| abstract |
Zinc, magnesium, a regular trivalent or regular tetravalent metal element X, and oxygen are included as constituent elements, and the atomic ratio of the metal element X to the sum of zinc, magnesium and the metal element X [X/(Zn+) Mg+X)] is 0.0001 or more and 0.6 or less, and the atomic ratio of magnesium to the sum total of zinc and magnesium [Mg/(Zn+Mg)] is 0.25 or more and 0.8 or less. |