Hydrothermal Synthesis and Characterization of Novel Brackebuschite-Type Transition Metal Vanadates: Ba<sub>2</sub>M(VO<sub>4</sub>)<sub>2</sub>(OH), M = V<sup>3+</sup>, Mn<sup>3+</sup>, and Fe<sup>3+</sup>, with Interesting Jahn–Teller and Spin-Liquid Behavior


A new series of transition metal vanadates, namely, Ba<sub>2</sub>M­(VO<sub>4</sub>)<sub>2</sub>(OH) (M = V<sup>3+</sup>, Mn<sup>3+</sup>, and Fe<sup>3+</sup>), was synthesized as large single crystals hydrothermally in 5 M NaOH solution at 580 °C and 1 kbar. This new series of compounds is structurally reminiscent of the brackebuschite mineral type. The structure of Ba<sub>2</sub>V­(VO<sub>4</sub>)<sub>2</sub>(OH) is monoclinic in space group <i>P</i>2<sub>1</sub>/<i>m</i>, <i>a</i> = 7.8783(2) Å, <i>b</i> = 6.1369(1) Å, <i>c</i> = 9.1836(2) Å, β = 113.07(3)°, <i>V</i> = 408.51(2) Å<sup>3</sup>. The other structures are similar and consist of one-dimensional trans edge-shared distorted octahedral chains running along the <i>b</i>-axis. The vanadate groups bridge across edges of their tetrahedra. Structural analysis of the Ba<sub>2</sub>Mn­(VO<sub>4</sub>)<sub>2</sub>­(OH) analogue yielded a new understanding of the Jahn–Teller effect in this structure type. Raman and infrared spectra were investigated to observe the fundamental vanadate and hydroxide vibrational modes. Single-crystal temperature-dependent magnetic studies on Ba<sub>2</sub>V­(VO<sub>4</sub>)<sub>2</sub>(OH) reveal a broad feature over a wide temperature range with maximum at ∼100 K indicating that an energy gap could exist between the antiferromagnetic singlet ground state and excited triplet states, making it potentially of interest for quantum magnetism studies

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oai:figshare.com:article/2562016Last time updated on 2/12/2018

This paper was published in FigShare.

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