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1 Jan 1962

Volume 33, Issue 1, pp. 1-518

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Nonstoichiometry and Lattice Defects in Transition Metal Hydrides

G. G. Libowitz

J. Appl. Phys. 33, 399 (1962); http://dx.doi.org/10.1063/1.1777131 (7 pages) | Cited 9 times

Online Publication Date: 11 June 2004

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The relationships between equilibrium hydrogen pressure, hydrogen content, and temperature have been derived for nonstoichiometric transition metal hydrides from both statistical mechanical and thermodynamic considerations. By comparing the derived equations with experimental pressure‐composition isotherms, the type of lattice defect causing deviations from stoichiometry as well as the energies of defect formation and interaction can be calculated. This was done for uranium hydride and palladium hydride. The energies obtained were 69 kcal∕mole for the vacancy formation energy, and 4.4 kcal∕mole for the attractive vacancy interaction energy in uranium hydride. The corresponding energies in palladium hydride were 58.0 kcal∕mole and 0.35 kcal∕mole. The derived relationships are of general applicability to any nonstoichiometric binary compound which is deficient in the volatile component.

Equilibration of Lattice Defects in Real Crystals

J. W. Mitchell

J. Appl. Phys. 33, 406 (1962); http://dx.doi.org/10.1063/1.1777132 (8 pages) | Cited 17 times

Online Publication Date: 11 June 2004

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This paper describes several mechanisms for the equilibration of lattice defects in a number of crystalline solids in which the state of equilibrium has been disturbed by changes of temperature, diffusion processes, and phase changes, including precipitation from solid solution and internal chemical reactions.

Reactions among Point Defects in Alkali Halides

A. B. Lidiard

J. Appl. Phys. 33, 414 (1962); http://dx.doi.org/10.1063/1.1777133 (8 pages) | Cited 19 times

Online Publication Date: 11 June 2004

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Existing knowledge of point defects and their interactions in uncolored alkali halide crystals is briefly reviewed. Attention is drawn to recent experimental and theoretical work which indicates that vacancy pairs are not highly mobile defects. This has important implications for some hypotheses on the kinetics of color center reactions at low temperatures.
This knowledge of defects in uncolored crystals is then applied to a discussion of the reactions which may take place between F centers and impurity ions in additively‐colored doped crystals and the theoretical possibilities are compared with experimental information on Z centers. Consideration of the thermodynamic equilibria in these reactions seems to eliminate the Z1 and Z2 centers of Pick as possible causes of either of the Z1 and Z2 absorption bands in KCl. (The Z2 model of Pick is identical with the Z1 model of Seitz and is a divalent impurity cation which has trapped an electron.) Two possible centers for the Z2 band presen tthemselves; (a) an associate of an F center with a divalent cation and (b) an associate of an F center with an impurity‐vacancy pair (the Z2 model of Seitz). The structure of the Z1 center is not resolved by these considerations. Attention is drawn to some paradoxical experimental results on Z1 and Z2 centers and further experiments to resolve outstanding questions are suggested.

Statistical Mechanics of Dilute Solid Solutions

R. F. Brebrick

J. Appl. Phys. 33, 422 (1962); http://dx.doi.org/10.1063/1.1777134 (4 pages) | Cited 10 times

Online Publication Date: 11 June 2004

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An apparently quite general model for an essentially‐ordered semiconductor compound containing impurity traces consists: (1) of atomic point defects randomly distributed over appropriate, equivalent sites and contributing to the internal energy of the crystal by terms linear in the concentration of each type of atomic point defect, and (2) an electronic energy band structure in which the concentration and type of ``impurity'' levels is determined by the concentration and type of atomic point defects. The assignment of donor or acceptor character to the native interstitials and vacancies is predicted in a specific case by analogy with the alkali halides. Otherwise the nature of the binding is irrelevant, provided the un‐ionized impurity level associated with each substitutional atomic point defect bears the same charge as that on the substituted atom. From the appropriate quasi‐grand partition function, one obtains the usual Fermi‐Dirac distribution for electrons as well as distribution functions for the atomic point defects. In addition, one obtains expressions for the chemical potentials of the thermodynamic components. The latter are utilized in a discussion of those aspects of the M☒N phase diagram pertinent to the semiconductor compound MN and in a discussion of amphoteric impurities.

Effect of Added Oxides on p‐Conducting Nickel Oxide

G.‐M. Schwab and H. Schmid

J. Appl. Phys. 33, 426 (1962); http://dx.doi.org/10.1063/1.1777135 (3 pages) | Cited 13 times

Online Publication Date: 11 June 2004

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It is a well‐known result of semiconductor physics, that the conductivity of a semiconducting oxide can be shifted in the direction of increased p conductivity or decreased n conductivity by addition of small proportions of oxides of lower cation valency and that the reverse is true in the case of higher valency of the added cation. This effect is understood on the basis of the corpuscular semiconductor theory of Wagner and Schottky and is even used for establishing the nature of the conduction mechanism in certain materials. It is generally supposed that the only necessary condition for this doping effect is solubility in the solid state and that this is granted by a similarity of the cation radii. No importance has been attributed to the chemical nature of the dope, and for this reason we have tried to dope p‐conducting nickel oxide with other oxides, differing not only in valence but also in their chemical nature.

On the Structure and Related Properties of the Oxides of Praseodymium

L. Eyring and N. C. Baenziger

J. Appl. Phys. 33, 428 (1962); http://dx.doi.org/10.1063/1.1777136 (6 pages) | Cited 26 times

Online Publication Date: 11 June 2004

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The structures of praseodymium oxide phases of composition PrO1.83, PrO1.81, PrO1.78, PrO1.71, and PrO1.69 are discussed in terms of the structures of PrO2.00 and PrO1.50 (C and A types). The way in which the existence of these several stable structures are mirrored in the physical and chemical properties is discussed.

Physical Chemistry of Compound Semiconductors

Jerome S. Prener

J. Appl. Phys. 33, 434 (1962); http://dx.doi.org/10.1063/1.1777137 (5 pages) | Cited 1 time

Online Publication Date: 11 June 2004

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The problem of point‐defect equilibria in compound semiconductors is considered. It is shown that the expected donor or acceptor properties of a defect in a compouud are entirely independent of the type of binding (ionic or covalent) in the compound. From general thermodynamic arguments it is shown that the number of degrees of freedom of a compound in internal equilibrium is one more than the number of chemical constituents of the compound independent of the number and nature of the defects it contains. The consequences of this are discussed and it is shown how mass action laws result, describing internal reactions among the defects. An example from the literature is presented to illustrate the methods of setting up and solving these mass action laws and how the solutions might be compared with experimental results. Finally, association between oppositely charged defects in solids is discussed.

Kinetics and Equilibria Involving Copper and Oxygen in Germanium

C. S. Fuller and K. B. Wolfstrin

J. Appl. Phys. 33, 438 (1962); http://dx.doi.org/10.1063/1.1777138 (9 pages) | Cited 5 times

Online Publication Date: 11 June 2004

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Germanium solutions supersaturated with respect to both oxygen and copper have been investigated in the range 300–500°C by means of conductivity and Hall effect measurements. Kinetics results indicate that the initial rates of disappearance of holes is second order in both the Cu and the O concentrations. The failure of the hole mobility to increase with degree of reaction suggests the formation of an ion cluster. Determinations of ionization energy during reaction show changes in the level scheme of Cu to occur and confirm previous work on the ionization properties of donors produced by oxygen. A tentative model is proposed consisting of an initial cluster of two Cu and four O atoms on which further oxygen reactions take place. The diffusion of oxygen is found to be accelerated by the presence of Cu.

Electrical Properties of Nonstoichiometric Semiconductors

J. H. Becker and H. P. R. Frederikse

J. Appl. Phys. 33, 447 (1962); http://dx.doi.org/10.1063/1.1777139 (7 pages) | Cited 36 times

Online Publication Date: 11 June 2004

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The electrical conductivity σ, thermoelectric power Q, and Hall coefficient R are examined as a function of the ratio of hole‐to‐electron concentrations p∕n for a nondegenerate semiconductor at constant temperature. From these relations the fundamental parameters of the material (forbidden band gap, mobilities, and effective masses) can be derived. This approach is particularly applicable to materials whose stoichiometry varies as a function of temperature and vapor pressure of the constituents P. For any model of this equilibrium decomposition, it is easy to transform the calculations in terms of p∕n into results as a function of P. As p∕n increases, σ passes through a minimum, while Q and R traverse minimum (negative), zero, and maximum (positive) values. These extrema are of special interest. In the simple case of one kind of imperfection, σ, Q, and R become independent of P in a certain pressure range (i.e., when the intrinsic condition n=p has been reached). It is then possible to derive the ratio of mobilities μn∕μp and the ratio of the average effective masses mn*∕mp* from σ(P) and Q(P) only. Hence, if μn or mn* are known (i.e., from measurements at lower temperatures), one can calculate these parameters for the other charge carrier.

Defects in Mixed Crystals of KCl☒KBr

A. Smakula, N. Maynard, and A. Repucci

J. Appl. Phys. 33, 453 (1962); http://dx.doi.org/10.1063/1.1777140 (3 pages) | Cited 25 times

Online Publication Date: 11 June 2004

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Mixed crystals of potassium chloride and bromide show strong internal strain evidenced by cracking. The minimum of the melting point occurs between 63 and 65 mole % KBr. The microhardness between 25 and 65 mole % KBr is more than twice that of either component. The lattice constant changes linearly with composition. The macrodensity deviates by several percent, indicating a high concentration of defects. The intensity of coloration by electrons shows that defects are not mainly due to vacancies but presumably to larger aggregates of submicroscopic size or interstitials. The broadening of exciton bands, as measured by shifts of the ultraviolet absorption edge, is greatest at a 2:1 KCl☒KBr ratio. This may indicate a certain short‐range order in KCl☒KBr mixed crystals.
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