NCMN Central Facility for X-Ray
The NCMN X-Ray Characterization Facility is dedicated to materials identification and characterization through non-destructive, X-Ray Diffraction (XRD) technique. The following equipments are utilized: (1) Bruker-AXS D8 Discover High-Resolution Diffractometer; (2) Rigaku D-Max/B Horizontal ?-2? X-Ray Diffractometer (3) Rigaku Multiflex ?-? diffractometer in vertical diffraction geometry and (4) Bruker Smart-Apex Single Crystal diffractometer
Powder X-Ray Diffraction
High Resolution X-Ray Diffraction
1. Bruker-AXS D8 Discover High-Resolution Diffractometer
This is a state-of-the-art machine including HI-STAR area detector, centric 1/4-circle Eulerian cradle, domed hot stage, hi-flux in-plane hardware, laser/video sample-alignment system, Göbel mirror, fine tilt stage, and dual-beam path analyzer module. The system can be configured for grazing-incidence in-plane XRD, grazing-incidence XRD, x-ray reflectivity, high-temperature XRD, high-resolution XRD (rocking curves, reciprocal space maps), texture (pole figures), residual stress, and microdiffraction and capillary diffraction. Bruker D8 Discover diffarctometer is configured in parallel beam geometry with Cu Kalpha radiation (wavelength of about 1.5418 Å).
2. Rigaku D/Max-B Diffractometer:
X-Rays are produced by a 1.8 kW, sealed tube Cobalt target. The diffracted beam then converges (is “focused”) into a diffracted beam monochromator which removes all radiation except the Co Kalpha wavelength (about 1.7903 Å) which then enters a scintillation counter. The sample and detector are rotated with respect to the incident beam at angles ? and 2?, respectively. A typical XRD scan consists of a plot of detector angle (2?) vs. diffracted intensity. These diffractograms can be printed out or saved to disk in application-friendly ASCII format.
3. Rigaku Multiflex Diffractometer:
This instrument consists of 2 kW copper target and ?-? goniometer. The sample holder remains horizontal during the scan and therefore, there is no need to use adhesive substances to mount samples on to a low background sample holder plate. Similar to D/max-B, Rigaku Multiflex is also configured in focusing geometry where a secondary monochromator removes the scattered signal except that corresponding to Cu Kalpha wavelength. Pre-aligned sample holder and friendly operating software makes the powder diffraction experiments very easy with this instrument.
4. Bruker Smart Apex Single Crystal Diffractometer:
Smart Apex Single Crystal Diffractometer is a dedicated instrument for Crystallography studies (absolute structure determination using a single crystal sample). This instrument delivers intense, monochromatic beam of Mo Kalpha radiation (0.7107 Å) produced using Graphite monochromator from a sealed Mo X-ray tube and collimated with a pinhole collimator. The single crystal is mounted on the tip of a glass fiber or a nylon loop affixed to a Goniometer head will be attached to a fixed ?, 3-axis goniometer. The sample is optically aligned using Video camera and a manual control module. The sample temperature can be varied from 100 – 400 K using Cryostream controller (Oxford Instruments). The detector (Smart Apex CCD camera) is placed at about 5 – 6 cm from the sample and uses Peltier technology to cool the CCD chip (-40 deg C) to minimize dark currents. The frame buffer computer is provided with softwares for sample centering, data collection (sample unit cell determination, and detailed structure determination), data integration, absorption correction, and structure determination and refinement.
Further analysis can be carried out in the facility on any of the user PCS equipped with qualitative and quantitative XRD software and the users have access to the latest International Center for Diffraction Data, PDF–4+ Database .
Most powder, thin-film, and bulk samples are acceptable. The sample holders can accommodate samples up to 30 x 30 x 10 cm in size (sometimes larger) with the 30 x 30 cm surface tangent to the diffracting circle. The amount of material needed for a diffraction pattern depends on the diffracting power of the sample and the type of analysis desired. For example, phase identification of a well crystallized powder, with small (< 40 mm) particle size, may only require 1 mg. or less.
Dr. Shah Valloppilly, Specialist