Patent ID: 8377203

Claim:
An oxide single crystal production method comprising: preparing a starting material by mixing La 2 O 3 and SiO 2 ; and growing a single crystal with a crystal growth orientation in a C-axis direction by processing the starting material by using a Czochralski method to obtain a product of an oxide single crystal having a target composition represented by La 9.33 Si 6 O 26 with a lattice constant “a” of 0.9717 nm (inclusive) to 0.9734 nm (inclusive) and lattice constant “c” of 0.7185 nm (inclusive) to 0.7220 nm (inclusive), wherein in said preparing, the starting material is prepared by adding an excess amount of La 2 O 3 by 0.1 to 5 wt % with respect to the total amount of La 2 O 3 and SiO 2 having a ratio defined by the target composition, such that the lattice constants of the oxide single crystal are “a” is 0.9646 nm to 0.9739 nm and “c” is 0.7077 nm to 0.7224 nm in an initial stage of said growing, and wherein said growing obtains the product of the oxide single crystal by setting a solidification rate (grown crystal weight÷charged raw material weight) at less than 45%, to minimize composition fluctuation of the single crystal due to the excess amount of La 2 O 3 .