Wolfgang Jeitschko, 27.05.1936--05.08.2020

Friends and colleagues mourn the loss of Professor Wolfgang Jeitschko, who passed away on August 5th, 2020. Death caught him by surprise during his daily afternoon nap. The solid state and materials chemistry community have lost an outstanding scientist. We honor the memory of Wolfgang.

Wolfgang Jeitschko was born on May 27th, 1936 in Prague (Czech Republic). His family moved to Linz (Austria), where he finished secondary-school in 1956. He studied chemistry at the University of Vienna and eventually joined the laboratory of Hans Nowotny. For the synthetic part of his thesis on complex carbides and nitrides, he moved to the renowned Metallwerke Plansee. Wolfgang graduated in 1964 and spent a postdoc period (1964–1966) at the Metallurgy Department of University of Pennsylvania with Erwin Parthé. From 1966 to 1967, Wolfgang returned to Vienna University as a research associate and lecturer in the Nowotny group. In 1967, he was appointed lecturer in the Metallurgy Department at University of Illinois at Urbana-Champaign (P. A. Beck group). His career then took an unusual step. Wolfgang joined the famous Central Research Department of DuPont Co. (1969–1975) where he worked on basic synthetic solid state chemistry and crystallography. In 1975, he was appointed University Professor (H3) at Justus-Liebig Universität Gießen from where he moved to Technische Universität Dortmund in 1979 as University Professor (H4). In 1982, he got the Chair of Inorganic Chemistry at Universität Münster. He retired in 2001.

Wolfgang Jeitschko has shaped solid state inorganic chemistry in Germany and internationally over decades. His main research activities focused on intermetallic compounds in all their diversity. Especially carbides of the transition metals and rare earth-based carbides were a key topic of the Jeitschko group. Striking examples are Sc₃C₄, the first structurally characterized carbide with C₃ units and carbides with high magnetic ordering temperatures, e.g. Gd₂OsC₂ with T_c = 320(5) K.

The second pillar of the Jeitschko group was solid state pnictide chemistry in its full width. Many studies concerned metal-rich phosphides, arsenides and antimonides, but also a huge number of polypnictides, especially in the field of phosphides were discovered. Striking examples are the binary transition metal phosphides (FeP₄, MnP₄, Tc₂P₃, Re₆P₁₃, ReP₄, Re₂P₅, or ReP₃) and of course the basic work on filled skutterudites (LaFe₄P₁₂), nowadays one of the important families of thermoelectric materials.

Another broad topic concerned flux synthesis of aluminum-rich compounds like NdRh₄Al_15.37, TbRe₂Al₁₀, Er₄Pt₉Al₂₄, Yb₆Cr₄Al₄₃ or CeTi₂Al₂₀ and in parallel zinc-rich intermetallics like NbZn₃, NbZn₁₆, MoZn_20.44, Ti₃Zn₂₂, TiZn₁₆ and a huge number of ternary TT‘₂Zn₂₀ phases. Many of these compounds are currently in the focus of solid state physics due to their outstanding magnetic and transport properties. Further work concentrated on borides (e.g. U₅Mo₁₀B₂₄, RE₂NiB₁₀, ThCrB₄ or ThCr₂B₆), silicide phosphides (Ag₂SiP₂, AuSiP, NiSi₂P₃), nitrides (e.g. Ce₂CrN₃ or Ce₃Si₆N₁₁) and stannides (CoSn₃, Os₄Sn₁₇, RhSn₄, ZrNiSn and ZrNi₂Sn), nicely demonstrating the width of Wolfgangs research interests. These include also early work on solid state electrolytes: e.g. lithium halogenidoboracites, Li₄B₇O₁₂X with X = Cl, Br, I or the phosphorus iodides Cu₂P₃I₂ and Ag₂P₃I₂.

Wolfgang also worked on oxides in the field of niobates, tantalates, rhenates and ternary mercury oxides. A remarkable example among the complex transition metal oxides is ferroelastic Gd₂(MoO₄)₃. This study motivated for joint work with Hans Wondratschek on twin domains and antiphase domains. Wolfgangs most important oxide project concerned the family of pnictide oxides. In 1974, he determined the structure of ZrCuSiAs in collaboration with V. Johnson. Many years later a large series of isotypic pnictide oxides RETPnO with T = Mn, Fe, Co, Ru, Zn and Pn = P, As, Sb was synthesized and crystallographically characterized in the Jeitschko group – the basic work for the pnictide oxide superconductors. These important results on a fascinating group of compounds kept him busy long after his retirement and made him a sought-after discussion partner at conferences.

Whenever phase pure samples were available, Wolfgang insisted on the study of their physical properties, mainly concerning the magnetic and transport behavior. The Jeitschko group had a long-term scientific cooperation with the group of Werner Müller-Warmuth (Institute of Physical Chemistry in Münster) in the field of ¹⁵¹Eu Mössbauer spectroscopy of many intermetallic europium compounds for studying the magnetic hyperfine interaction parameters. The magnetic structures were often determined from neutron diffraction data.

Finally, one should not forget the Lazy Pulverix programme (intensity calculation for X-ray powder patterns) which was developed with Klaus Yvon and Erwin Parthé. Today this code is still used as subroutine in basically all crystallographic computer packages.

Wolfgangs solid state research is well documented in more than 430 scientific publications in peer-reviewed journals. It is impossible to rate all these publications; therefore, citations over many years might be the best indicator for measuring sustainability of a scientific paper. In that view, his work on (i) the skutterudite LaFe₄P₁₂ [1] in the field of thermoelectrics, (ii) the structure of Ti₃SiC₂ [2], a material with outstanding mechanical properties, (iii) the metal flux as synthesis tool [3], (iv) basic crystal chemical work on the so-called H-pases [4], or (v) his pioneering synthetic and crystallographic work on the family of pnictide oxides [5], [6] was groundbreaking. All this work is still the basis for current research both in the field of solid state inorganic chemistry as well as in materials science. During his professorships in Gießen, Dortmund and Münster Wolfgang supervised 80 doctoral theses. His scientific precision, the synoptic look at chemical compounds and physical properties and his clear scientific language have certainly been shaping for most of his students.

Wolfgangs high international reputation was honored in 1991 with the Kurnakov Medal of the Academy of Science of the Soviet Union, in 2010 with the Carl-Hermann Medal of the German Crystallographic Society and by guest professorships in Geneva, Liège, Rennes, at Cornell University, at IIT Madras and at CNRS Bordeaux.

The group seminars had a special mode in Wolfgangs group. They rarely took place at University. Wolfgang liked travelling with the whole group to the external university seminar places, the Zaferna-Hütte (the ski hut of the Münster faculty of sports) in Mittelberg (Austria), at Meeresbiologische Wattstation Carolinensiel (biological research station of the biology department), and Landhaus Rothenberge (a seminar house of Universitätsgesellschaft Münster). These seminars were always combined with hiking and skiing, common dinners and social gathering and of course, an evening beer.

Wolfgang had a good international network and he was host for many PhD students, postdocs and young scientists from abroad. Especially the close scientific cooperation with Lviv University (Ukraine) is still firmly established in his former institute.

The regular active participation at national and international conferences in the field of solid state chemistry and crystallography was Wolfgangs obligation. And, he organized several meetings in Münster, the Hemdsärmelkolloquium (the annual in-official meeting of the German solid state chemists) in 1985, 1994 and 2004, the conference on Solid Compounds of Transition Elements (SCTE-10, he was a permanent member of the International Advisory Board [7]) in 1991 and the conference of the German solid state community (GDCh Fachgruppentagung with the key topic Functional Inorganic Materials) in 2000. Wolfgang was also teaching abroad. He visited several indian Universities (Madras, Madurai, Mumbai, Hyderabad, Bangalore) under the egide of the Deutscher Akademischer Austauschdienst in 1988, 1992, 1997, 2001 and 2003.

Wolfgang had broad interests and activities outside solid state chemistry. Besides gardening, he liked travelling to foreign countries, even to remote places. Over many years, he and his wife Marieluise regularly visited opera houses all over the world. Wolfgang enjoyed social gathering during the many post-sessions of scientific talks. He appreciated good food and excellent wine.

Wolfgang kept close contact to his active and former doctoral students, technical coworkers and their families. During his active time, every year, end of June we were all invited to Jeitschko’s garden to his summer party with the legendary table tennis tournament, a grill buffet lavishly stocked by Marieluise Jeitschko and diverse excellent beers. These parties often ended in the early hours of next day and created many contacts among his different student generations. We will all miss these discussions and the socializing with each other.