Walter Schottky

Walter SchottkyIn existographies, Walter Schottky (1886-1976) (IQ:#|#) (CR:1) was a German physicist, electrical engineer, and thermodynamicist, noted for []

Overview
In 1929, Schottky, in his Thermodynamics: The Theory of the Circular Processes of Physical and Chemical Changes and Equilibria, according to the standard established published "characteristic function tables" (see: characteristic function notation table), was, supposedly, the first to employ the symbol " G", in honor of Willard Gibbs, for the the isothermal, isobaric chemical potential; the gist of the assignment, barring a full English translation of his book, seems to have occurred in his section "Chemical Potential", where he first derives:

Schottky 1

calling W the the "absolute warm function" (absolute warmefunktion) or "absolute heat function" (or "heat content", is it was called prior to 1908), which he defines as follows:

Schottky 2

which we now call "enthalpy", the name Heike Onnes gave to this function in 1909. With substitution of Schottky's warm function, aka Onnes enthalpy function, we have:

Schottky 3

With division by T, we have:

Schottky equation 4f

which, of course, is the now-standard formula for Gibbs free energy. Schottky, however, concludes with the following formula:

Schottky 5

which, when T is divided through, yields the following:

Schottky 6

This specific definition of the isothermal-isobaric free energy, of note, was adopted that year by Ralph Fowler, in his Statistical Mechanics (1929), to represent the isothermal-isobaric chemical potential. At this point, however, a certain amount of terminological confusion arose, largely as a result of Francois Massieu (1869) using the Greek letter notation of – tψ’ (minus T psi primed) for the same function, a notation style Gibbs (1876) adopted, naming the same function ζ (zeta), which was named Φ (Phi) by Pierre Duhem (1897), and – Tψ (minus T psi) by Max Planck (1897), Schottky's PhD professor, ζ (zeta) by Otto Sackur (1912), Z by Percy Bridgman (1914), F by Gilbert Lewis (1923), Z by James Partington (1924), H by Theopile de Donder (1926), F by John Butler (1928), and finally, at last, ‘G’ by Schottky, which in 1933, in Edward Guggenheim’s Modern Thermodynamics, the book which solidified chemical thermodynamics, as we now define it, became the ‘by definition’ symbol of the isothermal-isobaric free energy, in honor of Gibbs.

The following is a translation of one of the opening pages of Schottky's Thermodynamics, so to give a glimpse of his deep thinking mindset: [1]

German (pg. 3)English (pg. 3)
wohl von A. HORSTKANN (1869, 1872/77)2. Eine sehr allgemeine, aber zugleich etwas abstrakte Behandlung hat das mit der Frage der chemischen Arbeiten zusammenhängende Problem des chemischen Gleichgewichts durch WILLARD Gams 1876/78' erfahren, und etwas später entwickelt H. v. Hnwionz3 aus Untersuchungen über die Temperaturabhängigkeit der elektromotorischen Kräfte den Begriff der Freien Energie, der sich schneller als die noch umfassenderen Ginsschen Überlegungen auch in der Praxis Eingang verschafft. Bei allen diesen Betrachtungen, die dann später u a durch VAN'T Hon, PLANCK, NERNST mit so großem Erfolge fortgeführt wurden, handelt es sich methodologisch, gleichwie in der physikalischen Thermodynamik, um eine Anwen-dung der allgemeinen außenthermodynamischen Beziehungen auf individuelle Ar-beits- und Wärmeeffekte des Systems.

Der einzige Unterschied besteht darin, daß es jetzt die Arbeits- und Wärmeeffekte bei einer chemischen Umsetzung, nicht mehr nur bei einer physikalischen Veränderung, sind, die der thermodynamischen Untersuchung unterzogen werden. Jedoch, ebenso wie in der „Physikalischen Thermodynamik", liefert auch in der „Chemischen" die Anwendung der außen-thermodynamischen Sätze auf die verschiedenen chemischen Veränderungen nur einen Bruchteil der zur völligen Kenntnis der Arbeits- und Wärmeeffekte benötig-ten Aussagen, und ebenso wie dort sieht sich der Forscher auch hier dem Problem gegenüber, die thermodynamisch nicht ableitbaren Gesetze für die spezifischen Arbeits- und Wärmeeffekte auf anderem Wege zu gewinnen: durch Empirie, molekularkinetische Betrachtungen, Statistik.

Als konsequenter Pfadsucher auf diesem Gebiet ist z. B. I. P. vAN DER WAALS zu nennen, der immer von neuem auf die Ergänzungsbedürftigkeit der rein thermodynamischen Beziehungen hinweist. Ein Theorem, dessen allgemeiner Charakter nur durch gewisse Bedingungen in der Wahl der ilun unterworfenen Systeme eingeschränkt wird (III, § 12), verdanken wir W. NERNST5, 1906, und in neuester Zeit ist es die statistische Mechanik und Quantentheorie, die weitere Einsichten und Aufschlüsse in Richtung des von NERNST beschrittenen Weges versprechen.

Dabei darf man nicht vergessen, daß die Begründer der chemischen Thermo-dynamik, voran W. GIBBS, noch einen großen Teil ihrer Gedankenarbeit einem Problem zuwenden mußten, das zwar schon in Angriff genommen, aber noch nicht gelöst worden war: dem Problem der quantitativen Erfassung chemischer Vorgänge überhaupt, dem Problem der Meßgrößen, durch welche der Fortschritt einer chemischen Umwandlung angegeben werden konnte, mathematisch ge-sprochen, dem Problem der „unabhängigen Variabeln" des Systems.


Auch heute noch tritt die Frage nach der Wahl und Bestimmung dieser Meßgrößen an keiner anderen Stelle mit derartiger Schärfe auf, wie in der chemischen Thermodynamik, und so ist denn die Darstellung einer chemischen Thermodynamik auch noch mit diesem Problem beschwert, das nicht ohne tiefes Eingehen auf das Wesen der chemischen Umsetzungen, insbesondere vom molekulartheoretischen Standpunkt aus, gelöst werden kann. Groß ist aber dafür auch der praktische Gewinn, den die Beherrschung einer so gründlich angefaßten chemischen Thermodynamik dem chemischen Forscher
probably by August Horstmann (1869, 1872/77) 2. The problem of chemical equilibrium associated with the question of chemical work was given a very general, but at the same time somewhat abstract treatment by Willard Gibbs in 1876/78, and a little later Hermann Helmholtz from studies on the temperature dependence of the electromotive forces the term free energy, which gets into practice faster than the even more extensive Gibbsian considerations. All of these considerations, which were later continued with such great success, among others, by Van't Hoff, Planck, Nernst, are methodologically, as in physical thermodynamics, an application of the general external thermodynamic relationships to individual work - and heat effects of the system.


The only difference is that it is now the work and heat effects of a chemical reaction, not just a physical change, that are subjected to the thermodynamic study. However, just like in "physical thermodynamics", in "chemical" the application of the external thermodynamic theorems to the various chemical changes provides only a fraction of the statements required for complete knowledge of the work and heat effects, and also there the researcher is faced with the problem of obtaining the thermodynamically non-derivable laws for the specific work and heat effects in another way: through empiricism, molecular kinetic considerations, statistics.

As a consistent path finder in this area, e.g. Johannes van der Waals, who always points out anew that the purely thermodynamic relationships need to be supplemented. We owe a theorem whose general character is limited only by certain conditions in the choice of the systems subject to ilun (III, § 12), Walther Nernst, 1906, and more recently it is statistical mechanics and quantum theory, which provides further insights and promise information in the direction of the path followed by Nernst.


It should not be forgotten that the founders of chemical thermodynamics (see: founders of chemical thermodynamics), especially Gibbs, still had to devote a large part of their thought work to a problem that had already been tackled but had not yet been solved: the problem of quantitative recording chemical processes in general, the problem of measured variables, by means of which the progress of a chemical conversion could be indicated, mathematically spoken, the problem of the "independent variables" of the system.

Even today the question of the choice and determination of these measured variables does not arise on anybody elsewhere with such acuity, as in chemical thermodynamics, and so the representation of chemical thermodynamics is also still burdened with this problem, which cannot be solved without going deeply into the nature of chemical reactions, especially from the molecular theoretical point of view But the practical gain that the researcher of such a thorough chemical thermodynamics ...









Schottky, in retrospect, is the eponym of a number of important things: “Schottky diode” (c.1928) and “Schottky barrier” in electrical engineering (c.1928), the “Schottky anomaly”, a peak of heat capacity, and “Schottky system” (Muschik, 1990), in thermodynamics, to name a few.

Education
In c.1908, Schottky completed his BS in physics at the University of Berlin, then in 1912 completed his PhD, under Max Planck, on the topic of “Relative Theoretical Energetics and Dynamics”. He then went to the University of Jena, where he studied under physicist Max Vienna, where he experimentally prove his theoretically derived his U 3/2 law for the glow electron current in electron tubes (Schottky equation). Then he went back to University of Berlin to habilitate, but then switched to work at Siemens in 1916, after which, while remaining tied to Siemens, he submitted his postdoctoral thesis on “thermodynamics of rare conditions in the steam room; thermal ionization and thermal glow” (Thermodynamik der seltenen Zustände im Dampfraum (Thermische Ionisierung und thermisches Leuchten)) at the University of Wurzburg in 1920. He then became professor of theoretical physics at the University of Rostock form 1923 to 1927, after which he returned to “Siemens & Halske in Berlin to work in their scientific laboratories, where he conducted research on semiconductor physics and electronics.

Quotes | On
The following are quotes on Schottky:

Schottky's interest in thermionic emission, in connection with thermionic valves, led to fundamental considerations of the thermodynamics of charged particles and to the development of the so-called ‘electrochemical potential’ (equal to the Fermi energy) as a determinant of thermodynamic equilibrium. This was an extension of the basic treatment of equilibrium by J. W. Gibbs. In essence, the equilibrium of a system demands that charged particles be in equilibrium both in their roles as particles of a chemical system and as charge carriers; that is, the electrochemical potential throughout the system should be equal and free of gradients. One of the results of Schottky's preoccupation with thermodynamics, was the realization that lattice vacancies and other singularities were subject to statistical treatment. The equilibrium density of lattice defects can thus be calculated. One result of this work is the name given to lattice vacancies: ‘Schottky defect’. The occupancy of localized electronic states is similarly determined by their position in relation to the electrochemical potential and by the temperature.”
— Ernest Braun (1992), “Selected Topics from the History of Semiconductor Physics and its Application” [2]

References
1. Schottky, Walter. (1929). Thermodynamics: The Theory of the Circular Processes of Physical and Chemical Changes and Equilibria (Thermodynamik: Die Lehre von den Kreispro?essen den Physikalischen und Chemischen Veränderungen und Gleichgewichten) (§: The Chemical Potential (Die chemischen Potentiale), pgs. 213-; Gibbs, 5+ pgs). Springer, 2013.
2. Braun, Ernest. (1992). “Selected Topics from the History of Semiconductor Physics and its Application”, in: Out of the Crystal Maze: Chapters from the History of Solid State Physics (editors: Lillian Hoddeson, Ernest Braun, Jurgen Teichmann, Spencer Weart) (§7:443-88; Schottky, pg. 449). Oxford.

Further reading
● Muschik, Wolfgang. (1990). Aspects of Non-Equilibrium Thermodynamics: Six Lectures on Fundamentals and Methods (Schottky, 5+ pgs). World Scientific.
● Fegley, Bruce; Osborne; Rose. (2013). Practical Chemical Thermodynamics for Geoscientists (Schottky, 5+ pgs). Academic Press.
● Machlin, Eugene. (2010). An Introduction to Aspects of Thermodynamics and Kinetics Relevant to Materials Science (Schottky, 5+ pgs). Elsevier.

External links
Walter Schottky – Wikipedia.
● Walter Schottky (German → English) – Wikipedia.

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