Cause, Consequence, and Control of Ag Vacancies in BaAgAs.

The impact of transition metal (Ag) deficiencies on the structural and transport properties of ThCrSi-type arsenides are investigated. We experimentally confirm a partial occupancy of Ag in BaAgAs, which can be predictably controlled within 0.053(5) ≤ ≤ 0.

BaCuTe ( = K, Rb, Cs) Featuring Polyanionic Copper-Telluride Frameworks with Ultralow Thermal Conductivity.

Three polyanionic tellurides, BaCuTe ( = K, Rb, Cs), were synthesized in salt flux. The isostructural tellurides crystallize in a new structure type, in the cubic 3 space group with a Wyckoff sequence of and large unit cell volumes of over 5500 Å. The structures feature a framework of [CuTe] tetrahedra and [CuTe] trigonal pyramids with disorder in the Cu sites.

A Recipe for a Great Meal: A Benchtop Route from Elemental Se to Superior Thermoelectric β-AgSe.

The low-temperature modification of β-AgSe has proven to be useful as a near-room-temperature thermoelectric material. Over the past years, research has been devoted to interstitial, vacancy, and substitutional doping into the parent β-AgSe structure, aiming at tuning the material's charge and heat transport properties to enhance thermoelectric performance. The transformation of β-AgSe into α-AgSe at ∼134 °C and the low solubility of dopants are the main obstacles for the doping approach.

Inducing Ferrimagnetic Exchange in 1D-FeSe Chains Using Heteroleptic Amine Complexes: [Fe(en)(tren)][FeSe].

[Fe(en)(tren)][FeSe] ( = ethylenediamine, CHN, = tris(2-aminoethyl)amine, CHN) has been synthesized by a mixed-ligand solvothermal method. Its crystal structure contains heteroleptic [Fe(en)(tren)] complexes with distorted octahedral coordination, incorporated between 1D-FeSe chains composed of edge-sharing FeSe tetrahedra. The twisted octahedral coordination environment of the Fe-amine complex leads to partial dimerization of Fe-Fe distances in the FeSe chains so that the FeSe polyhedra deviate strongly from the regular tetrahedral geometry.