Vacancies, which only represent empty sites, have zero mass and do not count. Also includes optional information about diffusion in nonstoichiometric oxides. Introduction into defect studies in ceramic materialsiii positron. In 1972 per kofstad published his nonstoichiometry, diffusion and electrical conductivity in binary metal oxides. V denotes vacancy l site in the original perfect lattice. Synthesis of visible light responsive iodinedoped mesoporous. Fundamentals of solid state ionics i defect chemistry. Using kroger vink notation, write a defect equation describing a reaction with the atmosphere oxygen in titanium dioxide which generates holes. In modern defect chemistry, we use krogervink notation after kroger and vink. This video discusses technique of writing a balanced defect reaction. Nov 21, 2003 defect reaction equations using krogervink notation. Write out the kroger vink notation for the following defect reactions. The structure of materials an introduction to materials.
I use chemformula from the chemmacros bundle because it lets you customize the size of the dots and the amount of horizontal shift of superscripts. Schottky defects consist of chargecompensating anion and cation vacancies. Cation and anion vacancies must be formed in the stoichiometric ratios, and if so, we find that the effective charges are automatically balanced. Defect chemistry and defect equilibria krogervink notation in a metal oxide mo 2. Fluorite structures caf2, srf2, zro2, uo2 are good at accommodating anion frenkel defects. Lecture notes thermodynamics and kinetics of materials. Effect of ca on the properties of gddoped ceria for itsofc.
Optimization of ionic conductivity in doped ceria using. Lecture notes massachusetts institute of technology. Following tables provide the most common notations. Kroger vink notation we will now start to consider defects as chemical entities we need a notation for defects. Dec 09, 2008 hi all im having some trouble trying to understand the kroger vink notation the following example is of donor doping for semi conductor, extrinsic the first equation is meant to be elecronic compenstaion while the bottom equation is ionic compensation. A simple and important expression for treating ionic conductivity, 1ir is as the product of the concentration, ci, of mobile species interstitial ions or vacancies, their charge, q and their mobility. Optimization of ionic conductivity in doped ceria using density functional theory and kinetic lattice monte carlo by shahriar anwar a dissertation presented in partial ful. In modern defect chemistry, we use kroger vink notation after kroger and vink. Xrd patterns of ca 1 x mg x tio 3 powders with x 1. Kroger vink notation, frenkel and schottky defects, and. Kroger and vink proposed a useful notation to describe point defect reac. This notation is completely general in that it can apply to any crystalline compound or even to pure crystals. You are right, talking about positive cations and negative anions is superfluous. It enables descrip tion and calculations of combinations.
It is primarily used for ionic crystals and is particularly useful for describing various defect reactions. It can describe any entity in a crystalline structure. Krogervink notation is a set of conventions that are used to describe electric charges and lattice positions of point defect species in crystals. The spectroscopy of crystal defects 2877 laboratory labels. I tried googling it and i can see people have done it but not how.
Allowing the volume of supercell to relax results in decrease in total volume by 1. Introduction into defect studies in ceramic materialsiii. We will provide a glimpse of this in the next subchapter. A perfect crystal in the krogervink notation thus is full of vacancies on interstitial sites. The neighboring zr and oxygen ions move towards the oxygen vacancy. We define vacancies and interstitials as particles which occupy a defined site in a crystal and which may have a charge. Point defects in ionic crystals university of virginia. In order to facilitate book keeping with respect to the electrical charge, we only note the excess charge relative to the neutral lattice.
Mar 26, 2018 section 2 deals with point defect chemistry, including solid solutions and nonstoichiometry, concluding with a description of the krogervink point defect notation and the formalism required for the incorporation of defect formation into chemical equations. Ensure that your reactions have charge, mass, and site balance. May 18, 2012 we use the krogervink notation to identify these different point defects, which is summarized in table 11. Defects in solids tilley major reference works wiley. Thomas lenosky and ju li university of pennsylvania. Krogervink notation standard notation for defects in ionic crystals composed of 3 parts main body identifies the defect v vacancy m metal x nonmetal subscript denotes site the defect occupies i interstitial x nonmetal m cation site superscript identifies the effective charge positive charge. Extrinsic defects in ionic crystals arise when impurity species. Lecture references key concepts mit opencourseware. Krogervink notation we will now start to consider defects as chemical entities we need a notation for defects. Ceria based electrolyte materials are very useful in intermediatetemperature solid oxide fuel cell itsofc. Defect structure of lndium tin oxide and its relationship to. Pdf investigation of structural and optical properties of.
What the entity is, as the main symbol a chemical symbol or v for vacancy. Ive never heard from the kroger vink notation before. Ion conduction mechanisms chapter two 42 p a g e s h ivaji u n iversity k olh apu r m r. Defect chemistry and defect equilibria introduction. A very clear way was suggested by kroger and vink, it is therefore called krogervink notation or notation by structure elements we already had a glimpse of this. Chemical composition, microstructure, bandgap energy and. Sites in a crystal are the points where the atoms, the interstitials, or the vacancies can be. Creation of oxygen vacancy by ag doping can be expressed according to the following kroger vink notation. Frenkel defects consist of vacancyinterstitial pairs. Introduction into defect studies in ceramic materialsiii structure, defects and defect chemistry z. Kroger vink notation is a set of conventions that are used to describe electric charges and lattice positions of point defect species in crystals. Traditional krogervink kv notation defines sites in ionic crystals as interstitial or belonging to host ions. There are two types of intrinsic point defects in ionic crystals. Krogervink notation in modern defect chemistry, we use krogervink notation.
A krogervink compatible notation for defects in inherently. The significant deviations are described in the following table. The scheme seems to have been used first by g d watkins in his work on radiationinduced defects in silicon. Kroger vink notation some departure from the typical kroger vink notation is used in the document.
I would either delete the words positivnegative, or put them in brackets. These provide perhaps the most convenient labels, easily chosen, avoiding duplication, and easily identified with a model when that is appropriate. Extrinsic point defects in ionic crystals impurities. How to utilize kroger vink notation to write intrinsic and extrinsic defect reactions in ionic crystals. Krogervink notation is a set of conventions that are used to describe electric charges and. This model was later corroborated and further developed. This is the follow up video to the first lecture on the kroger vink notations. Krogervink notations are typically used to depict the atomic defects with charges. Where null sometimes nil indicates the creation of defects from a perfect lattice. Deviations in notation from kroger vink type of defect kroger vink notation symbol alternative used metal vacancy oxygen vacancy free electon e ehydronium ion. Defect reactions 22 mass balance the defect reaction must balance with respect to the mass, i.
645 823 1480 14 1525 384 239 1400 51 272 1523 1273 1312 76 736 1198 1122 722 1269 932 1011 729 129 668 1400 1332 1022 950 903