The present disclosure is directed to methods of making Pb-free perovskites for short-wave IR (SWIR) devices and to various Pb-free perovskite materials disclosed herein. The perovskites disclosed herein have improved chemical stability and long-term stability, while the production methods disclosed herein have improved safety and lower cost.

A chalcogen-containing compound of the following Chemical Formula 1 which exhibits excellent phase stability even at a low temperature, particularly at a temperature corresponding to an operating temperature of a thermoelectric element, and also exhibits a significantly superior power factor and thermoelectric performance index due to its excellent electrical conductivity and low thermal conductivity caused by its unique crystal lattice structure, a method for preparing the same, and a thermoelectric element including the same. [Chemical Formula 1]—V.sub.1-2xSn.sub.4Bi.sub.2-xAg.sub.3xSe.sub.7, wherein V is vacancy and 0<x<0.5.

The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I]; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X]. The invention also relates to a process for producing a semiconductor device comprising said semiconducting material. Also described is a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I] selected from Cu.sup.+, Ag.sup.+ and Au.sup.+; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X].

A lead-based alloy containing alloying additions of bismuth, antimony, arsenic, and tin is used for the production of doped leady oxides, lead-acid battery active materials, lead-acid battery electrodes, and lead-acid batteries.

Methods of synthesizing Bi.sub.2S.sub.3CdS particles in the form of spheres as well as properties of these Bi.sub.2S.sub.3CdS particles are described. Methods of photocatalytic degradation of organic pollutants employing these Bi.sub.2S.sub.3CdS particles and methods of preventing or reducing microbial growth on a surface by applying these Bi.sub.2S.sub.3CdS particles in the form of a solution or an antimicrobial product onto the surface are also specified.

Methods of synthesizing Bi.sub.2S.sub.3CdS particles in the form of spheres as well as properties of these Bi.sub.2S.sub.3CdS particles are described. Methods of photocatalytic degradation of organic pollutants employing these Bi.sub.2S.sub.3CdS particles and methods of preventing or reducing microbial growth on a surface by applying these Bi.sub.2S.sub.3CdS particles in the form of a solution or an antimicrobial product onto the surface are also specified.

A method for making MnBi.sub.2Te.sub.4 single crystal is provided. The method includes: providing a mixture of polycrystalline MnTe and polycrystalline Bi.sub.2Te.sub.3 in Molar ratio of 1.1:11:1.1; heating the mixture in a vacuum reaction chamber to 700 C.900 C., cooling the mixture to 570 C.600 C. slowly with a speed less than or equal to 1 C./hour, and annealing the mixture at 570 C.600 C. for a time above 10 days to obtain an intermediate product; and air quenching the intermediate product from 570 C.600 C. to room temperature. The method for making MnBi.sub.2Te.sub.4 single crystal is simple and has low cost.

A liquid composition for forming a piezoelectric film formed of a metal oxide including at least Bi, Na, and Ti. A raw material of the Na is a sodium alkoxide, a raw material of the Ti is a titanium alkoxide, a diol and an amine-based stabilizer are included, and a molar ratio of the amine-based stabilizer with respect to the titanium alkoxide (titanium alkoxide:amine-based stabilizer) is 1:0.5 to 1:4. It is preferable that the metal oxide is included as 4% by mass to 20% by mass with respect to 100% by mass of the liquid composition.

A method for making MnBi.sub.2Te.sub.4 single crystal is provided. The method includes: providing a mixture of polycrystalline MnTe and polycrystalline Bi.sub.2Te.sub.3 in Molar ratio of 1.1:11:1.1; heating the mixture in a vacuum reaction chamber to 700 C.900 C., cooling the mixture to 570 C.600 C. slowly with a speed less than or equal to 1 C./hour, and annealing the mixture at 570 C.600 C. for a time above 10 days to obtain an intermediate product; and air quenching the intermediate product from 570 C.600 C. to room temperature. The method for making MnBi.sub.2Te.sub.4 single crystal is simple and has low cost.

A process for synthesizing a Mn.sup.4+ doped phosphor of formula I by electrolysis is presented. The process includes electrolyzing a reaction solution comprising a source of manganese, a source of M and a source of A. One aspect relates to a phosphor composition produced by the process. A lighting apparatus including the phosphor composition is also provided. A.sub.x[MF.sub.y]:Mn.sup.4+ (I) where, A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7.