Synthesis and Characterizations of a Polymorphic Sodium Cobalt Phosphate with Edge-Sharing Co2+Octahedral Chains

✍ Scribed by Pingyun Feng; Xianhui Bu; Galen D. Stucky

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 933 KB
• Volume: 131
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7390

✦ Synopsis

A new sodium cobalt phosphate with a three-dimensional framework structure has been prepared by the hydrothermal method and characterized by thermal analysis, susceptibility measurements, and single crystal X-ray diffraction. The oxide framework is built from octahedral and tetrahedral atoms (Co 2؉ and P 5؉ ) and consists of cross-linked infinite Co-O-Co chains that propagate along the crystallographic b-axis. The framework connectivity can be correlated to that of potassium titanyl phosphate (KTP) type structure. The structure of NaCoPO 4 is also compared to other divalent metal phosphates and a summary of structures isotypic to NaCoPO 4 is given. Magnetic susceptibility measurements show that the compound displays Curie-Weiss behavior down to a temperature of 13 K at which an antiferromagnetic phase transition occurs. The thermal analysis shows that the octahedral polymorph is a product of a phase transformation of the trigonal bipyramidal polymorph at about 710°C. The octahedral polymorph transforms into the tetrahedral polymorph at about 920°C. Crystal data for NaCoPO 4 :