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 Sr₂ TmO₃Cl (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 μ_eff = 2.0 μ_B V^-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θ_CW = -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.