Effects of the Oxygen Nonstoichiometry on the Physical Properties of La0.7Sr0.3MnO3-DELTADELTA Manganites (0

A new VIV/VV mixed-valence polyoxovanadate compound Ba6[V10O30(H2O)]·2.5H2O has been hydrothermally synthesized in an NaVO3–BaI2–(CH3)4NI aqueous solution system. The compound crystallizes cubic, Im , a=16.8323(2) ?, and Z=6. The structural analysis gave wR2=0.0597 for all of the unique 2641 reflections and 83 parameters and R1=0.0229 for 2217 reflections with FO>4SIGMA(FO). The phase contains discrete[V10O30(H2O)]12- polyoxovanadate ion and three types of Ba2+ cations, two of which connect the polyoxovanadate ion three-dimensionally. The remaining Ba2+ cation is attached to the discrete ion and is hydrated. The polyoxovanadate ion contains four VV2O7 units of corner-sharing tetrahedral VO4 pairs and one VIV2O10(H2O) unit. The two types of units are linked by corner-sharing. The VIV2O10(H2O) unit shows two types of unusual V–O polyhedral arrangements. One is a couple of VO5(H2O) octahedra sharing the water molecule, and the other consists of a VO6 octahedron and a VO5 square pyramid sharing a corner oxygen and includes a distant water molecule. Ba6 [V10O30(H2O)]·2.5H2O exhibits Curie–Weiss-like paramagnetic behavior without any magnetic transition down to 5 K, probably reflecting the discrete location of the polyoxovanadate ion.