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NIST Center for Neutron Research

BT1

Instrument purpose

To provide world-class neutron powder diffraction data for the precise determination of atomic and magnetic structures in polycrystalline materials using the Rietveld method and other advanced crystallographic analyses.

The NCNR Advantage

Tailored resolution: Features three interchangeable monochromators, allowing users to tailor the instrument response (intensity vs. resolution) specifically to their sample's needs.
Excellent data quality: Produces nearly perfect Gaussian peak shapes, simplifying the modeling of complex multi-phase materials and subtle symmetry lowering.
Exceptional Environment Flexibility: BT-1 is highly regarded for its ability to run samples under versatile specialized sample environment,
Mail-in Program: NCNR offers a robust mail-in service where NIST scientists collect the data for you. This is ideal for "basic" crystallographic needs (5 K – 300 K) and saves the time and cost of traveling to the facility

Research Domains

Energy Storage: Investigating and determining small gas molecules in the pores of zeolites and metal-organic frameworks (MOFs), lithium and sodium ion environments within battery electrode materials, and hydrogen or deuterium sites within a host material lattice.
Quantum Materials & Magnetism: Tracking magnetic phase transition and magnetic order; identifying and solving magnetic structures.
Advanced Functional Materials: Precise determination of oxygen vacancies and structural distortions in superconductors, subtle lattice distortion in ferroelectric and piezoelectric materials, and lattice changes in negative thermal expansion (NTE) materials.
Ceramics & Intermetallics: Precise determination of stoichiometry in oxides, and the site-ordering of different metals in an alloy. Analysis of phase fractions and thermal expansion over wide temperature ranges.

What You Can Measure

Precise crystal structures (unit cell dimensions, atomic positions, light atom detection, occupancy and vacancies, and thermal parameters).
Magnetic structure and moment determination.
Phase identification and quantification in complex mineralogical or industrial samples.
Structural changes under external stimuli (temperature, magnetic field, pressure, gas-loading, electric field).

Technical Specifications

Feature	Ge (311)	Cu (311)	Ge (733)
Primary Use	High Flux / Low Q	General Purpose / Balance	Ultra-High Resolution
Wavelength (λ	2.079 Å	1.540 Å	1.197 Å
Take-off Angle (2θ)	75°	90°	120°
Flux at Sample (n/cm²/s)	~1.16 x 10⁶	~4.40 x 10⁵	~1.20 x 10⁵
Resolution (∆d/d)	~0.33%	~0.17%	~0.08%
Detector Array	32 ³He detectors at 5° intervals covering up to 167° in 2q

Specialized Sample Environments

Extreme Temperatures: Seamless integration with NCNR’s sample environment suite, covering 0.05 K to 2000 K via dilution refrigerators, cryostats, and specialized furnaces.
Magnetic Fields: Vertical (up to 7 T) for probing magnetic phase diagrams.
Gas Loading & In-Situ: Specialized cells for gas adsorption (H₂/D₂, CO₂, etc.) and high-pressure environments (up to 2.5 GPa).
Standard Containers: Vanadium cans in various sizes (1.5 ml, 4.0 ml, 5.5 ml, 8.0 ml, 11.5 ml), optimized for low background.

Expertise & Support

On-Site Scientists: Our instrument scientists are international experts in structure determination from powder samples, Rietveld refinement, and magnetic crystallography. Provide hands-on assistance from experimental design to final publication.
Data Reduction: Automated software pipelines convert raw detector counts into standard formats (GSAS, FullProf) with built-in absorption and background corrections.
NIST Data Tools: Specialized Python scripts for real-time monitoring of thermal equilibrium and field dependence.