US 12,436,480 B2
Ferrite particles, electrophotographic developer carrier core material, electrophotographic developer carrier, and electrophotographic developer
Makoto Ishikawa, Kashiwa (JP); and Tetsuya Uemura, Kashiwa (JP)
Assigned to POWDERTECH CO., LTD., Kashiwa (JP)
Appl. No. 17/915,345
Filed by POWDERTECH CO.,LTD., Kashiwa (JP)
PCT Filed Mar. 17, 2021, PCT No. PCT/JP2021/010912
§ 371(c)(1), (2) Date Sep. 28, 2022,
PCT Pub. No. WO2021/200171, PCT Pub. Date Oct. 7, 2021.
Claims priority of application No. 2020-062122 (JP), filed on Mar. 31, 2020; and application No. 2020-068146 (JP), filed on Apr. 6, 2020.
Prior Publication US 2023/0152726 A1, May 18, 2023
Int. Cl. C04B 35/26 (2006.01); G03G 9/08 (2006.01); G03G 9/107 (2006.01); G03G 9/113 (2006.01)
CPC G03G 9/1085 (2020.08) [C04B 35/2625 (2013.01); G03G 9/0821 (2013.01); G03G 9/1132 (2013.01); C04B 2235/3248 (2013.01); C04B 2235/3274 (2013.01); C04B 2235/763 (2013.01); C04B 2235/768 (2013.01); C04B 2235/963 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A ferrite particle,
comprising a crystal phase component comprising a perovskite crystal represented by the compositional formula: RZrO3 (provided that R represents an alkaline earth metal element),
having a surface roughness Rz of 0.8 μm or more and 3.5 μm or less, and
having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula:
0.15×Rz≤Rzσ≤0.60×Rz  (1)
comprising the crystal phase component comprising the perovskite crystal in an amount of 0.05% by mass or more and 4.0% by mass or less when a phase composition analysis of a crystal phase constituting the ferrite particle is performed by a Rietveld analysis of an X-ray diffraction pattern.