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Magnetic properties of R2TIn8 and related tetragonal compounds
Čermák, Petr ; Javorský, Pavel (advisor) ; Isnard, Olivier (referee) ; Honda, Fuminori (referee)
Title: Magnetic properties of R2TIn8 and related tetragonal compounds Author: Petr Čermák Department / Institute: Department of Condensed Matter Physics Supervisor of the doctoral thesis: doc. Mgr. Pavel Javorský, Dr., Department of Condensed Matter Physics Abstract: Intermetallic compounds R2TIn8 (R = rare earth, T = transition metal), commonly called "218" because of stoichiometry, are structurally related to a class of well- known Ce-based heavy-fermions like CeCoIn5 or CeRhIn5. They are located between fully 3D cubic compound (e.g. CeIn3) and quasi-2D "115" superconductors, which makes them ideal candidates to study structural dimensionality effects on various properties. Recent developments in this field showed that it is possible to grow compounds with T = Pd or Pt with "218" stoichiometry. Therefore further study of "218" compounds is desired since much less is known about them compared to "115" compounds. We have focused mainly on the determination of magnetic structures and crystal field effects along the series of Rh based "218" compounds for various rare-earth elements. The single crystals of compounds with R = Nd, Tb, Dy, Ho, Er, Tm, La, Lu, Y were successfully grown. Results of bulk measurements (specific heat, susceptibility) together with magnetic structures determined from several neutron...
Magnetic properties of R2TIn8 and related tetragonal compounds
Čermák, Petr ; Javorský, Pavel (advisor) ; Isnard, Olivier (referee) ; Honda, Fuminori (referee)
Title: Magnetic properties of R2TIn8 and related tetragonal compounds Author: Petr Čermák Department / Institute: Department of Condensed Matter Physics Supervisor of the doctoral thesis: doc. Mgr. Pavel Javorský, Dr., Department of Condensed Matter Physics Abstract: Intermetallic compounds R2TIn8 (R = rare earth, T = transition metal), commonly called "218" because of stoichiometry, are structurally related to a class of well- known Ce-based heavy-fermions like CeCoIn5 or CeRhIn5. They are located between fully 3D cubic compound (e.g. CeIn3) and quasi-2D "115" superconductors, which makes them ideal candidates to study structural dimensionality effects on various properties. Recent developments in this field showed that it is possible to grow compounds with T = Pd or Pt with "218" stoichiometry. Therefore further study of "218" compounds is desired since much less is known about them compared to "115" compounds. We have focused mainly on the determination of magnetic structures and crystal field effects along the series of Rh based "218" compounds for various rare-earth elements. The single crystals of compounds with R = Nd, Tb, Dy, Ho, Er, Tm, La, Lu, Y were successfully grown. Results of bulk measurements (specific heat, susceptibility) together with magnetic structures determined from several neutron...
Matematické modelování růstu krystalů
Blechta, Jan ; Hron, Jaroslav (advisor) ; Souček, Ondřej (referee)
We present a numerical model of Bridgman crystal growth. Pseudo-incompressibility constraint is used to handle jumps in density during phase change. ALE formulation is employed to account for moving parts of the system. Field equations and movement of material interfaces are decoupled in fractional step manner. Naviér-Stokes problem is extended to solid phase where no flow is enforced by Darcy-like forcing. Latent heat of phase change is added to effective heat capacity as approximate Dirac-$\delta$. Backward Euler discretization in space and P2/P1/P1 in space are used. Transient and stationary solutions are being found and compared to temperatures measured directly inside a steady system. Influence of pull-rates on growth process and shape of phase interface are being examined. Powered by TCPDF (www.tcpdf.org)
Growth of InP crystals for radiation detectors and other application
Pekárek, Ladislav ; Yatskiv, Roman
Bulk InP single crystals were grown by Czochralski method. Various dopants were added to the melt to obtain single crystals suitable for radiation detectors and other application. The intentionally doped of InP crystals were characterized by measurements of resistivity and Hall coefficient. Prototype detectors were prepared and evaluated by spectral detection of alpha particles and x-rays.
Růst krystalů InP pro detektory záření a jiné použití
Pekárek, Ladislav ; Yatskiv, Roman
Bulk InP single crystals were grown by Czochralski method. Various dopants were added to the melt to obtain single crystals suitable for radiation detectors and other application. The intentionally doped of InP crystals were characterized by measurements of resistivity and Hall coefficient. Prototype detectors were prepared and evaluated by spectral detection of alpha particles and x-rays.
Crystal growth
Nitsch, Karel
Crystal growth is based on the atomistic approach initially formulated by Volmer, Kossel and Stranski, which describes the growth in terms of attachment of growth units at a crystal surface
Problémy krystalizace slitin na bázi B2-FeAl
Kopeček, Jaromír ; Jurek, Karel ; Šíma, Vladimír ; Lejček, Pavel
Although the main source of the grain boundary weakness in FeAl arises from environmental embrittlement, important source seems to be of the intrinsic nature. The single crystals prepared by Bridgman method contain the star cracks when grown with growth rates higher than 9 mm/h. At lower growth rates the stress induced by solidification is not high enough to cause crack initiation.
Detektory rtg a částicového záření na bázi indium fosfidu
Pekárek, Ladislav ; Žďánský, Karel
Indium phospide single crystals were grown by Czochralski method. Various dopants were added to the melt to obtain semi-insulating crystals suitable for detection purposes. Prototype detectors were prepared and evaluated by spectral detection of alpha particles and x-rays.
Preparation and properties of pyroelectric detectors for optoelectronic applications /III/
Novotný, Jan ; Zelinka, Jiří ; Podvalová, Zdislava ; Malina, Václav ; Vávra, Vladimír ; Franc, J. ; Fronc, Václav ; Fronc, Václav
The single crystals of TGS doped with Pt-ions and with L-alanine were grown as in ferroelectric phase as the full-shaped crystals. The growth rate along the axis c of the doped crystals is much higher than in an undoped one. Morphology, domain structure and hysteresis loops were investgated. The effect of the dopant on the growth velocity is explained on the basis of catalytic action of platinum complexes. The pyroelectric detectors were prepared from these materials and their parameters are presented.
Technology LATGS/PtIV single crystal for high sensitivity infrared detectors
Novotný, Jan ; Franc, J. ; Zelinka, Jiří
Single crystals of TGS doped with Pt/IV/ and L-alanin were grown from aqueous solutions. Surface morphology, domain structure and P-E hysteresis loops have been investigated. We have found that LATSGS/Pt/IV/ crystals are excellent materials for construction of infrared detectors.

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