Distribution of Metal Ions and Magnetic Properties in Spinel System Zn(1−x)Ga2x/3Cr2Se4

✍ Scribed by I. Okońska-Kozłowska; E. Malicka; A. Waśkowska; T. Mydlarz

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 182 KB
• Volume: 148
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8434

✦ Synopsis

DEDICATED TO PROFESSOR HEINZ D. LUTZ, UNIVERSITY OF SIEGEN, ON THE OCCASION OF HIS 65TH BIRTHDAY

A system of zinc-chromium selenides with Ga 3؉ substitution have been prepared by the chemical transport method. The X-ray structure of the single crystals and their magnetic properties have been studied to determine the cation distribution in the fcc cubic spinel. The magnetic properties of the system appeared to be strongly dependent on a location of the Ga admixture on the tetrahedral or the octahedral positions of the spinel sublattice. Three crystals with di4erent stoichiometry revealed distinct values of the saturation magnetic moment, sat , i.e., 5.2, 3.8, and (0.1 B . The Zn 2؉ ion de5ciency forced Ga 3؉ to occupy the tetrahedral sites and left all the Cr 3؉ ions on the octahedral sites in (Zn 0.63 Ga 0.37 )[Cr 2 ]Se 4 , for which a slightly lowered value of magnetic moments have been observed. In (Zn 0.95 ) 0.05 ) [Ga 0.03 Cr 1.93 ) 0.04 ]Se 4 , a lack of stoichiometry caused the Ga ions to locate on the octahedral sites. The small number of Ga 3؉ at these sites was able to considerably a4ect the magnetic exchange interactions. At high Ga 3؉ concentration in (Zn)[Ga 0.4 Cr 1.6 ]Se 4 , it turned out that the saturation magnetic moment:s value was below the limit of observations.