Table Of ContentMinerals and Rocks
11
Editor in Chief
P.1. Wyllie, Chicago, Ill.
Editors
W. von Engelhardt, Tlibingen . T. Hahn, Aachen
Werner Smykatz-Kloss
Differential Thermal
Analysis
Application and Results in Mineralogy
With 82 Figures
Springer-Verlag Berlin Heidelberg New York 1974
Dr. Werner Smykatz-Kloss
Mineralogisches Institut der Universitiit
7500 Karlsruhe/W. Germany
Volumes 1 to 9 in this series appeared under the title
Minerals, Rocks and Inorganic Materials
Library of Congress Cataloging in Publication Data
Smykatz-Kloss. Werner. 1938-
Differential thermal analysis.
(Minerals and rocks, v. 11)
Bibliography: p.
I. Thermal analysis. 2. Mineralogy, Determinative.
I. Title.
QE369D5S58 549',133 74-17490
ISBN-13: 978-3-642-65953-9 e-ISBN-13: 978-3-642-65951-5
DOT: 10.1007/978-3-642-65951-5
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© by Springer-Verlag Berlin· Heidelberg 1974.
Softcover reprint of the hardcover 1st edition 1974
The use of registered names. trademarks. etc. in this publication does not imply. even in the absence of a specific
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Dedicated to
Elvira, Verena, Bettina, and Nadine
Preface
At first glance it may seem presumptuous to want to add yet
another to the numerous books on Differential Thermal Analysis (DT A).
Thermoanalytical methods have been in use for some time, as shown by
the more than five thousand publications containing DTA or TG
curves listed by SMOTHERS and CHIANG in the bibliography to their
handbook and abstracted in the several volumes of Thermal Analysis
Abstracts (TAA), edited by J.P.REDFERN for the International Con
federation for Thermal Analysis (ICT A). Every three years the proceed
ings of ICTA meetings are published, bringing the latest results of
thermoanalytic research. There is also the Scifax DT A Data Index, edited
by R. C. MACKENZIE (1962) and modeled on the ASTM pattern card
index (used for X-ray investigations), a compilation of the DTA data
for several hundred minerals, and inorganic and organic materials. The
theoretical foundations of thermogravimetry and DTA have been
described in detail by LEHMANN, DAS and PAETSCH (1953), R.C.
MACKENZIE (1957, 1970), DUVAL (1963), WENDLANDT (1964), GARN
(1965), F.PAULIK et al. (1966), SMOTHERS and CHIANG (1966), and
KEATTCH (1969).
Thermoanalytical results are strongly influenced by various factors
relative to preparation and equipment (see 1-2.4 of this study). This is
the reason why we frequently find, in these books as well as in the
Scifax-Card catalog, contradictory data on the same substance. Mineral
ogical publications and textbooks therefore often stress that: "It is
possible only in rare cases, and even here only in specific questions, to
clearly identify a mineral by means of DT A alone" (GERMAN MULLER,
1964); that: "It is not possible to obtain an accurate quantitative
determination of the amount of a mineral in a sample by means of the
DT A method" (V AN DER MAREL, 1956); or: "Finer distinctions and
hence total mineral determination of ceramic raw materials can only
be obtained if DT A is supplemented by other analytical methods,
specifically X-ray diffraction" (LIPPMANN, 1959). Several authors have
published differing DT A curves for similar minerals, and these have some
times been interpreted to mean that the minerals reflect chemical or
genetic differences, even though no such distinctions would be found
VIII Preface
under truly comparable test conditions. Many publications give incom
plete descriptions of sample preparation and analysis and such details are
often omitted. A comparison of DT A data on minerals is thus possible
only on a limited basis or not at all, so justifying the above-quoted
statements of G. MULLER, LIPPMANN or V AN DER MAREL. With regard
to mineralogy, the best textbooks on thermoanalysis frequently merely
survey the application of DT A, i.e. they show characteristic curves for
particular mineral types and list the often widely differing data found in
the literature. It is not often that the causes of these differing data are
discussed, as for example they are in the chapter on carbonates by
WEBB and KRUGER in MACKENZIE'S Differential Thermal Analysis, Vol. 1
(1970). The disadvantage of all handbooks, even those as carefully
compiled as MACKENZIE'S (1957, 1970, 1972), is that they collect and
compare the data of many authors obtained under differing conditions
of analysis. It is the present author's opinion that, where an analytical
method depends so much on the equipment and procedure used as does
DTA , one analyst should be asked to work out the DT A charac
teristics of the most important minerals under the conditions recom
mended by leTA and other bodies. The assignment should include
consideration and standardization of all the factors that can influence
the shape of DT A curves and their data. Part II of this monograph
tackles this problem by facilitating the identification systematics by
means of procedural improvements and supplements (cf. 1-2.52; II-lO).
Part III of this book concerns special mineralogical applications of
DT A beyond the "usual" scope of qualitative and semiquantitative
mineral determinations, i.e. the relevance of DT A measurements to the
results of crystal chemistry, crystal physics, or petrology. The examples
given in Part III for the application of DT A to chemical composition,
degree of disorder, or formation of minerals constitute the first steps.
There must still be numerous investigative possibilities connected directly
with the field of mineralogy. For instance, DT A could be used to
some extent for clarification of structural order-disorder phenomena, for
detection of high-temperature modifications that are unstable at low
temperatures, and for studying variations in thermal behaviour due to
mixed-crystal formation, diadochy, etc.
DT A, originally a mineralogic method, is now used more frequently
in other fields of scientific research, whereas in mineralogy it is employed
almost exclusively for routine determinations. About 1930, more than
80% of all DT A determinations dealt with mineralogical matters; today
the proportion of DT A publications relating to all earth sciences
amounts to only 2 to 5%. This decrease is clearly evident from the two
specialized periodicals, Journal oj Thermal Analysis and Thermochimica
Acta. Of the approximately 180 papers given at the International
Preface IX
Coriference on Thermal Analysis in Davos (ICTA III, August 1971) only
10, and of the 305 papers given in Budapest (ICT A IV, July 1974) only
24 dealt with the geosciences. The emphasis of thermoanalytical research
seems to have shifted to the fields of chemistry and materials science.
The main reason why mineralogists neglect the DT A method is, in the
author's opinion, because the possibilities for the application of
differential thermal analysis to mineralogy are still far too little known.
The results of this study were obtained during the years 1966 to
1973 when the author was working in the mineralogical institutes of
the universities of Gottingen and Karlsruhe. I wish to thank all the
members of these institutes for their support, especially C. W. CORRENS
(Gottingen), E. ALTHAUS and H. WONDRATSCHEK (Karlsruhe) for many
critical discussions, H. U. BAMBAUER (MUnster), R. BEISING (Stuttgart),
W. ECHLE (Aachen), F.-J. ECKARDT and P. MULLER (Hannover), M.
GRAMSE, V. KUPl:IK, R. KURZE, G. MENSCHEL, K.-H. NITSCH, and R.
USDOWSKI (Gottingen), K. KAUTZ (Essen), H. KULKE (Bochum), F. LIPP
MANN (TUbingen), H. MEIXNER (Salzburg), R. METZ (Karlsruhe), G. MUL
LER (Heidelberg), K. H. SCHULLER (Selb), and H.-J. TOBSCHALL (Mainz)
for sample material, S. EBEL, R. EMMERMANN and U. LENNARTZ for che
mical analysis, R. BENDER and R. BENJES for typing the manuscript,
U. FRANK, B. LEST!, H. SCHNITTKA, and H. SIEGEL (all in Karlsruhe) for
drawing the figures.
Karlsruhe, September 1974 W. SMYKATZ-KLOSS
Contents
Part I. Methods
1. Thermogravimetry and Differential Thermal Analysis 1
2. Heat Changes and Their Measurement in DT A 2
2.1 Cause of Heat Changes . . . . . . . . . . 2
2.2 DT A Apparatus . . . . . . . . . . 3
2.3 Characteristics of DT A Curves and DT A Data 4
2.4 Factors Which Influence DTA Data 5
2.4.1 Furnace Atmosphere 5
2.4.2 Sample Arrangement 6
2.4.3 Thermocouples . 6
2.4.4 Heating Rate . . . 7
2.4.5 Reference Material 7
2.4.6 Grain Size and Packing Density 8
2.4.7 Amount of Sample ..... 8
2.4.8 Preparative Factors ..... 10
2.5 The Technique of Measurement and of Standardization 10
2.5.1 Recommendations of ICT A for the Publication of
Thermoanalytical Data .......... 10
2.5.2 Standardization and Indirect Characterization by
Means of PA-Curve and Standard Temperature 11
3. Calibration and Exactness of Measurement . . . . . . . . 13
3.1 Calibration . . . . . . . . . . . . . . . . . . . . 13
3.2 Exactness and Reproducibility of Measurements . . . . 15
3.3 Improvement of the Exactness of Measurement Using
Internal Standards 16
3.4 Sensibility of Proof . . . . . . . . . . . . . . . . . 17
XII Contents
4. Quantitative Determinations by DT A . . . 18
4.1 Difficulties in Quantitative DT A Determinations of
Minerals ............. 18
4.2 Determination of Thermodynamic Data 19
4.2.1 Equilibrium Temperatures 19
4.2.2 Heat of Reaction, LI H ..... 20
5. Methods Combined with DT A 21
+
5.1 DT A High-Temperature X-Ray Analysis 21
5.2 DT A + High-Temperature Microscopy 21
5.3 High-Pressure DT A ........ . 21
+
5.4 DT A Mass Spectrometer ..... . 22
5.5 Other Methods Related to or Combined with DTA 22
Part II. Application of Differential Thermal Analysis to Mineral
ogy: Identification and Semi-Quantitative Determination of
Minerals ....... . 24
1. Elements and Chalcogenides 24
1.1 Elements 24
1.2 Chalcogenides 25
2. Halogenides and Sulfates 31
2.1 Halogenides 31
2.2 Sulfates 33
3. Oxides and Hydroxides 36
3.1 Oxides . . . . . 36
3.2 Hydroxides 37
3.3 Soils and Iron Ores 40
4. Carbonates and Nitrates 41
4.1 Carbonates Free of Water and without Other Anions 43
4.2 Carbonates Free of Water with Other Anions 48
4.3 Hydrated Carbonates without Other Anions 50
4.4 Hydrated Carbonates with Other Anions 53
4.5 Nitrates .............. . 57
Contents XIII
5. Borates, Phosphates, and Arsenates 57
5.1 Borates ....... 57
5.2 Phosphates and Arsenates 57
6. Ortho-, Ring-, and Chain Silicates . . . . . . . . . . . . 63
7. Sheet Silicates .................... 64
7.1 Kaolinites ............ . 64
7.2 Pyrophyllite and Talc . . . . . . . . . 67
7.3 Montmorines (Smectites) and Vermiculites 69
7.4 Micas 71
7.5 Chlorites .. . . . . . 73
7.6 Serpentines . . . . . . 78
7.7 Palygorskite and Sepiolite 79
7.8 Clay Minerals with Mixed-Layer Structure 81
7.9 Mixtures of Sedimentary Minerals ("Clays") 84
8. Zeolites ....................... 88
9. Allophane, Opal, and Organic Matter of Soils and Sediments 91
10. Development of Identification Diagrams ......... 93
Part III. Special Application of Differential Thermal Analysis in
Mineralogy: Statements about Chemical Composition, Degree
of Disorder, and Genesis of Minerals . . . . . . . . . . . 107
1. Influence of the Chemical Composition on the Decomposition
Temperatures of Carbonates and Hydroxides 107
1.1 Substitution of Ca ++ by Mg + + or Pb ++ in Calcites 108
1.2 Substitution of Ca ++ by Sr ++, Ba ++, and Pb ++ in Aragon-
ites ....................... 109
1.3 Substitution of Mg++ by Fe++ and Mn++ in Dolomites 111
1.4 Hydrozincite and Aurichalcite ............ 114
1.5 The Incorporation of Al + + + into the Structure of Goethite 114
