Projects funded by the Research Council of Lithuania
Structural phases and dynamic effects in novel hybrid perovskite materials for future solar cells
Project implementer – Vilnius University
Project supervisor – prof. Robertas Grigalaitis
Budget – 150 000 Eur.
Duration – 2019-2022;
In the past few years, organic-inorganic hybrid perovskite methylammonium lead halides CH3NH3PbX3 (X = I, Br, Cl) have attracted huge interest as materials for effective and affordable third generation solar cell devices. The power conversion efficiency of cells containing these hybrid compounds is already above 20%, and arises from the combined interplay of several physical factors such as large absorption coefficient, suitable bandgap, long carrier diffusion length, low exciton binding energy and exceptional defect tolerance. The organic-inorganic perovskite films can be fabricated by simple wet chemistry methods in a non-evacuated ambient environment, thus considerably lowering solar cell manufacturing costs. Perovskite structure is also highly prominent for tuning material properties by full or partial substitution of elements at the respective sites of these compounds. Therefore, intense investigations are ongoing in this field in search of even more effective and stable materials and optimal solar cell architectures. As most of such studies involve layered hybrid perovskite structures and complete solar cell element characterizations, it is usually stressed that unambiguous interpretation of obtained results is challenging as bulk properties of the hybrid perovskites (including defect physics, ferroelectricity, exciton dissociation processes, carrier recombination, screening of charged defects, etc.) are still not well established.
During this project, for the first time a comprehensive study of a broadband dielectric response, structural phase transitions and molecular cation dynamics in single phase and novel mixed hybrid perovskite crystals will be performed. The systematic study will allow to determine the nature, stability and microscopic mechanisms of the structural phase transitions in novel halide based hybrid perovskites which are intended to revolutionize the green-energy sector.
Investigation and optimization of cutting-edge lead-free PMUT platform: from materials to devices
Project implementer – Vilnius University
Project supervisor – dr. Šarūnas Svirskas
Budget – 225 000 USD.
Duration – 2020-2023.
The project entitled “Investigation and optimization of cutting-edge lead-free PMUT platform: from materials to devices” is devoted to developing a new prototype lead-free piezoelectric micromachined ultrasonic transducer (PMUT) platform, which could be further used in future environmentally friendly systems and applications. The project involves synthesis and characterization of state-of-the-art lead-free materials, application-oriented optimization of material properties, thin film fabrication on flexible substrates, creation of PMUT prototypes and validation of their performance. For successful project implementation consortium of three members is formed with very different complementary fields of expertise. Project partners of Taiwan are experts in the applications of piezoelectric material for actuators and transducers, PMUT simulation and prototyping. Scientists from Institute of Solid State Physics, University of Latvia (Latvia) have strong background in solid state sintering of lead-free materials with potentially attractive piezoelectric properties. Lithuanian scientists of Vilnius University, Faculty of Physics (Lithuania) are leading experts in broadband dielectric spectroscopy, piezoelectric and acoustic research and characterization of ferroelectrics and related materials. The synergy of such versatile consortium gives opportunities to strongly influence the development and application of lead-free materials in a larger scale.
The aim of this project is to drive lead-free materials towards wide use in PMUT which can be attractive to various biological and other demanding applications. By applying different kinds of production techniques (PLD, tape-casting) it is expected to extend the application of lead-free materials and demonstrate novel PMUT devices.
Development of specialized unmanned aerial vehicle for detection and neutralization of unmanned aerial vehicles
Project implementer – Vilnius University
Project partners - Space Science and Technology Institute, UAB "Žvelk aukščiau"
Project supervisor – Dr. Saulius Rudys
Budget – 700 000 Eur.
Project duration – 2018 January 8 - 2022 January 7.
Aim of the project: development of effective (more effective than is available in this moment) solution for unmanned aerial vehicle detection and neutralizing.
Technologies of Unmanned Aerial Vehicles (UAVs) are developing especially rapidly these days. Field of implementation of UAVs is extremely wide – from consumer type to the complex scientific and military implementations. Unfortunately same as other technologies UAVs can be both beneficial and dangerous for the society. UAVs that fly into the manned air traffic zones, carrying illegal payloads (like drugs) or used as terrorist tools are especially dangerous. UAV technologies are developing much faster than the means for their control. There are many solutions for UAV detection and neutralization suggested worldwide, nonetheless all of these solutions have many drawbacks. Essential problem in UAV detection is that they are small (often confused with the birds), may emit low noise and electromagnetic radiation, reflect little of the radar signals. Means for neutralization are normally ground based and are of limited range. There are tendencies to use other UAVs for neutralization (thus increasing the range of operation), nonetheless in this case there are problems in detection, target approaching and UAV control at rapid changing environment. Therefore, for this moment there are no effective UAV detection and neutralizing technologies available. The main goal of the project – develop an effective (more effective than is available in this moment) solution for UAV detection and neutralizing. This will be achieved by transferring radar, optical and other detection and neutralization means and technologies directly to the “hunter” UAV, which will be intended to search, detect and neutralize potentially harmful UAVs. The possibility of implementation of low cost consumer radars into the UAV will be researched, thus decreasing the total cost of the system. The main challenge of the project – implement radar on the fixed wing aircraft (UAV) with payload of 25-50 kg, develop reliable hostile UAVs detection and tracking algorithms, ensure reliable signal transmission in complex electromagnetic environment, ensure
Projects funded by the Agency for Science, Innovation and Technology
Large directivity source for 250 GHz radation
Project implementer – Vilniaus universitetas
Project Supervisor – dr. Kęstutis Ikamas
Budget – 100 000 Eur.
Project duration – 2020-2021 m.
The terahertz (THz) frequency domain is characterized by a wide variety of phenomena and can be used in a many fields, such as: materials science, security technology, wireless communications. THz systems are not yet widely used due to the complexity, cost, and operating costs of existing technologies. This situation is likely to change as modern silicon electronics manufacturing technologies enable the development of monolithic microwave integrated circuits that already exceed the lower limit of the THz frequency range.
Research on the application of silicon electronics for THz frequencies has been carried out at the Institute of Applied Electrodynamics and Telecommunications since 2013. The results of the implemented projects (VP1-3.1-ŠMM-07-K-03-040, S-LAT-17-3) are chips with 88GHz oscillators and frequency multiplication and emitting 250GHz. The MITA TPP project aimed to develop a point-to-point 250 GHz radiation source corresponding to the sixth TRL stage.
NATO programme "Science for Peace"
Globular carbon based structures and metamaterials for enhanced electromagnetic protection
Project Implementer – Vilniaus universitetas
Project supervisor – dr. Jan Macutkevič
Budget – 400 000 Eur.
CERTAIN is focused on the development of innovative security-related technologies such as data protection through the production of metasurfaces with enhanced electromagnetic properties: microwave absorption and frequency dispersion, allowing effective guiding and trapping of high-frequency signals. The main goal of the project is to design and implement a new type of artificial magneto-electric materials as a basis for novel applications in radio frequency (RF) and microwave technology. These metasurfaces will be based on the metamaterial approach and will combine the advantages of both electric and magnetic properties in carbon-based magnetic globular structures, leading to multifunctional 2D-structures and to the concept of electromagnetic perfect absorber or wave concentrator.
Postdoctoral research fellowship
Compositional disorder in barium titanate: lattice dynamics and nuclear magnetic resonance study
Projekto No. 09.3.3-LMTK-712-19- 0052
Project duration - 2020-08-24 - 2022-08-23
Fellow: Šarūnas Svirskas
Supervisor: prof. Vytautas Balevičius
Barium titanate (BTO) was the first inorganic ferroelectric to be discovered. It has been investigated for more than 50 years but it is still relevant to the technologies nowadays. Exceptional physical properties made this material irreplaceable in the production of multilayered ceramic capacitors.
The lattice of BTO can be easily modified with various substituents. This feature makes BTO very attractive for novel applications. The different functionalities (i. e. ionic conductivity, piezoelectric effect) can be enhanced by different substituent ions. Thus, this material can be implemented in very important fields such as medicine or telecommunications. Unfortunately, the lack of knowledge about the states of substituents limits the applicability of compositionally disordered BTO. The frustrated dipolar interactions in BTO differ from other disordered perovskite oxides. The local displacement and disorder affects the macroscopic properties of BTO. The key to the applications is the understanding of these local phenomena.
The project aims to investigate the influence of rare-earth and transition metal ions to the macroscopic properties of BTO. By implementing advanced spectroscopic techniques (Raman, FTIR, dielectric and NMR spectroscopies) the properties of multiple compositionally disordered BTO systems will be investigated. These experiments will reveal the properties relevant to the applications and local processes occurring in the material. Such unique experimental studies can lead to the further outbreak in the field.
Unsintered multiferroic composites based on phosphate ceramic matrices: preparation and investigation
Projekto No. 09.3.3-LMTK-712-19- 0146
Duration: 2020-09-01 - 2022-08-31
Fellow: dr. Artyom Plyushch
Supervisor: prof. Robertas Grigalaitis
The aim of this project is to produce multiferroic phosphate matrix-based composites with ferroelectric and ferromagnetic inclusions, study their electric and magnetic properties and to evaluate their potential for practical applications. The technology for the production of the unsintered phosphate ceramics will allow the production of both bulk and sandwich (layered) multiferroic composites without the use of high-temperature synthesis, this allows to avoid the reactions between ferroelectric and ferromagnetic phases. The internship in foreign science centres is planned. The new skills of the magneto-electric effect measurement methods will be learned, the skills of the ceramics synthesis will be improved.
Lithuanian-Swiss Cooperation Programme
Broadband impedance study of memristor oxide films
Laboratory of Solid State Ionics has received funding from Lithuanian-Swiss cooperation programme to reduce economic and social disparities within the enlarged European Union under project agreement No CH-3-ŠMM-02/06.
Name of the project: Broadband impedance study of memristor oxide films
Project acronym: BISMOF
Beginning of project: 1 January 2016
Project ends: 30 September 2016
Total budget: 151 229 EUR 24 cnt.
This project is executed by VILNIUS UNIVERSITY (project leader T. Šalkus) and EIDGENÖSSISCHE TECHNISCHE HOCHSCHULE ZÜRICH (prof. J.L.M. Rupp).
Summary of the project
The project is devoted to the production of oxide thin films by PLD method and their detailed analysis by impedance spectroscopy. The project will be implemented by four secondments of Lithuanian researchers to Switzerland, where they, under supervision of Swiss partners, will produce strontium titanate and gadolinium doped ceria thin films and prepare the electrodes for electrical characterization. The impedance spectroscopy measurements will be performed in Lithuania with the modified broadband impedance spectrometer at high frequencies up to 10 GHz.
The films can find a potential application in the new generation memory elements, the so called memristors. The understanding of physical reasons for memristor element switching is the main aim of the project. Besides, the training of Vilnius University group researchers to work with PLD system and film characterization in Switzerland will be beneficial for Lithuanian scientists. The final discussion of the results will be in Vilnius during the common scientific seminar at the end of the project.
Achievements
Strontium titanate (STO) and ceria gadolinia (CGO) thin films were grown by PLD method in Switzerland. Platinum electrodes of a special geometry were formed by using photolithography. The films with the applied electrodes behave as memristors.
Memristor prototype produced during the current project (on the right hand side) compared to a standard 1.6 mm SMD resistor.
Further on the electrical properties were investigated. The film response to the triangular-shape voltage change in time shows memristive behaviour, hence their I-V curves have a hysteresis.
Cyclic voltammetry curves of CGO film. Blue poits show voltage increase and red points - voltage decrease. The profiles are typical for memristors.
The impedance spectroscopy investigation at high frequencies on oxygen solid electrolyte films was performed for the first time. A semicircle was observed in the complex plane plot of impedance, and it is related to oxygen ion relaxation process in the film. Temperature dependences of CGO film conductivity was deduced from impedance spectra. Arrhenius graph (logarithm of conductivity vs. inverse temperature) shows similar conductivity values compared to the bulk conductivity of ceramics with the same chemical composition.
Impedance spectrum in complex plane plot of the CGO thin film (on the left hand side) and temperature dependence of its conductivity (on the right hand side).
Conclusions
Lithuanian scientists learned the technological conditions of STO and CGO thin film growth by PLD.
Individual STO and CGO thin film samples have been produced, and they were suitable for high frequency impedance spectroscopy investigation.
Cyclic voltammetry results on STO and GDC thin films with crossbar electrode configuration showed memristor behaviour.
High frequency impedance spectrometer has been modified, allowing usage of DC bias when measuring impedance.
Relaxation type electrical parameter dispersion was observed in CGO thin film impedance spectra. The conductivity of CGO film was nearly identical to the conductivity of ceramics bulk.
Swiss-Lithuanian Ferroelectrics: From controlled internal fields to energy harvesting / medical diagnostics / microelectronic applications.
Laboratory of Microwave Spectroscopy has received funding from Lithuanian-Swiss cooperation programme to reduce economic and social disparities within the enlarged European Union under project agreement No CH-3-ŠMM-01/02.
Project acronym: SLIFE.
Project started on 1st Dec 2012, ends on 31st March 2016. Total budget: 2,488,955 LTL
This project is executed by three parties: Vilnius University (J. Banys), Kaunas University of Technology (R. Kažys) and Ecole Polytechnique Fédérale de Lausanne (N. Setter).
Summary of the project:
Ferroelectrics are ubiquitous materials in modern technology with substantial interest in further extending their functionality in components of medical-diagnostic equipment (using the piezoelectric effect), microelectronics and communications (ferroelectric switching and dielectric properties), and energy harvesting (piezo-, pyroelectric, and photovoltaic effects).
Ferroelectricity is the property of some polar materials to undergo polarization reorientation when subjected to external electric field. Real ferroelectric materials have internal electric fields due to finite size, charged defects, and inhomogeneities in the material. This is even more pronounced in thin films. These inevitable fields are often considered a hurdle, typically causing degradation of properties.
Several recent studies showed strongly enhanced properties (piezoelectric, dielectric, photovoltaic) originating from internal fields, hinting that internal fields could be beneficial if properly addressed. This triggers us to propose the present project, in which, leveraging on our complementary competences, we aim to better understand internal fields in ferroelectrics and use them to obtain enhanced functionality.
The following program is planned: Ferroelectric films will be prepared in Lausanne and Vilnius and crystals will be purchased. Internal fields will be introduced into the films by dopants, substrate and electrode choice, and growth protocols. Special poling procedures will be applied on both single crystals and thin films and studied (Lausanne, Vilnius, Kaunas). Characterization will be done in Lausanne (local characterization by advanced scanning force techniques and detailed electrical / photoelectrical measurements coupled with theory and modelling), Vilnius (dielectric spectroscopy / pyro- and piezoelectric characterization), and Kaunas (piezoelectric, in particular ultrasonic characterization). Demonstrators will be prepared in Lausanne (photovoltaics), Vilnius (tunable dielectrics) and Kaunas (piezoelectrics) using the new materials developed during the project and based on the new insights developed in-concert by the three partners.