Patent ID: 7862975

Claim:
A carrier core material for an electrophotographic developer comprising Li ferrite, maghemite, and Fe 3 O 4 , wherein a part thereof is substituted with Mn, a Li content is 1 to 2.5% by weight, a Mn content is 2 to 7.5% by weight, and a silicon content is 25to 10,000 ppm, a compression breaking strength is 130MPa or more, an SF-1 is 125 to 145, the following equation (1) is satisfied when respective cumulative strengths of spinel crystal structure (110), (210), (211), and (311) faces in X-ray diffraction are respectively I 110 , I 210 , I 211 , and I 311 , a vacuum resistivity R 500 across a 2 mm gap when a measurement voltage of 500 V is applied is 1Ã—10 6 to 5Ã—10 9 Î©, and a vacuum resistivity R 1000 across a 6.5 mm gap when a measurement voltage of 1,000 V is applied is 5Ã—10 7 to 1Ã—10 1 Î©; 2<100Ã—( I 110 +I 210 +I 21l )/ I 311 < 14 (1).