Specimen preparation – part 1 TEM specimen preparation

Specimen preparation – part 1

TEM specimen preparation I TEM- specimen preparation indirect image direct image Replica Bulk Interfacial Particles Top view Cross section primary thinning Ø = 3 mm Cut cutting Dimpeln Self-supporting specimen Thin to electron transparency: Mechanical grinding Electropolishing chemical etching Ion etching FIB (focussed ion beam) S. on a carrier network embedded s. on a carrier network Ultramikrotom Block Cutting Embed Dispersion on a carrier film …

TEM specimen preparation II Preparation sequence: - Taking a circular sample with Ø = 3 mm - Grinding on thickness = 100 microns - Ion beam etching to hole formation sampling (Ø=3mm) ~100 µm ~10-80 nm TEM specimen (schema) Hole etched areas considered area pressed tensile specimen (LM-picture)

Disk preparation General steps in TEM specimen preparation Disk grinding Dimpling Low angle Ion milling (bulk, plan view, cross section and small objects)

TEM specimen preparation III Hole Fringe in hole near magnified image detail grain boundary precipitation dislocation

Punching of discs

A simple jig for hand polishing The specimen (S) is glued to the central post (B) while a guard ring (G) is set to protude by an amount equal to the desired final thickness. This is held in place by a lock ring (L).

TEM Grid

Preparation of coated or thin Material by the sandwich method

Bonding of the coated material specimens to a sandwich. The glue is applied to the coating surface by brush and treated in that way that only a thin layer remains. The parts are put on top of one another and pressed together with the clamp. For the further preparation a small plug is inserted to close the metal tube on one side nach H.J. Penkalla FZ Julich

Assembling of the preparation. At first the tube filled with the epoxy, then the first filler half-cylinder is inserted, after that the sandwich and the second half-cylinder are following. The preparation is fixed in the Teflon holder and after heating for 40 min at 100°C the assembly is ready for sawing. nach H.J. Penkalla FZ Julich

Specimen pre-preparation Shematic drawing of the sandwich compound cross-section Grouping of all necessary parts and tools using for sandwich preparation

Mix G-1 epoxy with fibers or powder and transfer the mixture to a brass tube Cure the G-1 epoxy on a hot plate for 10 minutes at 130°C Disk grind, dimple grind and Ion mill to perforation Slice the filled tubes using a diamond saw to obtain 3 mm diametre disk Steps to the preparation of TEM specimens from powders and fibers Step 1 Step 2 Step 3 Step 4

Longitudinal wires cross-sections wire specimen Double grid specimen holder grid holder+ M Bond 610 Teflon band Metallic bulk Teflon band Metallic bulk Metallic bulk grid + specimen gluing, pressing, heating MBond 610 grid grid polishing, dimpling, ion thinning for transparency ~200A°

Perpendicullar wires cross-sections I Fixing plate specimen wires + M Bond 610 M Bond 610 Step I Step II Step III gluing, pressing, heating Inserting into the rod + tube + M Bond610

Perpendicullar wires cross-sections II Step IV Step V Step VI tube tube rod rod Disk polishing Dimpling, grinding, polishing(6µm 1µm) Ion thinning for both sides for transparency

Coating cross-sections I Cutting the plate Plate polishing and dises D=3mm cutting Disk dipling, grinding and polishing (6µm 1µm) Ion thinning for both sides

Coating cross-sections II Step II Cutting 2 plates Gluing Pressing + Heating (175°/ 1h) Teflon band Teflon band M Bond 610 Dimensions correction by polishing

rod M Bond 610 M Bond 610 M Bond 610 specimen tube Specimen inserting into the rod and Into the tube + glue M Bond610 Step III M Bond 610 Tube with specimen Teflon bulk Heating (curing) 175°/ 1h Cutting the disks Coating cross-sections III

specimen grinding wheel A horizontal axis by rotating grinding wheel dünnt the central area around a vertical axis rotating sample Princip of the hollow grinding

Dimple Grinder Gatan Model 656

Mechanicel pre-thinning Gatan precision with a sef of different dimple and polishing wheels

mechanical preparation of specimen Glue specimen specimen holder start first step second step

Geometry of a dimpled specimen The relationship between the diameter of the dimple grinder wheel (D), the diameter of the dimple (2r) and the dimple depth (d) is given by the approximation.