STATION 9.1
High Flux Powder Diffraction

Description

The Station has two principle modes of operation: conventional powder diffraction using the 2-circle diffractometer; or, image-plate configurations for either high pressure diamond anvil cell experiments or a curved system (CIP) for diffraction from crystalline powders, liquids and amorphous materials. A number of environmental chambers or additional external systems permit non-ambient temperature regimes to be studied.

News

Spring 05
The monochromator vessel has been replaced enhancing beam alignment and automating the defining beam size onto the sample.
Summer 05
A new bespoke Stoe furnace for capillary samples was installed allowing temperature regimes up to 1700k to be investigated.

Functional Description

A wavelength range from 0.4Å to 1.7Å is available but wavelengths of 1.0Å or shorter are typically used due to optimal flux and low harmonic content. Variable temperature regimes (90K to 373K) and (290K to 1700K) are available for sealed capillary experiments.

Technical Description

Station 9.1 is situated 15m from the 5 Tesla superconducting wavelength shifter. The station receives approximately 5 mrad from the source. At wavelengths greater than 1.0Å the lambda/3 harmonics become more significant and can only be partially removed from the signal accepted at the detector.

Monochromator
Si(111) channel-cut crystal, temperature controlled 30°C , 0.1 mdeg. resolution (Dl/ l~1.7x10 -4).

HRPD
Capillary geometry is the preferred method for HRPD using Debye-Scherrer geometry. Capillary sizes from 0.3mm to 2mm diameter are used, but 0.5mm is most common. The typical step size for the detector axis is 0.01mdeg, but 0.005mdeg is possible.

High Pressure
A 0.5mm x 0.5mm monochromatic beam is further reduced by a Pt disc pinhole of 70um diameter. Merril-Basset DACs are used and data is collected on A4-sized image-plates. A wavelength of 0.46Å is typically used.

High Pressure studies have now moved to Station 9.5 unless there is a specific reason for needing to use 9.1.

Development

A much improved working environment has been constructed directly adjoining the 9.1 hutch, removing the need to work on the gantry above.
A microscope and spark eroder have been purchased for use with the High Pressure Facility.

Proposed Development

Installation of a new monochromator vessel for improved efficiency in station set-up and alignment.
Commissioning of a Stoe capillary furnace.

Set-up Time

The diffractometer configuration at a defined wavelength can take up to 1.5hrs.
The High Pressure configuration takes approximately 3 hrs.