TEM 原理及制样

Lecture13:TEM sample preparation

Contents

1TEM sample holders1 2Parts of a TEM holder4

2.1Types of TEM holder (5)

2.2In-situ TEM holders (6)

3TEM sample preparation9

3.1Electrolytic polishing (9)

3.2Ion milling technique (12)

3.3Cross section sample preparation (17)

3.4Replica technique (18)

4Focused ion beam TEM sample preparation20 1TEM sample holders

The specimen holder is used to insert the sample into the TEM from outside for imaging.The sample is loaded onto the TEM stage for imaging.Now, TEM holder and stage are essentially integrated.The TEM holder plays and important role since it allows for introduction of a sample in ambient conditions into an instrument that is held in ually the holder region is pumped separately before the sample is fully introduced in the TEM.A schematic diagram of some of the pumps used in the TEM is showed infigure1.

There are2main types of holder in the TEM

1.Top loading-the sample has no connection to the outside.After de-

livery of the sample to the stage the holder is withdrawn.Top loading holders were used in earlier instrument version,especially for high res-olution since this minimizes external vibrations.A schematic of a top loading holder is shown infigure2.

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MM3030:Materials Characterisation

Figure1:Pumping system in a TEM.Taken from Transmission Electron microscopy-Williams and Carter.

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MM3030:Materials Characterisation

Figure2:Top entry loader in(A)cross section and(B)top view.Taken from Transmission Electron microscopy-Williams and Carter.

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MM3030:Materials Characterisation

Figure3:Schematic of a side entry holder.Taken from Transmission Electron microscopy-Williams and Carter.

2.Side loading-these are the most commonly used holders now.The

advantage of the side loading holders is that it is possible to provide external stimuli(heat,current,load)while imaging.

2Parts of a TEM holder

The focus will be on the side loading holder since it is ubiquitous in use.A schematic of the holder is shown infigure3.Various parts of the holder can be identified from thefigure

1.O-ring-Provides the mechanical link to the TEM column.The o-ring

separates the portion of the holder in the ambient from the portion in vacuum.Typically a viton o-ring is used and some holders have more than one.The o-rings are usually greased but the excess grease should be removed before inserting in the TEM since this can affect the vacuum.The way in the holder is inserted in the instrument depends on the specific TEM.

2.Jewel bearing-This provides the other mechanical link of the holder

to the TEM.This is used for mechanical translation of the sample(in the x-y plane).

3.The cup-this actually holds the sample.Typical TEM samples are3

mm discs though bulk holders are available(not very common).

4.Clamping ring-this clamps and holds the sample in place.Both the

cup and the clamping ring are exposed to the electron beam and hence

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