Patent ID: 8023180

Claim:
A method for making a fluoroberyllium borate non-linear optical crystal, comprising: (1) preparing a high temperature solution containing a fluoroberyllium borate compound and a flux by mixing the fluoroberyllium borate compound and the flux, heating the mixture at a rate of 10-30° C./hour to a temperature of 750-800° C., keeping the mixture at a temperature of 750-800° C. for 10-40 hours, then cooling the mixture to a temperature of 2-10° C. above the saturating point; wherein the molecular formula of the fluoroberyllium borate compound is MBe 2 BO 3 F 2 , wherein M is selected from the group consisting of Rb or Cs; wherein the flux is a mixture of M 2 CO 3 , B 2 O 3 and M′F, wherein M′ is selected from the group consisting of Li, Na and M; and wherein the molar ratio of the fluoroberyllium borate compound to the flux is MBe 2 BO 3 F 2 :M 2 CO 3 :B 2 O 3 :M′F=1:(0.3-0.75):(0.6-3.5):(0.3-2); and (2) growing the fluoroberyllium borate crystal by putting a seed crystal fixed on an end of a crystal hanging bar into the high temperature solution while rotating the crystal hanging bar at a rate of 0-100 rpm, cooling the solution to its saturating point, then cooling the solution at a rate of 0.5-5° C./day, and obtaining the desired crystal by pulling the crystal out of the solution surface while cooling it to room temperature at a rate of 5-50° C./hour to obtain a non-linear optical crystal of the fluoroberyllium borate.