HEiDi

Single crystal diffractometer on hot source

HEiDi

The single crystal diffractometer HEiDi is designed for detailed studies on structural and magnetic properties of single crystals using hot unpolarised neutrons and Bragg’s Law:
2 d_hkl sin (Θ) = λ
(typically 0.55 Å < l < 1.2 Å).

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)

Typical 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

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 profile analysis
Determination of sample orientation, e.g. for preparation of experiments on three axes instruments
Presentation of fundamentals of crystallography and structure analysis for education

Sample Environment

Closed cycle cryostat (2 K – RT)
Mirror furnace (RT – 1500 K)
Micro furnace (RT – 500 K)
Uniaxial pressure cell (from PUMA)

Technical Data

Beam-tube

SR9B (hot source)
Flux at sample 1.4·10⁷ cm^-2s^-1 (λ ≈ 1.17 Å)
Gain by hot source × 10 (λ ≈ 0.6 Å)

Wavelength

2Θ_M	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

Q-range

2Θ_M	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

Optical components

Single detector optimized for small wavelengths (sensitivity >90% at 0.3 Å)
Analyzer PG(002); optional for studies of purely elastic scattering and background suppression
Neutron filters for suppression of λ/2- or λ/3-contamination of the monochromatized beam

Instrument Scientists

Dr. Martin Meven
Phone: +49 (0)89 289-14727
E-Mail: martin.meven@frm2.tum.de

Dr. Andrew Sazonov
Phone: +49 (0)89 289-11764
E-Mail: andrew.sazonov@frm2.tum.de

Dr. Hao Deng
Phone: +49 (0)89 289-54725
E-Mail: hao.deng@frm2.tum.de

HEIDI
Phone: +49 (0)89 289-14828

Operated by

Publications

Find the latest publications regarding HEiDi in our publication database iMPULSE:

impulse.mlz-garching.de

Citation of the instrument

Heinz Maier-Leibnitz Zentrum. (2015). HEiDi: Single crystal diffractometer at hot source. Journal of large-scale research facilities, 1, A7. http://dx.doi.org/10.17815/jlsrf-1-20

For citation please always include the DOI.

Gallery

HEiDi

FWHM

Figure 1: FWHM of reflections from a Si sample measured with a wavelength of 0.87 Å using the Cu (220) monochromator.

MLZ is a cooperation between:

> Technische Universität München

> Helmholtz-Zentrum Geesthacht

> Forschungszentrum Jülich