The invention discloses micron-nano pore gradient oxide ceramic films with biological activity, which are prepared by the following methods: The surface structures are biomedical engineering materials; Inorganic precursor coating solutions or the organic precursor coating solutions are prepared with or without micron and nanopore additives; The surface structures of the substrate are treated in the following steps: (1) The surfaces of the substrate are coated by the inorganic precursor coating solutions or the organic precursor coating solutions with or without micron and nanopore additives; (2) The substrate with coatings are dried, sintered, naturally cooled, and cleaned. (3) The biomedical engineering materials with the micron-nanopore gradient oxide ceramic films, especially biomimetic micro-nanoporous gradient alumina film, yttrium partially stabilized zirconia film, and alumina doped yttrium partially stabilized zirconia films in this invention greatly improve biocompatibility and biological activity.

The electrolyte membrane of the present disclosure includes a plurality of crystal domains. At least one of the crystal domains includes a first crystal subdomain and a second crystal subdomain. Each of the first crystal subdomain and the second crystal subdomain includes Ba, Zr, M, and O. M is a trivalent element. The concentration of M in the first crystal subdomain is different from the concentration of M in the second crystal subdomain.

An inorganic oxide of the present invention has a composition represented by General formula (1): M.sub.2LnX.sub.2(AlO.sub.4).sub.3 (where M includes Ca, Ln includes Tb, and X includes at least either one of Zr and Hf). Then, a number of Tb atoms in General formula (1) is 0.1 or more to 1 or less. Moreover, a crystal structure of the inorganic oxide is a garnet structure. A phosphor made of this inorganic oxide is capable of being excited by short-wavelength visible light, and can radiate narrow-band green light.

A sintering aid mixture for sintering solid-state ion conductors, electrode materials, or the like for solid-state batteries is provided. The mixture includes at least one sol-gel precursor and/or at least one sol-gel direct precursor produced from at least one sol-gel precursor.

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.

At least partial substitution of zirconium by hafnium in ion-conducting zirconium-based ceramics provides enhanced chemical stability in alkaline and acid environments.

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.

A method of controlling the ionic conductivity of a polymer member, including providing a plurality of particles of bi-doped garnet, dispersing the plurality of particles of bi-doped garnet in a PEO matrix to yield a polymer member, nucleating spherulites at bi-doped garnet particle sites, and growing spherulites to a critical density to provide ionic conductivity pathways throughout the polymer member.