Para o desenvolvimento da nanociência atual há forte demanda por equipamentos capazes de caracterizar sistemas em escalas da ordem nanométrica. Este contexto impulsionou o desenvolvimento de microscópios ópticos de varredura em campopróximo (Scanning Near-field Optical Microscope SNOM). Diferentemente da microscopia óptica tradicional, os SNOMs detectam a radiação eletromagnética evanescente e, conseqüentemente, a resolução não é limitada pelo critério de Rayleigh. No Laboratório de Materiais Magnéticos IFUSP desenvolvemos um SNOM sensível a efeitos Kerr magnetoópticos (MO-SNOM). Dessa maneira, associamos a alta resolução da técnica à alta sensibilidade dos efeitos magnetoópticos. Trata-se se uma área relativamente pouco explorada e carente de resultados sistemáticos na literatura. Utilizando o MO-SNOM, caracterizamos partículas microestruturadas de Co70.4Fe4.6Si15B10 amorfo com dimensões de 16x16x0.08 microm3 e 4x4x0.08 microm3. Os resultados compreendem dezenas de imagens de susceptibilidade magnetoóptica diferencial com resolução melhor que 200 nm e curvas de histerese local. Em primeira análise, a demonstração de resultados sistemáticos ajuda a estabelecer a técnica. O comportamento magnético das partículas, estudadas sob várias condições de campo aplicado, se mostrou determinado basicamente pela anisotropia de forma. As curvas de histerese local mostraram comportamentos intrinsecamente locais e motivaram uma interessante discussão sobre os parâmetros de caracterização magnética convencionais. As medidas realizadas indicam que o efeito Kerr magnetoótico transversal em campopróximo é similar ao campo-distante. Os resultados são fortemente sustentados por medidas de microscopia magnetoóptica de campo-distante, simulações micromagnéticas e medidas de microscopia de força magnética. Medidas complementares revelam o potencial do MO-SNOM para caracterizações de objetos extensos quanto a potenciais de pinning. Além disso, medidas em filmes finos de NiFe/FeMn acoplados por exchange-bias evidenciam a alta sensibilidade do MO-SNOM, estimada de DM ~ 2 x 10-12 emu. / To support nanosciences evolution, there is a strong demand for developing new instrumentation devoted to nano-scale characterization. In this context, the development of the Scanning Near-field Optical Microscope (SNOM) took place. In contrast to traditional optical microscopes, SNOM deals with evanescent electromagnetic radiation and, consequently, the resolution is no longer limited by the Rayleigh criterion. At Laboratório de Materiais Magnéticos (LMM) IFUSP a SNOM devoted to magneto-optical Kerr effect measurements (MO-SNOM) has been developed. The MOSNOM associates the high resolution of the near-field technique to the high sensibility of the magneto-optical Kerr effect. Near-field magneto-optical microscopy is not yet wellestablished and there is a lack of systematic results in the literature. Using the MO-SNOM, amorphous Co70.4Fe4.6Si15B10 particles with 16x16x0.08 microm3 and 4x4x0.08 microm3 dimensions were studied. With resolution better than 200 nm, several magneto-optical differential susceptibility images and local hysteresis loops were obtained. The systematic results uphold the establishment of this new technique. Under the different applied field conditions, the magnetic behavior of the particles was found to be determined by shape anisotropy. Local hysteresis loops presented shapes intrinsic of local field induced process. The unusual hystesesis loops motivated interesting discussion about the conventional magnetic parameters. The MO-SNOM measurements indicate that the near-field transverse magneto-optical Kerr effect is similar to the far-field case. The results are highly supported by far-field magneto-optical microscopy, micromagnetic simulations and magnetic force microscopy measurements. Complementary measurements indicate the MO-SNOM potential to extensive magnetic surface characterization related to pinning potential distribution. Furthermore, measurements on the exchange-bias coupled NiFe/FeMn thin films make evident the MO-SNOM high sensitivity, estimated to be DeltaM ~ 2 x 10-12 emu.

科学研究費補助金 研究種目:基盤研究(C)(2) 課題番号:09640721 研究代表者:野水 勉 研究期間:1997-1998年度

The theoretical part of this doctoral thesis provides a comprehensive overview on the topic of preparation and subsequent utilization of magnetic derivatives of biological materials for xenobiotic separation from water. Main attention is paid to magnetic modification of waste materials and by-products originating from agricultural and food industry, which represent widely available and low-cost materials, and also to magnetic modification of microbial cells. In addition to the description of magnetic particle preparation and individual developed techniques of magnetic modification, a brief characterization of selected pollutants and a detailed table overview on utilization of magnetically responsive biomaterials for biosorption of organic dyes, heavy metals, pharmaceutical and personal care products together with ubiquitous industrial endocrine disruptors and also of crude oil derivatives is presented. Experimental part of this thesis is focused on the preparation and optimization of new types of magnetic materials. Emphasis is placed on the employment of simple, fast and simultaneously low-cost magnetic modification techniques (e.g., postmagnetization using microwave-synthesized magnetic iron oxides or one-step modification by magnetic fluids). Selected plant materials (barley and rye straw) were chemically modified to significantly (up to five-times) increase the maximum adsorption capacities for tested dyes. All prepared biomaterials exhibited a great magnetic response and simultaneously relatively high adsorption capacity for selected xenobiotics under experimental conditions used. Factors substantially affecting adsorption process, such as pH, initial concentration, incubation time or temperature were also studied. Adsorption equilibrium data were assessed using Langmuir, Freundlich or Sips isotherm models. Experimental data from time dependence study were analyzed by chosen kinetic models, namely the pseudo-first-order and pseudo-second-order ones and by intraparticle diffusion model. Thermodynamic parameters (Gibbs free energy, enthalpy and entropy) describing the nature of adsorption were also included in study.

Para o desenvolvimento da nanociência atual há forte demanda por equipamentos capazes de caracterizar sistemas em escalas da ordem nanométrica. Este contexto impulsionou o desenvolvimento de microscópios ópticos de varredura em campopróximo (Scanning Near-field Optical Microscope SNOM). Diferentemente da microscopia óptica tradicional, os SNOMs detectam a radiação eletromagnética evanescente e, conseqüentemente, a resolução não é limitada pelo critério de Rayleigh. No Laboratório de Materiais Magnéticos IFUSP desenvolvemos um SNOM sensível a efeitos Kerr magnetoópticos (MO-SNOM). Dessa maneira, associamos a alta resolução da técnica à alta sensibilidade dos efeitos magnetoópticos. Trata-se se uma área relativamente pouco explorada e carente de resultados sistemáticos na literatura. Utilizando o MO-SNOM, caracterizamos partículas microestruturadas de Co70.4Fe4.6Si15B10 amorfo com dimensões de 16x16x0.08 microm3 e 4x4x0.08 microm3. Os resultados compreendem dezenas de imagens de susceptibilidade magnetoóptica diferencial com resolução melhor que 200 nm e curvas de histerese local. Em primeira análise, a demonstração de resultados sistemáticos ajuda a estabelecer a técnica. O comportamento magnético das partículas, estudadas sob várias condições de campo aplicado, se mostrou determinado basicamente pela anisotropia de forma. As curvas de histerese local mostraram comportamentos intrinsecamente locais e motivaram uma interessante discussão sobre os parâmetros de caracterização magnética convencionais. As medidas realizadas indicam que o efeito Kerr magnetoótico transversal em campopróximo é similar ao campo-distante. Os resultados são fortemente sustentados por medidas de microscopia magnetoóptica de campo-distante, simulações micromagnéticas e medidas de microscopia de força magnética. Medidas complementares revelam o potencial do MO-SNOM para caracterizações de objetos extensos quanto a potenciais de pinning. Além disso, medidas em filmes finos de NiFe/FeMn acoplados por exchange-bias evidenciam a alta sensibilidade do MO-SNOM, estimada de DM ~ 2 x 10-12 emu. / To support nanosciences evolution, there is a strong demand for developing new instrumentation devoted to nano-scale characterization. In this context, the development of the Scanning Near-field Optical Microscope (SNOM) took place. In contrast to traditional optical microscopes, SNOM deals with evanescent electromagnetic radiation and, consequently, the resolution is no longer limited by the Rayleigh criterion. At Laboratório de Materiais Magnéticos (LMM) IFUSP a SNOM devoted to magneto-optical Kerr effect measurements (MO-SNOM) has been developed. The MOSNOM associates the high resolution of the near-field technique to the high sensibility of the magneto-optical Kerr effect. Near-field magneto-optical microscopy is not yet wellestablished and there is a lack of systematic results in the literature. Using the MO-SNOM, amorphous Co70.4Fe4.6Si15B10 particles with 16x16x0.08 microm3 and 4x4x0.08 microm3 dimensions were studied. With resolution better than 200 nm, several magneto-optical differential susceptibility images and local hysteresis loops were obtained. The systematic results uphold the establishment of this new technique. Under the different applied field conditions, the magnetic behavior of the particles was found to be determined by shape anisotropy. Local hysteresis loops presented shapes intrinsic of local field induced process. The unusual hystesesis loops motivated interesting discussion about the conventional magnetic parameters. The MO-SNOM measurements indicate that the near-field transverse magneto-optical Kerr effect is similar to the far-field case. The results are highly supported by far-field magneto-optical microscopy, micromagnetic simulations and magnetic force microscopy measurements. Complementary measurements indicate the MO-SNOM potential to extensive magnetic surface characterization related to pinning potential distribution. Furthermore, measurements on the exchange-bias coupled NiFe/FeMn thin films make evident the MO-SNOM high sensitivity, estimated to be DeltaM ~ 2 x 10-12 emu.

La manipulation de micro et nanoparticules magnétiques et leurs applications dans les domaines de la biologie, la biodétection et du diagnostic a continuellement gagné en intérêt ces dernières années. Ce travail de thèse explore l’utilisation des propriétés magnétiques des particules en suivant deux axes distincts.Dans un premier axe, nous avons utilisé des particules magnétiques dans une analyse par biocode barre pour la capture et la concentration de cibles biologiques. La détection a été effectuée à l’aide d’un nouveau biocapteur à onde évanescente. Le but était de pouvoir procéder à un génotypage plaquettaire sans utiliser la « Polymérase Chain Reaction » (PCR), en collaboration avec l’Etablissement Français du Sang Rhône-Alpes. Nous nous sommes servis du système biallélique HPA-1 comme preuve de concept, en utilisant des cibles de type oligonucléotide synthétique pour valider nos protocoles d’analyse. Nous avons réussi à détecter une concentration de 2 fmol/l de cibles non marquées. Notre test permet de discriminer les deux allèles du gène HPA-1, qui ne diffèrent que d’un nucléotide. Notre approche par biocode barre permet d’abaisser le seuil inférieur de détection de notre biocapteur d’un facteur 125 000. Nous avons pu détecter 6.105 copies de cible synthétique, sans passer par une amplification PCR. La prochaine étape consistera à adapter le test pour analyser des échantillons biologiques réels.Dans un deuxième axe, nous avons exploré l’assemblage de particules magnétiques sous champ magnétique, de manière à fabriquer des filaments permanents ancrés sur une surface et orientables. Les filaments ont pu être greffés sur des supports homogènes de verre, d’or et sur des supports mixte verre/or fonctionnalisés de manière orthogonale. Les filaments ont pu être localisés dans des zones précises du support, soit en employant des pointes concentrant le champ magnétique localement (spots de 500 µm), soit en jouant sur la fonctionnalisation sélective sur support mixte (carrés d’or de 1 mm de côté). Typiquement l’assemblage de particules de 200 nm de diamètre a permis d’obtenir des filaments de 5 µm de longueur pour 200 à 400 nm de largeur. Les conditions de formation des filaments restent toutefois à améliorer.Les filaments magnétiques permanents ont été employés pour deux applications. Tout d’abord nous avons employé les filaments magnétiques orientables pour valider un banc d’imagerie polarimétrique par résonance de plasmon de surface (P-SPRI) développé par le LCFIO (Palaiseau). Les premières mesures tendent à montrer que l’anisotropie des filaments peut être détectée par le banc de P-SPRI, il est toutefois nécessaire de poursuivre les travaux pour mieux valider ces résultats. Deuxièmement nous avons employé des filaments magnétiques biofonctionnalisés avec des oligonucléotides sondes, pour procéder à un génotypage plaquettaire. Dans des conditions de mesure non optimisées, l’hybridation d’oligonucléotides cibles fluorescents sur les filaments ancrés sur support permet de multiplier par trois le signal de fluorescence par rapport à une hybridation sur surface plane, grâce à une augmentation de la surface spécifique du support. / Manipulation and utilization of magnetic nano/microparticles have raised some interest in the field of biology, biodetection and diagnostics during the last few years. This work explores the uses of magnetic properties of particles in two different axes.In a first part, we used magnetic particles in a bio-barcode assay for the capture and biological target concentration steps. The detection was done using a new evanescent wave biosensor. The aim was to perform a platelet genotyping without polymerase chain reaction (PCR) with the collaboration of the French national blood service (EFS). We used the biallelic system HPA-1 as proof-of-concept, using synthetic oligonucleotides as target in order to validate our protocols. The assay allows to specifically detect single nucleotide polymorphism for HPA-1 gene with a detection of 2 fmol/l of label-free target synthetic oligonucleotides. Our bio-barcode assay allows to lower the inferior limit of detection of our biosensor by a factor of 125 000. We can detect 6.105 copies of synthetic target without using a PCR amplification step. The next step will be to adapt our assay to analyze real biological samples.In a second part, we explored the assemblage of magnetic particles with a magnetic field to create permanent filaments anchored on a surface and that can be actuated. The filaments could be grafted on homogeneous glass or gold supports and also on mixed glass/gold supports with orthogonal functionalization. Filaments could be localized on precise support zones using either metallic tips concentrating locally the magnetic field (500 µm spots) or selective functionalization on mixed supports (1 mm gold squares). Assembling 200 nm diameter particles allowed to typically obtain filaments 5 µm long and 200 - 400 nm wide. The filament formation conditions could still be improved.Permanent magnetic filaments were used for two applications. Firstly, we used magnetic filaments which can be actuated to validate a polarimetric surface resonance imaging biosensor (P-SPRI) developed by the LCFIO (Palaiseau). First measurements tend to show that the anisotropy can be detected by the P-SPRI biosensor. It is necessary to continue this work to better validate the results already obtained. Secondly, we used magnetic filaments biofunctionalized by oligonucleotide probes to type platelets. In non-optimized measurement conditions, the hybridization of fluorescent target oligonucleotides on filaments anchored on a surface allows to multiply by 3 the fluorescence signal compared to hybridization on plane surface by increasing the support specific surface.

The thesis has been focused on micro method for isolation of PCR- ready DNA iusing magnetic particles from cereal products. Cereal biscuits and cereal products for babies were selected for the analysis. These were homogenized using plastic copist in lysis buffer with cetyltrimethylammonium bromide (CTAB). The homogenates were purified using chloroform- octanol mixture. The effect of isopropanol in the preparation of homogenates was tested, too. Homogenates were used for DNA isolation by magnetic particles. Two ways to isolate magnetic particles with bounded DNA (magnetic separator and magnetic needle have been tested. Isolated DNA was analyzed spectrophotometrically its concentration and purity were assessed. . After that, amplification of the DNA was tested in PCR. Two sets of primers specific for plant ribosomal DNA were used for their amplification. PCR products of expected length 700 bp and 220 bp were detected by agarose gel electrophoresis. It was shown that DNA isolated from seeds and cereal products using magnetic particles was in PCR-ready quality.

Currently, there is a growing interest in the use of probiotic products, and there are many of them in the market. With the growing interest, greater emphasis is placed on the identification of declared probiotic microorganisms. Precise identification of microbial composition is often a difficult task and it requires more advanced methods especially in the field of molecular diagnostics. The diploma thesis was focused on the verification of the presence od declared probiotic microorganisms in probiotic food supplements GS Laktobacily Forte 21, Biopron 9 Premium and Linex® Forte. DNA was isolated from the complex matrices by phenol extraction, commercial kit and magnetic carriers F79/L3-PLL in the quality suitable for PCR. Subsequently, the isolated DNA was amplified by real-time polymerase chain reaction using genus- and species-specific primers. The specific PCR product was subjected to agarose gel electrophoresis, whereas species identification was not always in compliance with the data declared by producers. The next part of the thesis was focused on polymerase chain reaction with high-resolution melting analysis to distinguish bacterial strains belonging to the Lactobacillus group and to identify probiotic microorganisms present in the complex matrices of the probiotic food supplements. Eight primer sets were tested (V1F HRM a V1R-HRM, CHAU-V3F a CHAU-V3R, CHAU-V6F a CHAU-V6R, LAC2 a LAC4, LAC1 a LAC2, P1V1 a P2V1, poxcDNAFw a poxPromRVC, poxcDNAFw a poxPromRVT). Three primer pairs (V1F HRM a V1R-HRM, poxcDNAFw a poxPromRVC, poxcDNAFw a poxPromRVT) were evaluated as the most suitable for distinguishing Lactobacillus bacterial strains.

Isolation of deoxyribonucleic acid (DNA) is an important step in the molecular diagnostics of microorganisms. A high quality of isolated DNA is necessary for DNA amplification by the polymerase chain reaction (PCR). The conventional DNA isolation using phenol chloroform extraction and DNA precipitation in ethanol is time consuming and requires the use of toxic phenol. Magnetic separation techniques using magnetic solid particles are one of modern methods to speed up the nucleic acids isolation. The aim of this work was to use two different types of magnetic particles for solidphase DNA extraction. The amounts of DNA in separation mixtures were measured using ultraviolet spectrophotometry (UV). The first experimental conditions were tested on chicken erythrocytes DNA. Phosphate buffer (pH 7, 7.6 and 8) was used for adsorption of DNA on magnetic particles. It was shown that approximately almost one half of DNA was adsorbed to the particles. The elution conditions of DNA were also optimized. Secondly, bacterial DNA was tested. This DNA eluted from the particles was in PCR ready quality. High resolution melting (HRM) curve analysis is a simple, low-cost method for amplicon discrimination and easy connection with real-time polymerase chain reaction (PCR). In this contribution, we report rapid species identification of strains belonging to the Lactobacillus group using HRM-PCR. Three different DNA isolation methods were used in this work: phenol extraction, separation using magnetic particles and commercial kit. Ten sets of targeted gene fragments primers (LAC1 – LAC2, LAC2 – LAC4, P1V1 – P2V1, Gro F – Gro R, 3BA-338f – Primer 1, V1F – V1R, CHAU - V3F – CHAU - V3R, CHAU - V6F – CHAU - V6R, poxcDNAFw – poxPromRVC, poxcDNAFw – poxPromRVT) were tested for amplification of the 16S rRNA gene. Use of GroF/R and LAC2/4 primers pairs successfully identify strains belong to the Lactobacillus group. The variance between used extraction methods for evidence of HRM curves was found.

Isolation of deoxyribonucleic acid (DNA) is an important step in the molecular diagnostics of microorganisms. A high quality of isolated DNA is necessary for DNA amplification by the polymerase chain reaction (PCR). The conventional DNA isolation using phenol-chloroform extraction and DNA precipitation in ethanol is time-consuming and requires the use of toxic phenol. Alternative method of DNA isolation is use of commercially available kits which, however, are expensive and their efficiency is low. Magnetic separation techniques using magnetic solid particles are one of modern methods to speed up the nucleic acids isolation. The aim of this work was to use two different types of magnetic particles for solid-phase DNA extraction. Magnetic microparticles P(HEMA – co – GMA) containing –NH2 group and nanoparticles PLL, whitch contains polylysine. The amounts of DNA in separation mixtures were measured using ultraviolet spectrophotometry (UV). The first experimental conditions were tested on chicken erythrocytes DNA. Phosphate buffer (pH 7, 7.6 and 8) was used for adsorption of DNA on magnetic particles. It was shown that approximately almost one half of DNA was adsorbed on the particles. The elution conditions of DNA were also optimized. Secondly, bacterial DNA was tested. After optimalization, the developed method was used for DNA isolation from real food supplements. This DNA eluted from the particles was in PCR ready quality. High resolution melting (HRM) curve analysis is a simple, low-cost method for amplicon discrimination and easy connection with real-time polymerase chain reaction (PCR). In this thesis, we report rapid species identification of strains belonging to the Lactobacillus group using HRM-PCR. Three different DNA isolation methods were used in this work: phenol extraction, separation using magnetic particles and commercial kit. Ten sets of targeted gene fragments primers (LAC1 – LAC2, LAC2 – LAC4, P1V1 – P2V1, Gro F – Gro R, 3BA-338f – Primer 1, V1F – V1R, CHAU - V3F – CHAU - V3R, CHAU - V6F – CHAU - V6R, poxcDNAFw – poxPromRVC, poxcDNAFw – poxPromRVT) were tested for amplification of the 16S rRNA gene. Use of GroF/R and LAC2/4 primers pairs successfully identify strains belong to the Lactobacillus group. The variance between used extraction methods for evidence of HRM curves was found.

The research work in this thesis has been devoted to understand the formation mechanism of single-crystalline and textured polycrystalline nanoparticles and nanoflakes of SmCo5 and Nd2Fe14B prepared by surfactant-assisted (SA) ball milling and to study their microstructural and magnetic properties. The nanoparticles and nanoflakes are promising candidates to be used as hard magnetic phase for the fabrication of high-energy-density exchange-coupled nanocomposite magnets. The influence of a range of different surfactants, solvents and milling parameters on the characteristics of ball-milled powder has been systematically investigated. Small fraction (~10 wt.%) of SmCo5 nanoparticles of average diameter 15 nm along with textured polycrystalline nanoflakes of average diameter 1 µm and average thickness of 100 nm were obtained after SA – ball milling of SmCo5 powder. Isolated single-crystalline particles (200-500 nm) and textured polycrystalline flakes (0.2-1.0 µm) of Nd2Fe14B have been prepared in bulk amount (tens of grams), after SA – ball milling of dynamic-hydrogen-disproportionation-desorption-recombination (d-HDDR) processed Nd2Fe14B powder. These single-crystalline Nd2Fe14B particles are promising for their microstructure for the fabrication of exchange-coupled nanocomposite permanent magnets. The SmCo5 and Nd2Fe14B flakes and particles were well aligned in magnetic field: the former showed [001] out-of-plane orientation while the latter showed [001] in-plane orientation. A maximum degree of texture values of 93 % and 88 % have been obtained for the magnetically-oriented SmCo5 flakes and Nd2Fe14B single-crystalline particles, respectively. SA – ball milling resulted in an increase of coercivity of SmCo5 particles from 0.45 T for un-milled powder to a maximum value of 2.3 T after 1 h of milling, further milling resulted in a decrease of the coercivity. The coercivity of SA – ball-milled Nd2Fe14B particles decreased drastically from 1.4 T for un-milled d-HDDR powder to 0.44 T after 0.5 h of milling, isolated single-crystalline particles (200-500 nm size) obtained after 4 h of SA – ball milling showed a coercivity of 0.34 T. The drastic decrease in coercivity of ball-milled Nd2Fe14B particles is attributed to the morphological change because the demagnetization in Nd2Fe14B magnets is governed by nucleation mechanism. A remarkable enhancement in coercivity from 0.26 T to 0.70 T for ethanol-milled sample and from 0.51 T to 0.71 T for oleic-acid-milled samples has been obtained after an optimum heat-treatment at 400 0C. An increase of α-Fe and Nd2O3 phase contents and a sharp change of lattice parameter c of Nd2Fe14B was observed when heat-treating above 400 0C. The change in lattice parameter at higher temperature is thought to be due to partial substitution of carbon atoms present in the surfactant or solvent, for boron atoms. / Das Ziel dieser Arbeit ist es, den Mechanismus der Herstellung von einkristallinen und texturierten polykristallinen Nanopartikeln und Nanoflakes aus SmCo5 und Nd2Fe14B durch Tensid-gestütztes Kugelmahlen zu verstehen. Des Weiteren soll deren Gefüge und magnetische Eigenschaften untersucht werden. Die Nanopartikel sind vielversprechende Kandidaten zur Verwendung als hartmagnetische Phase in hochentwickelten, austauschgekoppelten Nanokomposit-Magneten. Der Einfluß der Art der verwendeten Tensid, Lösungsmittel sowie Mahlparameter auf die Eigenschaften der kugelgemahlenen Pulver wurde systematisch untersucht. Ein kleiner Anteil (~10 m.%) von SmCo5 Nanopartikeln mit mittlerem Durchmesser von 15 nm zusammen mit texturierten polykristallinen Plättchen mit mittlerem Durchmesser von 1 µm und mittlerer Dicke von 100 nm wurden nach Tensid-gestütztes Kugelmahlen erzeugt. Alleinstehende einkristalline Partikel (200-500 nm) und texturierte polykristalline Plättchen (0,2-1,0 µm) aus Nd2Fe14B wurden in größeren Mengen (einige 10 g) hergestellt. Das verwendete Ausgangspulver wurde hierbei durch dynamisches-Hydrierung-Disproportionierung-Desorption-Rekombination (d-HDDR) hergestellt und anschließend Tensid-gestütztes Kugelmahlen. Die genannten einkristallinen Nd2Fe14B Partikel sind ebenfalls vielversprechend als hartmagnetischer Bestandteil von austauschgekoppelten Nanokomposit-Magneten. Die SmCo5- und Nd2Fe14B-Plättchen und -Partikel wurden alle in einem Magnetfeld ausgerichtet: erstere zeigten aus der Ebende herauszeigende und letztere in der Ebene liegende [001]-Orientierung. Ein maximaler Texturgrad von 93% wurde für im Magnetfeld ausgerichtete SmCo5 flakes bzw. 88% für einkristalline Nd2Fe14B Partikel erzielt. Tensid-gestütztes Kugelmahlen führte zu einem Anstieg der Koerzitivfeldstärke von SmCo5 Partikeln von 0,45 T für ungemahlenes Pulver auf 2,3 T nach einer Mahldauer von 1 h. Weiteres Mahlen führte zu einem Abfall der Koerzitivfeldstärke. Die Koerzitivfeldstärke von Tensid-gestütztes Kugelmahlen Nd2Fe14B Partikeln verringerte sich stark von 1,4 T von ungemahlenem d-HDDR Pulver auf 0,44 T nach 0,5 h Mahlen. Freistehende einkristalline Partikel (200-500 nm groß), welche nach 4 h Tensid-gestütztes Kugelmahlen erhalten wurden, zeigten eine Koerzitivfeldstärke von 0,34 T. Der starke Abfall der Koerzitivfeldstärke von gemahlenen Nd2Fe14B Partikeln wird die morphologischen Veränderungen zurückgeführt, da die Ummagnetisierung nukleationsgesteuert ist. Ein bemerkenswerter Anstieg der Koerzitivfeldstärke von 0,26 T auf 0,70 T wurde für eine in Ethanol gemahlene Probe verzeichnet, sowie ein Anstieg von 0,51 auf 0,71 T für eine Probe, welche mit einer Zugabe von Oleinsäure gemahlen wurde. Beide Proben wurden einer optimierten Wärmebehandlung bei 400°C unterzogen. Bei höheren Temperaturen wurde für Nd2Fe14B ein Anstieg der Menge an α-Fe und Nd2O3 gefunden und eine sprungartige Veränderung des Gitterparameters c der Nd2Fe14B Phase. Die Veränderung des Gitterparameters wird auf die partielle Substitution von Kohlenstoffatomen des Tensid oder Lösungsmittels gegen Boratome zurückgeführt.