Diffusionsvorgänge in festen Stoffen

In Situ and Operando Spectroscopy for Assessing Mechanisms of Gas Sensing

“…The second model explains the sensing effects by changes in the oxygen stoichiometry, that is, by the variation of the amount of the (sub-)surface oxygen vacancies and their ionization (reduction-reoxidation mechanism, Table 1). The origin of both models can be traced back to the 1950s, that is, to the mechanistic description of reactions in and on solid materials; [48,49] since then they have been repeatedly discussed in mechanistic studies (see, for example, references [2,66,87,88]). It must also be kept in mind that the mechanism may be influenced significantly by the materials and operating conditions (e.g.…”

“…[92-95, 102, 103] Nevertheless, diffusion at grain boundaries and at the surface can be much faster than bulk diffusion. [49] 3. From "Prototype Structures" to "Operating Sensors"…”

“…[227] From the changes in surface potential and work function, for example, dipole moments of adsorbed molecules were obtained, and conductivity measurements served as a simple and sensitive tool to follow adsorption much more accurately than by direct volumetric measurement. [40] The results of numerous electrical studies over more than 60 years on metal oxides can be found in many reviews and books (see, for example, references [41,43,44,[48][49][50]112] and references therein). In light of these activities, it is remarkable to read recent statements that "there have as yet been no studies on the effect of the conducting or defect properties of the catalysts on their catalytic behavior" [228] and that there is "an urgent need for better knowledge concerning the relation between the conducting properties of the bulk and of the surface region […] to obtain a fuller understanding of the connection between these properties and the catalytic behavior."…”

How Is Oxygen Incorporated into Oxides? A Comprehensive Kinetic Study of a Simple Solid‐State Reaction with SrTiO3 as a Model Material

“…[5] The treatment ranges from homogeneous reactions within solids to nonlinear kinetics of complex reactions. The special aspects of interfacial reactions including relevance for heterogeneous catalysis are considered for example, in references [6,7]. Recently, substantial progress was achieved in several respects, for example: 1) in the understanding of elementary chemical reaction steps at gassolid interfaces; [8][9][10][11][12] 2) in connecting elementary rate constants with effective parameters measured in relaxation kinetics; [13][14][15][16][17] 3) in including space charges into chemical diffusion; [18][19][20] 4) in taking into account coupling diffusion with internal reactions; [21,22] 5) in the study of complex and nonlinear processes.…”

Wie wird Sauerstoff in Oxide eingebaut? Kinetische Studie einer “simplen” Feststoffreaktion am Modellmaterial SrTiO3

“…Die besonderen Aspekte von Grenzflächenreaktionen einschließlich ihrer Bedeutung für die heterogene Katalyse werden etwa in Lit. [6,7] behandelt. In letzter Zeit wurden einige wichtige Fortschritte bei bestimmten Aspekten des Gebiets erzielt, z.…”