Influence of vacancies and mixed valence on the transport processes in solid solutions with the spinel structure

Abstract In the spinel compounds of ACr2 X 4 type, and in the spinel series of Zn1−xGa2x/3Cr2Se4, ZnCr2-xInxSe4, Zn1−xCuxCr2Se4 and Li1+xTi2-x,O4, the influence of vacancies and mixed valence on the transport processes is considered. For this purpose, a procedure of calculation of the ion packing coefficients was used and calculations of the fulfilment coefficient, the difference of the Pauling electronegativities and the vacancy parameter were introduced. For the spinel compounds of ACr2 X 4 type (where A=Zn, Cd, Mn; X=O, S, Se) the vacancy parameter strongly increases with an increase of the anion radius. The vacancy parameter was found to decrease most with an increase of the imperfection degree of the spinel structure in Zn1−xGa2x/3Cr2Se4. For the spinel series ZnCr2-x, InXSe4, the vacancy parameter remains almost constant with an increase of the In concentration. For the spinel series Zn1−xCuxCr2Se4, the appearance of the Cr mixed valence with an increase of x makes the carrier transport easier, lead...

[1]  J. Warczewski,et al.  Seebeck effect in the antiferromagnetic single crystals of ZnCr2−xInxSe4 (0.0 , 1992 .

[2]  J. Kusz,et al.  Crystal and Magnetic Structure of the Magnetically Modulated Spinels Zn1-xGa2x/3Cr2Se4 Where (X=0.0, 0.1, 0.2, 0.3, 0.5) , 1991 .

[3]  Duda,et al.  Influence of the valence of the substituted cations on the electrical properties of the magnetically modulated spinels Zn1-xAxCr2Se4 (A=Cu, Ga2/3). , 1990, Physical Review B (Condensed Matter).

[4]  M. Jung,et al.  Einkristalle des Systems Zn1−xIn2/3(1−x)Cr2−yInySe4 , 1989 .

[5]  J. Kusz,et al.  MAGNETIC STRUCTURE OF CuxZn1-xCr2Se4 , 1988 .

[6]  N. Tsuda,et al.  Seebeck Coefficient of Li1+xTi2-xO4 , 1987 .

[7]  M. R. Harrison,et al.  The superconductor-semiconductor transition in the Li1+xTi2-xO4 spinel system , 1985 .

[8]  N. Tsuda,et al.  Semiconducting Properties of Li1.1Ti1.9O4 , 1984 .

[9]  H. Morawiec,et al.  Positron annihilation study of martensitic transformation in CuZnAl alloy , 1984 .

[10]  H. D. Lutz,et al.  Röntgenographische und schwingungsspektroskopische Untersuchungen an Spinell‐Mischkristallen des Systems (Zn, Ga) Cr2Se4 , 1984 .

[11]  H. D. Lutz,et al.  Darstellung, elektrische und magnetische eigenschaften von Zn1−xGa0,667xCr2Se4-spinell-einkristallen , 1984 .

[12]  J. Warczewski,et al.  Effect of double exchange on magnetic properties of Cu x Zn 1 − x Cr 2 Se 4 , 1983 .

[13]  I. Okońska-Kozłowska,et al.  Mischkristallbildung im System CuxZn1−xCr2Se4 , 1978 .

[14]  L. Treitinger,et al.  Influence of Se-deficiencies on the properties of In-doped CdCr2Se4 single crystals , 1977 .

[15]  D. Johnston,et al.  Superconducting and normal state properties of Li1+xTi2−xO4 spinel compounds. I. Preparation, crystallography, superconducting properties, electrical resistivity, dielectric behavior, and magnetic susceptibility , 1976 .

[16]  R. D. Shannon.  Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides , 1976 .

[17]  K. Kudo,et al.  A classification of normal spinel type compounds by “Ionic packing factor” , 1974 .

[18]  G. Sawatzky,et al.  Monovalent copper in the chalcogenide spinel CuCr2Se4 , 1974 .

[19]  Tsuneo Watanabe.  Electrical Resistivity and Hall Effect of ZnCr2Se4 , 1974 .

[20]  P. Larsen,et al.  Origin of the conductivity minimum and the negative magnetoresistance in n-type sulpho-spinels , 1973 .

[21]  W. B. Pearson,et al.  The crystal chemistry and physics of metals and alloys , 1972 .

[22]  W. J. Thomas,et al.  Electronegativities of the Elements , 1956 .