Synthesis, structure and magnetic properties of the oxysulfide and oxyselenide system Ln-V-O-X

Two quaternary oxysulfide compounds, Ce₅V₃O ₇S₆ and La₅V₃O₇S₆, were synthesized using the molten KCl salt flux method. Chapter 1 provides a structural and magnetic comparison study of the two compounds. Ce₅ V₃O₇S₆ Crystallizes in the P_mmn space group with a = 17.771 Å, b = 3.765 Å, c = 10.1481 Å and V = 710.69 Å3. La₅V₃O ₇S₆ crystallizes in the same space group with a = 17.9960 Å, b = 3.8213 Å, c = 10.2633 Å and V = 710.73 Å 3. The structures consist of chains of sulfur edge-shared VS ₄O₂ octahedra where the oxygen atoms occupy the axial positions. La and Ce atoms occupy the interstitial sites. Magnetic measurements reveal both compounds to exhibit Curie-Weiss behavior.; The quaternary oxyselenide compound CeVOSe₂ was synthesized using the molten KCl salt flux method. Chapter 2 provides a structural and magnetic study of the compound. CeVOSe₂ crystallizes in the C _2/m space group with a = 11.660(6) Å, b = 3.852(2) Å, c = 8.399(2) Å and cell volume (V) = 710.3 Å3. Angles α, β, γ are 90.00(0), 90.11(6), and 90.00(0) degrees, respectively. The structure consists of planes formed from edge shared VO₂Se₄ chains and VSe₆ octahedron chains oriented along the ‘b’ axis. Cerium atoms occupy the interstitial sites between planes. Magnetic measurements reveal that this compound exhibits Curie-Weiss behavior.; Chapter 3 provides a structural and computational analysis of a new quaternary barium vanadium oxysulfide, Ba₃V₂O₃S ₄. The compound was synthesized using the molten salt flux method. This solid-state compound crystallizes in the hexagonal space group P6₃ (no. 173) with a = 10.1661(6) Å, c = 5.9306(4) Å, V = 530.81(6) Å3, and Z = 2. It consists of face-sharing VS₆ octahedron chains and discrete VO₃S tetrahedrons. The Ba atoms are located in the interstitial sites.; Chapter 4 describes cyclic voltammetry experiments performed on elemental vanadium in molten KCl at 1050°C. Three peaks were observed at potentials of −60 mV, + 450 mV and +750 mV. The peaks were referenced to the negative edge of the background potential window. Peaks at −60 mV and +750 mV are correlated respectively to V2+ → V0 and V3+ → V2+ redox reactions. The peak at +450 mV may appear due to chemical reaction following V2+ oxidation.; Two new software packages have been developed for use in our laboratory PC and are described in Chapter 5 RPTConvert and SCalc2000. RPTConvert is a program that will extract data from *.RPT files produced by the Iridium (version 5.14G) EDX analysis software used at NIU and calculate an empirical formula. SCalc2000 allows synthetic chemists to quickly calculate reactant quantities to produce a given mass of a compound with a particular stoichiometry. The programs have been written for the Windows 95/98 operating systems using the Microsoft Visual Basic programming language.