Systematic control of α-Fe₂O₃ crystal growth direction for improved electrochemical performance of lithium-ion battery anodes

• Nan Shen,
• Miriam Keppeler,
• Barbara Stiaszny,
• Holger Hain,
• Filippo Maglia and
• Madhavi Srinivasan

Beilstein J. Nanotechnol. 2017, 8, 2032–2044, doi:10.3762/bjnano.8.204

• reaction, leading to finely dispersed metal nanocrystals in a Li2O matrix. This process is associated with large volume changes and also exhibits irreversible phase transformation (from a hexagonal anionic packing to a cubic phase [11]) that causes a poor long-time cycling behavior with severe capacity

• electrochemical performance in LIBs [17]. Also, ethylenediamine is used in the hydrothermal synthesis of α-Fe2O3 nanoparticles, leading to a shuttle-like nanorod morphology [27]. Diamines increase the pH of the reaction mixture, supporting the phase transformation of FeOOH to α-Fe2O3. In addition, diamines form

• SCA but using NaOH(aq) to adjust the pH value for the phase transformation of FeOOH to α-Fe2O3 were also conducted. These approaches result in micrometer-sized particles without a periodically repeating unit in the nanometer regime. Figure 2a illustrates the XRD patterns of samples obtained from a

Formation of ferromagnetic molecular thin films from blends by annealing

• Peter Robaschik,
• Ye Ma,
• Salahud Din and
• Sandrine Heutz

Beilstein J. Nanotechnol. 2017, 8, 1469–1475, doi:10.3762/bjnano.8.146

• the β-MnPc films generated from the blended film. To further investigate the phase transformation we have conducted FTIR spectroscopy measurements (Figure 3b) on the same films deposited on KBr substrates. The ν(C≡N) stretching peaks of TCNQ for the as-deposited blended film can be found at 2185 and

• . However, for the MnPc:TCNQ blended film that was annealed without cover it seems that both phthalocyanine and TCNQ molecules sublime. Furthermore, for the covered sample, one peak of the γ(C–H) out-of-plane deformation of the MnPc ligand shows a shift from 728 to 724 cm−1 and can be attributed to phase

• transformation to the β-phase [25]. We believe that the successful crystallisation of the β-phase MnPc at lower temperatures compared to the α→β phase transition thanks to the blending with sacrificial TCNQ molecules is due to two main factors. Firstly, the presence of TCNQ hinders crystallisation of the MnPc

Structural properties and thermal stability of cobalt- and chromium-doped α-MnO₂ nanorods

• Romana Cerc Korošec,
• Polona Umek,
• Alexandre Gloter,
• Jana Padežnik Gomilšek and
• Peter Bukovec

Beilstein J. Nanotechnol. 2017, 8, 1032–1042, doi:10.3762/bjnano.8.104

• [18]. In cryptomelane, the phase transformation MnO2→Mn2O3 is limited to a maximal temperature of 800–900 °C, indicating that K+ ions enhance the structural stability [17]. This is of great importance in some applications where local overheating could cause structural changes. In some cases, doped

3D Nanoprinting via laser-assisted electron beam induced deposition: growth kinetics, enhanced purity, and electrical resistivity

• Brett B. Lewis,
• Robert Winkler,
• Xiahan Sang,
• Pushpa R. Pudasaini,
• Michael G. Stanford,
• Harald Plank,
• Raymond R. Unocic,
• Jason D. Fowlkes and
• Philip D. Rack

Beilstein J. Nanotechnol. 2017, 8, 801–812, doi:10.3762/bjnano.8.83

• resemble that of amorphous carbon [68]. Following the laser treatment, the characteristic π* and σ* peaks have sharper spectral features, indicating that the carbon has been transformed from amorphous to graphitic. The laser treatment thus induces C phase transformation from amorphous to graphite, which is

Diffusion and surface alloying of gradient nanostructured metals

• Zhenbo Wang and
• Ke Lu

Beilstein J. Nanotechnol. 2017, 8, 547–560, doi:10.3762/bjnano.8.59

• interfaces in the nanostructured layer make it possible to study interfacial diffusion and relative characteristics, such as interfacial structure, precipitation, phase transformation, plastic deformation, and chemical reaction, at lower temperatures. In comparison, it is difficult to obtain enough

• . The following process at T2 enhanced the growth (or phase transformation) kinetics of alloyed layers because the thermal stability in the surface layers was improved by the introduced alloying elements and/or compounds during the previous process. The effects of both processes at T1 and at T2 on the

Formation and shape-control of hierarchical cobalt nanostructures using quaternary ammonium salts in aqueous media

• Ruchi Deshmukh,
• Anurag Mehra and
• Rochish Thaokar

Beilstein J. Nanotechnol. 2017, 8, 494–505, doi:10.3762/bjnano.8.53

• because of exposure to ambient atmosphere during the sample preparation process. The samples were further subjected to a controlled heat-treatment in nitrogen environment at 50 °C and 350 °C (below the phase-transformation temperature of cobalt) [38]. Figure 6e shows an increased intensity of the

Annealing-induced recovery of indents in thin Au(Fe) bilayer films

• Anna Kosinova,
• Ruth Schwaiger,
• Leonid Klinger and
• Eugen Rabkin

Beilstein J. Nanotechnol. 2016, 7, 2088–2099, doi:10.3762/bjnano.7.199

• indents by mechanical polishing. The mechanism of the hillock formation upon heating is in that case related to the martensite–austenite phase transformation, which is affected by residual stress and very different from the irreversible mechanisms discussed in the present study. Conclusion From the

Microwave synthesis of high-quality and uniform 4 nm ZnFe₂O₄ nanocrystals for application in energy storage and nanomagnetics

• Christian Suchomski,
• Ben Breitung,
• Ralf Witte,
• Michael Knapp,
• Sondes Bauer,
• Tilo Baumbach,
• Christian Reitz and
• Torsten Brezesinski

Beilstein J. Nanotechnol. 2016, 7, 1350–1360, doi:10.3762/bjnano.7.126

• peak (II) in the potential range from 1.2 to 1.0 V corresponds to the formation of Li0.9ZnFe2O4. The sharp peak (III) at 0.98 V (first plateau in Figure 8a) indicates the phase transformation from spinel to rock-salt-type ZnxFeyO due to decomposition of LixZnFe2O4 (with x ≈ 1.5). However, we note that

Influence of synthesis conditions on microstructure and phase transformations of annealed Sr₂FeMoO_6−x nanopowders formed by the citrate–gel method

• Marta Yarmolich,
• Nikolai Kalanda,
• Sergey Demyanov,
• Herman Terryn,
• Jon Ustarroz,
• Maksim Silibin and
• Gennadii Gorokh

Beilstein J. Nanotechnol. 2016, 7, 1202–1207, doi:10.3762/bjnano.7.111

• nm and a superstructural ordering of iron and molybdenum cations of 88%. Keywords: magnetic materials; microstructure; nanoparticles; phase transformation; sol–gel preparation; Introduction Due to their unique and extremely important magneto-transport and magnetic properties [1][2], metal oxide

• , independent of the pH of the initial solutions. It can be seen that the synthesis of the solid solution of strontium ferromolybdate proceeds through a number of parallel chemical reactions that leads to several phase transformation processes. It can be seen in the XRD data presented in Figure 2 that during

• the SrMoO4 intermediate phase and to reach 100% of Sr2FeMoO6−x phase transformation, the temperature should be raised up to T = 1060 K and held at this temperature for 1 h. The final Sr2FeMoO6−x synthesis should be carried out at T = 1120 K for 4 h – precisely in these conditions, a single-phase

Orientation of FePt nanoparticles on top of a-SiO₂/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

• Martin Schilling,
• Paul Ziemann,
• Zaoli Zhang,
• Johannes Biskupek,
• Ute Kaiser and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2016, 7, 591–604, doi:10.3762/bjnano.7.52

• of the {110} ring in FePt is a direct proof for chemical order in the L10 phase we conclude that most of the particles were transformed from the A1 into the L10 phase by annealing at 630 °C for 45 min, while the previous step at 570 °C for 60 min was not sufficient to trigger the phase transformation

Surfactant-controlled composition and crystal structure of manganese(II) sulfide nanocrystals prepared by solvothermal synthesis

• Elena Capetti,
• Anna M. Ferretti,
• Vladimiro Dal Santo and
• Alessandro Ponti

Beilstein J. Nanotechnol. 2015, 6, 2319–2329, doi:10.3762/bjnano.6.238

• stemming from a β-MnS core, whereas 30 nm α-MnS cubes were obtained at 180 °C [19]. A more detailed investigation gave similar results for the reaction of manganese(II) chloride and thioacetamide in oleylamine, confirming the key role of temperature [26]. These authors also described the β→α and γ→α phase

• transformation of MnS NCs subject to high pressure. The formation of α- vs γ-MnS NCs was also shown to depend on the heating rate (15 °C/min: α-MnS; 25 and 35 °C/min: γ-MnS) when manganese(II) diethyldithiocarbamate was heated in octadecene at 320 °C in the presence of a large excess of both oleic acid and

Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries

• Luc Aymard,
• Yassine Oumellal and
• Jean-Pierre Bonnet

Beilstein J. Nanotechnol. 2015, 6, 1821–1839, doi:10.3762/bjnano.6.186

• . For instance, theMg2CoH5 lattice parameters a and c rise until x = 1 (from 4.4940(3) to 4.517(2) Å and from 6.582(1) to 6.608(1) Å, respectively; a cell volume expansion of 1.44%), evoking a phase transformation. For Mg2NiH4 the lattice parameter c decreases from 6.538(1) to 6.477(2) Å, which is

• concomitant with a phase transformation involving a low-hydrogen-content hydride for x ≤ 3: Mg2NiH4 → Mg2NiH [23][24]. The reaction mechanism can therefore be summarized as follows: The reaction with Mg2FeH6 during the conversion process with lithium ions is the first example for the production of an

Two-phase equilibrium states in individual Cu–Ni nanoparticles: size, depletion and hysteresis effects

• Aram S. Shirinyan

Beilstein J. Nanotechnol. 2015, 6, 1811–1820, doi:10.3762/bjnano.6.185

• .6.185 Abstract In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase

• first-order phase transformations which start from a new phase nucleation (nucleation energy barrier) and it should be taken into account. Size effects in multicomponent nanomaterials, where the first-order phase transformation starts from a nucleation and includes a change of composition of chemical

• the condition of the energy minimum are constructed and the difference between the equilibrium and solubility curves is explained. The concluding remarks are given in last part of the manuscript. Theory: thermodynamic approach for phase transformation Surface-induced size effect Let us first briefly

Self-assembly of nanostructures and nanomaterials

• Isabelle Berbezier and
• Maurizio De Crescenzi

Beilstein J. Nanotechnol. 2015, 6, 1397–1398, doi:10.3762/bjnano.6.144

• , strain, thickness, phase transformation, structural changes) and results from the interaction between different factors (e.g., deposit/substrate, liquid/gas/solid phases, crystals). Besides these intrinsic parameters, a number of extrinsic factors, including thermal treatment, chemical and

Thermal treatment of magnetite nanoparticles

• Beata Kalska-Szostko,
• Urszula Wykowska,
• Dariusz Satula and
• Per Nordblad

Beilstein J. Nanotechnol. 2015, 6, 1385–1396, doi:10.3762/bjnano.6.143

• assumed that phase transformation in nano-granular systems occurs from 200 to 600 °C with different contribution from both oxides, γ-Fe2O3 and α-Fe2O3 [20]. It should also be underlined that the data regarding the behavior of nanosystems at elevated temperatures are very different and generalizations

• particles heated at the highest temperature no doublet is seen, which can be the effect of the thermal phase transformation between Fe oxides. The spectra consist of a sextet with a relatively wide line at half maximum, which is connected with the overlapping of the magnetite, maghemite and hematite

Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

• Valentin S. Teodorescu,
• Cornel Ghica,
• Adrian V. Maraloiu,
• Mihai Vlaicu,
• Andrei Kuncser,
• Magdalena L. Ciurea,
• Ionel Stavarache,
• Ana M. Lepadatu,
• Nicu D. Scarisoreanu,
• Andreea Andrei,
• Valentin Ion and
• Maria Dinescu

Beilstein J. Nanotechnol. 2015, 6, 893–900, doi:10.3762/bjnano.6.92

• crystallization, surface nanostructuring, phase transformation and modification of physical properties of thin films. Here we show the effects of nanostructuring produced at the surface and under the surface of amorphous GeTiO films through laser pulses using fluences of 10–30 mJ/cm2. The GeTiO films were

• ], phase transformation and modification of physical properties of thin films [13][14][15][16]. The laser fluence values used for these applications are below the ablation threshold of the irradiated material in order to prevent a loss of material during laser processing. The absorption length of

Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

• Matthias Augustin,
• Daniela Fenske,
• Ingo Bardenhagen,
• Anne Westphal,
• Martin Knipper,
• Thorsten Plaggenborg,
• Joanna Kolny-Olesiak and
• Jürgen Parisi

Beilstein J. Nanotechnol. 2015, 6, 47–59, doi:10.3762/bjnano.6.6

• different nanostructured MnOx species via one calcination process. This is advantageous for the investigation of the properties of the manganese oxides, as it rules out any synthesis-caused effects. The temperature- as well as the time-dependent phase transformation processes occurring during the oxidation

• attributed this Mn3O4/Mn5O8 phase transformation to a one-phase mechanism for Mn3O4 particles exhibiting BET surface areas of more than 10 m2/g. That is, the small particle diameters provide sufficient reaction sites for oxidation of the surface of the particles. Feitknecht also reported similar reflection

• °C. However, this is probably due to an additional time dependence of the phase transformation of Mn5O8 to α-Mn2O3, which was also suggested by Dimesso et al. [28]. In their report the α-Mn2O3 phase was observed to be the minor species second to Mn5O8 after calcination at 400 °C in air for 1 h, but

Size-dependent density of zirconia nanoparticles

• Agnieszka Opalinska,
• Iwona Malka,
• Wojciech Dzwolak,
• Tadeusz Chudoba,
• Adam Presz and
• Witold Lojkowski

Beilstein J. Nanotechnol. 2015, 6, 27–35, doi:10.3762/bjnano.6.4

• stability of the surface layers in contrast to bulk materials, where a phase transformation would occur under the given conditions [33]. ZrO2 samples were prepared in the presence of D2O and subsequently dried in vacuum at 25 °C or at 800 °C, followed by immersion in H2O for 60 min. A comparison of the FTIR

Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

• D. J. Lockwood,
• N. L. Rowell,
• A. Benkouider,
• A. Ronda,
• L. Favre and
• I. Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2498–2504, doi:10.3762/bjnano.5.259

• dioxide prevents further metal ion reduction. Since the gold salt reduction process is not possible on SiO2, the reaction immediately stops after the formation of SiO2 [30]. After the selective galvanic deposition of gold clusters on the substrate, the samples were loaded into the MBE chamber. The phase

• transformation from the small Au nanoclusters located within the SiO2-cover-free nanopits to the Au0.18Si0.82 eutectic alloy is obtained by thermal annealing at 550 °C for 30 min. The annealing and growth experiments were performed in the MBE growth chamber of a Riber SIVA32 system with a base pressure of 10−11

Cathode lens spectromicroscopy: methodology and applications

• T. O. Menteş,
• G. Zamborlini,
• A. Sala and
• A. Locatelli

Beilstein J. Nanotechnol. 2014, 5, 1873–1886, doi:10.3762/bjnano.5.198

• direction. By cooling the sample from growth to room temperature, a phase transformation occurs in the graphene film, which develops neighboring phases characterized by flat and buckled morphology. Adjacent striped-shaped domains of different carbon surface density alternate on the film at microscopic

• density of C adatom gas on the Au layer readily condense to form graphene islands. Upon subsequent cooling to room temperature, the morphology and structure of graphene remain unchanged. In fact, we could not detect any evidence of phase transformation or formation of stripe-shaped domains resembling

Growth evolution and phase transition from chalcocite to digenite in nanocrystalline copper sulfide: Morphological, optical and electrical properties

• Priscilla Vasthi Quintana-Ramirez,
• Ma. Concepción Arenas-Arrocena,
• José Santos-Cruz,
• Marina Vega-González,
• Omar Martínez-Alvarez,
• Víctor Manuel Castaño-Meneses,
• Laura Susana Acosta-Torres and
• Javier de la Fuente-Hernández

Beilstein J. Nanotechnol. 2014, 5, 1542–1552, doi:10.3762/bjnano.5.166

• for 100% intensity in the XRD pattern). From TEM images, it can be observed that the phase transformation occurs from 220 to 260 °C and involves three stages: the nucleation, the shape evolution of the chalcocite crystals and the transition of the chalcocite to the digenite phase. Nanoparticles are

• predominant at 230 °C while nanodisks and prisms are the main morphology at 240 °C. A full phase transition from chalcocite to digenite is obtained at 260 °C. Wang et al. obtained nanodisks of chalcocite Cu2S at 220 °C [15]. But, in our case, this temperature is the first stage to the phase transformation

• tailoring of the Cu/S stoichiometric ratio and the phase transformation had been reached at temperatures between 230 to 700 °C [21]. Grozdanov and Najdoski found that the electrical sheet resistance decreases as the copper content decreased [25]. This is consistent with our results. Conclusion Copper

Synthesis, characterization, and growth simulations of Cu–Pt bimetallic nanoclusters

• Subarna Khanal,
• Ana Spitale,
• Nabraj Bhattarai,
• Daniel Bahena,
• J. Jesus Velazquez-Salazar,
• Sergio Mejía-Rosales,
• Marcelo M. Mariscal and
• Miguel José-Yacaman

Beilstein J. Nanotechnol. 2014, 5, 1371–1379, doi:10.3762/bjnano.5.150

• and ethanol were used as received without further purification. Preparation of Cu–Pt bimetallic nanoclusters In a first step, the H2PtCl6·xH2O metal ions were transferred into a toluene solution by a phase transformation process. An aqueous solution of 30 mM of 5 mL Pt precursor was mixed with a 60 mM

Nanoscale particles in technological processes of beneficiation

• Sergey I. Popel,
• Vitaly V. Adushkin and
• Anatoly P. Golub'

Beilstein J. Nanotechnol. 2014, 5, 458–465, doi:10.3762/bjnano.5.53

• dominate over those of thermal conductivity. Since the vapor temperature is significantly higher than that of the liquid and the phase equilibrium is violated, it is necessary to take into account the heat exchange between vapor and liquid due to phase transformation. Furthermore, imperfection of dense gas

• of the wave of phase transformation. Furthermore, since the convective transport dominates over thermal conductivity, the convective flows of mass, momentum and energy are conserved when passing the Knudsen layer under the condition of the violation of the phase equilibrium. The structure of the

• to the value of 3100 K, which is 1.4 times higher than the corresponding value obtained under the assumptions of the model in [8][9][10][11], which takes into account adiabatic compression of the vapor but does not take into account the phase transformation liquid–vapor. Thus the model described in

Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

• Annalena Wolff,
• Walid Hetaba,
• Marco Wißbrock,
• Stefan Löffler,
• Nadine Mill,
• Katrin Eckstädt,
• Axel Dreyer,
• Inga Ennen,
• Norbert Sewald,
• Peter Schattschneider and
• Andreas Hütten

Beilstein J. Nanotechnol. 2014, 5, 210–218, doi:10.3762/bjnano.5.23

• . The experiments show that during this aggregation process, a phase transformation towards the stoichiometric Co2FeO4 phase occurs. Such phase transformations have been discussed previously [12]. The lack of literature concerning the more cobalt-rich ferrite phase currently prevents a more detailed

• mesocrystals remain after the aggregation of primary building blocks can be explained by the starting composition. Before the secondary particle is formed, a phase transformation from the iron-rich phase to cobalt-rich phase takes place. The initial starting composition is richer in iron though, while the

Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

• Xiaoxing Ke,
• Carla Bittencourt,
• Sara Bals and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2013, 4, 77–86, doi:10.3762/bjnano.4.9

• -temperature phase transformation is also obtained by using low-energy electron irradiation [44]. Another alternative to improve the crystallinity of as-deposited nanostructures is to use higher energy electron irradiation in TEM, with 200 kV electrons used to remove the amorphous carbon [32]. In this context