The invention discloses a
lithium niobate substrate blackening method. A reducing
reagent utilized in the method is prepared by mixing
iron powder and
lithium carbonate powder. The
lithium niobate substrate blackening method comprises the steps: 1, putting an
iron powder and
lithium carbonate mixture into a square
corundum crucible; 2, flatly putting and burying a
lithium niobate substrate into the mixture; 3, putting the square
corundum crucible into a
thermal treatment furnace and treating in the
argon atmosphere; 4, putting into a diluted
hydrochloric acid solution to be soaked when a temperature reduces to be close to a
room temperature and then washing and spin
drying. The method has short reaction time, small consumed time in a
lithium niobate substrate blackening process and suitability for large-scale production; by means of high
temperature resistance and acid-base resistance, the square
corundum crucible can be used for a long time; furthermore, the square corundum crucible brings convenience to taking and putting wafers, and the square corundum crucible is stabler in a furnace tube of the
thermal treatment furnace and is not prone to inclining. The method has the advantages of convenience, simpleness and easiness in operation, safety and reliability. By adjusting conditions of a mixture proportion, reaction time,
reaction temperature and the like, the lithium niobatesubstrates of different blackened degrees can be obtained.