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.

Make Selenium Reactive Again: Activating Elemental Selenium for Synthesis of Metal Selenides Ranging from Nanocrystals to Large Single Crystals.

The inertness of elemental selenium is a significant obstacle in the synthesis of selenium-containing materials at low reaction temperatures. Over the years, several recipes have been developed to overcome this hurdle; however, most of the methods are associated with the use of highly toxic, expensive, and environmentally harmful reagents. As such, there is an increasing demand for the design of cheap, stable, and nontoxic reactive selenium precursors usable in the low-temperature synthesis of transition metal selenides with vast applications in nanotechnology, thermoelectrics, and superconductors.

The Structure of Boron Monoxide.

Boron monoxide (BO), prepared by the thermal condensation of tetrahydroxydiboron, was first reported in 1955; however, its structure could not be determined. With the recent attention on boron-based two-dimensional materials, such as borophene and hexagonal boron nitride, there is renewed interest in BO. A large number of stable BO structures have been computationally identified, but none are supported by experiments.

Yb Substitution and Ultralow Thermal Conductivity of the CaYbAlSb (0 ≤ ≤ 0.81(1)) System.

A series of Yb-substituted Zintl phases in the CaYbAlSb (0 ≤ ≤ 0.81(1)) system has been synthesized by initial arc melting and post-heat treatment, and their isotypic crystal structures were characterized by both powder and single crystal X-ray diffraction analysis. All four title compounds adopted the CaAlAs-type structure (space group , Pearson code 28, = 4).

High Seebeck Coefficient from Screen-Printed Colloidal PbSe Nanocrystals Thin Film.

Thin-film thermoelectrics (TEs) with a thickness of a few microns present an attractive opportunity to power the internet of things (IoT). Here, we propose screen printing as an industry-relevant technology to fabricate TE thin films from colloidal PbSe quantum dots (QDs). Monodisperse 13 nm-sized PbSe QDs with spherical morphology were synthesized through a straightforward heating-up method.

Modulation of transport properties S/Br substitution: solvothermal synthesis, crystal structure, and transport properties of BiSBr.

The solvothermal synthetic exploration of the Bi-S-halogen phase space resulted in the synthesis of two bismuth sulfohalides with common structural motifs. BiSI was confirmed to have the previously reported composition and crystal structure. In contrast, the bromide analogue was shown to have a formula of neither BiSBr nor BiSBr, in contrast to the previous reports.

Machine Learning-Guided Discovery of Ternary Compounds Containing La, P, and Group 14 Elements.

We integrate a deep machine learning (ML) method with first-principles calculations to efficiently search for the energetically favorable ternary compounds. Using La-Si-P as a prototype system, we demonstrate that ML-guided first-principles calculations can efficiently explore crystal structures and their relative energetic stabilities, thus greatly accelerate the pace of material discovery. A number of new La-Si-P ternary compounds with formation energies less than 30 meV/atom above the known ternary convex hull are discovered.

Possible unconventional order parameter in single crystals of SrPtP superconductor.

Anisotropic properties of single crystals of SrPtP were studied using London penetration depth and electrical resistivity measurements. The upper critical field,Hc2(T), was determined from four-probe electrical resistivity measurements for three orthogonal directions of a magnetic field with respect to the crystal. The London penetration depth,λ(T), was determined from the magnetic susceptibility of the Meissner-London state measured using a tunnel-diode resonator technique.

Semiconducting silicon-phosphorus frameworks for caging exotic polycations.

A series of novel semiconductors AAeSiPX (A = Na, K, Rb, Cs; Ae = Sr, Ba; X = Cl, Br, I) is reported. Their crystal structures feature a tetrahedral Si-P framework with large zeolite-like pores hosting two types of cations, monoatomic A and unprecedented octahedral X@Ae. Mixing of the A and Ba cations was detected by single crystal X-ray diffraction and confirmed by multinuclear solid state NMR.

As-Se Pentagonal Linkers to Induce Chirality and Polarity in Mixed-Valent Fe-Se Tetrahedral Chains Resulting in Hidden Magnetic Ordering.

A novel mixed-valent hybrid chiral and polar compound, FeAsSe(en)(HO), has been synthesized by a single-step solvothermal method. The crystal structure consists of 1D [FeSe] chains connected via [AsSe]-Se pentagonal linkers and charge-balancing interstitial [Fe(en)] complexes ( = ethylenediamine). Neutron powder diffraction verified that interstitial water molecules participate in the crystal packing.

NHC-Stabilized Au Nanoclusters and Their Conversion to Au Nanoclusters.

Herein, we describe the synthesis of a toroidal Au cluster stabilized by -heterocyclic carbene and halide ligands reduction of the corresponding NHC-Au-X complexes (X = Cl, Br, I). The significant effect of the halide ligands on the formation, stability, and further conversions of these clusters is presented. While solutions of the chloride derivatives of Au show no change even upon heating, the bromide derivative readily undergoes conversion to form a biicosahedral Au cluster at room temperature.

Tuning of Cr-Cr Magnetic Exchange through Chalcogenide Linkers in Cr Molecular Dimers.

A set of three Cr-dimer compounds, Cr(en) (: S, Se; : Br, Cl; : ethylenediamine), with monoatomic chalcogenide bridges have been synthesized via a single-step solvothermal route. Chalcogenide linkers mediate magnetic exchange between Cr centers, while bidentate ethylenediamine ligands complete the distorted octahedral coordination of Cr centers. Unlike the compounds previously reported, none of the chalcogenide atoms are connected to extra ligands.

Evolution of Bonding and Magnetism Changes in Valence Electron Count in CuFeCoGe.

A series of solid solutions, CuFeCoGe ( = 0, 0.2, 0.4, 0.

From Three-Dimensional Clathrates to Two-Dimensional Zintl Phases AMSb (A = Rb, Cs; M = Ga, In) Composed of Pentagonal M-Sb Rings.

Three new antimonide Zintl phases, RbGaSb, CsGaSb, and CsInSb, were discovered during exploration of corresponding A-M-Sb (A = Rb, Cs; M = Ga, In) ternary systems while searching for new clathrates. The AGaSb phases crystallize in the tetragonal space group 4/ (No. 137) in the LiBS structure type, while CsInSb crystallizes in lower symmetry in the orthorhombic space group (No.

Add a Pinch of Tetrel: The Transformation of a Centrosymmetric Metal into a Nonsymmorphic and Chiral Semiconductor.

Centrosymmetric skutterudite RhP was converted to a nonsymmorphic and chiral compound RhSi P (space group P2 2 2 ) by means of partial replacement of Si for P. The structure, determined by a combination of X-ray crystallography and solid state P NMR, exhibits branched polyanionic P/Si chains that are unique among metal phosphides. A driving force to stabilize the locally noncentrosymmetric cis-RhSi P and fac-RhSi P fragments is π-electron back-donation between the Rh t -type orbitals and the unoccupied antibonding Si/P orbitals, which is more effective for Si than for P.

Unprecedented superstructure in the type I family of clathrates.

The first arsenic-based clathrate exhibiting superstructural ordering due to optimization of Au-As, As-As, and Ba-Au bonding is reported. BaAuAs crystallizes in a unique 2/ monoclinic clathrate structure. The synthesis, crystal and electronic structure, and transport properties are discussed.

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides.

An innovative method of synthesis is reported for the large and diverse (RE)(TM) (Tt)S (RE = rare-earth, TM = transition metals, Tt = Si, Ge, and Sn) family of compounds (∼1000 members, ∼325 contain Si), crystallizing in the noncentrosymmetric, chiral, and polar 6 space group. Traditional synthesis of such phases involves the annealing of elements or binary sulfides at elevated temperatures. The atomic mixing of refractory components technique, presented here, allows the synthesis of known members and vastly expands the family to nearly the entire transition metal block, including 3d, 4d, and 5d TMs with oxidation states ranging from 1+ to 4+.