A mixed ionic and electronic conductor represented by Formula 1:

T.sub.xVa.sub.yA.sub.1-x-yM.sub.zO.sub.3-,

wherein T includes at least one monovalent cation, A includes at least one of a monovalent cation, a divalent cation, and a trivalent cation, M includes at least one of a trivalent cation, a tetravalent cation, and a pentavalent cation, M is an element other than Ti and Zr, Va is a vacancy, is an oxygen vacancy, 0<x, y0.25, 0<z<1, and 01.

A perovskite material represented by Formula 1:

Li.sub.xA.sub.yM.sub.zO.sub.3-Formula 1 wherein in Formula 1, 0<x1, 0<y1, 0<x+y<1, 0<z1.5, 01, A is H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, or a combination thereof, and M is Ni, Pd, Pb, Fe, Ir, Co, Rh, Mn, Cr, Ru, Re, Sn, V, Ge, W, Zr, Mo, Hf, U, Nb, Th, Ta, Bi, Li, H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Mg, Al, Si, Sc, Zn, Ga, Ag, Cd, In, Sb, Pt, Au, or a combination thereof.

Magnetodielectric (MD) metamaterials have a magnetodielectric (MD) substrate of a ferrite composition or composite having a characteristic impedance matching an impedance of free space and at least one frequency selective surface (FSS). The FSS has a plurality of frequency selective surface elements disposed in a pattern and supported on the MD substrate. The FSS has a conducting composition and is configured to permit one or more of transmission, reflection, or absorption at a selected resonant frequency or selected frequency band. Articles incorporating magnetodielectric metamaterials are provided.

Acoustically active articles having a composition including a nano-structured metal oxide are provided. The nano-structured metal oxide has the formula M1xM2yOz, where M1 is selected from the group consisting of alkali metals, alkaline earth metals, and combinations thereof, M2 is a transition metal or post-transition metal, and M2 has an atomic number no greater than 78. The articles can lower a resonant frequency of a cavity by no less than 50 Hz when the cavity is filled with the article and the resonant frequency is in a range from about 50 Hz to about 1500 Hz.

Mixed-metal oxides and lithiated mixed-metal oxides are disclosed that involve compounds according to, respectively, Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub. and Li.sub.1+Ni.sub.xMn.sub.yCo.sub.zMe.sub.O.sub.. In these compounds, Me is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, and combinations thereof; 0x1; 0y1; 0z<1; x+y+z>0; 00.5; and x+y+>0. For the mixed-metal oxides, 15. For the lithiated mixed-metal oxides, 0.11.0 and 1.93. The mixed-metal oxides and the lithiated mixed-metal oxides include particles having an average density greater than or equal to 90% of an ideal crystalline density.

An organic matter decomposition catalyst that contains a perovskite type complex oxide represented by A.sub.xB.sub.yM.sub.zO.sub.w, wherein A contains 90 at % or more of at least one element selected from the group consisting of Ba and Sr, B contains 80 at % or more of Zr, M is at least one element selected from the group consisting of Mn, Co, Ni, and Fe, y+z=1, x>1, z<0.4, and w is a positive value that satisfies electrical neutrality.

The invention relates to a method for preparing a composite metal oxide hollow fibre. A certain stoichiometry of composite metal oxide raw material and a polymer binding agent are added to an organic solvent, and mixed mechanically to obtain an evenly dispersed spinning solution having a suitable viscosity. After defoaming treatment, the spinning solution is extruded through a spinneret and, after undergoing a certain dry spinning process, enters an external coagulation bath; during this period, a phase inversion process occurs and composite metal oxide hollow fibre blanks are formed. The blanks are immersed in the external coagulation bath and the organic solvent is displaced; after natural drying, the blanks undergo a heat treatment process; during this period, polymer burn off, in situ reaction, and in situ sintering processes occur to obtain the composite metal oxide hollow fibre.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.

In one embodiment, the present disclosure relates to a positive electrode active material in which a lithium cobalt oxide is doped with a doping element including a metallic element and a halide element, wherein the positive electrode active material is represented by Formula 1 and satisfies Equation 1, and a positive electrode for a lithium secondary battery and a lithium secondary battery, either of which include the positive electrode active material:

Li(Co.sub.1-x-y-zM.sup.1.sub.xM.sup.2.sub.yM.sup.3.sub.z)O.sub.2-aH.sub.a [Formula 1]

(2x+3y+4za)/(x+y+z+a)<2.5. [Equation 1]

Disclosed is a lithium complex oxide sintered plate including a plurality of primary grains having a layered rock-salt structure, the primary grains being bonded. The lithium complex oxide has a composition represented by the formula: Li.sub.x(Co.sub.1-yM.sub.y)O.sub.2 (wherein, 1.0x1.1, 0<y=0.1, 0<1, and M is at least one selected from the group consisting of Mg, Ni, Al, and Mn), and the primary grains have a mean tilt angle of more than 0 to 30 or less, the mean tilt angle being a mean value of the angles defined by the (003) planes of the primary grains and the plate face of the lithium complex oxide sintered plate.