Journal of large-scale research facilities, 1, A7 (2015) http://dx.doi.org/10.17815/jlsrf-1-20 Published: 18.08.2015 HEiDi: Single crystal di�ractometer at hot source Heinz Maier-Leibnitz Zentrum RWTH Aachen University, Institute of Crystallography Forschungszentrum Jülich, Jülich Centre for Neutron Science Instrument Scientists: - Martin Meven, Institut für Kristallographie, RWTH Aachen and Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, phone: +49(0) 89 289 14727, email: martin.meven@frm2.tum.de - Andrew Sazonov, Institut für Kristallographie, RWTH Aachen and Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, phone: +49(0) 89 289 11764, email: andrew.sazonov@frm2.tum.de Abstract: The single crystal di�ractometer HEiDi, which is operated by the Institute of Crystallogra- phy, RWTH Aachen University and JCNS, Forschungszentrum Jülich, is designed for detailed studies on structural and magnetic properties of single crystals using unpolarised neutrons and Bragg’s Law: 2dhkl sin Θ = λ (typically 0.55 Å < λ < 1.2 Å). 1 Introduction Because of the large variety of short wavelengths and resolutions, HEiDi is suitable for studies on a lot of crystalline compounds – many of them of potential interest for energy or data storage technologies – like: • HT superconductors (e.g. cuprates, FeAs-pnictides) • Multiferroics (e.g. manganates) and other complex ferro- and antiferromagnetic compounds (e.g. olivines) • Ionic conductors (e.g. nickelates) • Ferroelectrics (e.g. KDP family) • Mixed crystals (e.g. AsSe compounds) • Highly absorbing compounds (e.g. with Gd, Sm, Eu, Dy) • Frustrated magnetic materials (e.g. pyrochlores) 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-1-20 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A7 (2015) http://dx.doi.org/10.17815/jlsrf-1-20 Figure 1: Instrument HEiDi (Copyright by W. Schürmann, TUM). 2 Applications (in general) • Structure analysis • Hydrogen bonds • Static and dynamic disorder • Harmonic and anharmonic mean square displacements • Twinning • Magnetic structure and order • Structural and magnetic phase transitions • Incommensurate structures 3 Applications (in detail) • Studies of atomic positions and bond distances in compounds with heavy and light elements or elements of similar electron shells • Temperature dependent studies for determination of phase transitions • Studies of order – disorder phase transitions, e.g. H bonds by determination of anisotropic mean square displacements using large Q range up to sin(Θ)/λ > 1 • Structure determination of compounds with highly absorbing elements (Gd, Sm, Cd, Dy) with short wavelengths • Studies on magnetic phase transitions and T dependencies (ferri, ferro and antiferro magnets, multiferroics) • Studies on HT superconductors (e.g. cuprates, FeAs pnictides) • Sample characterisation by pro�le analysis • Determination of sample orientation, e.g. for preparation of experiments on three axes instru- ments • Presentation of fundamentals of crystallography and structure analysis for education 2 http://dx.doi.org/10.17815/jlsrf-1-20 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-1-20 Journal of large-scale research facilities, 1, A7 (2015) Figure 2: Schematic drawing of HEiDi. 4 Sample Environment • Closed cycle cryostat (2 K – RT) • Mirror furnace (RT – 1500 K) • Micro furnace (RT – 500 K) • Uniaxial pressure cell (from PUMA) 5 Technical Data 5.1 Beam-tube • SR-9b (hot source) • Flux at sample 1.4 · 107 n cm-2s-1 (λ ≈ 1.17 Å) • Gain by hot source x 10 (λ ≈ 0.6 Å) 5.2 Wavelength 2ΘM Ge(311) Cu(220) Ge(422) Cu(420) 20° 0.503 0.443 0.408 0.280 40° 1.168 0.870 0.793 0.552 50° 1.443 1.079 0.993 0.680 5.3 Q-range 2ΘM Ge(311) Cu(220) Ge(422) Cu(420) 20° 1.46 1.95 2.12 3.09 40° 0.74 0.99 1.09 1.57 50° 0.60 0.80 0.87 1.27 3 http://dx.doi.org/10.17815/jlsrf-1-20 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 1, A7 (2015) http://dx.doi.org/10.17815/jlsrf-1-20 5.4 Optical components • Single detector optimised for small wavelengths (sensitivity > 90% at 0.3 Å) • Analyzer PG(002); optional for studies of purely elastic scattering and background suppression • Neutron �lters for suppression of λ /2- or λ /3-contamination of the monochromatised beam 4 http://dx.doi.org/10.17815/jlsrf-1-20 https://creativecommons.org/licenses/by/4.0/ Introduction Applications (in general) Applications (in detail) Sample Environment Technical Data Beam-tube Wavelength Q-range Optical components