Engineering Sr-doping for enabling long-term stable FAPb1−xSrxI3 quantum dots with 100% photoluminescence quantum yield

The Pb substitution in quantum dots (PQDs) with lesser toxic metals has been widely searched to be environmentally friendly, and be of comparable or improved performance compared to the lead-perovskite.

High-Pressure Synthesis and Superconducting Properties of NaCl-Type In1−xPbxTe (x = 0–0.8)

We have investigated the Pb-substitution effect upon the superconductivity of NaCl-type In1−xPbxTe. Polycrystalline samples with x = 0–0.8 were synthesized using high-pressure synthesis. The lattice parameter was systematically increased by Pb substitution. For x ≤ 0.6, bulk superconductivity was observed, and the superconducting transition temperature increased from 3 K (for InTe) to 5 K by Pb substitutions. From analyses of specific heat jumps at the superconducting transition, conventional (phonon-mediated) weak-coupling pairing mechanisms were suggested for In1−xPbxTe.

The crystal structure of veenite

The crystal structure of veenite is reported for the first time from a sample from the type locality of Madoc (Ontario, Canada). It has been solved and refined by X-ray single-crystal diffraction on the basis of 4973 observed reflections (with Fo > 4σ(Fo)) with a final R1 = 0.0396. Veenite is monoclinic P21, with unit-cell parameters a = 8.429(2), b = 26.069(5), c = 8.962(2) Å, β = 117.447(2)o. The bulk veenite composition is Ag0.15Pb16.029Sb8.836As6.99S39.95 (for Z = 1) corresponding to N = 4.09 (Me8NS8N + 8, theoretical value is 4.0), with the percentage of the Ag-(As,Sb) substituted end-member only equal to 3.51 mol.%, i.e., a nearly pure Pb-Sb-As sulfosalt. The crystal structure is typical for the N = 4 sartorite homologue, with zig-zag walls of trigonal coordination prisms of Pb which separate slabs of diagonally oriented double-layers populated by Sb and As with partial Pb substitution. Orientation of three-membered crankshaft chains formed by strong (As,Sb) – S bonds on the two surfaces of double-layers differs substantially from that in dufrénoysite, which is a pure Pb-As (N = 4) sulfosalt.

X-ray powder diffraction reference patterns for Bi1−xPbxOCuSe

The structures and powder X-ray reference diffraction patterns of the “natural superlattice” series Bi1−xPbxOCuSe (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) have been investigated. As the ionic radius of Pb2+ is greater than that of Bi3+, the unit-cell volume of Bi1−xPbxOCuSe increases progressively from x = 0 to 0.1, namely, from 137.868(5) to 139.172(11) Å3, as expected. The structure of Bi1−xPbxOCuSe is built from [Bi2(1−x)Pb2xO2]2(1−x)+ layers normal to the c-axis alternating with [Cu2Se2]2(1−x)− fluorite-like layers. Pb substitution in the Bi site of Bi1−xPbxOCuSe leads to the weakening of the “bonding” between the [Bi2(1−x)Pb2xO2]2(1−x)+ and the [Cu2Se2]2(1−x)− layers. Powder patterns of Bi1−xPbxOCuSe were submitted to be included in the Powder Diffraction File.