Melinda Majerová

Project selection:

International projects

The technologically undemanding of aluminate glasses with interested optical properties
Technologicky nenáročná príprava hlinitanových skiel so zaujímavými optickými valstnosťami
Program: Open Mobility
Duration: 1.1.2023 – 31.12.2024
Project leader: Ing. Majerová Melinda, PhD.
Annotation: The alumina-rare-earth oxide glasses with high alumina content have been reported recently to have excellent mechanical properties, especially hardness, which is comparable to that of single crystal sapphire. These glasses can be applied in transparent ballistic protection, or other applications, which at the same time require good transparency, outstanding mechanical properties, and highchemical durability. Alumina-rare-earth glasses (REAl) doped with a transition metal or lanthanide elements, such as Er, Yb or Nd, are important and promising solid-state laser materials with possible application in luminescence systems, window materials for a variety of lamps and ultimately for fiber-optic telecommunication systems, too. The advantage of these REAl glasses over crystalline aluminates is that they can bind into matrix higher content of optically active ions and thus have higher emission efficiency as crystalline aluminates.Preparation of these glasses in bulk is difficult, because Al2O3 is a reluctant glass former, which necessitates the use of highquenching rates, in some instances as high as 107 K.s-1. Special ways of preparation are therefore required. Weber et al. used containerless melting techniques to prepare Y3Al5O12 and Er3Al5O12 glasses. Containerless melting techniques with the use of an aero-acoustic levitator (AAL) or a conical nozzle levitator (CNL) were used to eliminate heterogeneous nucleation on melting container surfaces and thus to suppress crystallization on cooling [1]. But these methods are very technologically and energeticallydemanding and time consuming. McMillan et al. prepared CaO-Al2O3 glasses, containing 50 mol % Al2O3 via splat quenching technique [2]. The recent work of Rosenflanz [3] et al. describes a novel process for preparing of high alumina glasses and glass ceramics with aluminate glass matrix and dispersed nanosized crystals of rare earth aluminates, with hardness between 14.4 and 18.3 GPa and the fracture toughness between 2.1 and 4.2 MPa.m1/2. Fully dense bulk glasses were obtained by pressure-assisted sintering of glass microbeads. Glass microspheres in the system Re2O3-Al2O3 (Re = Y, La, Gd) composition were prepared by flame-spraying technique in a hydrogen-oxygen burner. Prnova et all. prepared Y2O3-Al2O3 glasses doped by Er3+ and Nd3+ ionsby combination of sol-gel Pechini method and flame synthesis in which methane-oxygen flame was used. The prepared glasses exhibit good optical properties, comparable with commercially used materials. In other work, Majerova et all prepared by combination of solid-state synthesis and flame synthesis gehlenite glasses with high alumina content, doped by different values of Bi3+ and Ni2+. The prepared glasses had very interesting optical properties compared with commercially used materials. In this project, binary aluminate glasses in system Al2O3-Yb2O3, doped by different amount of Er3+ ion and ternary Al2O3-Yb2O3-ZrO2 will be preparedby combination of sol-gel method and flame synthesis. The flame synthesis in combination with hot-pressing technique proves to be a suitable technologically and economically undemanding method for preparation of aluminate glasses will be easily applicable in practice in large-scale industrial production. Also, ytterbium-aluminate glasses are highly interesting for their potential laser applications. Another valuable benefit of this work will be, that these systems have not been prepared in large quantities and we knowrelatively little about their properties. Prepared systems will be obtained in form of glass microspheres and will be subsequently hot-press sintered and characterized by OM, SEM, XRD, HT XRD, DSC analysis. Finally, optical properties of prepared glasses will be measured by UV-VIS-NIR spectroscopy and results will be compared with commercially used materials. This project is submitted in cooperation with Belgian partner – Ghent University, because the rich experiences with solution methods and UV-VIS-NIRmeasurements optical properties of many different kinds of glasses and ceramics materials.[1] J. K. R. Weber, J. H. Abadie, A. D. Hixson, P. C. Nordine, G. A.Jerman, T. E. Mitchell, Glass Formation and Polyamorphism in Rare-earth Oxide – Aluminum Oxide Compositions, J. Am. Ceram. Soc., 83, 1868-1872, 2000[2] A. Y. Haeri, Ch. T. Ho, R.Weber, J. Diefenbacher, P. F. McMillan, Elastic properties of aluminate glasses via Brillouinspectroscopy, Journal of Non- crystalline solids, 241, 200-203, 1998.[3] A. Rosenflanz, M. Frey, B. Endres , T. Anderson, E. Richards, C. Schardt, Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides, Nature, 430, 761-764, (2004)

National projects

Ion exchange strengthened aluminosilicate glass/glass-ceramics with additional functionalities
Aluminosilikátové sklo/sklokeramika spevnené iónovou výmenou s ďalšími funkciami
Program: VEGA
Duration: 1.1.2021 – 31.12.2024
Project leader: Ing. Majerová Melinda, PhD.
Annotation: The project aims to improve the mechanical properties of glass-ceramics by ion exchange technology known mainly in connection with the strengthening of common oxide glasses (eg Gorilla glass used in mobile phones). Mechanical stresses on the surface of ion exchange strengthened ceramics doped with suitable additives will allow modification of other properties, such as optical, due to changes in the composition of the glass matrix (chemical environment of optically active additives) or deformation of the coordination polyhedra of optically active ions. The use of silver ions in ion exchange will make it possible to create glass / glass-ceramic surfaces with high durability and antibacterial properties.
SQUID magnetometry of nano- and microparticles, nanocolloids and nanostructures in new applications in the field of biomedicine and materials research associated with the development of new measurement methods and procedures
SQUID magnetometria nano-a mikročastíc, nanokoloidov a nanoštruktúr v nových aplikáciach v oblasti biomedicíny a materiálového výskumu spojených s rozvojom nových meracích metód a postupov
Program: VEGA
Duration: 1.1.2021 – 31.12.2024
Project leader: Ing. Maňka Ján, CSc.
Annotation: The theme of the project is the development of magnetic measurement methods and methodologies forbiomedicine and materials research. Its aim is to contribute to a better understanding of the following: impact of stress on iron metabolism at the systemic and cellular levels; magnetic properties of metal proteins such as transferrin, haemoglobin, and ferritin; thermal and photoluminescent properties of aluminous glasses doped with rare earth elements and transition elements; magnetic properties of high-entropy alloys, and colloids of the high-entropy alloys nanoparticles in ionic liquids – actors with a high application impact on the development of new measurement methods, instrumentation and a new generation of ecological industrial applications. The interdisciplinary character of the project is given by the studied samples and research themes.