To provide a lithium ion conductive crystal body having a high density and a large length and an all-solid state lithium ion secondary battery containing the lithium ion conductive crystal body. A Li.sub.5La.sub.3Ta.sub.2O.sub.12 crystal body, which is one example of the lithium ion conductive crystal body, has a relative density of 99% or more, belongs to a cubic system, has a garnet-related type structure, and has a length of 2 cm or more. The Li.sub.5La.sub.3Ta.sub.2O.sub.12 crystal body is grown by a melting method employing a Li.sub.5La.sub.3Ta.sub.2O.sub.12 polycrystal body as a raw material. With the growing method, a Li.sub.5La.sub.3Ta.sub.2O.sub.12 crystal body having a relative density of 100% can also be obtained. In addition, the all-solid state lithium ion secondary battery has a positive electrode, a negative electrode, and a solid electrolyte, in which the solid electrolyte contains the lithium ion conductive crystal body.

A dielectric composition containing a complex oxide represented by the formula of xAO-yBO-zC.sub.2O.sub.5 as the main component, wherein A represents at least one element selected from the group including Ba, Ca and Sr, B represents Mg, and C represents at least one element selected from the group including Nb and Ta, and x, y and z meet the following conditions, x+y+z=1.000, 0.198≦x≦0.375, 0.389≦y≦0.625, and x/3≦z≦x/3+1/9.

A dielectric composition containing a complex oxide represented by the formula of xAO-yBO-zC.sub.2O.sub.5 as the main component, wherein A represents at least one element selected from the group including Ba, Ca and Sr, B represents Mg, and C represents at least one element selected from the group including Nb and Ta, and x, y and z meet the following conditions, x+y+z=1.000, 0.000<x≦0.281, 0.625≦y<1.000, and 0.000<z≦0.375.

Disclosed are embodiments of making a barium magnesium tantalate. The method can include providing barium magnesium tantalate and incorporating one of Ba.sub.2MgWO.sub.6, Ba.sub.8LiTa.sub.5WO.sub.24, Ba.sub.8LiTa.sub.5WO.sub.24, Ba.sub.2MgWO.sub.6, Ba.sub.3LaTa.sub.3O.sub.12, Ba.sub.8LiTa.sub.5WO.sub.24, BaLaLiWO.sub.6, Ba.sub.4Ta.sub.2WO.sub.12, Ba.sub.2La.sub.2MgW.sub.2O.sub.12, BaLaLiWO.sub.6, Sr.sub.3LaTa.sub.3O.sub.12, and SrLaTaO.sub.12 into the barium magnesium tantalate to form a solid solution having a high Q value.

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 0.124≤Sn.sup.4+/(Sn.sup.2++Sn.sup.4+)≤0.148.

A piezoelectric composition including copper and a complex oxide having a perovskite structure represented by a general formula ABO.sub.3, in which an A site element in the ABO.sub.3 is potassium or potassium and sodium, a B site element in the ABO.sub.3 is niobium or niobium and tantalum, the copper is included in n mol % in terms of a copper element with respect to 1 mol of the complex oxide, and n satisfies 0.100≤n≤1.000.

There are provided a lithium-containing garnet crystal high in density and ionic conductivity, and an all-solid-state lithium ion secondary battery using the lithium-containing garnet crystal. The lithium-containing garnet crystal has a chemical composition represented by Li.sub.7-xLa.sub.3Zr.sub.2-xTa.sub.xO.sub.12 (0.2≦x≦1), and has a relative density of 99% or higher, belongs to a cubic system, and has a garnet-related structure. The lithium-containing garnet crystal has a lithium ion conductivity of 1.0×10.sup.−3 S/cm or higher. Further, this solid electrolyte material has a lattice constant a of 1.28 nm≦a≦1.30 nm, and lithium ions occupy 96h-sites in the crystal structure. The all-solid-state lithium ion secondary battery has a positive electrode, a negative electrode and a solid electrolyte, and the solid electrolyte is constituted of the lithium-containing garnet crystal according to the present invention.

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.

The invention relates to Eu.sup.2+-activated phosphors, to a process of its preparation, the use of these phosphors in electronic and electro optical devices, such as light emitting diodes (LEDs) and solar cells and especially to illumination units comprising said magnesium alumosilicate-based phosphors.

The present invention discloses a dielectric ceramic formula enabling one to obtain a multilayer ceramic capacitor by alternatively stacking the ceramic dielectric layers and base metal internal electrodes. The dielectric ceramic composition comprises a primary ingredient:

[(Na.sub.1-xK.sub.x).sub.sA.sub.1-s].sub.m[(Nb.sub.1-yTa.sub.y).sub.uB1.sub.vB2.sub.w)]O.sub.3

wherein:
A is at least one selected from the alkaline-earth element group of Mg, Ca, Sr, and Ba;
B1 is at least one selected from the group of Ti, Zr, Hf and Sn;
B2 is at least one selected from transition metal elements;
and wherein:
x, y, s, u, v, and w are molar fractions of respective elements, and m is the molar ratio of [(Na.sub.1-xK.sub.x).sub.sA.sub.1-s] and [(Nb.sub.1-yTa.sub.y).sub.uB1.sub.vB2.sub.w)]. They are in the following respective range:
0.93≤m≤1.07;
0.7≤s≤1.0;
0.00≤x≤0.05; 0.00≤y≤0.65;
0.7≤u≤1.0; 0.0≤v≤0.3; 0.001≤w≤0.100;
a first sub-component composes of at least one selected from the rare-earth compound,
wherein the rare-earth element is no more than 10 mol % parts with respect to the main component; and
a second sub-component composes a compound with low melting temperature to assist the ceramic sintering process, said frit, which is Li free and could be at least one selected from fluorides, silicates, borides, and oxides. The content of frit is within the range of 0.01 mol % to 15.00 mol % parts with respect to the main component.