HEiDi

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

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

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

Q-range

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