JEOL 6490 Low-Vacuum Scanning Electron Microscope

Location

JGB5.108

Overview

Installed in 2008, our W-filament JEOL 6490LV SEM has secondary electron (SE), back-scattered electron (BSE), and energy-dispersive X-ray (EDS) detectors. The 6490 can operate in high- or low-vacuum modes, allowing sub-micron-scale imaging and X-ray compositional data collection without needing to coat or modify your sample. The EDS detector can be used to create a qualitative and semi-quantitative elemental analysis of sub-micron point volumes, X-ray mapping over mm-scale single fields of view, and X-ray line scans.

This SEM received a major upgrade. We installed a Gatan PanaCL detector, allowing the collection of cathodoluminescence signals; an Oxford Instruments Nordlys Nano EBSD detector; and upgraded the EDS detector to the far more powerful Oxford Instruments X-Max 50. The EBSD and EDS detectors will be configured for simultaneous collection, and both will run through Oxford Instrument’s very user-friendly Aztec software. After this upgrade, fully automated Large Area Mapping is an option for the collection of SE, BSE, EBSD, EDS, and CL data.

Examples

EDS X-ray map of a garnet surrounded by deforming rock. 1024×1024 pixels, step size of 1.5 microns, dwell time of four milliseconds.

A pottery shard was used to create the following images, on the 75 mm stage.

Broken pottery edge, with brown-colored glaze on the right. BSE image, low vacuum mode.

Closeup of vesicle in pottery glaze. BSE image, low vacuum mode.

Closeup of pottery glaze crystallites. BSE image, low vacuum mode.

Contact between brown, crystallite-rich glaze and grey-colored glaze. BSE image, low vacuum mode.

Closeup of unglazed broken pottery surface. BSE image, low vacuum mode.

Vesicular basalt from Tillamook, Oregon, with zeolite micro-crystals growing in vesicles.

Wide angle view of an edge of one of the zeolite-filled vesicle chambers. BSE image, low vacuum mode.

65x BSE view of zeolite on edge of vesicle. BSE image, low vacuum mode.

270x view of radiating crystallite pattern in the zeolite. BSE image, low vacuum mode.

1,900x view of asbestiform zeolite crystals within the vesicle. BSE image, low vacuum mode.

Requirements of Samples

Because the SEM can operate in high- or low-vacuum modes, a conductive coating is not required for insulating samples. However, conductive samples (or those with a conductive coating) are preferable for optimal image acquisition and chemical analysis. Carbon coating is available in the DGS Electron Microbeam Laboratory.
Samples must be dry (water is the main concern, but some oil-saturated samples might also be unsuitable).

Sample Shape and Size

Typical samples are thin sections and materials < 1 cm in diameter.
Four 1-cm diameter samples can be loaded into the SEM simultaneously.
Samples up to 5 cm in diameter may also be analyzed, with the warning that large samples pose the possibility of colliding with the detectors.
The stage can be tilted up to 55° from the horizontal.