A spinel compound oxide particle includes metallic atoms, aluminum atoms, oxygen atoms, and molybdenum atoms, wherein the metallic atoms are selected from the group consisting of zinc atoms, cobalt atoms, and strontium atoms, and a crystallite size in a [111] plane is 100 nm or more. Included are a step (1) of firing a first mixture including a molybdenum compound and a metallic-atom-containing compound or a first mixture including a molybdenum compound, a metallic-atom-containing compound, and an aluminum compound to prepare an intermediate; and a step (2) of firing, at a temperature higher than a temperature selected in the step (1), a second mixture including the intermediate or a second mixture including the intermediate and an aluminum compound.

A method of preparing a positive electrode active material includes forming a pre-sintered product by mixing a transition metal precursor having a nickel content of 70 atm % or more and a lithium raw material and performing primary sintering, and forming a lithium composite transition metal oxide by performing secondary sintering on the pre-sintered product, wherein the primary sintering is performed such that a ratio of a spinel phase of the pre-sintered product is in a range of 7% to 16%.

Described herein is a nanocrystalline ferrite having the formula Ni.sub.1−x−yM.sub.yCo.sub.xFe.sub.2+zO.sub.4, wherein M is at least one of Zn, Mg, Cu, or Mn, x is 0.01 to 0.8, y is 0.01 to 0.8, and z is −0.5 to 0.5, and wherein the nanocrystalline ferrite has an average grain size of 5 to 100 nm. A method of forming the nanocrystalline ferrite can comprise high energy ball milling.

Methods of forming spinel ferrite nanoparticles containing a chromium-substituted copper ferrite as well as properties (e.g. particle size, crystallite size, pore size, surface area) of these spinel ferrite nanoparticles are described. Methods of preventing or reducing microbe growth on a surface by applying these spinel ferrite nanoparticles onto the surface in the form of a suspension or an antimicrobial product are also described.

An active material has: a core portion made of an active material base material; and a coating portion located on a surface of the core portion. The coating portion contains an element A comprising at least one selected from the group consisting of titanium (Ti), zirconium (Zr), tantalum (Ta), niobium (Nb), and aluminum (Al). The active material has two or more inflection point in a first-order derivative obtained with respect to a peak attributed to the element A, the first-order derivative being obtained based on a constituent element average intensity profile measured for the coating portion with use of an energy dispersive X-ray spectrometer.

According to an embodiment, provided is a cathode active material for a lithium secondary battery, the cathode active material including a nickel-based composite metal oxide including a secondary particle in which a plurality of primary particles are agglomerated, wherein the secondary particle includes a central portion and a surface portion, the surface portion includes a nickel-based composite metal oxide doped with manganese, and an amount of manganese present in the grain boundaries of the plurality of primary particles present in the surface portion is greater than an amount of manganese present inside the primary particles.

Methods of forming spinel ferrite nanoparticles containing a chromium-substituted copper ferrite as well as properties (e.g. particle size, crystallite size, pore size, surface area) of these spinel ferrite nanoparticles are described. Methods of preventing or reducing microbe growth on a surface by applying these spinel ferrite nanoparticles onto the surface in the form of a suspension or an antimicrobial product are also described.

A spinel-type nickel-manganese-lithium-containing composite oxide, a preparation method thereof, and a secondary battery and an electric apparatus containing the same are provided. A body material of the spinel-type nickel-manganese-lithium-containing composite oxide is represented by a general formula Li.sub.xNi.sub.yMn.sub.zM.sub.mO.sub.4Q.sub.q, and both element P and one or more elements selected from elements Nb, W, and Sb are doped in the body material, where based on mass of the spinel-type nickel-manganese-lithium-containing composite oxide, doping content k of the element P satisfies 0.48 wt %≤k≤3.05 wt %, doping content g of the one or more elements selected from the elements Nb, W, and Sb satisfies 0.05 wt %≤g≤0.31 wt %, and 2≤k/g≤20. The secondary battery provided in this application has good high-temperature storage performance and high-temperature cycling performance.

Stabilized lithium- and manganese rich manganese-nickel-oxide electrode materials for Li-ion batteries with structurally-integrated layered, lithiated spinel- and rock salt components are described, as are methods to synthesize them. In these methods, selected annealing temperatures and times are used to control the amount of a stabilizing lithiated spinel component, as well as the extent of disorder in the composite electrode structure to optimize electrochemical performance. The stabilized lithium- and manganese rich manganese-nickel-oxide electrode materials can be structurally-integrated with other lithium-metal-oxide or lithium-metal-polyanionic components, as well.

A method of obtaining a nickel zinc cobalt spinet ferrite in ceramic form that includes the following: obtaining a precipitate (1) of iron, nickel, zinc, and cobalt hydroxides by co-precipitation, rinsing the precipitate (2), drying and grinding (3) the rinsed precipitate in order to obtain a powder; forming (4) into a compact by pressing the powder, and sintering (5) the compact. The sintering (5) includes a progressive temperature rise of 2° C. to 4° C. per minute, from an ambient temperature to reach a maximum temperature comprised between 950° C. and 1.010° C., maintaining at the maximum temperature for forty-five minutes to three hours, a progressive fall in temperature of 2° C. to 4° C. per minute to reach ambient temperature. The foregoing and, in particular, the sintering, enable a material to be obtained that is particularly well-adapted to the manufacture of an antenna configured for frequencies less than one gigahertz.