According to example embodiments, a two-dimensional (2D) material element may include a first 2D material and a second 2D material chemically bonded to each other. The first 2D material may include a first metal chalcogenide-based material. The second 2D material may include a second metal chalcogenide-based material. The second 2D material may be bonded to a side of the first 2D material. The 2D material element may have a PN junction structure. The 2D material element may include a plurality of 2D materials with different band gaps.

According to example embodiments, a two-dimensional (2D) material element may include a first 2D material and a second 2D material chemically bonded to each other. The first 2D material may include a first metal chalcogenide-based material. The second 2D material may include a second metal chalcogenide-based material. The second 2D material may be bonded to a side of the first 2D material. The 2D material element may have a PN junction structure. The 2D material element may include a plurality of 2D materials with different band gaps.

Preparation of semiconductor nanocrystals and their dispersions in solvents and other media is described. The nanocrystals described herein have small (1-10 nm) particle size with minimal aggregation and can be synthesized with high yield. The capping agents on the as-synthesized nanocrystals as well as nanocrystals which have undergone cap exchange reactions result in the formation of stable suspensions in polar and nonpolar solvents which may then result in the formation of high quality nanocomposite films.

The present invention provides a production method that can produce a garnet-type compound containing zirconium and lithium, the compound being in the form of fine particles, with high productivity. The method produces a garnet-type compound containing Zr, Li, and element M.sup.1 (wherein M.sup.1 is at least one element selected from the group consisting of La, Sc, Y, and Ce) as constituent elements. The method includes a first step of (1) mixing a first raw material and a second raw material to obtain a precipitate, the first raw material being a solution containing a zirconium carbonate complex and having a pH of at least 7.0 and not more than 9.5, and the second raw material containing a compound containing the above element M.sup.1 as a constituent element; and (2) a second step of mixing the precipitate and a third raw material containing Li as a constituent element to obtain a mixture, and then firing the mixture at a temperature of less than 1,000 C. to obtain a fired product. The first raw material is prepared by mixing, at a prescribed molar ratio, at least a compound that contains a carbonate species and a compound that contains a zirconium species.

Provided is a method for forming a ferroelectric film of a metal oxide having a fluorite-type structure at a low temperature of lower than 300 C., and a ferroelectric film obtained at a low temperature. The present invention provides a production method of a ferroelectric film comprising a crystalline metal oxide having a fluorite-type structure of an orthorhombic crystal phase, which comprises using a film sputtering method comprising sputtering a target at a substrate temperature of lower than 300 C., to deposit on the substrate a film of a metal oxide which is capable of having a fluorite-type structure of an orthorhombic crystal phase, and having a subsequent thermal history of said film of lower than 300 C.; or applying an electric field to said film after said deposition or after said thermal history of lower than 300 C. Also provided are the ferroelectric film, which is formed on an organic substrate, glass, or metal substrate, which can be used only at low temperatures, and a ferroelectric element and a ferroelectric functional element or device using the ferroelectric film.

A reducing agent for use in production of a product gas containing carbon monoxide, the reducing agent being brought into contact with a raw material gas containing carbon dioxide to reduce the carbon dioxide to produce the product gas; the reducing agent containing a composite metal oxide represented by Ce.sub.1-x(M).sub.xO.sub.y, where M is a metal element with an ionic radius smaller than an ionic radius of Ce with an identical valence number and an identical coordination number, x represents a positive real number, and y represents a real number from 1 to 4. The reducing agent that has a high conversion efficiency of carbon dioxide to carbon monoxide, and can be used, for example, in a chemical looping method, and a method for producing a gas using such a reducing agent.

An embodiment may solve the problem of low sinterability of electrolytes of existing high entropy perovskite oxide materials through an electrolyte with improved structural stability of a matter at high temperatures without unnecessary enthalpy change, and provide a bidirectional proton conductive fuel cell with improved proton conductivity and electrochemical performance by using such an electrolyte.

A dielectric contains an oxide containing hafnium and cerium. The molar ratio of the content of cerium to the sum of the content of hafnium and the content of cerium is greater than or equal to 0.031 and less than or equal to 0.052. The molar ratio of the content of oxygen to the sum of the content of hafnium and the content of cerium is greater than 0 and less than or equal to 1.50.

A dielectric contains an oxide containing hafnium and cerium. The molar ratio of the content of cerium to the sum of the content of hafnium and the content of cerium is greater than or equal to 0.031 and less than or equal to 0.052. The molar ratio of the content of oxygen to the sum of the content of hafnium and the content of cerium is greater than 0 and less than or equal to 1.50.

A chalcogenide perovskite having an average particle size of less than 1 m and a composition other than BaZrS.sub.3.