Section Oxides & Fluorides

Section Oxides & Fluorides


The section specializes in the bulk growth of oxide and fluoride single crystals. Such crystals are used as substrates for ferroelectric and oxide electronic applications as well as optical, piezoelectric, or laser components. We also prepare reference and benchmark samples to enable studies on the properties of materials with highest structural perfection and purity. Through collaborations and service to companies and research institutions we provide the materials basis for many research projects inside and outside IKZ.

Research activities

In our section, we develop single crystal substrates of oxide semiconductors such as β-Ga2O3. We prepare oxide crystals with perovskite structure as lattice-matched substrates e.g. for strained ferroelectric layers or thin films comprising new functionalities. We research tailored oxide and fluoride crystals for optical applications and lasers. And we provide thermochemical analysis and develop tailored growth techniques to enable crystal growth of novel compounds.


Junior Research Group "Fluoride Crystals for Photonic Applications"

Fluoride single crystals are key components for a variety of photonics applications such as laser materials, high power optical isolators, as well as nonlinear frequency converters and optical windows with superior properties in the deep-UV region. Fluoride compounds can overcome the current limitation in handling power of optical isolators. They are also very promising for solid state laser cooling (optical refrigeration), a technique enabling to cool down solid materials to cryogenic temperature by laser excitation.

The Junior Research Group is particularly engaged in melt growth of high-quality fluoride single crystals doped with rare-earth ions for laser cooling. Main challenges are to mitigate formation of foreign phases and color centers and to minimize oxygen contamination and internal strain. Fluorination of raw materials helps to prepare highest purity crystals. The application-relevant properties of grown crystals are demonstrated in collaboration with the IKZ Center for Laser Materials.

Stefan Püschel, Felix Mauerhoff, Christian Kränkel, Hiroki Tanaka
Laser cooling in Yb:KY3F10: a comparison with Yb:YLF (Link zu DOI: 10.1364/OE.472633)
DOI: 10.1364/OE.472633

Stefan Püschel, Felix Mauerhoff, Christian Kränkel, Hiroki. Tanaka
Solid-state laser cooling in Yb:CaF2 and Yb:SrF2 by anti-Stokes fluorescence
Opt. Lett. 47 (2022) 333–336
DOI: 10.1364/OL.449115

Stefan Püschel, Sascha Kalusniak, Christian Kränkel, Hiroki Tanaka
Temperature-dependent radiative lifetime of Yb:YLF: refined cross sections and potential for laser cooling
Opt. Express 29, (2021) 11106–11120
DOI: 10.1364/OE.422535

Dr. Hiroki Tanaka

Dr. Hiroki Tanaka

Ph. +49 30 6392 2821

Single Crystals of Oxide Semiconductors

We manufacture transparent conducting or semiconducting oxide single crystals. The topic is primarily known from our pioneering work on 2" β-Ga2O3 single crystals (Czochralski method), and other binary oxides (In2O3, SnO2). In recent years, we have developed gallium based spinels (MgGa2O4, ZnGa2O4, CoGa2O4), barium stannate (BaSnO3) and lanthanum indate (LaInO3). As substrates and thin films, these crystals enable new device structures in power electronics, optoelectronics, for sensors and ferrimagnetic thin layers, and as scintillator material.


The growth of these crystals is hampered by the tendency to decompose at high temperatures near the melting point. We therefore use novel and proprietary methods and technologies (e.g. dynamic gas atmospheres) to increase compound and growth stability to enable large crystal volumes. A special focus is on the control and characterization of the electrical and optical properties in dependence on growth, doping and annealing conditions.

Zbigniew Galazka
Transparent Semiconducting Oxides - Bulk Crystal Growth and Fundamental Properties
ISBN 9789814800945; Jenny Stanford Publishing, 2020

Zbigniew Galazka
Growth of bulk β-Ga2O3 single crystals by the Czochralski method
J. Appl. Phys. 131 (2022) 031103
DOI: 10.1063/5.0076962

Zbigniew Galazka, Steffen Ganschow, Palvan Seyidov, Klaus Irmscher, Mike Pietsch, Ta-Shun Chou, Saud Bin Anooz, Raimund Grueneberg, Andreas Popp, Andrea Dittmar, Albert Kwasniewski, Manuela Suendermann, Detlef Klimm, Thomas Straubinger, Thomas Schroeder, Matthias Bickermann
2 Inch Diameter, Highly Conducting Bulk β-Ga2O3 Single Crystals Grown by the Czochralski Method for High Power Switching Devices
Appl. Phys. Lett. 120 (2022) 152101
DOI: 10.1063/5.0086996

Zbigniew Galazka, Andreas Fiedler, Andreas Popp, Steffen Ganschow, Albert Kwasniewski, Palvan Seyidov, Mike Pietsch, Andrea Dittmar, Saud Bin Anooz, Klaus Irmscher, Manuela Suendermann, Detlef Klimm, Ta-Shun Chou, Jana Rehm, Thomas Schroeder, Matthias Bickermann
Bulk Single Crystals and Physical Properties of ß-(AlxGa1-x)2O3 (x = 0- 0.35) Grown by the Czochralski Method
J. Appl. Phys. 133 (2023) 035702
 DOI: 10.1063/5.0131285

Dr. Zbigniew Galazka

Dr. Zbigniew Galazka

Ph. +49 30 6392 3020

Substrate Crystals for Advanced Functional Oxides

Our primary focus is to develop new bulk crystals with tailored lattice parameters, mainly with perovskite, pyrochlore or magnetoplumbite structure. As substrates, such crystals serve as the literal foundation for the preparation of epitaxially grown oxide thin films with interesting ferroelectric, superconducting, ferromagnetic, piezoelectric, multiferroic, or electron transport properties. Some of the bulk crystals are attractive for optical applications as well. Most of the compounds are exclusively grown at IKZ for our academic and industrial research partners.

The growth temperature is typically in the range between 1500°C and 3000°C. Depending on the material properties at such high temperatures and the requirements on structural quality and purity, the crystals are grown by crucible-based or crucible-free methods from the melt or from melt fluxes. Insufficient heat transport, internal strain in the crystals and crucible stability are critical issues that must be carefully controlled. The crystals are investigated by their structural quality and chemical composition.

Christo Guguschev, Carsten Richter, Mario Brützam, Kaspars Dadzis, Christian Hirschle, Thorsten M. Gesing, Michael Schulze, Albert Kwasniewski, Jürgen Schreuer, Darrell G. Schlom
Revisiting the Growth of Large (Mg,Zr):SrGa12O19 Single Crystals: Core Formation and Its Impact on Structural Homogeneity Revealed by Correlative X-ray Imaging
Crystal Growth & Design 22 (2022) 2557–2568
DOI: 10.1021/acs.cgd.2c00030

Christo Guguschev, Detlef Klimm, Mario Brützam, Thorsten M. Gesing, Mathias Gogolin, Hanjong Paik, Andrea Dittmar, Vincent J. Fratello, Darrell G. Schlom
Single crystal growth and characterization of Ba2ScNbO6 – A novel substrate for BaSnO3 films
J. Crystal Growth 528 (2019) 125263
DOI: 10.1016/j.jcrysgro.2019.125263

Christo Guguschev, Julia Hidde, Thorsten M. Gesing, Mathias Gogolin, Detlef Klimm
Czochralski growth and characterization of TbxGd1−xScO3 and TbxDy1−xScO3 solid-solution single crystals
CrystEngComm 20 (2018) 2868–2876
DOI: 10.1039/C8CE00335A

Dr. Christo Guguschev

Dr. Christo Guguschev

Ph. +49 30 6392 3124

Crystals for Benchmarking and Service

Individual single crystals are demanded as benchmark and reference materials in different fields of science, e.g. geology, materials science, solid-state chemistry and physics. They are used by research institutions, companies and technology ventures for detailed investigation, to demonstrate their application potential or to assess conditions for a commercial production. If the required material falls within our range of capabilities and is not commercially available, we can prepare and provide it.

We have expertise in crystal growth for a number of different compounds and provide crystals with highest quality and purity. While our core area of research is melt growth at high temperatures, we can employ a variety of growth approaches and techniques. In-house characterization provides a thorough assessment of the crystals’ properties. Depending on the target and effort of the research, we can operate by joint development agreement, full-cost accounting or scientific collaboration.

Florian Flatscher, Martin Philipp, Steffen Ganschow, Martin R. Wilkening, Daniel Rettenwander
The natural critical current density limit for Li7La3Zr2O12 garnets
Journal of Materials Chemistry A 8, 15782-15788 (2020)
DOI: 10.1039/c9ta14177d

Maki Hamada, Steffen Ganschow, Detlef Klimm, George Serghiou , Hans-Josef Reichmann, Matthias Bickermann
Wüstite (Fe1-xO)  – Thermodynamics and crystal growth
Z. Naturforschung B 77 (2022) 463–468
DOI: 10.1515/znb-2022-0071

Claudia Kofahl, Lars Dörrer, Brendan Muscutt, Simone Sanna, Stepan Hurskyy, Uliana Yakhnevych, Yuriy Suhak, Holger Fritze, Steffen Ganschow, and Harald Schmidt
Li self-diffusion and ion conductivity in congruent LiNbO3 and LiTaO3 single crystals
Phys. Rev. Materials 7 (2023) 033403
DOI: 10.1103/PhysRevMaterials.7.033403

Dr. Zbigniew Galazka

Dr. Steffen Ganschow

Ph. +49 30 6392 3024

Thermochemische Analyse und Phasendiagramme

We use thermochemical analysis to determine how a particular material can be best grown as a single crystal with desired properties. Incongurent melting, material decomposition, or metal oxidation state instability are common problems that can be mitigated by establishing proper phase diagrams. We optimise source material compositions for the respective growth methods and suggest the optimal growth atmosphere. With our expertise we also support the other IKZ activities regarding their process technologies.

The optimal crystal growth conditions are found by determining the phase diagram of binary or ternary systems with Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) in oxidising, reducing or inert atmospheres up to 2400 °C. DTA analysis can be supplemented with evolved gas analysis using a quadrupole mass-spectrometer. Additionally, we employ X-ray diffraction, thermal conductivity (laser-flash) measurements and provide thermodynamic calculations.

Detlef Klimm, Bartosz Szczefanowicz, Nora Wolff, Matthias Bickermann
Phase diagram studies for the growth of (Mg,Zr):SrGa12O12 crystals
Journal of Thermal Analysis and Calorimetry 147 (2022) 7133–7139
DOI: 10.1007/s10973-021-11050-4

Detlef Klimm, Binderiya Amgalan, Steffen Ganschow, Albert Kwasniewski, Zbigniew Galazka, Matthias Bickermann
The Thermal Conductivity Tensor of β-Ga2O3 from 300 to 1275 K
Cryst. Res. Technol. 58 (2023) 2200204
DOI: 10.1002/crat.202200204

Nora Wolff, Detlef Klimm, Klaus Habicht, Katharina Fritsch
Crystal growth and thermodynamic investigation of Bi2M2+O4 (M = Pd, Cu)
CrystEngComm 23 (2021) 3230-3239
DOI: 10.1039/d1ce00220a


Dr. Roberts Blukis

Ph. +49 30 6392 3145