Postgraduate study programme

• Homogenization processes in glass preparation by melting

Supervisor: Prof. Ing. Lubomír Němec, DrSc.
Supervisor specialist: Doc.Ing. Jaroslav Kloužek, CSc.
The glass preparation from crystalline raw materials involves several processes which form a homogeneous glass melt from the arising mixture of melt, undissolved particles and bubbles. The kinetics of the dissolution and separation (bubble removal) processes in the stage of melt affects substantially the energy consumption and melting performance of the glass melting spaces. The significant factors of enhancement of the dissolution processes are the natural and forced convection of the melt whereas the application of an additive force as the centrifugal force, e.g., accelerates the bubble separation from the melt. The important role of process topology in the continuous melting space is described by a new relative quantity called utilisation of the space. The space utilisation can be significantly affected by the character of the melt flow in the space. The topic applies the mathematical modelling of dissolution and separation processes in the melting spaces in order to define the optimal conditions and design of the glass melting spaces.

• Heavy metal oxide glasses

Supervisor: Doc. Ing. Jaroslav Kloužek, CSc.
Supervisor specialist: Ing. Petr Kostka, Ph.D.
The glass network of heavy metal oxide glasses is formed by oxides such as TeO₂, GeO₂ or Sb₂O₃ instead of SiO₂. These glasses stand out in comparison with conventional glasses particularly by wide interval of transparency ranging up to much longer wavelengths, lower phonon energies, higher refractive index, outstanding nonlinear properties, high solubility of rare-earth ions accompanied by high quantum yield of radiative transition etc. The work will focus on the preparation and characterization of new materials – glasses – containing antimony and/or bismuth oxides. Characterization of the prepared materials will include their basic properties such as density, molar volume, thermal stability, chemical resistance, hardness, optical transmission, refractive index, etc. Correlation between structural units forming the glass network and the resulting properties will be investigated and the influence of processing conditions during glass preparation on these properties will be evaluated.

• Chalcogenide glasses and optical fibres

Supervisor: Doc. Ing. Jaroslav Kloužek, CSc.
Supervisor specialist: Ing. Petr Kostka, Ph.D.
Glass network of chalcogenide glasses is formed by S, Se or Te in combination with metals and/or semimetals. The presence of oxygen in these materials is usually undesirable. Real applications of this type of glass are conditioned mainly by high purity of the prepared or manufactured materials. Procedures for preparing high-purity chalcogenide glasses allowing for their use in fiber optics, already exist. The work will include the preparation of chalcogenide glasses, optimization of their composition, dotation of materials by rare earth ions and examination of the relationship between the vitreous matrix and the dopant. It is also possible to focus some of the efforts on new technological procedures for further material purification. The subsequent step will be to prepare preforms for optical fibres drawing, including the processing of structured preforms for drawing optical microstructured fibres (photonic crystal fibres) and characterization of prepared fibres.
 

• Modeling of new glass melting spaces

Supervisor: Prof. Ing. Lubomír Němec, DrSc.
Supervisor specialist: Ing. Marcela Jebavá, Ph.D.
The new glass melting spaces are focused on the considerable decrease of the specific energy consumption joint with CO₂ reducement and with high specific melting performance. Besides the phenomena kinetics, a great attention has to be paid to the utilisation of the space for the given phenomenon and to phenomena ordering. The objective of the work is to apply the new melting principles and mathematically model the melting spaces which fulfil the present energetic and efficiency requirements.