The present invention relates to a method of producing metal nanoparticles and metal sulfide nanoparticles using a recombinant microorganism co-expressing metallothionein and phytochelatin synthase, which are heavy metal-adsorbing proteins, and to the use of metal nanoparticles and metal sulfide nanoparticles synthesized by the method. The present invention provides a method for synthesizing metal nanoparticles which have been difficult to synthesize by conventional biological methods. The present invention makes it possible to synthesize metal nanoparticles in an environmentally friendly and cost-effective manner, and also makes it possible to synthesize metal sulfide nanoparticles. In addition, even metal nanoparticles which could have been produced by conventional chemical or biological methods are produced in a significantly increased yield by use of the method of the present invention.

A negative electrode active material includes a compound represented by a composition formula of Mg.sub.xMe.sub.1-xO.sub.1-xH.sub.2x, where Me is at least one selected from the group consisting of Mn, Fe, Co, Ni, and Cu, and 0.5x0.9.

Devices are provided, which in embodiments, comprise a source configured to generate oxygen ions via a redox reaction; and an oxygen ion transport material through which oxygen ions generated from the source are transported. The oxygen ion transport material may have either: Formula I A.sup.x+B.sub.2.sup.y+C.sub.4.sup.z+O.sub.12 .sup.2? wherein x+2y+4z=24 and (x, y, z) is (4, 2, 4), (x, y, z) is (2, 1, 5), or (x, y, z) is (3, 2.5, 4); Formula II A.sub.4.sup.x+B.sub.5.sup.y+C.sub.4.sup.z+O.sub.22.sup.2? wherein 4x+5y+4z=44 and (x, y, z) is (2, 4, 4) or (x, y, z) is (3, 3.2, 4) or (x, y, z) is (2.5, 3.6, 4); or Formula III Bi.sub.2MO.sub.4X; wherein A, B, and C are independently selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, lanthanoids, P, Th, and combinations thereof, and wherein M is selected from rare earth elements and combinations thereof and X is selected from halogens and combinations thereof. Methods of using the devices are also provided, which in embodiments, which comprise transporting oxygen ions generated from the source through the oxygen ion transport material.

In a perovskite-type composite oxide powder according to the present invention, the geometric standard deviation value of the maximum Feret diameter of the perovskite-type composite oxide powder calculated by performing image analysis on an SEM image acquired with a scanning electron microscope is equal to or greater than 1.01 and less than 1.60, and when it is assumed that the perovskite-type composite oxide powder is spherical, the ratio (B/A) of an area value B directly calculated by the image analysis to an area value A calculated from the maximum Feret diameter is equal to or greater than 0.7 and less than 1.0. In this way, the perovskite-type composite oxide powder is used as the air electrode material of an SOFC, and thus high conductivity as compared with a conventional air electrode material is obtained.

There is disclosed an electrode material for cells. The electrode material includes carbon, and a crystalline material composed of a layered double hydroxide and/or a cation-deficit metal oxide having a rock-salt structure. Carbon is complexed with the cation-deficit metal oxide and/or the layered double hydroxide.

Provided is a black fine particulate near-infrared reflective material which is a perovskite-type complex oxide containing at least an alkaline earth metal element, titanium element, and manganese element, having a BET specific surface area within a range of 3.0-150 m.sup.2/g. The Hunter L value, as an indicator of blackness, is 30 or less, and the reflectivity at a wavelength of 1200 nm, as an indicator of near-infrared reflective power, is 40% or above.

Provided is a black fine particulate near-infrared reflective material which is a perovskite-type complex oxide containing at least an alkaline earth metal element, titanium element, and manganese element, having a BET specific surface area within a range of 3.0-150 m.sup.2/g. The Hunter L value, as an indicator of blackness, is 30 or less, and the reflectivity at a wavelength of 1200 nm, as an indicator of near-infrared reflective power, is 40% or above.

The invention relates to electrodes that contain active materials of the formula: A.sub.aM.sub.bX.sub.xO.sub.y wherein A is one or more alkali metals selected from lithium, sodium and potassium; M is selected from one or more transition metals and/or one or more non-transition metals and/or one or more metalloids; X comprises one or more atoms selected from niobium, antimony, tellurium, tantalum, bismuth and selenium; and further wherein 0<a6; b is in the range: 0<b4; x is in the range 0<x1 and y is in the range 2y10. Such electrodes are useful in, for example, sodium and/or lithium ion battery applications.

To provide metal-containing trimanganese tetraoxide combined particles with which a metal-substituted lithium manganese oxide excellent as a cathode material for a lithium secondary battery can be obtained, and their production process. Metal-containing trimanganese tetraoxide combined particles containing a metal element (excluding lithium and manganese). Such metal-containing trimanganese tetraoxide combined particles can be obtained by a production process comprising a crystallization step of crystalizing a metal-substituted trimanganese tetraoxide not by means of metal-substituted manganese hydroxide from a manganese salt aqueous solution containing manganese ions and metal ions other than manganese.

To provide metal-containing trimanganese tetraoxide combined particles with which a metal-substituted lithium manganese oxide excellent as a cathode material for a lithium secondary battery can be obtained, and their production process. Metal-containing trimanganese tetraoxide combined particles containing a metal element (excluding lithium and manganese). Such metal-containing trimanganese tetraoxide combined particles can be obtained by a production process comprising a crystallization step of crystalizing a metal-substituted trimanganese tetraoxide not by means of metal-substituted manganese hydroxide from a manganese salt aqueous solution containing manganese ions and metal ions other than manganese.