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Synthesis and characterization of K2NiF4-type CaLnCoO4 (Ln = Sm and Gd) |
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| Authors: | Hideki Taguchi Katsuyuki Nakade |
| Affiliation: | a Research Laboratory for Surface Science, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan b Kyoto Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, JST, 1-7 Hikari-dai, Seika-cho, Soraku-gun, Kyoto 619-0237, Japan c Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, 1-3 Tatara-miyakotani, Kyo-tanabe, Kyoto 610-0321, Japan |
| Abstract: | K2NiF4-type CaLnCoO4 (Ln = Sm and Gd) has been synthesized at 1173 or 1223 K in air using citric acid (CA) and ethylene glycol (EG). CaLnCoO4 (Ln = Sm and Gd) has an orthorhombic structure with the space group Bmab. The average particle sizes are approximately 300 nm for CaSmCoO4 and approximately 170 nm for CaGdCoO4, respectively. The global instability index (GII) indicates that the crystal structure of CaGdCoO4 is more stable than that of CaSmCoO4. CaLnCoO4 (Ln = Sm and Gd) is a p-type semiconductor and shows paramagnetic behavior above 5 K. The 1/χ-T curve of CaSmCoO4 deviates from the Curie-Weiss law, whereas the 1/χ-T curve of CaGdCoO4 follows the Curie-Weiss law in the temperature range of 5 ≤ T ≤ 300 K. From the values of the observed effective magnetic moment (μeff) of CaLnCoO4 (Ln = Sm and Gd), it is considered that the spin state of the Co3+ ion is low. |
| Keywords: | A Oxides B Sol-gel chemistry C X-ray diffraction D Crystal structure D Magnetic properties |
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