Patent ID: 7090724

Claim:
A Langasite single crystal ingot comprising a single crystal of Langasite having the formula La 3 Ga 5 SiO 14 and having a composition within a range in a La 2 O 3 /Ga 2 O 3 /SiO 2 phase diagram defined by a point at which La 2 O 3 is 47.82 wt. %, Ga 2 O 3 is 46.50 wt %, and SiO 2 is 5.68 wt. %; a point at which La 2 O 3 is 47.97 wt. %, Ga 2 O 3 is 46.27 wt %, and SiO 2 is 5.76 wt. %; and a point at which La 2 O 3 is 48.03 wt. %, Ga 2 O 3 is 46.49 wt %, and SiO 2 is 5.48 wt. %, wherein amounts of lanthanum oxide, gallium oxide, and silicon oxide in a longitudinal cross section and a transverse cross section of a straight part of the Langasite single crystal ingot, excluding the shoulder of the ingot, are ±0.05 wt. % of the composition, a diameter of the Langasite single crystal ingot is 85 mm or more, and the Langasite single crystal ingot is substantially free of growth striations.