Experimental and theoretical investigations on the composition-dependent structural phase transition in Cu₂Cd_xZn_1−xSnS₄

Mercurial possibilities: determining site distributions in Cu2HgSnS4 using 63/65Cu, 119Sn, and 199Hg solid-state NMR spectroscopy

“…Given that Cu 2 ZnSnS 4 , Cu 2 CdSnS 4 , and Cu 2 HgSnS 4 exhibit different site distributions, solid solutions derived from them are likely to complex site disorder, as observed in Cu 2 Zn 1Àx -Cd x SnS 4 , for example. 9,21 As a complementary method to confirm the site distributions established from earlier structural determinations on the parent compounds, solid-state nuclear magnetic resonance (NMR) spectroscopy provides valuable information on the local environments around specific atoms, as has been demonstrated for (Cu 1Àx Li x ) 2 ZnSnS 4 , Cu 2 Zn 1Àx -Cd x SnS 4 , and Cu 2 ZnSn(S 1Àx Se x ) 4 , among other semiconducting and catalytic compounds. [22][23][24][25][26][27] To clarify the site distributions, we report here an analysis of the 63/65 Cu, 119 Sn, and 199 Hg NMR spectra for Cu 2 HgSnS 4 and compare these results to our recent work on Cu 2 ZnSnS 4 and Cu 2 CdSnS 4 .…”

Mere Anarchy is Loosed: Structural Disorder in Cu2Zn1–xCdxSnS4

“…As observed, these peaks essentially overlap for the lightly substituted Cd members ( x = 0–0.3) corresponding to a nearly undistorted structure (η = 1.002), but they are visibly split for the more heavily substituted Cd members ( x = 0.4–1.0) as the structure contracts along c (η = 0.992–0.969) (Figure ). The abrupt transition near x = 0.4 has been proposed to be related to a change in structure, from I 4̅ (Cu 2 ZnSnS 4 to Cu 2 Zn 0.7 Cd 0.3 SnS 4 ) to I 4̅2 m (Cu 2 Zn 0.6 Cd 0.4 SnS 4 to Cu 2 CdSnS 4 ). − However, it is very important to appreciate that the observation of this peak splitting alone offers no direct information about the site distributions, and the assignment of space groups is merely inferred based on the structures of the end members Cu 2 ZnSnS 4 and Cu 2 CdSnS 4 .…”

“…All cations are centered within tetrahedral sites lying on planes at z = 0, 1/4, 1/2, and 3 In addition to the basic models described above for Cu 2 Zn 1−x Cd x SnS 4 , in which only disorder of Zn and Cd atoms occurs within the sites in the parent structures, more complex models have been proposed in which Zn and Cd atoms also disorder within the Cu sites in the I4̅ ("partially disordered kesterite") or I4̅ 2m structures ("disordered kesterite"). 16,17 Further, the simple substitution of Cd within Zn sites has been challenged, and instead, a continuous transformation has been suggested to take place in which Cu enters the Zn sites, and Cd enters the Cu sites on progressing from Cu 2 ZnSnS 4 to Cu 2 CdSnS 4 . 16 In short, the central question is whether the disorder in Cu 2 Zn 1−x Cd x SnS 4 involves two (Zn, Cd) or three (Cu, Zn, Cd) atoms.…”

“…In most studies of the solid solution Cu 2 Zn 1– x Cd x SnS 4 , where x represents the proportion of Cd substituted for Zn, an abrupt structural transition has been proposed to take place at around x = 0.4. ,− The structure adopted by the lightly Cd-substituted members ( x = 0–0.3) is in space group I 4̅, whereas the structure adopted by the more heavily Cd-substituted members ( x = 0.4–1.0) is in space group I 4̅2 m (Figure ). All cations are centered within tetrahedral sites lying on planes at z = 0, 1/4, 1/2, and 3/4.…”

Crystal structure of mechanochemically prepared Ag2FeGeS4

“…Originally, A 2 I B II C IV S 4 compounds were prepared by solid-state reaction in evacuated and sealed ampoules starting from the elements according to the standard technique described in [11]. With our newly developed synthesis method, such compounds can also be produced [12][13][14][15]. Our synthesis approach consists of two steps: milling in a high energy mill, where the starting materials ideally should react with each other, and subsequent annealing in an atmosphere of H 2 S in order to increase the crystallinity of the ground materials.…”