Synthesis and Characterization of Oxide Chloride Sr2VO3Cl, a Layered S = 1 Compound

The mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) Å, and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a μeff = 2.0 μB V-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θCW = −50 K), in line with the V-O-V advantageous super-exchange paths in the V-O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state

Sr₂Te₄V₂O₁₃Cl₂, a Layered Structure Forming a Canted Antiferromagnetic Ground State

The 2D oxychloride, Sr2Te4V2O13Cl2, was synthesized by high-temperature solid-state synthesis in a closed silica ampule with low internal pressure of inert atmosphere. The crystal structure, determined by single-crystal diffraction, can be described with the orthorhombic space group, Pca21 (No. 29), with the pseudo-tetragonal unit cell, a = b = 8.802(1) Å and c = 19.221(2) Å. Cl, as well as Sr and Te, forms layers similar to that of Cu in SrCu2(BO3)2 (“SrCuBO”), one of the 11 Archimedean lattices. V(IV) shows the classical square pyramidal coordination, containing one short V–O distance, indicative of a vanadyl ion; furthermore, a relatively short V–V interatomic distance of 3.927(1) Å is found across a superexchange path V–O–V with an angle of 173.9(2)°. Initial magnetic investigations suggest that the compound is a canted antiferromagnet with a slightly negative Curie–Weiss constant of θCW = −5.5 K and an effective magnetic moment of μeff = 1.71 μB V–1. A significant second-order-like entropy release in the specific heat capacity measurement is observed in the same temperature range as a magnetic anomaly, as measured by magnetic susceptibility. This suggests a long-range ordering of magnetic spins below 3 K. Further magnetic data, in combination with the noncentrosymmetric atomic lattice, indicate that the ground state is a canted antiferromagnet