Abstract: A ceramic thermal spray coating material and a method of preparing a ceramic thermal spray coating material are disclosed. The ceramic thermal spray coating material comprises a ceramic granule powder and an organic compound containing stearic acid having an ammonium group, which is modified on the surface of the ceramic granule powder. Further, the method includes: preparing ceramic granule powders; adding stearic acid having an ammonium group and the ceramic granule powders to a first solvent to prepare a first mixed solution; evaporating the first solvent from the first mixed solution; and modifying a surface of the ceramic granule powders with an organic compound by evaporating the first solvent.

Abstract: Proposed is an yttrium-based granular powder for thermal spraying. The yttrium-based granular powder includes at least one yttrium compound powder selected from the group consisting of Y2O3, YOF, YF3, Y4Al2O9, Y3Al5O12, and YAlO3, and a silica (SiO2) powder. The yttrium-based granular powder is prepared by mixing the yttrium compound powder having a mean grain diameter of 50 nm to 900 nm and the silica powder having a mean grain diameter of 50 nm to 900 nm. The yttrium-based granular powder includes less than 10 wt % of a Y—Si—O mesophase. A thermal spray coating produced using the yttrium-based granular powder can exhibit low porosity, high density, and excellent plasma resistance.

Abstract: Disclosed is a light-emitting element according to an embodiment, comprising: a light-emitting structure comprising a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer; and a light extractor arranged on the light-emitting structure, the light extractor comprising: a first nitride semiconductor layer with a first wet etch rate, arranged on the first conductivity-type semiconductor layer, a second nitride semiconductor layer with a second wet etch rate, arranged on the first nitride semiconductor layer, and a third nitride semiconductor layer with a third wet etch rate, wherein the first and third wet etch rates are lower than the second wet etch rate.