Institute of High Pressure Physics

of the Polish Academy of Sciences

This site uses 'cookies'. Block them in your browser if needed.

Polski

Main Menu

BIP

Unipress Equipment

Education

European Projects

Local Services

Start

Publiczna obrona rozprawy doktorskiej mgr Marii Michaliny Szoły

Tuesday, 14 November 2023 19:28 |

Dnia 23 listopada 2023 r. (czwartek) o godz. 14:00 w sali seminaryjnej Instytutu Wysokich Ciśnień Polskiej Akademii Nauk w Warszawie, ul. Sokołowska 29/37, odbędzie się publiczna obrona rozprawy doktorskiej mgr Marii Michaliny Szoły.

Temat rozprawy: „THz spectroscopy of Dirac matter”

Pełna treść zawiadomienia

Rozprawa doktorska i recenzje dostępne są na stronie BIP IWC PAN

High pressure - high temperature synthesis of iron-based superconductors

Thursday, 26 October 2023 11:00 |

High pressure is known to be beneficial for enhancing the physical and magnetic properties of materials as well as improving the quality of synthesized material. The high pressure - high temperature synthesis (HP-HTS) technique developed at UNIPRESS provides a possibility to grow various kinds of materials in relatively large volumes (10-15 cm). The working principle of HP-HTS technique has been described in the recent article published by “Mohammad Azam, Manasa Manasa, Andrzej Morawski, Tomasz Cetner, and Shiv J. Singh” entitled “High Gas Pressure and High-Temperature Synthesis (HP-HTS) Technique and Its Impact on Iron-Based Superconductors” Crystals 13, 1525 (2023), Impact factor 2.7. The research team of Dr. Singh from NL-6 has studied the impact of high pressure on improvement of the superconducting properties and material quality of iron-based superconductors.

Figure: The block diagram of HP-HTS technique, presented at our institute, consisting of a three-stage oil-based compressor, high-pressure chamber (C), and a control unit monitor.

The second recenlty published paper presents a comparative study of the superconducting properties of iron-based high T_c materials by conventional synthesis process (CSP) and HP-HTS technique. This paper is published by Manasa Manasa, Mohammad Azam, Tatiana Zajarniuk, Ryszard Diduszko, Jan Mizeracki, Tomasz Cetner, Andrzej Morawski, Andrzej Wiśniewski, Shiv J. Singh, “Comparison of Gd addition effect on the superconducting properties of FeSe_0.5Te_0.5 bulks under ambient and high-pressure conditions” in Ceramics International (2023), Impact Factor: 5.2.

Figure: The variation of (a) lattice parameter ‘c’ (b) the onset transition temperature (T_c), (c) transition width (ΔT), (d) room temperature resistivity ρ_300K and (e) residual resistivity ratio RRR (ρ_300K / ρ_20K) with weight% of Gd addition for the parent FeSe_0.5Te_0.5 i.e. FeSe_0.5Te_0.5 + xGd (x = 0, 0.03, 0.05, 0.07, 0.1, and 0.2) prepared by CSP and HP-HTS

Publiczna obrona rozprawy doktorskiej mgr. Pavlo Sai

Monday, 16 October 2023 18:29 |

Dnia 27 października 2023 r. (piątek) o godz. 14:00 w sali seminaryjnej Instytutu Wysokich Ciśnień Polskiej Akademii Nauk w Warszawie, ul. Sokołowska 29/37, odbędzie się publiczna obrona rozprawy doktorskiej mgr. Pavlo Sai.

Temat rozprawy: „Terahertz plasma excitations in AlGaN/GaN nanostructures”

Pełna treść zawiadomienia

Rozprawa doktorska i recenzje dostępne są na stronie BIP IWC PAN

Interesting properties of the "dark charge" in wide InGaN/GaN wells

Wednesday, 04 October 2023 17:26 |

The strong electric field in wide InGaN/GaN wells causes spatial separation of electrons and holes in the ground state.

Fig.1 Potential profile in the In_0.17Ga_0.83N/GaN well and energy levels of electrons (blue) and holes (red). The length of the bars shows the range of the wave function at a given level. It can be seen that the lowest states of electrons and holes do not overlap, so transitions between these states are prohibited, while the higher excited states can participate in recombination (radiative and non-radiative).

The wave functions of electrons and holes in the ground states do not overlap, but they effectively shield the electric field in the well. The charge in these states is called "dark charge" (because recombination is unlikely). We can only detect the presence of a "dark charge" by its effect on light emission from excited states. The research was performed by Artem Bercha, Grzegorz Muziol, Mikolaj Chlipala and Witold Trzeciakowski from our Institute, and the results are published in the work Long-Lived Excitations in Wide (In,Ga)N/GaN Quantum Wells, PHYSICAL REVIEW APPLIED 20, 034040 (2023), demonstrating the long the lifetime of a dark charge (on the order of milliseconds), while the lifetimes in typical quantum wells are on the order of nanoseconds.

Apel o utworzenie odrębnych ministerstw Nauki i Szkolnictwa Wyższego oraz Edukacji Narodowej

Saturday, 28 October 2023 09:27 |

Dnia 23.10.2023 został podpisany Apel o utworzenie odrębnych ministerstw Nauki i Szkolnictwa Wyższego oraz Edukacji Narodowej.

Instytut Wysokich Ciśnień wyraża poparcie dla tego stanowiska.

Treść apelu:

Z całą mocą apelujemy o utworzenie odrębnych ministerstw Nauki i Szkolnictwa Wyższego oraz Edukacji Narodowej.

Utworzenie w 2021 roku jednego ministerstwa obejmującego naukę, szkolnictwo wyższe i oświatę doprowadziło do spadku znaczenia badań naukowych i obniżenia realnych nakładów przeznaczanych na ten cel. Pokazało również całkowitą odmienność mechanizmów finansowania i zarządzania edukacją szkolną względem edukacji akademickiej i nierozerwalnie z nią związanych badań naukowych.

Połączenie tych jakże ważnych dziedzin rozwoju nowoczesnego społeczeństwa w jednym resorcie nie przyniosło przewidywanych korzyści. Miało natomiast negatywny wpływ na dostosowywanie polskiego systemu szkolnictwa wyższego i nauki do dynamicznie zmieniających się stosunków społecznych w Polsce i w innych krajach europejskich oraz sprostania wyzwaniom, jakie stawia przed nauką współczesny świat.

Nauka i edukacja na poziomie wyższym stanowią fundament pomyślnego rozwoju Polski i powinny być objęte działaniem odrębnego ministerstwa. Deklarujemy jak najdalej idącą współpracę zmierzającą do utworzenia resortu nauki i szkolnictwa wyższego.

Prof. dr hab. Marcin Pałys - Przewodniczący Rady Głównej Nauki i Szkolnictwa Wyższego

Prof. dr hab. Marek Konarzewski - Prezes Polskiej Akademii Nauk

Prof. dr hab. Maciej Żylicz - Prezes Fundacji na rzecz Nauki Polskiej

Electrical Tuning of Terahertz Plasmonic Crystal Phases

Thursday, 19 October 2023 10:44 |

High-quality AlGaN/GaN grating-gate structures allowed the discovery of two distinct, electrically tunable phases in semiconductor-based plasmonic crystals. It opens new paths to cost-effective, compact, controllable devices for terahertz (THz) optoelectronics.

Research on GaN based plasmonic crystals has been reported in Physical Review X (2023), a prestigious and high-impact journal (IF 14.4). GaN-based plasmonic crystals were fully processed by our Institute collaborating with CEZAMAT, Warsaw University of Technology, where the sub-micrometer electron-beam patterning of the grating-gate electrodes of a large active area was done. The theoretical part of the work was supported by a Ukrainian theoretician team from V. Ye. Lashkaryov Institute of Semiconductor Physics in the frame of the long-term program of support of the Ukrainian research teams. Moreover, the subject is also interesting for the recently started ERC Advanced Grant, which aims on THz amplification.

The publication “Electrical Tuning of Terahertz Plasmonic Crystal Phases” P. Sai, V. V. Korotyeyev, M. Dub, M. Słowikowski, M. Filipiak, D. B. But, Y. Ivonyak, M. Sakowicz, Y. M. Lyaschuk, S. M. Kukhtaruk, G. Cywiński and W. Knap, Physical Review X 13, 041003 (2023) is an important part of the Ph.D. thesis of MSc Pavlo Sai, which defense is planned for October 27, 2023.

Figure: THz transmittance contour plot of AlGaN/GaN plasmonic crystal at different voltages applied to the grating-gate electrode. It demonstrates the transition between the delocalized phase, where THz radiation is absorbed with the entire grating-gate structure that is realized at a weakly modulated 2D electron gas regime, and the localized phase when THz radiation interacts only with the ungated portions of the plasmonic crystal.

ICNS-14 Unipress contribution

Tuesday, 10 October 2023 11:31 |

The 14th International Conference on Nitride Semiconductors (ICNS-14) will be held on November 12-17, 2023 in Fukuoka, Japan. The conference will present high-impact scientific and technological advances in materials and devices based on group-III nitride semiconductors, and feature plenary sessions, parallel topical sessions, poster sessions and an industrial exhibition.

Scientists from Unipress - Institute of High Pressure Physics Polish Academy of Sciences will present their latest results in numerous contributions: one invited lecture (Michał Boćkowski), 17 oral presentations and 17 poster presentations. We also contributed as co-authors to other research prestented during this conference. Full ICNS-14 program can be found here.

Important contribution to GaN phase diagram determination

Monday, 02 October 2023 14:46 |

Is it possible to melt GaN like other semiconductors: silicon or GaAs? What temperature and pressure is needed? Theoretical physicists from Institute of High Pressure Physics PAS made an important step towards solving this fundamental question. The results of their calculations were recently published in Chemistry of Materials (Impact factor 10.5) by J. Piechota, S. Krukowski, B. Sadovyi, P. Sadovyi, S. Porowski and I. Grzegory, in a publication entitled “Melting versus Decomposition of GaN: Ab Initio Molecular Dynamics Study and Comparison to Experimental Data” Chem. Mater. 2023, 35, 18, 7694–7707 doi: 10.1021/acs.chemmater.3c01477.

Authors determined the conditions in which the N₂ molecules are found, thus being a fingerprint of GaN decomposition, in contrast to higher pressures >15GPa at 4000K that indicate the possibility of GaN melting. Importantly the results of previous experimental work are now being confirmed by theoretical calculations which well justifies the use of the chosen method for modeling and designing difficult experiments to determine the melting curve of GaN.

More Articles...

Acknowledgements

Logos of projects donators