New Results of Chemical Transport as a Method for the Preparation and Thermochemical Investigation of Solids

Abstract

Chemical transport experiments are a valuable aid of great potential in the synthesis and thermochemical characterization of solids. Compounds of interest can often only be crystallized by this method. The use of a transport balance allows very detailed observations, particularly of the course of the experiment over time (simultaneous or sequential deposition of multiple-phase solids). The computer program CVTRANS enables a quantitative thermochemical description of the experiment based on the cooperative transport model. A compilation of recent results illustrates the development and efficiency of the method. The transport of phosphides, anhydrous phosphates and sulfates, and rare-earth oxide and oxohalide compounds are treated in detail.

On the feasibility of phosphide generation from phosphate reduction: The case of Rh, Ir, and Ag

“…Solid state reactions of the elements tend to be time consuming (days to weeks) and are heavily dependent on diffusion distances in the solid state; thus, multiple heating and grinding cycles must be employed [8,9]. The use of molten media or exploitation of vapor transport processes using multizoned furnaces can decrease the heating time and result in well-formed crystals [10]. Solidstate metathesis [11,12] and solvothermal synthesis [13][14][15] are faster methods for generating transition-metal phosphides and can be tuned to prepare materials that are microcrystalline or nanocrystalline.…”

Monolayer Tungsten Disulfide (WS2) via Chlorine‐Driven Chemical Vapor Transport

“…A temperature gradient is typically established between the source zone and the growth zone in a sealed ampule using values from thermodynamic calculations. As a result, bulk crystals are slowly grown in the zone where formation is favored …”

“…As a result, bulk crystals are slowly grown in the zone where formation is favored. [37][38][39][40] Although CVT is ubiquitously used to synthesize bulk crystals, it was only recently reported that atomically thin TMDs, including WS 2 , can be grown using CVT in a sealed ampule by carefully controlling mass transport. [41,42] While using I 2 and metal chlorides as transport agents, the presented closed-tube technique still requires metal oxides and sulfur as precursors, akin to CVD where stoichiometry is always a consideration.…”

Single Crystal Growth and Crystal Structure of Mercurous Diarsenate(V), (Hg2)2(As2O7)

“…Phase analysis of the resulting intense yellow powder revealed (Hg 2 ) 2 As 2 O 7 as the main phase and (Hg 3 ) 3 (AsO 4 ) 4 [4] and HgAs 2 O 6 [5,6] as by-products. Plate-like canary yellow single crystals of the title-compound with an edge-length of up to 0.8 mm were grown by subsequent chemical transport reactions [8] of the polycrystalline material [50 mg of HgCl 2 (Merck, p.A.) as transport agent, temperature gradient 550 Ǟ 500°C, reaction time 5 d].…”