Hydrothermal synthesis of single crystals of transition metal vanadates in the glaserite phase

• The hydrothermal synthesis of glaserite-type vanadates is demonstrated.
• Synthesis from stoichiometric component reactions yields 0.2–0.5 mm size crystals.
• Hydrothermal recrystallization of glaserite powder yields 2–3 mm size crystals.
• The structure varies according to the alkali and alkaline earth metals selected.
• Ideal (P-3m1) and distorted (P-3 and P21/c) glaserite structures are observed.

A series of transition metal vanadate crystals were prepared using a high temperature (580 °C) hydrothermal method. The compounds all had the general formula A2AEM(VO4)2 (A=K, Na, Li; AE=Ba, Sr; M=Co, Fe, Mn). They are all variations of the glaserite structural type and range in symmetry from P-3m1 to P-3 to P21/c. Most of the derivatives contain a planar three-fold rotation operation, making them possible spin frustration candidates. Single crystal structural analyses were performed on many of the derivatives to obtain a detailed understanding of the distortions of the tetrahedral building blocks that accommodate the symmetry distortions. A hydrothermal growth method was developed to grow high quality single crystals of sizes up to 2–3 mm/edge. This method can be generalized for large crystal growth to enable magnetic and neutron diffraction studies that require relatively large single crystals.

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