Download ch10-2

Introduction
 Really broad subject
 Many different ways
 Method depends on:
- The information you need
- Time constraints
- Availability of equipment
- Your skills
- The material
Sample requirements:
 Electron transparency
 Stable under electron beam
 Conducting
 Non magnetic
Safety first
 Basic lab safety instruments
 Know your material
 Polishing solutions may be poisonous
Sample geometry
PREPARING A SELF-SUPPORTING
DISK FOR FINAL THINNING
 Making 100 - 200 um thick slice
Ductile materials - Wafering saw or spark plasma erosion
Brittle materials – razor blade or ultramicrotome
 Cutting the 3-mm disk
from the slice
Ductile – mechanical punch
Brittle materials - spark erosion
ultrasonic drilling, grinding drill
 Prethinning the disk to a few
micrometers - Dimpling
Chemicals or Tripod polisher
Final
thinning
 Electropolishing
- Only for metals, fast, may change surface
chemistry
 Ion milling
- Variables are ion energy, angle of incidence, vacuum, initial
surface topology, initial chemistry, initial orientation, initial
crystallography of the surface, beam energy, and beam
profile.
SPECIMENS ON GRIDS/WASHERS
 Alternative for self-supporting samples
 Faster (on average)
 Sample may be crushed and put on grid
 Carbon film commonly used
Ultramicrotomy
Focused ion beam instrument (FIB)
 SEM with built-in ion mill
 Accurate but expensive
Cleaving
 Used for layered materials
- Graphite, mica
Storing samples
• Dry and inert
atmosphere
• Old samples may be
polished again
Summary