Anhydrous alkali copper sulfates – a promising playground for new Cu²⁺ oxide complexes: new Rb-analogues of fumarolic minerals.

Abstract

This is a 'preproof' accepted article for Mineralogical Magazine. This version may be subject to change during the production process.

Exploring new belousovite-related zinc and cadmium alkali sulfate halides: synthesis and structural variability

“…Notably, in all these structures the M 2+ cation adopts a mixed oxyfluoride octahedral coordination; in addition, these structures have been reported for the smaller univalent cations (Li + , Na + , K + and NH 4 + ); larger ones (Tl + , Rb + and Cs + ) are either not tolerated or have not been addressed. Hence, the AM(SO 4 )X family provides yet another example of morphotropism, a rather common phenomenon for anhydrous sulfates which we had addressed recently for A 2 Cu(SO 4 ) 2 and A 2 M 2 (SO 4 ) 3 compositions (Siidra et al, 2021b(Siidra et al, , 2022. Among fluoride sulfates, the prime structure-driving factor is probably the size of the alkali cation; in contrast, the belousovite architecture demonstrates a striking flexibility adopting a variety of cations and anions of quite different sizes.…”

Calciolangbeinite-O, a natural orthorhombic modification of K2Ca2(SO4)3, and the langbeinite–calciolangbeinite solid-solution system

“…Note also that both cubic and orthorhombic modifications of langbeinite-type K 2 Mn 2 (SO 4 ) 3 (Oelkrug et al , 1988) and cubic K 2 Fe 2 (SO 4 ) 3 (Lander et al , 2017) are known among synthetic compounds. Synthetic sulfates K 2 Cu 2 (SO 4 ) 3 and Rb 2 Cu 2 (SO 4 ) 3 , as well as so-called ‘hydrolangbeinite’ Rb 2 Cu 2 (SO 4 ) 3 (H 2 O), having the langbeinite-type stoichiometry, differ from langbeinite-type compounds in both structure and unit-cell metrics (Lander et al , 2017; Siidra et al , 2021), due to the Jahn-Teller distortion of the Cu 2+ -centred polyhedra. It is also noteworthy that such Cu-bearing sulfates are described as synthetic analogues of fumarolic minerals (Siidra et al , 2021).…”

Multiple dimensionalities in A2M3(SO4)4 (A = Rb, Cs; M = Co, Ni) analogues

“…12,15,16 Nevertheless, to date the study of phases with heavier alkali metals, namely Rb and Cs remains scarce. To the best of our knowledge, A 2 M 2 (SO 4 ) 3 ( A = Rb and K; M = Co, Ni, Cu, Fe or Mn) 9,17–21 and A 2 M (SO 4 ) 2 ( A = Rb or Cs and M = Cr, Fe, Co or Cu) 22,23 have been reported. The synthesis of such types of materials is subtle, strongly related to the particular mineral forming environments in nature.…”