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Richard Gaal

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Publications associées (51)

Ultrasensitive 1D field-effect phototransistors: CH3NH3PbI3 nanowire sensitized individual carbon nanotubes

László Forró, Richard Gaal, Bálint Náfrádi, Massimo Spina, Endre Horvath, Eric Joseph Bonvin

Field-effect phototransistors were fabricated based on individual carbon nanotubes (CNTs) sensitized by CH3NH3PbI3 nanowires (MAPbI(3)NWs). These devices represent light responsivities of R = 7.7 x 10(5) A W-1 under low-lighting conditions in the nW mm(-2) ...

2016

Quantum versus classical protons in pure and salty ice under pressure

Richard Gaal, Livia Eleonora Bove Kado

It is generally accepted that nuclear quantum effects (NQEs) trigger the transition to the nonmolecular form of ice under increasing pressure. This picture is challenged in salty ice, where Raman scattering measurements up to 130 GPa of molecular ice VII c ...

Amer Physical Soc2016

Anisotropic transport properties of tungsten disulfide

Helmuth Berger, László Forró, Richard Gaal, Bálint Náfrádi, Jacim Jacimovic, Andrea Pisoni

Single crystals of WS2 were prepared by chemical vapor transport method using sulfur as a transport agent. Measurements of electrical resistivity, Seebeck coefficient and thermal conductivity as a function of temperature, along the in-plane and the out-of- ...

Pergamon-Elsevier Science Ltd2016

Effect of salt on the H-bond symmetrization in ice

Richard Gaal, Philippe Gillet, Livia Eleonora Bove Kado

The richness of the phase diagram of water reduces drastically at very high pressures where only two molecular phases, proton-disordered ice VII and proton-ordered ice VIII, are known. Both phases transform to the centered hydrogen bond atomic phase ice X ...

National Academy of Sciences2015

Calibration of optical tweezers with non-spherical probes via high-resolution detection of Brownian motion

László Forró, Richard Gaal, Sylvia Jeney, Flavio Maurizio Mor

Optical tweezers are commonly used and powerful tools to perform force measurements on the piconewton scale and to detect nanometer-scaled displacements. However, the precision of these instruments relies to a great extent on the accuracy of the calibratio ...

Elsevier Science Bv2015

Microengineered CH3NH3PbI3 Nanowire/Graphene Phototransistor for Low-Intensity Light Detection at Room Temperature

László Forró, Richard Gaal, Arnaud Magrez, Bálint Náfrádi, Massimo Spina, Endre Horvath, Laurent Syavoch Bernard, Mario Joe Lehmann, Eric Joseph Bonvin

The first hybrid phototransistors are reported where the performance of a network of photoactive CH3NH3PbI3 nanowires is enhanced by CVD-grown monolayer graphene. These devices show responsivities as high as ≈2.6 × 106 A W- ...

2015

Nanowires of Methylammonium Lead Iodide (CH(3)NH(3)Pbl(3)) Prepared by Low Temperature Solution-Mediated Crystallization

László Forró, Richard Gaal, Massimo Spina, Endre Horvath

We report the synthesis of Methylammonium Lead Iodide (CH3NH3PbI3) nanowires by a low temperature solution processed crystallization using a simple slip-coating method. The anisotropic particle shape exhibits advantages over nanoparticles in terms of charg ...

Amer Chemical Soc2014

Ultra-Low Thermal Conductivity in Organic-Inorganic Hybrid Perovskite CH3NH3PbI3

László Forró, Richard Gaal, Jacim Jacimovic, Massimo Spina, Endre Horvath, Andrea Pisoni

We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples' morphologies indicate the minor ro ...

Amer Chemical Soc2014

Enhanced low-temperature thermoelectrical properties of BiTeCl grown by topotactic method

Helmuth Berger, Philippe Bugnon, László Forró, Richard Gaal, Arnaud Magrez, Ana Akrap, Jacim Jacimovic, Xavier François Mettan, Sergiy Katrych, Andrea Pisoni

We developed a topotactic strategy to grow BiTeCl single crystals. Structural characterization by means of X-ray diffraction was performed, and the high crystallinity of the material was proven. Measurements of the thermoelectrical coefficients electrical ...

Pergamon-Elsevier Science Ltd2014

L4Fe2As2Te1-xO4-yFy (L = Pr, Sm, Gd): A layered oxypnictide superconductor with T-c up to 45 K

László Forró, Richard Gaal, Sergiy Katrych, Janusz Andrzej Karpinski, Andrea Pisoni

The synthesis and structural and physical properties of iron lanthanide oxypnictide superconductors, L4Fe2As2Te1-xO4 (L = Pr, Sm, Gd), with transition temperature at similar to 25 K are reported. Single crystals have been grown at high pressure using the c ...

Amer Physical Soc2014

Signatures of quantum criticality in the thermopower of Ba(Fe1-xCox)(2)As-2

László Forró, Richard Gaal, Stevan Arsenijevic

We demonstrate that the thermopower (S) can be used to probe the spin fluctuations (SFs) in proximity to the quantum critical point (QCP) in Fe-based superconductors. The sensitivity of S to the entropy of charge carriers allows us to observe an increase o ...

Amer Physical Soc2013

Electrical conductivity of multi-walled carbon nanotubes-SU8 epoxy composites

László Forró, Claudio Grimaldi, Richard Gaal, Arnaud Magrez, Marijana Mionic Ebersold

We have characterized the electrical conductivity of the composite which consists of multi-walled carbon nanotubes dispersed in SU8 epoxy resin. Depending on the processing conditions of the epoxy (ranging from non-polymerized to cross-linked), we obtained ...

Amer Inst Physics2013

Tuning the length dispersion of multi-walled carbon nanotubes by ball milling

László Forró, Claudio Grimaldi, Richard Gaal, Arnaud Magrez, Marijana Mionic Ebersold, Rita Smajda, Primoz Rebernik Ribic

The statistical analysis of the length distribution of catalytic chemical vapour deposition synthesized multi-walled carbon nanotubes cut by planetary ball milling is reported. The nanotube lengths follow a log-normal distribution in a broad range of grind ...

Amer Inst Physics2013

From nanotubes to single crystals: Co doped TiO2

Helmuth Berger, László Forró, Richard Gaal, Arnaud Magrez, Bálint Náfrádi, Neda Nikseresht Ghanepour, Jacim Jacimovic, Endre Horvath

Millimeter-sized cobalt doped rutile crystals with a bi-pyramidal shape are obtained by chemical vapour transport using scroll-type H2Ti3O7 nanotubes as a precursor in which Co2+ ions are introduced by a simple ion exchange method prior to the growth. Desp ...

Amer Inst Physics2013

Pr4Fe2As2Te1-xO4: A layered FeAs-based superconductor

László Forró, Richard Gaal, Sergiy Katrych, Janusz Andrzej Karpinski, Andrea Pisoni

We report crystal growth at high pressure, structure determination, and magnetic and transport studies of an oxypnictide superconductor Pr4Fe2As2Te1-xO4. Its structure resembles the known 1111 phase except for the considerably larger c lattice constant and ...

Amer Physical Soc2013

Electrical property measurements of Cr-N codoped TiO2 epitaxial thin films grown by pulsed laser deposition

László Forró, Richard Gaal, Arnaud Magrez, Jacim Jacimovic

The temperature dependent resistivity and thermo-electric power of Cr-N codoped TiO2 were compared with that of single element N and Cr doped and undoped TiO2 using epitaxial anatase thin films grown by pulsed laser deposition on (100) LaAlO3 substrates. T ...

AIP American Institute of Physics2013

Low temperature resistivity, thermoelectricity, and power factor of Nb doped anatase TiO2

László Forró, Richard Gaal, Arnaud Magrez, Jacim Jacimovic

The resistivity of a very high quality anatase TiO2 doped with 6% of Nb was measured from 300K down to 40 mK. No sign of superconductivity was detected. Instead, a minute quantity of cation vacancies resulted in a Kondo scattering. Measurements of thermo-e ...

Amer Inst Physics2013

Carbon nanotubes-SU8 composite for flexible conductive inkjet printable applications

László Forró, Richard Gaal, Jürgen Brugger, Arnaud Magrez, Kristopher Pataky, Marijana Mionic Ebersold

We have developed a conducting composite based on multi-walled carbon nanotubes and bisphenol A novolak epoxy resin (SU8) for inkjet printing purposes. We could deposit regular conducting stripes and arrays of 150 mu m spots on glass and on flexible polyet ...

Royal Society of Chemistry2012

Defects and localization in chemically-derived graphene

László Forró, Andrzej Sienkiewicz, Richard Gaal, Arnaud Magrez, Luka Ciric, Jacim Jacimovic, George Cristian Vaju

We have performed electron spin resonance (ESR) measurements on a large assembly of graphene oxide (GO) and reduced graphene oxide (RGO) flakes. In GO samples the Curie tail is coming from 1.4 x 10(18) cm(-3) of localized spins. Although reduction of GO wa ...

Amer Physical Soc2012

Pressure dependence of the large-polaron transport in anatase TiO2 single crystals

Helmuth Berger, László Forró, Richard Gaal, Arnaud Magrez, Jacim Jacimovic, George Cristian Vaju, Radomir Zikic

We have measured the pressure and temperature dependences of the resistivity and the thermoelectric power of anatase, TiO2. The resistivity varies with T-3 at high temperatures, and its absolute value is in the 1 Omega cm range. Below 60 K, the resistivity ...

IOP Publishing - EPL Association2012

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