A process for the synthesis of transition metal chalcogenides (TMC) having formula (I). More particularly, the present work relates to a one pot single phase process for the synthesis of a TMC system having formula (I) by wet chemistry. Formula (I) is represented as A.sub.x-B.sub.y.

A bacterially induced crystal particle is formed by a composite shell that encloses a hollow space. The composite shell layer includes a biomaterial and a metallic material. The biomaterial includes cell wall or cell membrane of a bacterium. The metallic material includes oxides, sulfides, selenides, acid salt compounds of a transition metal, or any combination thereof. When the bacterially induced crystal particle is spheric, the composite shell is formed by two dome-shaped portions, and a thickness of each of the dome-shaped portions is not less than 1/73 of a diameter of the bacterially induced crystal particle. Alternatively, when the bacterially induced crystal particle is rod-shaped, the thickness of the dome-shaped portions is not less than 1/73 of a width of the bacterially induced crystal particle, and a thickness of the cylindrical portion is not less than 1/37 of the width of the bacterially induced crystal particle.

A chalcogen-containing compound of the following Chemical Formula 1 which exhibits excellent phase stability at a low temperature, particularly at a temperature corresponding to the driving temperature of a thermoelectric element, and also exhibits an excellent thermoelectric performance index through an increase in a power factor and a decrease in thermal conductivity, a method for preparing the same, and a thermoelectric element including the same:
V.sub.1-xM.sub.xSn.sub.4Bi.sub.2Se.sub.7-yTe.sub.y  [Chemical Formula 1]
In the above Formula 1, V is a vacancy, M is an alkali metal, x is greater than 0 and less than 1, and y is greater than 0 and less than or equal to 1.

A chalcogen-containing compound of the following Chemical Formula 1 which exhibits excellent phase stability at a low temperature, particularly at a temperature corresponding to the driving temperature of a thermoelectric element, and also exhibits an excellent thermoelectric performance index through an increase in a power factor and a decrease in thermal conductivity, a method for preparing the same, and a thermoelectric element including the same:
V.sub.1-xM.sub.xSn.sub.4Bi.sub.2Se.sub.7-yTe.sub.y  [Chemical Formula 1]
In the above Formula 1, V is a vacancy, M is an alkali metal, x is greater than 0 and less than 1, and y is greater than 0 and less than or equal to 1.

The present invention provides the use of a lead (IV) containing compound to prepare a lead chalcogenide nanocrystal and a method for producing broadband lead chalcogenide nanocrystals in a low cost, size-controllable and scalable method, the method comprising contacting a lead (IV) containing compound with an organic acid and a chalcogen-containing reagent.

A solid-state ion conductor includes a compound of Formula 1:

Li.sub.(6−a)x+2y−b*z−6A.sub.1−xM.sup.a.sub.xO.sub.yX.sup.b.sub.z   Formula 1

wherein, in Formula 1, A is an element having an oxidation state of +6, M is an element having an oxidation state of a, wherein a is +2, +3, +4, +5, or a combination thereof, X is an element having an oxidation state of b, wherein b is −1, −3, or a combination thereof, and 2<[(6−a)x+2y−b*z−6]≤6.5,0 ≤x≤1, y>0, and z≥0.

A method of producing nanoparticles comprises effecting conversion of a molecular cluster compound to the material of the nanoparticles. The molecular cluster compound comprises a first ion and a second ion to be incorporated into the growing nanoparticles. The conversion can be effected in the presence of a second molecular cluster compound comprising a third ion and a fourth ion to be incorporated into the growing nanoparticles, under conditions permitting seeding and growth of the nanoparticles via consumption of a first molecular cluster compound.

Provided in this disclosure are oxidative dehydrogenation catalysts that include a mixed metal oxide having the empirical formula:
Mo.sub.1.0V.sub.0.12-0.49Te.sub.0.05-0.17Nb.sub.0.10-0.20O.sub.d
wherein d is a number to satisfy the valence of the oxide. The oxidative dehydrogenation catalyst is characterized by having XRD diffraction peaks (2θ degrees) at 22±0.2, 27±0.2, 28.0±0.2, and 28.3±0.1. The disclosure also provides methods of making the catalysts that include wet ball milling.

Disclosed herein are solar cells with kesterite-based absorbers that hold promise as a low-cost and durable technology to renewably produce electricity using solar energy conversion. The current state-of-the-art (SOA) for such kesterite solar cells is Cu.sub.2ZnSn(S,Se).sub.4 and novel materials are required to suppress the formation bandgap-fluctuation- and charge-carrier-recombination-inducing defects and eventually to achieve solar cell efficiencies higher than the SOA. Three important material properties that govern the efficiency of a solar cell are the concentrations of performance-degrading defects, band gap, and chemical stability. Disclosed here is a stable material, specifically Cu.sub.2CdGe(S,Se).sub.4, as a new candidate that can exhibit higher defect formation energies than Cu.sub.2ZnSnS.sub.4 and a nearly optimal bandgap, which can eventually result in higher solar-cell efficiencies in solar energy conversion.

A quantum dot including a nanoparticle template including a first semiconductor nanocrystal including a Group II-VI compound, a quantum well including a second semiconductor nanocrystal disposed on the nanoparticle template, the second semiconductor nanocrystal including a Group IIIA metal excluding aluminum and a Group V element; and a shell comprising a third semiconductor nanocrystal disposed on the quantum well, the third semiconductor nanocrystal including a Group II-VI compound, wherein the quantum dot does not include cadmium, a band gap energy of the second semiconductor nanocrystal is less than a band gap energy of the first semiconductor nanocrystal, the band gap energy of the second semiconductor nanocrystal is less than a band gap energy of the third semiconductor nanocrystal, and the quantum dot includes an additional metal including an alkali metal, an alkaline earth metal, aluminum, iron, cobalt, nickel, copper, zinc, or a combination thereof.