Fyzikální ústav Akademie věd ČR

Laboratory of preparation of optical materials and thermal analysis

Research team: Karel Nitsch, Miroslava Rodová, Antonín Cihlář, Robert Král

Scope
  • Searching for and preparation of materials - crystals, epitaxial layers, nanostructures and glasses - of high quality and purity with interesting optical properties and with their possible application in laser hosts in near IR range, as neutrons, gama and X-rays radiations detectors in industrial and medical application.
  • Preparation of model crystalline systems for luminescence mechanism study.
  • Thermal analysis study of properties of solids and glasses prepared by rapid cooling.

Research and development in the field of materials preparation
Materials studied:
  • Halides crystals - chlorides, bromides and iodides (pure and doped by transient metals and metals of rare earth) alkaline - Na, K, Rb, Cs, lead PbX2 (X - Cl, Br, I), double alkali- lead - KPb2Cl5, CsPbCl3, CsPbBr3, RbPb2Cl5, RbPb2Br5.
  • Epitaxial layers - aluminum and iron rare earth garnet.
  • Phosphate glasses - double phosphates (PO3)- of alkali metals (Li, Na, K, Cs) and metals of rare earth (Y, Ce, Gd, Pr. La) doped by (Ce, Er, Pr, Yb ...).
Experimental method:
Preparation:
  • starting materials of high purity by means of chemical methods and zone refining
  • single crystals from the melt by the Bridgman method
  • single crystals from the high temperature solutions
  • phosphate glasses
  • garnet epitaxial layers by LPE (cooperation with Dr. M. Kučera, Faculty of Mathematics and Physics, Charles University Praha)
Study and optimization of crystal growth conditions:
  • Study of molten state influence (characterized by the thermal treatment and thermal history of the melt)
  • Study of influence of growth conditions and temperature field in the furnace and in the ampoule on the crystal quality.
Characterization methods:
  • Characterization of state of the melt using electric resistance measurements
  • determination of supercooling
Research in the field of thermal analysis
  • DTA, DSC, TMATermická analýza – materials purity control, determinations of phase transitions, construction of phase diagrams, thermal properties of the glasses, crystallization study of glasses, measurement of glassy melts viscosity using penetration method.
  • Thermomicroscopy – study of glassy melts nucleation and crystallization
Laboratory equipment:
  • Zone refining
  • Bridgman crystal growth apparatuses
  • Simultaneous TG – DTA/DSC thermal analyzer (25 - 1500oC) and thermo-mechanical analyzer (25 - 1400oC)
  • Apparatus for thermo-microscopy, magnifications: 6,3 - 144 x, temperature range: -186 - +600oC.

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