Abstract:
Provided is a Cd-free blue fluorescent quantum dot with a narrow fluorescence FWHM. The quantum dot (1) does not contain cadmium and its fluorescence FWHM is 25 nm or less. The quantum dot is preferably a nanocrystal containing zinc and selenium or zinc and selenium and sulfur. Further, the quantum dot preferably has a core-shell structure in which the nanocrystal serves as a core (1a) and the surface of the core is coated with a shell (1b).
Abstract:
Provided is a method for preparing quantum dots of lead selenide, comprising the following steps: 1) mixing selenium powder with octadecene, heating with stirring to dissolve the selenium powder fully, maintaining the temperature, then cooling to room temperature to obtain a stock solution of selenium; 2) mixing lead compound, oleic acid, octadecene and benzophenone together, and dissolving to obtain a stock solution of lead, then maintaining the temperature at 130-190°C; 3) adding the stock solution of selenium into the stock solution of lead rapidly, and maintaining the temperature at 100-160°C, after cooling, quantum dots of lead selenide are initially prepared; 4) adding the initially prepared quantum dots of lead selenide into a mixture of toluene and methanol, centrifugating and the supernatant to obtain a precipitate, then redissolving the precipitate with toluene to obtain a transparent solution of quantum dots of pure lead selenide. The method is safe in operation, simple, good in reproducibility and low in cost.
Abstract:
A CdTe single crystal, wherein chlorine concentration in the crystal is between 0.1 and 5.0 ppmwt and resistivity at room temperature is not less than 1.0 × 10 9 Ω·cm is obtained by growing the crystal according to one of a vertical gradient freezing method, a horizontal gradient freezing method, a vertical Bridgman method, a horizontal Bridgman method, and a liquid encapsulated Czochralski method by using a CdTe polycrystal, in which 50 to 200 ppmwt of chlorine is doped, as a raw material.
Abstract:
A CdTe single crystal which has a chlorine content of 0.1 to 5.0 ppmwt and exhibits a resistivity at room temperature of 1.0 X 19 ohmcm or more; and a method for preparing the CdTe single crystal which comprises using a CdTe polycrystal doped with chlorine in an amount of 50 to 200 ppmwt as a raw material and growing a single crystal through a method selected from among a vertical gradient freezing method, a horizontal gradient freezing method, a vertical Bridgman method, a horizontal Bridgman method and a liquid sealing Czochralski method.
Abstract:
Shaped nanocrystal particles and methods for making shaped nanocrystal particles are disclosed. One embodiment includes a method for forming a branched, nanocrystal particle. It includes (a) forming a core having a first crystal structure in a solution, (b) forming a first arm extending from the core having a second crystal structure in the solution, and (c) forming a second arm extending from the core having the second crystal structure in the solution.
Abstract:
In the present invention, when hollow polyhedral fine particles consisting of atoms of a first element and atoms of a second element are produced, atoms of the first element and atoms of the second element are structured in a reversed micelle composed of a surfactant. Thereby, hollow polyhedral fine particles can be synthesized by simple and easy procedures.
Abstract:
Ceramic compositions which exhibit the phenomenon of superconductivity are disclosed. Methods of making and using the compositions are included. The compositions comprise 1-2-3 ceramic compositions (e.g., Y, Ba, Cu/Ag) with the fourth constituent comprising sulfur, selenium or tellurium. Unexpectedly high temperature (e.g., non-cryogenic) and essentially atmospheric pressure superconductor characteristics are shown.