Research projects

The semiconductors based on ZnO doped by magnetic impurities belong to a new class of advanced materials, dilute magnetic semiconductors, which have recently received much experimental and theoretical attention as a suitable spin source for spintronic applications. Some of the highly doped wide band gap materials like (Zn,Mn)O reveal a ferromagnetic like behavior near and above room temperature, which is considered as a major criterium for spintronic applications. The present project focuses on material and technological aspects of transition metal (TM) and rare earth (RE) doped ZnO thin films fabricated by metalorganic chemical vapor deposition (MOCVD) technique. The TM and RE elements will be incorporated either by ion implantation followed by annealing or by in-situ MOCVD using MO precursors as TM sources. The corresponding bulk materials will be prepared by ceramic route or as single crystals. The sythetized materials will be chemically and structurally characterized and their magnetic and electric transport properties will be thoroughly examined. The thermodynamic and electronic structure calculations will be used as auxiliary tools to model the MOCVD process and to interpret the physical properties.

Nanostructures for optics and photonics will be deposited in crystals and amorphous materials using ion implantation, which offers a many possibilities of the functional devices preparation. We will focus on a more detailed study of single crystal materials and glasses implanted by metal and light ions. The combination of appropriate substrate and implanted ion enables us to prepare materials with the desired properties (optical, electrical). Our intention is to define relation between the nano-particles morphology and the optical properties (band gap, photoluminescence), structural changes and dopant positioning in the host matrix. Energetic ions modifying solid materials will be used for the fundamental study of stopping powers of ions in solid compounds and simultaneously will be provided validation of semi-empirical models used in simulation. The simulations and knowledge of empirical stopping powers are irreplaceable in nanostructure synthesis using ion implantation. Measurement of ion stopping in compounds will be realized using transmission and backscattering ion beam methods.

The research focused on graphene and other 2D materials is in the forefront of materials science. The proposed project addresses the investigation of graphene based materials (graphene and its composites with transition metal dichalcogenides) interaction with ion beams. The ion beam irradiation depending on the used ion beam parameters induces formation of defects, structural disorder and introduction of dopants. Only few works have been published on the proposed topic so far; however, most of the unusual properties of 2D materials like exotic  ferromagnetism, anomalously high electrical and thermal conductivity or electrocatalytic activity are associated with this phenomenon. The project will be focused on ion beam irradiation of various graphene forms, such as bulk powder, assembled papers and CVD deposited layers. In addition, the composites of graphene with transition metal dichalcogenides in the form of papers and CVD layers will be investigated.

Silicate glass is one of the most important and widely spread technical materials. It is frequently used in the applications where it is exposed to the particle radiations of different energies. Therefore, it is very important to study the changes in glass caused by the radiation both from technical applications point of view (changes in glass properties) as well as from point of view of glass science (changes in glass structure).The project will perform a systematic investigation of changes in glass structure and properties caused by electrons irradiation in different energy ranges from about 3 keV up to MeV's and by proton irradiation (MeV). The compositional changes and inhomogeneities on the micron scale will be characterized by EPMA. Evolution of structural changes will be studied by XPS, NMR, and Raman spectroscopy. Surface topographies will be characterized by AFM and SEM. Moreover, the molecular dynamics simulations will be used as a theoretical tool for the interpretation of the experimental findings. Chemical durability of glass irradiated with electrons/protons will be established and nanoindentation methods will be used for the characterization of mechanical properties. Expected results may enhance the applicability of glass and improve its limiting properties.

The interactions between metals and polymers will be studied using complementary analytical techniques on different metal-polymer and metal-polymer-metal systems. The research is of interest from the fundamental point of view and for broad practical utilization of metal coated polymers in analytical chemistry, electronics, food packaging etc. The specimens will be prepared by sputtering or vacuum deposition of 10-100 nm thick layers of different metals Au, Ag, Pd and Pt on various polymers PET, PMMA, PE and PTFE. The structure characterization will be provided using profilometer, TEM, AAS spectroscopy, RBS, ERD). The electrical resistance and magnetic properties will be measured. Nanointendenter device will be used for the determination of the layers adhesion. The layer morphology will be studied using AFM and SEM. Ion implantation and ion assisted mixing of metal particles and polymer structure will be used for composite preparation. For mobility and diffusion study of metals in polymer substrate RBS, XPS will be used.

Complex investigations of point defects in ZnO are proposed in the present project. Positron annihilation spectroscopy (PAS) including also variable energy PAS using slow positron beam will be used as a principal technique for defect studies. State-of-art ab-initio theoretical calculations will be employed for interpretation of PAS data. Defects in ZnO single crystals will be compared with those in epitaxial and nanocrystalline ZnO thin films. Defects studies will be combined with electrical (temperature-dependent Hall effect, deep level transient spectroscopy) and optical (photoluminescence, optical transmission) measurements in order to find a link between predominant defect configurations and specific electrical and optical properties of ZnO samples. Moreover, in the present project we intend to investigate interaction of hydrogen and nitrogen with point defects in ZnO and influence hydrogen and nitrogen on electrical and optical properties. A new UHV chamber for on-line sputtering of ZnO films will be constructed and connected to slow positron beam. This novel setup enables to perform variable energy PAS investigations of thin ZnO films in-situ during film deposition. It gives us an exclusive possibility to investigate formation of defects and incorporation of impurities into ZnO lattice during film growth.

Main aim of the project is the characterization of the structures based on LiTaO3, single crystal SrTiO3, BaTiO3 and KTaO3 doped Pb, Mg materials using ion beam analysis. Crystalline structures investigated in this research are very promising for the preparation of planar lasers or are applicable in microelectronics - high permittivity materials. The dopant depth profiles, stoichiometry of crystalline structures will be measured by RBS, ERDA and PIXE.The positions of the interstitial dopants in doped crystals and the crystal modification under the used  deposition technologies can be determined by the innovative analytical technique (RBS-channeling) and the crystal lattice changes will be studied by comparative method XRD in collaboration with Forschungzentrum Rossendorf. The important part will be the study of superlattice structures and their interfaces using RBS-channeling. The results of the above mentioned analyses will be confronted with properties of the prepared structures.

This project, aiming at preparation of novel micro- and nano-structured materials and systems, their modification by radiation and other techniques, their characterization by full arsenal of diagnostic methods available at participant laboratories, and the study of their chemical, physico-chemical and bio-properties, is inherently multidisciplinary and its goals cannot be achieved under standard research financing. Cooperation of 4 participants will lead to strong synergetic effect on common research. Attention will be paid to systems with potential application in medicine, tissue engineering, microelectronics, optoelectronics and sensor construction and further to processes of diffusion, aggregation, self-organization, material degradation by irradiation, interaction of cells with new materials and effects of radiation on biological objects (e.g. living cells). Nuclear analytical techniques will be used in material and biomedical and environmental research. The project will involve master and PhD students, who will asquire partical experience in multidisciplinary research.

The materials doped by erbium ions are currently used for optical signal amplification or generation. Important factors influencing the luminescence properties of a lasing ion is the surounding crystal field. In this project we would like to use the ion-implantation technique followed by subsequent annealing as a useful way to influence the crystal field of implanted ion in LiNbO₃, ZnO and special glasses.

This project continue in previous projects SPIRIT no. 117 (2011) and RITA No. 025646 (2007-2009)  .

The NMI3 project falls within the activity 'Research Infrastructures' of the EU 7th Framework programme. The Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy (NMI3) brings together 18 partners from 12 countries, including 8 research infrastructures, together with other interested organisations (see overview on the web).

NPL is funded as one of the partners within the NMI3 program of FP7. Therefore, within its Access activities,  we are able to support our users from EU member countries and associated states (see the list), except those from Czech Republic, by the reimbursement of travel and subsistence expenses.

For more information on user access to the NPL experimental facilities, see this page.