Tag: important

SPOTLIGHT TALK – 08/05/2024

The Warsaw Doctoral School in Natural and Biomedical Sciences and the Institute of High Pressure Physics PAS cordially invites you to a SPOTLIGHT TALK.

The talk is given by Prof. Eugen Rabkin (Department of Materials Science and Engineering, Technion – Israel Institute of Technology, 3200003 Haifa, Israel).

When and where?

8th May 2024 2024, 12:30 pm
at the IHPP PAS New Technologies Building, Al. Prymasa Tysiąclecia 98 Duration: 60 min + more

Abstract

We studied the uniaxial compression behavior of micro- and nanoparticles of several elemental metals (Au, Ni, Ag, Mo, Pt) and alloys (Ni-Co, Ni-Fe, Au-Ag, Cu-Au). The particles were obtained by solid state dewetting of thin metal films and bi-layers deposited on sapphire substrates. The high homological temperatures employed in dewetting process ensure the low concentration of dislocations and their sources in the particles. The particles compressed with a flat diamond punch exhibit purely elastic behavior up to very high values of strain approaching 10%, followed by a catastrophic plastic collapse. The uniaxial yield strength of the particles defined as an engineering stress at the point of catastrophic collapse reached the astonishing values of 34, 41 and 46 GPa for the smallest faceted particles of Ni, disordered Cu₃Au, and Mo, respectively. The atomistic molecular dynamic simulations of the particle compression demonstrated that the catastrophic plastic yielding of the particles is associated with the multiple nucleation of dislocations at the facet corners or inside the particles. The latter, homogeneous nucleation mode resulted in higher particle strength. The size effect in compression was observed both in the experiments and in atomistic simulations, with smaller particles exhibiting higher compressive strength. We discussed the stronger size effect observed in the experiment (as compared with simulations) in terms of the effect of residual defects trapped in the particles. Finally, we produced Au-Ag core-shell nanoparticles by coating the single crystalline Ag nanoparticles with a polycrystalline Au shell. The core-shell nanoparticles exhibited much lower strength than their single crystalline pure Ag counterparts. We related this decrease in strength with the active role of grain- and interphase boundaries in the polycrystalline Au shell in decreasing the energy barrier for dislocations nucleation.

SPOTLIGHT TALK – 26/04/2024

The Warsaw Doctoral School in Natural and Biomedical Sciences and the Institute of Organic Chemistry PAS cordially invites you to a SPOTLIGHT TALK.

The talk is given by Prof. Herre van der Zant (Kavli Institute of Nanoscience, Delft University of Technology, Netherlands).

When and where?

On Friday, 26th April 2024 at 10 a.m.
Aula IOC/ICP PAS, Warsaw, Kasprzaka 44/52

This event is supported by the Polish National Agency for Academic Exchange, grant no. BPI/STE/2021/1/00034/U/00001.

SPOTLIGHT TALK – 24/04/2024

The Warsaw Doctoral School in Natural and Biomedical Sciences and the Institute of High Pressure Physics PAS cordially invites you to a SPOTLIGHT TALK.

The talk is given by Prof. Eva Monroy (Quantum Photonics, Electronics and Engineering Laboratory, PHELIQS of CEA-Grenoble, France).

When and where?

24th April 2024, 13:00 pm
at the IHPP PAS New Technologies Building, Al. Prymasa Tysiąclecia 98, seminar room, 2nd floor
Duration: 60 min + more

Abstract

The COVID pandemic triggered a demand for UV lamps for disinfection, which was initially met with low-pressure mercury lamps. Presently, there is a transition towards the use of AlGaN LEDs, which are regarded as a safer and more environmentally sustainable alternative. Despite their advantages, the efficiency and cost-effectiveness of LEDs at 270 nm remain low due to several unsolved challenges, including the optimization of electrical injection. Moreover, the 250-270 nm spectral range, which corresponds to the peak efficiency for disinfection, is associated with risk of cancer and cataracts, prompting research into alternative UV sources with reduced penetration depth, notably within the 220-230 nm spectrum. In this domain, cathodoluminescent UV lamps emerge as a viable solution to obtain substantial radiant power while mitigating associated health risks.

This presentation will focus on the development of efficient UVC emitters by exploring the growth of AlGaN/AlN dots-in-a-wire structures, quantum dot superlattices, and ultrathin GaN/AlN quantum wells using plasma-assisted molecular beam epitaxy. For nanowires, we fine-tune growth conditions to ensure uniform active regions suitable for electron beam interaction. With quantum dots or wells, we optimize aluminum content and growth conditions to achieve strong emission at wavelengths below 230 nm. These nanostructures show internal quantum efficiency higher than 50% and maintain performance under varying pumping power, making them versatile for different device applications.

SPOTLIGHT TALK – 09-11/04/2024

The Warsaw Doctoral School in Natural and Biomedical Sciences and the Maria Sklodowska-Curie National Research Institute of Oncology cordially invite you to a SPOTLIGHT TALK.

The talk is presented by William James Becker, PhD (National Institute of Health, National Cancer Institute, Vaccine Branch).

When and where?

9th, 10th and 11th April 2024, 12:00 pm
at the Maria Sklodowska-Curie National Research Institute of Oncology, ul. W.K. Roentgena 5, seminar room im. Prof. Jana Steffena, 4^nd floor

Introduction to Flow Cytometry – on 9th April 2024, 12:00

Working Safely with Lab Animals – on 10th April 2024, 12:00

Second-generation checkpoint inhibitors and a cancer vaccine synergizes in preclinical models of cancer – on 11th April 2024, 12:00

SPOTLIGHT TALK – 03/04/2024

The Warsaw Doctoral School in Natural and Biomedical Sciences and the Institute of High Pressure Physics PAS cordially invites you to a SPOTLIGHT TALK.

The talk is given by Prof. Markus Winterer (Nanoparticle Process Technology, Faculty of Engineering University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany).

When and where?

3rd April 2024, 12:30 pm
at the IHPP PAS New Technologies Building, Al. Prymasa Tysiąclecia 98 Duration: 60 min + more

Abstract

Although experiments investigating the atomistic structure of disordered materials are facile today through modern instruments for (X-ray) scattering (XS) and spectroscopy (EXAFS) it is still a challenge to extract the relevant information especially in case of very small nanoparticles. In our contribution we will introduce X-ray scattering and X-ray absorption spectroscopy as tools to investigate local and crystal structure of materials and present recent advances in data analysis of this inverse problem using Reverse Monte Carlo (RMC) analysis.

RMC simulations enable the analysis of XS data as well as EXAFS spectra data via partial pair distribution (pPDF) functions obtained from a physical, structural model. In case of nanoparticles and scattering data this approach suffers from the termination of the pPDF’s due to the finite size of the particles. This produces artifacts in the computed scattering intensity due to the long-range probing distance of scattering which are eliminated by using the Debye scattering equation (DSE) for computing the scattering intensity from a particle model. Computational efficiency is provided by binning the distance distribution of atom pairs in the DSE. Simultaneous refinement of XS data and EXAFS spectra of small nanoparticles are thus enabled using a mutual structural model. This method allows the self-consistent extraction of complementary information on local structure contained in EXAFS and long-range order in XS data. We describe this novel method using XS and EXAFS data of nanocrystalline LaFeO3 and SnO2 are presented.