Crystal growth of Germanium-based oxide spinels by the Float Zone Method

• Published in: Journal of crystal growth Vol. 283; no. 1-2; pp. 185 - 192
• Main Authors: Hara, Shigeo, Yoshida, Yoshiyuki, Ikeda, Shin-Ichi, Shirakawa, Naoki, Crawford, Michael K., Takase, Kouichi, Takano, Yoshiki, Sekizawa, Kazuko
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.09.2005; Elsevier
• Subjects: A1. Growth model; A2. Floating zone technique; B1. Oxide; B2. Magnetic materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Magnetic properties and materials; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Studies of specific magnetic materials; B1. Oxide; A1. Growth model; 81.10.Fq; A2. Floating zone technique; B2. Magnetic materials; Antiferromagnetism; Crystal growth; Pyrochlore; Oxides; Evaporation; Floating zone; Bl. Oxide; Melting points; 81.10.Fq A1. Growth model; Monocrystals; Spinels; Growth mechanism; Magnetic materials; Germanium oxides; Frustration
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2005.05.078

We have succeeded in growing single crystals of the oxide spinels GeNi2O4 and GeCo2O4. Both materials have the pyrochlore lattice, and show antiferromagnetic-like order. Thus, magnetic frustrations and relevant phenomena are strongly expected. To obtain single crystals of these materials, we employed a conventional floating-zone method. For the crystal growth of GeCo2O4, no severe difficulties were found. For GeNi2O4, it was necessary to avoid intense the evaporation of GeO2 due to the higher melting point of GeNi2O4 than that of GeCo2O4. Therefore, it was quite difficult to obtain single crystals of GeNi2O4 by the same procedure as GeCo2O4. We show the importance of the starting composition and crystal growth atmosphere for both spinels.