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 Y.sub.2O.sub.3, YOF, YF.sub.3, Y.sub.4Al.sub.2O.sub.9, Y.sub.3Al.sub.5O.sub.12, and YAlO.sub.3, and a silica (SiO.sub.2) 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.

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 Y.sub.2O.sub.3, YOF, YF.sub.3, Y.sub.4Al.sub.2O.sub.9, Y.sub.3Al.sub.5O.sub.12, and YAlO.sub.3, and a silica (SiO.sub.2) 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.

A method for producing a solid composition according to the present disclosure is a method for producing a solid composition that is used for forming a functional ceramic having a first crystal phase. The method for producing a solid composition includes: producing an oxide composed of a second crystal phase different from the first crystal phase; and mixing the oxide and an oxo acid compound.

A paramagnetic garnet-type transparent ceramic that exhibits a high laser damage threshold, said ceramic being a sintered body of a Tb-containing rare earth-aluminum garnet represented by formula (1), and being characterized in that the average sintered grain size is 10-40 μm, and the insertion loss at a wavelength of 1,064 nm in the optically effective region along the length direction of a 20 mm-long sample is 0.05 dB or less.

(Tb.sub.1-x-yY.sub.xSc.sub.y).sub.3(Al.sub.1-zSc.sub.z).sub.5O.sub.12  Formula (1)

(In the formula, 0≤x<0.45, 0≤y<0.08, 0≤z<0.2, and 0.001<y+z<0.20.)

A refrigerator is provided, including rare earth cold accumulating material particles filled in a cold accumulating vessel. The rare earth cold accumulating material particles are a rare earth oxide or a rare earth oxysulfide. The rare earth cold accumulating material particles define a sintered body. An average crystal grain size of the sintered body is 0.5 to 5 μm, a porosity of the sintered body is 10 to 50 vol. %, and an average pore size of the sintered body is 0.3 to 3 μm. In an arbitrary cross-section of the rare earth cold accumulating material particles, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.

A refrigerator is provided, including rare earth cold accumulating material particles filled in a cold accumulating vessel. The rare earth cold accumulating material particles are a rare earth oxide or a rare earth oxysulfide. The rare earth cold accumulating material particles define a sintered body. An average crystal grain size of the sintered body is 0.5 to 5 μm, a porosity of the sintered body is 10 to 50 vol. %, and an average pore size of the sintered body is 0.3 to 3 μm. In an arbitrary cross-section of the rare earth cold accumulating material particles, a number of pores per a unit area of 10 μm×10 μm is 20 to 70.

Described herein is a plasma resistant protective coating composition and bulk composition that provides enhanced erosion and corrosion resistance upon the coating composition's or the bulk composition's exposure to harsh chemical environment (such as hydrogen based and/or halogen based chemistries) and/or upon the coating composition's or the bulk composition's exposure to high energy plasma. Also described herein is a method of coating an article with a plasma resistant protective coating using electronic beam ion assisted deposition, physical vapor deposition, or plasma spray. Also described herein is a method of processing wafer, which method exhibits a reduced number of yttrium based particles.

Described herein is a plasma resistant protective coating composition and bulk composition that provides enhanced erosion and corrosion resistance upon the coating composition's or the bulk composition's exposure to harsh chemical environment (such as hydrogen based and/or halogen based chemistries) and/or upon the coating composition's or the bulk composition's exposure to high energy plasma. Also described herein is a method of coating an article with a plasma resistant protective coating using electronic beam ion assisted deposition, physical vapor deposition, or plasma spray. Also described herein is a method of processing wafer, which method exhibits a reduced number of yttrium based particles.

A YAG sintered body has a predetermined surface where intragranular pores are exposed. On the predetermined surface, arithmetic average roughness Ra satisfies Ra≤0.5 μm, and a ratio between maximum height Rz and maximum valley depth Rv satisfies Rv/Rz≤0.7. With this configuration, the predetermined surface of a processed surface is smoothed to have improved plasma resistance and exhibit a particle-suppressing effect.

A YAG sintered body has a predetermined surface where intragranular pores are exposed. On the predetermined surface, arithmetic average roughness Ra satisfies Ra≤0.5 μm, and a ratio between maximum height Rz and maximum valley depth Rv satisfies Rv/Rz≤0.7. With this configuration, the predetermined surface of a processed surface is smoothed to have improved plasma resistance and exhibit a particle-suppressing effect.