dimpled specimen IFW Universität Hannover Leibniz Universität

dimpled specimen IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 1

The extration replica technique (a) polished surface (b) etched to expose second phase (c) carbon coated (d) re-etched and replica floated off IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 2

Single stage replication: a-specimen b-carbon coating c-final replica Two stage replication: d-specimen, e-intermediate thick plastik coating, f- plastic replica (inverted), g-carbon coating, h-final carbon replica IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 3

Carbide in steel IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 4

Precision cut-off and grinding • Automatic cut-off machine Accutom 50 Application area: Automatic cut-off and grinding Cut-off of samples for TEM-preparation Grinding of samples for TEM/SEM-sample preparation Producer: Struers Variable wheel speed of 300 rpm - 5000 rpm Feed speed: 0. 005 mm/s -3. 000 mm/s Position accuracy: 5 µm Al 2 O 3 and diamond cut-off wheels Diamond cup wheels for hard, brittle and ductile materials (91 µm, 40 µm) IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 5

Wire saw A wire saw produces very fine slices from a material with just small stress to the sample. This procedure is applied to brittle materials, but also for cross section preparartions. IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 6

Duo Mill Ion mill Application area: ion milling of mechanically prepared specimens ion milling of electro polished specimens cooled ion milling of beam sensitive specimens Producer: GATAN Inc. Operation voltage: 1000 V - 4000 V Cathode: Octogun 2 coolable specimen stages (liquid nitrogen) Vacuum: 2 rotation pumps, 1 oildiffussion pump IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 7

Precision Ion Polishing System (PIPS) Application area: ion milling of mechanically prepared specimens ion milling of electro polished specimens Producer: GATAN Inc. Operation voltage: 2000 V - 5000 V Vacuum: 1 membrane pump, 1 turbo molecular pump (oil free) IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 8

thin with the ion etching system ion source specimen ion beam ion source the surface of the rotating sample, with the help of two ion beams removed IFW, Universität Hannover © Leibniz Universität Hannover, IW the ablation rate depends on the angle between ion beam and sample surface Mo. Ko Sommersemester 2004, K. Tracht Seite 9

Mounting specimens in an ion beam mashine a) Schematic diagram b) and c) two types of holder which permit double-sided thinning In c) the gear teeth engage in a mount which enables the whole plate to be rotated while ion beams are directed at both sides of the disc D IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 10

Electrolytic thinning Tenu. Pol-5 Application area: electrolytic thinning of TEM samples automatic shut-off through infra-red sensor Producer: Struers Controlled operation temperature down to 30°C with cooling unit. IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 11

Tenupol 5 Installation of the electropolisher Tenupol in a fume cabinet Tenupol specimen holder and installation of a disc specimen IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 12

Elektropolishing Schematic diagram illustrating the action of a jet thinning technique IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 13

Tenupol 5 IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 14

Tenupol 5 IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 15

Ideal current-potential curve IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 16

current density typical current density-voltage curve at the thin electroplating of metals gas development polishing etching voltage The best polishing conditions prevail in the range of 2 IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 17

Fluid dynamic parameters Polishing profiles dependendent on the fluid dynamic parameters IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 18

FIB preparation: Lamellar-Transportation I Transmission Electron Microscope Sample Preparation Using a Focused Ion Beam in-situ: using a Kleindiek-micromanipulator IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 19

FIB: Focussed Ion Beam IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 20

FIB Preparation of TEM specimens Mechanical thinning on about 100 microns and defining a sample area Advantages: • targeted preparation • Fast preparation (approx. 2 hours) Disadvantages: Material ablation with high intensity ion beam • No samples for HRTEM because of the sample thickness (100 nm) and surface amorphisation • high investment costs FIB Material removal with ion beam of lower intensity, until a thin lamella remains. These will be removed and directly in the TEM can be investigated IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 21

FIB preparation: Lamellar-Transportation II Fixing the TEM lamella to W-tip by means FIB-deposition, then complete Isolation of Lamella IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 22

FIB preparation of Nanowires Nachfolgende FIB-Abscheidung IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 23

FIB preparation : gradually after processing Transportation to sample holding system IFW, Universität Hannover © Leibniz Universität Hannover, IW Mo. Ko Sommersemester 2004, K. Tracht Seite 24