Darinka Primc
@lbl.gov
Department of Chemical and Biomolecular Engineering
University of California Berkeley
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Darinka Primc, Luca Indrizzi, Elena Tervoort, Fang Xie, and Markus Niederberger
Royal Society of Chemistry (RSC)
By combining the non-classical crystallization with the nanoscale Kirkendall effect, Cu3N mesocrystals are synthesized by a surfactant-assisted method and transformed into heterostructured Cu3N–Cu2O mesocrystals and Cu2O nanocages.
Julie C. Fornaciari, Darinka Primc, Kenta Kawashima, Bryan R. Wygant, Sumit Verma, Leonardo Spanu, C. Buddie Mullins, Alexis T. Bell, and Adam Z. Weber
American Chemical Society (ACS)
Direct conversion of methane to methanol has been a long-sought objective. Partial oxidation by thermal catalysis is possible but suffers from a rapid loss in methanol selectivity with increasing m...
Hammam Al-Bustami, Guy Koplovitz, Darinka Primc, Shira Yochelis, Eyal Capua, Danny Porath, Ron Naaman, and Yossi Paltiel
Wiley
There is an increasing demand for the development of a simple Si-based universal memory device at the nanoscale that operates at high frequencies. Spin-electronics (spintronics) can, in principle, increase the efficiency of devices and allow them to operate at high frequencies. A primary challenge for reducing the dimensions of spintronic devices is the requirement for high spin currents. To overcome this problem, a new approach is presented that uses helical chiral molecules exhibiting spin-selective electron transport, which is called the chiral-induced spin selectivity (CISS) effect. Using the CISS effect, the active memory device is miniaturized for the first time from the micrometer scale to 30 nm in size, and this device presents memristor-like nonlinear logic operation at low voltages under ambient conditions and room temperature. A single nanoparticle, along with Au contacts and chiral molecules, is sufficient to function as a memory device. A single ferromagnetic nanoplatelet is used as a fixed hard magnet combined with Au contacts in which the gold contacts act as soft magnets due to the adsorbed chiral molecules.
Darinka Primc and Markus Niederberger
American Chemical Society (ACS)
The synthesis of multicomponent mesocrystals represents an emerging strategy for obtaining nanomaterials with unique functionalities as a result of combining porosity and crystallographic order. This study presents the first synthesis of multicomponent Sb–Nb:TiO2 mesocrystals (Sb-mesoNb/TO) by using a microwave-assisted nonaqueous sol–gel method. Structural and chemical analyses, carried out using various transmission electron microscopy techniques, show that Sb-mesoNb/TO are 25–35 nm in size and composed of crystallographically aligned Nb:TiO2 subunits, embedded in a porous amorphous Sb-rich scaffold (Sb-scaffold). On the basis of the characterization of the intermediate products, the formation mechanism is proposed, involving a kinetically controlled particle-based assembly process. The latter is triggered by the occurrence of the Sb-scaffold in the early reaction stages, acting as a support for heterogeneous nucleation of Nb:TiO2 subunits. Subsequently, Nb:TiO2 subunits grow and assemble in a mutual cr...
Guy Koplovitz, Darinka Primc, Oren Ben Dor, Shira Yochelis, Dvir Rotem, Danny Porath, and Yossi Paltiel
Wiley
There is an increasing demand for realizing a simple Si based universal memory device working at ambient temperatures. In principle, nonvolatile magnetic memory can operate at low power consumption and high frequencies. However, in order to compete with existing memory technology, size reduction and simplification of the used material systems are essential. In this work, the chiral‐induced spin selectivity effect is used along with 30–50 nm ferromagnetic nanoplatelets in order to realize a simple magnetic memory device. The vertical memory is Si compatible, easy to fabricate, and in principle can be scaled down to a single nanoparticle size. Results show clear dual magnetization behavior with threefold enhancement between the one and zero states. The magnetization of the device is accompanied with large avalanche like noise that is ascribed to the redistribution of current densities due to spin accumulation inducing coupling effects between the different nanoplatelets.
Darinka Primc, Mario Bärtsch, Davide Barreca, Giorgio Carraro, Chiara Maccato, Cinzia Sada, and Markus Niederberger
Royal Society of Chemistry (RSC)
Doping of TiO2 enables tailoring of the phase composition, microstructure and topography of titania–hematite photoanodes during annealing, resulting in remarkable photocurrents.
Darinka Primc, Guobo Zeng, Richard Leute, Michael Walter, Leonhard Mayrhofer, and Markus Niederberger
American Chemical Society (ACS)
Anatase TiO2 is among the most studied photocatalytic materials for solar energy conversion and environmental cleanup. However, its poor visible light absorption and high facet-dependent performance limits its utilization. In this study chemical substitution (doping) of TiO2 nanoparticles with metal ions (Sb, Cr, or Sb/Nb and Cr/Nb) is presented as an alternative strategy to address both issues simultaneously. Highly crystalline doped and codoped TiO2 nanoparticles were successfully synthesized by a microwave-assisted nonaqueous sol–gel synthesis. The structural and compositional analysis done by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) showed that depending on the doping applied, variations in particles size and morphology were observed. Doped and codoped samples showed improved absorption in the visible range and in comparison to the undoped TiO2 displayed improved photocatalytic (PC) activity. The variations of the PC ...
Irene Villa, Anna Vedda, Mauro Fasoli, Roberto Lorenzi, Niklaus Kränzlin, Felix Rechberger, Gabriele Ilari, Darinka Primc, Bodo Hattendorf, Florian J. Heiligtag,et al.
American Chemical Society (ACS)
Defect engineering operated on metal oxides by chemical and structural modifications may strongly affect properties suitable for various applications such as photoelectrochemical behavior, charge transport, and luminescence. In this work, we report the tunable optical features observed in undoped monoclinic HfO2 nanocrystals and their dependence on the structural properties of the material at the nanoscale. Transmission electron microscopy together with X-ray diffraction and surface area measurements were used to determine the fine structural modifications, in terms of crystal growth and coalescence of crystalline domains, occurring during a calcination process in the temperature range from 400 to 1000 °C. The fit of the broad optical emission into spectral components, together with time-resolved photoluminescence, allowed us to identify the dual nature of the emission at 2.5 eV, where an ultrafast defect-related intrinsic luminescence (with a decay time of a few nanoseconds) overlaps with a slower emissi...
Darinka Primc, Blaž Belec, and Darko Makovec
Springer Science and Business Media LLC
Wei Cheng, Felix Rechberger, Darinka Primc, and Markus Niederberger
Royal Society of Chemistry (RSC)
TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability.
Darko Makovec, Sašo Gyergyek, Darinka Primc, and Ivan Plantan
Elsevier BV
D. Primc and D. Makovec
Royal Society of Chemistry (RSC)
Bi-magnetic, sandwich-type, composite nanoparticles were synthesized by the topotactic growth of a shell of soft-magnetic maghemite (γ-Fe2O3) on platelet core nanoparticles of hard-magnetic barium hexaferrite (BaFe12O19) in an aqueous suspension.
Wei Cheng, Yanrui Ju, Payam Payamyar, Darinka Primc, Jingyi Rao, Christoph Willa, Dorota Koziej, and Markus Niederberger
Wiley
Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W18 O49 nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H2 at room temperature.
Aleš Štefančič, Darinka Primc, Gašper Tavčar, and Tomaž Skapin
Royal Society of Chemistry (RSC)
Fluoride aerogels, a new class of inorganic aerogels, are obtained by supercritical drying of fluoride sol/gels in MeOH-containing media.
Ana Mraković, Jovan Blanuša, Darinka Primc, Marija Perović, Zvonko Jagličić, Vladan Kusigerski, and Vojislav Spasojević
Elsevier BV
Darko Makovec, Darinka Primc, Sašo Šturm, Alojz Kodre, Darko Hanžel, and Miha Drofenik
Elsevier BV
Darinka Primc, Miha Drofenik, and Darko Makovec
Wiley
Ultrafine strontium hexaferrite (SrFe12O19) nanoparticles have been synthesized by the hydrothermal treatment of an appropriate suspension of Sr and Fe hydroxides in the presence of a large excess of OH– at temperatures between 130 and 170 °C. To avoid the parallel formation of any undesired hematite (α-Fe2O3) during the synthesis, a large excess of Sr in the starting composition (Fe/Sr = 3) had to be used. When the treatment was performed below 170 °C, ultrafine nanoparticles were formed. The TEM images show they have a disc-like shape, approximately 12 nm wide, but only around 4 nm thick. The EDS analysis showed their composition corresponded to SrFe12O19. When the temperature of the hydrothermal treatment exceeded 170 °C, larger hexagonal platelet crystals appeared as a consequence of Ostwald ripening. The evolution of the size and morphology of the nanoparticles with the temperature of the hydrothermal treatment was also monitored by XRD and measurement of the magnetic properties.
D Primc, D Makovec, D Lisjak, and M Drofenik
IOP Publishing
The hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH− results in the formation of Ba hexaferrite at temperatures as low as 150 °C. This low formation temperature enables the synthesis of uniform, ultrafine Ba hexaferrite nanoparticles. These nanoparticles have a disc-like shape, approximately 10 nm wide, but only approximately 3 nm thick. When the temperature of the hydrothermal treatment is increased, large platelet Ba hexaferrite crystals appear as a consequence of secondary re-crystallization (Ostwald ripening). In this work, this undesired process of secondary re-crystallization has been evaluated. We show that the secondary re-crystallization can be totally suppressed with the use of an oleic acid surfactant. The addition of oleic acid enabled the synthesis of uniform, ultrafine nanoparticles at temperatures up to 240 °C. The nanoparticles were hydrophobic and could be suspended in nonpolar liquids to form relatively concentrated ferrofluids. Such stable suspensions of hexaferrite nanoparticles will be technologically important, especially as precursors for the preparation of new nanostructured materials, for example nanocomposites or nanostructured ceramic films.