Provided is a high-density lithium-containing garnet crystal body. The lithium-containing garnet crystal body has a relative density of 99% or more, belongs to a tetragonal system, and has a garnet-related type structure. A method of producing a Li.sub.7La.sub.3Zr.sub.2O.sub.12 crystal, which is one example of this lithium-containing garnet crystal body, includes melting a portion of a rod-like raw material composed of polycrystalline Li.sub.7La.sub.3Zr.sub.2O.sub.12 belonging to a tetragonal system while rotating it on a plane perpendicular to the longer direction and moving the melted portion in the longer direction. The moving rate of the melted portion is preferably 8 mm/h or more but not more than 19 mm/h. The rotational speed of the raw material is preferably 30 rpm or more but not more than 60 rpm. By increasing the moving rate of the melted portion, decomposition of the raw material due to evaporation of lithium can be prevented and by increasing the rotational speed of the raw material, air bubbles can be removed.

Methods for producing ethylene using nanowires as heterogeneous catalysts are provided. The method includes, for example, an oxidative coupling of methane catalyzed by nanowires to provide ethylene.

Methods for producing ethylene using nanowires as heterogeneous catalysts are provided. The method includes, for example, an oxidative coupling of methane catalyzed by nanowires to provide ethylene.

The present invention relates to a method for preparing uniform metal oxide nanoparticles. According to the preparation method of the present invention, it is possible to maintain the temperature and pressure inside the reactor in a stable and constant manner by removing water generated in the reaction step for forming metal oxide nanoparticles. Thus, the uniformity of nanoparticles formed is increased, and the reproducibility between batches can be increased even in a repeated process and and a large-scale reaction. Therefore, the preparation method of the present invention can be used to synthesize uniform nanoparticles reproducibly in large quantities.

A method of preparing a sintered solid electrolyte includes (a) coprecipitating a mixed solution including a lanthanum precursor, a zirconium precursor, a gallium precursor, a complexing agent, and a pH adjuster to provide a solid electrolyte precursor; (b) washing and drying the solid electrolyte precursor to provide a washed and dried solid electrolyte precursor; (c) mixing the washed and dried solid electrolyte precursor with a lithium source to provide a mixture; (d) calcining the mixture to provide a calcined solid electrolyte, which is a gallium (Ga)-doped lithium lanthanum zirconium oxide (LLZO), as represented by Chemical Formula 1 below,
Li.sub.xLa.sub.yZr.sub.zGa.sub.wO.sub.12,  Chemical Formula 1 where 5≤x≤9, 2≤y≤4, 1≤z≤3, and 0<w≤4; and (e) sintering the calcined solid electrolyte at a temperature ranging from 1,000° C. to 1,300° C. to provide the sintered solid electrolyte, wherein a ratio (M1:M2) of moles (M1) of lithium element to moles (M2) of gallium element ranges from 6.7:0.1 to 5.8:0.4.

The present invention provides a positive electrode active material prepared using a preparation method including mixing lithium complex metal oxide particles with a nanosol of a ceramic-based ion conductor and heat treating the resultant to form a coating layer including the ceramic-based ion conductor on the lithium complex metal oxide particles, thereby forming a coating layer including a ceramic-based ion conductor to a uniform thickness on a lithium complex metal oxide particle surface, and as a result, capable of minimizing capacity decline and enhancing a lifespan property when used in a secondary battery, a method for preparing the same, and a lithium secondary battery including the same.

A lithium ion-conducting compound, having a garnet-like crystal structure, and having the general formula: Li.sub.n[A.sub.(3-a′-a″)A′.sub.(a′)A″.sub.(a″)][B.sub.(2-b′-b″)B′.sub.(b′)B″.sub.(b″)][C′.sub.(c′)C″.sub.(c″)]O.sub.12, where A, A′, A″ stand for a dodecahedral position of the crystal structure, where A stands for La, Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and/or Yb, A′ stands for Ca, Sr and/or Ba, A″ stands for Na and/or K, 0<a′<2 and 0<a″<1, where B, B′, B″ stand for an octahedral position of the crystal structure, where B stands for Zr, Hf and/or Sn, B′ stands for Ta, Nb, Sb and/or Bi, B″ stands for at least one element selected from the group including Te, W and Mo, 0<b′<2 and 0<b″<2, where C and C″ stand for a tetrahedral position of the crystal structure, where C stands for Al and Ga, C″ stands for Si and/or Ge, 0<c′<0.5 and 0<c″<0.4, and where n=7+a′+2.Math.a″−b′−2.Math.b″−3.Math.c′−4.Math.c″ and 5.5<n<6.875.

Synthesizing lithium lanthanum zirconate includes combining a reagent composition with a salt composition to yield a molten salt reaction medium, wherein the reagent composition comprises a lithium component, a lanthanum component, and zirconium component having a lithium:lanthanum:zirconium molar ratio of about 7:3:2; heating the molten salt reaction medium to yield a reaction product; and washing the reaction product to yield a crystalline powder comprising lithium lanthanum zirconate.

A nanoparticle structure and method of forming the same are provided. The nanoparticle structure comprises a metal oxide nanoparticle. The metal oxide nanoparticle may comprise ceria and zirconia. The nanoparticle structure may further comprise an antibody connected to the metal oxide nanoparticle. The method comprises forming a metal oxide nanoparticle. The method may further comprise connecting an antibody to the metal oxide nanoparticle.

Zirconium and yttrium oxide-based composition with a specific surface area of at least 12 m 2/g following calcination at 1000° C. for 10 hours. This composition is obtained via a method wherein a mixture of zirconium and yttrium compounds is precipitated with a base; the resulting precipitate-containing medium is heated; a compound selected from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and the salts thereof and carboxymethylated fatty alcohol ethoxylate-type surfactants is then added to said precipitate, and, finally, the precipitate is calcined. Said composition can be used as a catalyst.