| Abstract
| - By using a hydrothermal method, a new open-framework manganese (II) borophosphate has been successfully prepared. The structure has 2-D 8-MR channels along the [010] and [001] directions, respectively. Magnetic measures reveal that the compound exhibits a canted antiferromagnetic behavior below 8.0 K.
- A new three-dimensional (3-D) manganese(II) borophosphate, [NH4]4[Mn9B2(OH)2(HPO4)4(PO4)6](denoted MnBPO-CJ26), has been synthesized by a hydrothermal method. The structure has beendetermined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group C2/c (No.15) with a = 32.603(7) Å, b = 10.617(2) Å, c = 10.718(2) Å, and β = 108.26(3)°. Its structure featuresanionic manganese-phosphate layers [Mn9(OH)2(HPO4)4(PO4)6]10-, which are made up from MnO5, MnO6,PO4, and HPO4 polyhedral units. These anionic layers, parallel to the bc plane, are further connected byBO4 tetrahedra through vertex oxygen atoms forming a novel open framework with 2-D eight-memberedring (8-MR) channels along the [010] and [001] directions. Charge neutrality is achieved by protonatedNH3 molecules. The structure has unique B/P and Mn/P ratios (B/P = 1/5, Mn/P = 9/10). Magneticmeasurements indicate that Curie−Weiss behavior above 100 K with C = 4.404(3) cm3 mol-1 K and θ= −51.2(5) K. The value of C is consistent with an S = 5/2 ion with g ∼ 2.0 (4.38 cm3 mol-1 K).However, the magnetic data reveal a spontaneous magnetization at 8.0 K, indicating a canting of Mn2+moments in the antiferromagnetic ground state.
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