Conversion Reactions of Solids: From a Surprising Three‐Step Mechanism towards Directed Product Formation

Abstract

Directed conversion reactions from binary to multinary compounds are discovered from the reaction of Bi2 S3 and Bi2 Se3 with NiCl2 ⋅6 H2 O in polyol media under basic conditions. Control of the synthesis conditions allows the preparation of NiBiSe and superconducting Ni3 Bi2 S2 and Ni3 Bi2 Se2 . The formation of Ni3 Bi2 S2 from Bi2 S3 is found from an unexpected three-step reaction path with Bi and NiBi as intermediates. In the more complex Ni/Bi/Se system, the mechanism found can be used to selectively direct the reaction between the competing ternaries and to suppress side-product formation. Contrary to solid-state reactions (500-900 °C) control of product formation is reached at reaction temperatures and times between 166-300 °C and 0.5-10 h, respectively. The formation of different phases is discussed from results of DFT calculations.

Binary–Ternary Bi2S3–AgBiS2 Rod-to-Rod Transformation via Anisotropic Partial Cation Exchange Reaction

“…24 Similarly, Bi 2 S 3 and Bi 2 S 3−x Se x NRs were used as the starting reactant and template for the synthesis of Cu 3 BiS 3−x Se x NRs. 25 Bi 2 S 3 NRs could be also used as a precursor for the conversion to Ni 3 Bi 2 S 2 crystallites, 26 and Bi 2 S 3 nanoribbons as a template to produce Ni 3 Bi 2 S 2 nanoribbons. 27 In addition, it is noted that an early work by Qian et al proposed that AgBiS 2 nanowhiskers were possibly formed from a molecular-chain-type structure of the Bi−S compound.…”

Half antiperovskites VII – DFT modelling of shandites that are isoelectronic to Co3Sn2S2

“…To date in the phase diagram Co−Sb−S only CoSbS, but no “Sb 2 Co 3 S 2 ” is known. However, the coexistence of both stoichiometries is known for NiBiSe and Bi 2 Ni 3 Se 2 [39] …”

“…However, the coexistence of both stoichiometries is known for NiBiSe and Bi 2 Ni 3 Se 2 . [39] The non-trivial relation of cell volumes and compositions is illustrated in Figure 2 from calculations on the equations-ofstate (EOS). Here, the results from PBE + D3-calculations are shown.…”

Many Faces of Ni3Bi2S2: Tunable Nanoparticle Morphology via Microwave-Assisted Nanocrystal Conversion

“…EDX mapping reveals their enhanced bismuth content (up to ∼35 atom %), so that they most likely correspond to the elemental-bismuth impurities found in XRD. 32,33 assumed that NiBi plays a key role as an intermediate in the transformation of Bi 2 S 3 into the ternary compound Ni 3 Bi 2 S 2 . It was argued that NiBi may appear as a result of nickel intercalation into elemental bismuth that is obtained via Bi 2 S 3 reduction in ethylene glycol under alkaline conditions.…”

“…The same reaction mechanism was proposed for Ni 3 Pb 2 S 2 , too . Later investigations of the reaction mechanism proved its complexity: it was assumed that formation of NiBi and Bi intermediates plays an important role in the reaction pathway., , The two-step morphological templating was proposed for the synthesis of Ni 3 Bi 2 S 2 starting from bismuth; however, the retention of the starting material size and shape was observed only in the case when the morphology of the precursor was spherical. In contrast, the synthetic approach employed in ref allows preserving of the Bi 2 S 3 nanoribbons shape despite the different Bi/S ratio in the binary and the ternary phases as well as the formation of elementary Bi observed in diffraction patterns .…”