A PRACTICAL GUIDE FOR THE PREPARATION OF SPECIMENS FOR X-RAY FLUORESCENCE AND X-RAY DIFFRACTION ANALYSIS
EDITED BY
VICTOR E. BUHRKE The Buhrke Company
RON JENKINS International Centre for Diffraction Data
OEANE K. SMITH Pennsylvania State University
~ WI LEY-VCH . New York / Chichester / Weinheim / Brisbane / Singapore / Toronto
CONTENTS
PREFACE xxi
INTRODUCTION xxlli
1 GENERAL INTRODUCTION 1
1.1 Sampling / 1
1.1.1 What Is Sampling? / 1
1.1.2 Kinds of Materials Sampled / 3
1.1.3 Record Keeping / 3
1.1.4 Meaningful Sampling / 3
1.1.5 Sampling for Scientific Investigation / 4
1.1.6 Sampling for Analytical Truth / 4
1.1.7 Matching Sampling Methodology with Analytical Goals-Heterogeneity / 5
1.2 Basic Statistical Definitions / 7
1.2.1 Introduction / 7
1.2.2 The Representative Sample / 7
1.2.3 Mean / 8
1.2.4 Dispersion / 9
1.2.5 Sampling Errors / 11
1.2.6 Replication / 13
1.2.7 Practicalities and Compromises / 14
1.3 Obtaining a Representative Sample from the Bulle / 15
1.4 Sampling Procedures / 16
1.4.1 Cone and Quartering / 17
1.4.2 Alternate Sh~veling / 18
lx
X CONTENTS
1.4.3 Linear Japan Cake / 18 1.4.4 Riffle Splitting / 19 1.4.5 Sectorial Splitting / 19
1.4.6 The Holistic Approach to Sampling / 20 1.5 Methods of Comminuting Powders for X-ray Diffraction / 21
1.5.1 Requirements for an Ideal Specimen / 21 1.5.2 Ideal Particle Size for X-Ray Diffraction Applications / 22
1.6 Grinding for X-Ray Diffraction Applications / 22
1.6.1 Mechanical Grinding: Precautions and Considerations / 22
1.6.2 Dry Grinding for X-Ray Diffraction Applications / 23 1.6.3 Wet Grinding for X-Ray Diffraction Applications / 23 1.6.4 Types of Grinding / 25
1.6.5 Effects of Grinding / 26 1. 7 Absorption Problems / 26
1.7.1 Absorption ofX-rays / 26 1.7.2 Scattering and Diffraction of X-rays / 28 1.7.3 Absorption in X-ray Fluorescence / 30 1.7.4 Absorption in X-ray Diffraction / 30
1.8 Crystallinity and Particle Effects in X-ray Diffraction Applications / 31
2 SPECIME,N PREPARATION PROCEDURES IN X-RAY · FLUORESCENCE ANALYSIS
2.1 Common Problems in Preparing and Presenting Specimens for X-ray Fluorescence / 35 2.1.1 General / 35 2.1.2 Types of Samples Analyzed / 35
2.2 Presenting the Specimen to the Spectrometer / 36 2.2.1 Physical Form of the Specimen in X-ray Fluorescence
Analysis / 36 2.2.2 Specimen Placement / 37 2.2.3 Photochemical Decomposition / 38
2.3 Handling Samples Without Pretreatment / 39 2.4 Use of Pressed Powder Pellets / 40
2.4.1 General / 40 2.4.2 Direct Pelletizing of the Specimen / 40
2.5 Lithium and Sodium Tetraborate Fusion Methods / 41 2.5 .1 Advantages of Fusion / 41 2.5.2 Choice of Fusion Mixture / 42
35
CONTENTS XI
2.5.3 Choice of Reaction Crucible / 42
2.5.4 Controlling the Fusion Reaction / 44
2.6 Liquids and Solutions / 44
2 .. 6.1 General / 44
2.6.2 Preconcentration Methods / 45
2.6.3 Direct Methods / 46
2.6.4 Concentration by Evaporation / 46
2.6.5 Use of Ion-Exchange Resins / 47
2.7 Handling Very Small Samples / 47
2.7.1 Size of the Specimen in X-ra:; Fluorescence Analysis / 47
2. 7 .2 Direct Analysis of Limited Quantities of Sample / 49
2.8 Radioactive Samples / 51
2.9 Special Problems with Low Atomic NumberElements / 51
3 SPECIMEN PREPARATION IN X-RAY FLUORESCENCE 59
3.1 Whole Rock Analysis / 59
3.1.1 General / 59
3.1.2 Specimen Preparation Procedures / 60
3.1.3 Special Problemsand Hints / 64 3.2 Limes, Dolomitic Limes, and Ferrolimes / 65
3.2.1 General Discussion / 65
3.2.2 Sampling / 66
3.2.3 Specimen Preparation-Fused Glass Disk / 66
3.2.4 Results / 67
3.2.5 Discussion / 68 3.3 Limestones, Dolomites, and Magnesites / 68
3.3.1 General Discussion / 68
3.3.2 The Pressed Powder Method / 68
3.3.3 Determination of Carbon Dioxide, C02 / 70
3.3.4 Calibration Standards / 70
3.3.5 Results / 71 3.4 Natural and By-product Gypsum / 71
3.4.1 General Discussion / 71
3.4.2 Remarks / 71 3.4.3 Elements Determined / 72
3.4.4 Dehydration of Gypsum / 72
3.4.5 Drying of Gypsum / 72
3.4.6 Grinding / 72 3.4.7 Results / 75
XII CONTENTS
3.4.8 Reference Materials / 75 3.4.9 Discussion / 75
3.5 Glass Sands / 76 3.5.1 General Discussion / 76 3.5.2 Selection of a Representative Sample / 76 3.5.3 Fusion with Lithium Tetraborate and Lithium
Fluoride / 77 3.5.4 Discussion / 78
3.6 Cements, Clinker, and Raw Materials / 79 3.6.1 Types and Compositions of Cements / 79 3.6.2 Pressed Powder Briquet Preparation / 80 3.6.3 Fused Bead Preparation / 81 3.6.4 AS1M C 114 Qualification / 82
3.7 Preparation ofMetals / 83 3.7.1 Sampling / 83 3.7.2 Solubility of Elements / 83 3.7.3 Alloy Metallographie Structure / 85 3.7.4 Parameters Affecting the Analytical Surface Finish / 86 3.7.5 Effective Thickness and Volume / 87 3.7.6 Hardness / 88
3.8 Aluminum and Its Alloys / 88 3.8.1 Surface Preparation Techniques / 88 3.8.2 X-ray Fluorescence Tests / 89 3.8.3 Discussion of Selected Surface Preparation
Techniques / 90 3.9 Titanium / 92 3.10 Cast Iron / 93
3.10.1 General Discussion / 93 3.10.2 Specimen Preparation Procedure / 94
3.11 Steel / 95 3.11.1 Evaluation of Grinding Materials / 96 3.11.2 Special Problems and Hints / 98_
3.12 Aluminum-Bearing Materials / 100 3.12.1 General Discussion of the Problem / 100 3.12.2 Specimen Preparation Procedure / 101 3.12.3 Special Problemsand Hints / 101
3.13 Alumina / 102 3.13.1 General Discussion / 102 3.13.2 Specimen Preparation Procedure for Aluminas / 102
CONTENTS XIII
3.13.3 Fusion Specimen Preparation for Aluminas / 103 3.13.4 Special Problemsand Hints / 103
3.14 Bath Electrolyte / 103 3.14.1 General Discussion ofthe Problem / 103 3.14.2 Specimen Preparation Procedure for Bath Samples / 104 3.14.3 Special Problemsand Hints / 104
3.15 Surface Waters / 105 3.15.1 Use oflon-exchange Resins / 105 3.15.2 Coprecipitation Methods for Surface Waters / 106 3.15.3 Surface Adsorption / 106 3.15.4 Other Concentration Methods / 106
3.16 Oil Analyses / 106 3.16.1 General Discussion ofthe Problem / 106 3.16.2 Special Problemsand Hints for Oil Analyses / 107
3.17 Coal Derivatives-Pitch and Asphalts / 108 3.17.1 General Discussion ofthe Problem / 108 3.17 .2 Selection of a Representative Sample of Pitch or
Asphalt / 108 J. 17 .3 Preparation of Pitch Specimens / 109 3.17.4 Special Problemsand Hints / 112 3.17 .5 Particle Size Effect in the Analysis of Silicon in
Pitch / 112 3.17 .6 General Discussion / 114
3.18 Leaves and Vegetation / 115 3.18.1 General Discussion / 115 3.18.2 Selection of a Representative Sample of Leaves or
Vegetation / 116 3.18.3 Collection of Leaves from a Tree / 116 3.18.4 Specimen Preparation / 117 3.18.5 Discussion / 118
4 SPECIMEN PREPARATION IN X-RAY DIFFRACTION
4.1 Common Problems in Preparing and Presenting Specimens for X-ray Diffraction / 123
4.2 Geometries of Diffraction Equipment / 125 4.3 Properties of Materials and Samples / 128
4.3.1 Crystallite Statistics / 128 4.3.2 Specimen Configurations / 132
4.4 Effects of Crystal Properties on Specimens / 134
123
xlv CONTENTS
4.4.1 Crystallite Size and Patticle Size / 134 4.4.2 Specimen and Sample Homogeneity / 134 4.4.3 Crystallite Perfection and Peak Shapes / 135 4.4.4 Peak Resolution in Complex Patterns / 136 4 .4.5 Particle Shapes and Preferred Orientation / 136
4.4.6 Absorption Effects and Depth of Penetration / 137
4.4. 7 Microabsorption / 138 4.4.8 Background / 139 4.4.9 Surface Roughness / 140 4.4.10 Crystal Perfection and Extinction / 140
4.5 Preparing Specimens for Simple Routine Analysis / 141 4.5.1 Goal of Specimen Preparation / 141 4.5.2 Fiat Specimen Supports / 141 4.5.3 The Cavity Mount / 142 4.5.4 Slurry Mounts / 143 4.5.5 Alternative Cavity Mounting Techniques, Back-loading
Cavity Mounts / 145 4.5.6 Alternative Cavity Mounting Techniques, Side-Drifted
Specimens / 148 4.5.7 Alternative Fiat Surface Techniques, Top Dusted
Mounts / 149 ·
4.5.8 Creating Spheroidal Particle Aggregates / 151 4.5.9 Bonded Specimens / 151
4.6 Preparing Specimens for Reference Patterns / 152 4.6.1 Preliminary Pattern / 152 4.6.2 Preparing Specimens for Accurate d-spacing
Measurements: Background Information / 153 4.6.3 Thin Specimen on Fiat Support / 154 4.6.4 Interna! Standard Pattern / 155 4.6.5 Intensity Patterns / 156 4.6.6 Long Duration Pattern / 156 4.6.7 Reference-Intensity-Ratio Pattern / 157
4.7 Processing Small Samples for Diffractometry / 157 4.7.1 Collecting or Concentrating Material for Analysis / 158 4.7.2 Preparing the Specimen / 160 4.7.3 Concentrating Phases in Large Bulle Samples / 161 4.7.4 Preparation ofMounts for Diffractometry / 161
4.8 Procedures for Specimen Preparation by Aerosol Suspensions / 162 4.8.1 lntroduction / 162
CONTENTS XV
4.8.2 Simple Aspirator Bottles / 163
4.8.3 Tubular Aerosol Suspension Chamber (TASC) / 165
4.8.4 Microhood for Special Materials / 169
5 SPECIFIC AREAS OF SPECIMEN PREPARATION IN X-RAY POWDER DIFFRACTION 171
5.1 Ceramics / 171
5.1.1 Powders of Stahle and Common Ceramics / 171
5.1.2 Specimen Mounting of Ceramic Materials / 172 5.1.3 Atmospheric-sensitive or Toxic Ceramics / 172
5.1.4 Ceramic Compacts or Ceramic Thin Films / 174 5.2 Preparation of Bulk Metals and Alloys / 175
5.2.1 General Discussion of the Problem / 175
5.2.2 Specimen Preparation Procedures for Metals / 175
5.2.3 Special Problems and Hints / 177 5.2.4 Step-by-step Procedure for Metals / 178
5.3 Minerals / 179 5.3.1 Analysis ofMinerals / 180
5.3.2 Beneficiation of Minerals / 180 5.3.3 Identification of Sedimentary Minerals / 183 5.3.4 Determination of Crystalline Silica / 183
5.4 Aluminum Ores / 185 5.4.1 Grinding Samples of Aluminum Ores / 186 5.4.2 Packing ofthe Specimen / 187
5.5 Clays / 187
5.5.1 lntroduction / 187 5.5.2 Specimen Preparation of Clays / 188
5.5.3 Pretreatment of Clays / 188
5 .5 .4 Size Separation of Clays / 190 5.5.5 Slide Preparation and Analysis of Clays / 193
5.6 Preparation of Zeolites for X-ray Diffraction / 196 5.6.1 Introduction / 196 5.6.2 Dehydrated Zeolites / 196
5.6.3 Zeolite Equilibration / 196 5.6.4 Effect of Cations in Zeolites / 197 5.6.5 Particle Size and Preferred Orientation in Zeolites / 198
5.7 Air-sensitive Samples / 199 5.7.1 Alkali and Alkaline-earth Metals / 199 5.7.2 Samples Stored under Water / 199
XVI CONTENTS
5.7.3 Other Samples / 199 5.8 Thin Films / 200
5.8.l lntroduction / 200 5.8.2 Specimen Holders / 201 5.8.3 Specimen Preparation Methods for Thin Films / 201
5.9 Microsamples / 205 5.10 Forensic Samples / 207
5.10.1 Preparation of Debye-Scherrer Specimens for Forensic Work / 208
5.10.2 Preparation of Gandolfi Specimens / 210 5.11 Paper and Plastics / 210
5 .11.1 Small Samples / 210 5.11.2 Intermediate Sized Samples / 210 5.11.3 Large Samples / 211
5.12 Gemstones / 211 5.13 Energetic Materials / 212
5.13.1 Preparation of Specimens from Energetic Materials / 213 5.13.2 Special Precautions in Dealing with Energetic
Materials / 213 5.13.3 Reducing the Size ofLarger Energetic Specimens / 214
6 SPECIAL PROBLEMS IN THE PREPARATION OF X-RAY DIFFRACTION SPECIMENS 21 7
6.1 High Pressure Studies / 217 6.1.1 Diamond Anvil Cells / 217 6.1.2 Specimen Preparation for the Diamond Anvil Cell / 219 6.1.3 Large Volume High Pressure-Temperature Devices / 220 6.1.4 Pressure Medium / 220 6.1.5 X-ray Diffractic,n Pressure Calibrants / 223 6.1.6 High Pressure Work with Synchrotron Sources / 223
6.2 Specimen Preparation and Laboratory Procedures for Residual Stress and Strain Determination by X-ray Diffraction / 224 6.2.1 Specimen Preparation for Stress Measurements / 225 6.2.2 Mounting Procedures / 226 6.2.3 Specimen Displacement Errors / 228 6.2.4 Parallel-beam Optics / 230 6.2.5 Sequence of Procedures in Conducting Stress
Measurements / 234 6.3 Measurements on Single Crystals / 237
CONTENTS XVII
6.3.1 ldentification of Crystal Faces / 238
6.3.2 Orientation of Single Crystal Specimens / 239
6.3.3 Example of an Orientation Experiment / 240 6.3.4 Final Cornments / 241
6.4 Unusual Tricks with Unusual Samples / 242 6.4.1 Isolation of Material / 242 6.4.2 Reactive Materials / 242 6.4.3 Taxie Materials / 243 6.4.4 Radioactive Materials / 243 6.4.5 Flowing Materials / 244
6.4.6 High Temperature Diffraction / 244 6.4. 7 Low Temperature Diffraction / 245 6.4.8 Organic Materials / 245 6.4.9 Bulk Specimens for the Diffractometer / 245
6.5 Preparing Specimens for the Synchrotron / 246 6.5.1 Effects of Data Recording / 246 6.5.2 Intensity Values / 246 6.5.3 Importance of Proper Alignment / 246 6.5.4 Statistics Applied to Samples and Sampling / 247 6.5.5 Methods for Commuting Powders / 247
6.5.6 Preparing Specimens for Simple Routine Analysis / 247 6.5.7 Use of Standards in X-ray Diffraction Analysis / 247
6.5.8 Preparing Specimens for Accurate d-spacing Measurements / 248
6.5.9 Preparing Specimens for Accurate Intensities / 248
7 SPECIMEN PREPARATION FOR CAMERA METHODS
7 .1 Tue Debye-Scherrer Camera / 253 7 .1.1 Geometry of the Debye-Scherrer Camera / 253 7 .1.2 Preparing Mounts for the Debye-Scherrer Camera / 253
7.1.3 Self-supporting Specimens / 254 7 .1.4 Rod Mounted Specimens / 254 7 .1.5 Capillary Mounts for the Debye-Scherrer Camera / 256 7.1.6 Preparing Debye-Scherrer Specimens for Nonambient
Measurements / 257 7.2 The Gandolfi Camera / 257
7.2.1 Gandolfi Mounts / 258 7 .2.2 Handling Very Small Specimens in the Gandolfi
Camera / 258
253
XVIII CONTENTS
7.3 The Guinier Camera / 260
7.3.1 Mounting the Specimen in the Guinier Camera / 261
7.3.2 Foils and Glues / 261
7.3.3 Moving the Specimen in the Guinier Camera / 262
7.3.4 Capillary Techniques with the Guinier Camera / 262
7.3.5 Nonambient Temperatures-High Temperatures / 263
7.3.6 Nonambient Temperatures-Low Temperatures / 264
8 SPECIMEN PREPARATION EQUIPMENT 265
8.1 lntroduction / 265
8.2 Grinding and Pulverizing Equipment / 265
8.2.1 Large Crushing and Pulverizing Equipment / 266
8.2.2 Splitters / 268
8.2.3 Mills / 268
8.2.4 Mortars / 268
8.3 Special Equipment / 269
8.3.1 Presses / 269
8.3.2 Fluxers / 270
8.3.3 Aerosol Suspension Devices / 270
8.3.4 Liquid Specimen Holders / 271
8.3.5 Metallic Specimens / 271
8.4 Preparing X-ray Diffraction Specimen Holders / 272
8.4.1 Specimen Holders for Large Specimens / 273
8.4.2 Specimen Holders for Small Specimens / 273
8.5 Recovering Damaged Platinum Ware / 273
8.5.1 General Hints on the Use of Platinum Crucibles / 273
8.5.2 Discussion of the Problem / 27 4
8.5.3 Repair Procedure / 274
8.5.4 Special Problems and Hints / 275
8.6 Specimen Preparation Kit for X-ray Diffraction / 276
8.6.1 Kit for Preparing Specimens / 276
8.6.2 Sources for Kit Items / 278 8.7 Equipment for Preparation of Zeolite Specimens / 279
8.7.1 Equipment Suppliers, Zeolite Preparation / 279 8.8 Vendor Addresses / 280
9 USE OF STANDARDS IN X-RAY FLUORESCENCE ANALYSIS 285
9.1 Standards-An Overview / 285
9.1.1 lntroduction / 285
CONTENTS xlx
9.1.2 Definitions / 286
9.1.3 Catalogues / 287
9.1.4 Origin and Types / 287
9.1.5 Preparation Procedure / 288
9.1.6 Certificate Evaluation / 288
9.1.7 Applications / 289
9.1.8 Conclusion / 296 9.1.9 Monitor Samples / 296
9.1.10 Procedure / 300
9.1.11 Frequency of Monitor Measurement / 302
9.2 Recalibration / 305
9.2.1 Introduction / 305
9.2.2 Quality Standard Programs / 305
9.3 Instrumental Short- and Long-term Drift / 306
9.3.1 Overview / 306
9.3.2 Recalibration / 307
9.3.3 Specimens Used for Drift Correction and Recalibration / 308
9.4 Sources for Reference Materials for X-ray Diffusion and X-ray Fluorescence / 308
9.4.1 Office of Standard Reference Data / 308
9.4.2
9.4.3
9.4.4
GLOSSARY
BIBLIOGRAPHY
INDEX
Alternate Sources of Standard Materials / 309
Sources for X-ray Fluorescence Standards / 309 • Addresses for Sources ofX-ray Fluorescence and X-ray
Diffraction Standards / 310
313
321
327
