenges and how to overcome them will also be applicable to other kinds of multicomponent metal NPs.FePt NPs are of interest for bit-patterned media (BPM), a prospective architectural paradigm shift for the magnetic recording industry that overcomes the storage density limits of current recording media by using discrete magnetic bits rather than continuous media. [ 13 ] While reducing the bit size increases the storage density, it also increases bits' susceptibility toward thermal demagnetization, which would cause data loss. Superparamagnetism occurs when thermal energy ( k B T ) is suffi cient to overcome a NP's magnetocrystalline anisotropy energy ( KV ), where K is the magnetocrystalline anisotropy constant and V is the volume, which induces random reorientation of the magnetization direction. Magnetocrystalline anisotropy is the coupling of the moment to a favored crystal direction. Other magnetic anisotropies are known, such as those arising from the NP surface, anisotropic shapes, or strain, but for unstrained NPs of approximately spherical shape, magnetocrystalline anisotropy is usually the predominant magnetic anisotropy. The L1 0 intermetallic phase of FePt has an extremely large K of ≈ 10 7 erg cm −3 , [ 14 ] which makes is attractive for BPM, as well as for permanent magnet applications. [ 12 ] In addition to thermal stability, another requirement for BPM is for the variance in the fi eld required to change the magnetization direction of the bits (commonly referred to as the switching fi eld distribution) to be small, in order to avoid high rates of read and write errors. [ 15 ] A narrow switching fi eld distribution can be achieved with periodically spaced bits that have similar magnetic properties. [16][17][18] Monodisperse FePt NPs synthesized using wet-chemical approaches are stabilized by ligands that facilitate self-assembly into highly ordered structures. [ 8 ] Such methods produce disord...

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mentioning

confidence: 99%

Composition‐Mediated Order‐Disorder Transformation in FePt Nanoparticles

Johnston‐Peck

Cullen

Tracy

2013

Part & Part Syst Charact

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“…The high-quality CdSe QDs with zinc-blende structure was obtained by Chergui et al when the phosphonic acid (PA) was added to TOP-Se. In the absence of PA, only wurtzite dots were obtained [38]. The present experiment scheme also is a convenient route to acquire zinc-blende structure CdSe QDs.…”

Section: Methodsmentioning

confidence: 85%

A greener synthetic route to monodisperse CdSe quantum dots with zinc-blende structure

Wang

Jiang

et al. 2008

Journal of Crystal Growth

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“…Recently, synthesis of semiconductor nanocrystals with crystal phase controlled has attracted much attention because of the important influence of crystal structure on the properties in semiconductor nanocrystals. ZnO [24], CdSe [25], CdS [26], ZrO 2 [27], and SnS [28] nanocrystals with metastable crystal structure have been obtained. Synthesis of semiconductor nanocrystals with crystal phase controlled is helpful to understand the relationship of the properties on the crystal structure in nanocrystals.…”

Section: Introductionmentioning

confidence: 99%