A mixed conductor represented by Formula 1:

A.sub.xTi.sub.5yG.sub.zO.sub.12Formula 1 wherein, in Formula 1, A is a monovalent cation, G is at least one of a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, or a hexavalent cation, with the proviso that G is not Ti or Cr, wherein 0<x<2, 0.3<y<5, 0<z<5, and 0<3.

A solid electrolyte material that includes a composite oxide containing Li and Bi, and at least one solid electrolyte having a garnet structure, a perovskite structure, and a LISICON structure.

Disclosed is a tin oxide containing antimony and at least one element A selected from the group consisting of tantalum, tungsten, niobium, and bismuth. The antimony and the at least one element A selected from the group consisting of tantalum, tungsten, niobium, and bismuth are preferably dissolved in a solid state in tin oxide. The ratio of the number of moles of the element A to the number of moles of antimony, i.e., [(the number of moles of the element A/the number of moles of antimony)], is preferably 0.1 to 10.

There are provided a solid electrolyte material having high density and ion conductivity, and an all solid lithium ion secondary battery using the solid electrolyte material. The solid electrolyte material has a garnet-related structure which has a chemical composition represented by Li.sub.7-x-yLa.sub.3Zr.sub.2-x-yTa.sub.xNb.sub.yO.sub.12 (0x0.8, 0.2y1, and 0.2x+y1) and relative density of 99% or greater, and belongs to a cubic system. The solid electrolyte material has lithium ion conductivity which is equal to or greater than 1.010.sup.3 S/cm. The solid electrolyte material has a lattice constant a which satisfies 1.28 nma1.30 nm, and has a lithium ion which occupies only two or more 96h sites in a crystal structure. The all solid lithium ion secondary battery includes a positive electrode, a negative electrode, and a solid electrolyte. The solid electrolyte includes the solid electrolyte material.

According to one embodiment, a negative electrode active material includes particles and a carbon material. The particles is represented by Li.sub.2+aA.sub.dTi.sub.6bB.sub.bO.sub.14c, where A is at least one element selected from the group consisting of Na, K, Mg, Ca, Ba, and Sr; B is a metal element other than Ti; and a, b, c, and d respectively satisfy 0a5, 0b6, 0c0.6, and 0d3. The carbon material covers at least a part of surfaces of the particles.

Provided are an oxide semiconductor excellent in transparency, mobility, and weatherability, etc., and a semiconductor device having the oxide semiconductor, a p-type semiconductor being realizable in the oxide semiconductor. The oxide semiconductor consists of a composite oxide, which has a crystal structure including a pyrochlore structure, containing at least one or more kinds of elements selected from Nb and Ta, and containing Sn element, and its holes become charge carriers by the condition that Sn.sup.4+/(Sn.sup.2++Sn.sup.4+) which is a ratio of Sn.sup.4+ to a total amount of Sn in the composite oxide is 0.124Sn.sup.4+/(Sn.sup.2++Sn.sup.4+)0.148.

In general, according to one embodiment, there is provided an active material. The active material contains a composite oxide having an orthorhombic crystal structure. The composite oxide is represented by a general formula of Li.sub.2+wNa.sub.2xM1.sub.yTi.sub.6zM2.sub.zO.sub.14+. In the general formula, the M1 is at least one selected from the group consisting of Cs and K; the M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al; and w is within a range of 0w4, x is within a range of 0<x<2, y is within a range of 0y<2, z is within a range of 0<z6, and is within a range of 0.50.5.

A dielectric composition including a tungsten bronze type composite oxide as a main component represented by (Ba.sub.1-xSr.sub.x).sub.aR.sub.bZr.sub.cTa.sub.dO.sub.30+0.5e in terms of an atomic ratio. In the dielectric composition, c=(2a+3b?10)?e and d=(20?2a?3b)+e are satisfied. R includes at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc. In the dielectric composition, 0.000?x?0.500, 5.100?a?5.860, 0.000?b?0.100, and ?0.150?e?0.150 are satisfied.

A solid electrolyte material that includes a composite oxide containing Li and Bi, and at least one solid electrolyte having a garnet structure, a perovskite structure, and a LISICON structure.

A lithium garnet material has the formula Li.sub.7-?La.sub.3Z.sub.2z-x-y-zM1.sub.xM2.sub.yM3.sub.zO.sub.12, where M1 is one or a combination of (Y, In, Mg, Ca, Ba, Sc, Sr, Ru) with oxidation number (valence) lower than 4+, M2 is one or a combination of (Bi, Ta, Nb, Mo, Sb, Te) with oxidation number (valence) higher than 4+, and M3 is one or a combination of (Hf, Ti, Sn, Si) with oxidation number (valence) equal to 4+, subject to 0<x?1, 0?y?1, 0?z?2, 0<x+y+z?2, and ?0.2<?<0.2. Also provided is a lithium garnet material which is the same as the aforementioned lithium garnet material except that M1 is one or a combination of (Y, In, Mg, Ca, Ba, Sr, Ru) and M2 is one or a combination of (Bi, Ta, Nb, Mo, Sb, Te, W). Lithium oxide solid-state electrolyte materials have the same formula as the aforementioned lithium garnet materials but also include Ge for M3.