Proposed is a method for manufacturing a spherical YOF-based powder. Specifically, proposed is a method for manufacturing a spherical YOF-based powder. The YOF-based powder injected into the plasma jet and melted into the refrigerant in a droplet state is sprayed and quenched, thereby improving density and controlling the component ratio through particle spheroidization.

Proposed is a method for manufacturing a spherical YOF-based powder. Specifically, proposed is a method for manufacturing a spherical YOF-based powder. The YOF-based powder injected into the plasma jet and melted into the refrigerant in a droplet state is sprayed and quenched, thereby improving density and controlling the component ratio through particle spheroidization.

A film-forming powder containing a rare earth oxyfluoride has an average particle size D50 of 0.6-15 μm, a total volume of ≤10 μm pores of 0.51-1.5 cm.sup.3/g as measured by mercury porosimetry, and a BET surface area of 3-50 m.sup.2/g is suitable for forming a dense film in high yields or deposition rates and high productivity. The film-forming powder having a greater pore volume can be prepared by forming a rare earth ammonium fluoride complex salt on surfaces of rare earth oxide particles to provide precursor particles, and heat treating the precursor particles at a temperature of 350 to 700° C.

A film-forming powder containing a rare earth oxyfluoride has an average particle size D50 of 0.6-15 μm, a total volume of ≤10 μm pores of 0.51-1.5 cm.sup.3/g as measured by mercury porosimetry, and a BET surface area of 3-50 m.sup.2/g is suitable for forming a dense film in high yields or deposition rates and high productivity. The film-forming powder having a greater pore volume can be prepared by forming a rare earth ammonium fluoride complex salt on surfaces of rare earth oxide particles to provide precursor particles, and heat treating the precursor particles at a temperature of 350 to 700° C.

A coating material containing an oxyfluoride of yttrium and having a Fisher diameter of 1.0 to 10 μm and a tap density TD to apparent density AD ratio, TD/AD, of 1.6 to 3.5. The coating material preferably has a pore volume of pores with a diameter of 100 μm or smaller of 1.0 cm.sup.3/g or less as measured by mercury intrusion porosimetry. A coating containing an oxyfluoride of yttrium and having a Vickers hardness of 200 HV0.01 or higher. The coating preferably has a fracture toughness of 1.0×10.sup.2 Pa.Math.m.sup.1/2 or higher.

A coating material containing an oxyfluoride of yttrium and having a Fisher diameter of 1.0 to 10 μm and a tap density TD to apparent density AD ratio, TD/AD, of 1.6 to 3.5. The coating material preferably has a pore volume of pores with a diameter of 100 μm or smaller of 1.0 cm.sup.3/g or less as measured by mercury intrusion porosimetry. A coating containing an oxyfluoride of yttrium and having a Vickers hardness of 200 HV0.01 or higher. The coating preferably has a fracture toughness of 1.0×10.sup.2 Pa.Math.m.sup.1/2 or higher.

A film-forming powder containing a rare earth oxyfluoride has an average particle size D50 of 0.6-15 μm, a total volume of 10 μm pores of 0.51-1.5 cm.sup.3/g as measured by mercury porosimetry, and a BET surface area of 3-50 m.sup.2/g is suitable for forming a dense film in high yields or deposition rates and high productivity. The film-forming powder having a greater pore volume can be prepared by forming a rare earth ammonium fluoride complex salt on surfaces of rare earth oxide particles to provide precursor particles, and heat treating the precursor particles at a temperature of 350 to 700° C.

A film-forming powder containing a rare earth oxyfluoride has an average particle size D50 of 0.6-15 μm, a total volume of 10 μm pores of 0.51-1.5 cm.sup.3/g as measured by mercury porosimetry, and a BET surface area of 3-50 m.sup.2/g is suitable for forming a dense film in high yields or deposition rates and high productivity. The film-forming powder having a greater pore volume can be prepared by forming a rare earth ammonium fluoride complex salt on surfaces of rare earth oxide particles to provide precursor particles, and heat treating the precursor particles at a temperature of 350 to 700° C.

The present invention provides a crystal of a europium compound containing europium. The present invention enables the preparation of a crystal of a europium compound having a powder X-ray diffraction pattern having a first diffraction peak in diffraction angle (2θ) range of 34.3° to 36.1° in which a half width of the first diffraction peak is 1.8° or less, and/or having a second diffraction peak in diffraction angle (2θ) range of 28.6° to 29.6° and a third diffraction peak in diffraction angle (2θ) range of 36.8° to 38.4° in which a half width of the second diffraction peak is 1.0° or less and a half width of the third diffraction peak is 1.6° or less, and being at least one compound selected from compounds represented by formulae (1) to (4):

EuCl.sub.x  (1)

Eu(OH).sub.2  (2)

Eu(OH).sub.2Cl  (3)

EuOCl  (4) x is 0.05 or more and 5 or less.

A forming method of an yttrium oxide fluoride (YOF) coating film and a (YOF) coating film formed thereby are disclosed. The YOF coating film has no or extremely small pores therein and a nanostructure to increase light transmittance thereof, and has high hardness and high bonding strength and thus can protect a transparent window of a display device. The method for forming an YOF coating film involves the steps of: providing pretreated YOF powder having a particle diameter ranging from 0.1 to 12 μm; receiving a transfer gas supplied from a transfer gas supply unit and receiving the pretreated YOF powder supplied from a powder supply unit to transfer the pretreated YOF powder in an aerosol state; and colliding/smashing (spraying) the pretreated YOF powder transferred in the aerosol state with/onto a substrate in a process chamber to form an YOF coating film on the substrate.