A ferrite particle having a spinel crystal structure belonging to a space group Fd-3m and having a ferrite composition represented by a specific formula, a carrier for an electrophotographic developer including the ferrite particle and a resin coating layer configured to coat a surface of the ferrite particle, an electrophotographic developer including the carrier for an electrophotographic developer and a toner, and a ferrite particle production method for producing the ferrite particle.

An electrostatic latent image developing carrier includes carrier particles each including a carrier core and first and second coat layers covering a surface of the carrier core. The first and second coat layers give a layered structure in which the first coat layer and the second coat layer are layered in order from the surface of the carrier core. The first coat layer contains a fluororesin. The second coat layer contains a silicone resin and a fluorine silane in an amount of at least 1% by mass relative to a mass of the silicone resin. An area S.sub.A of a region of a surface region of the first coat layer that is covered with the second coat layer and an area S.sub.B of a region thereof that is not covered with the second coat layer satisfy a relationship represented by 0.05S.sub.B/(S.sub.A+S.sub.B)0.50.

A two-component developer includes toner particles and carrier particles. The toner particles each include a toner mother particle and first resin particles. The carrier particles each include a carrier mother particle and second resin particles. An amount of the second resin particles is at least 0.010 parts by mass and no greater than 0.100 parts by mass relative to 100 parts by mass of the carrier mother particles. The first resin particles and the second resin particles have a number average primary particle diameter of at least 40 nm and no greater than 100 nm and a blocking rate (measurement temperature: 160 C.) of less than 30% by mass. A difference in blocking rate between the first resin particles and the second resin particles is no greater than 5% by mass, and a difference in number average primary particle diameter therebetween is no greater than 5 nm.

Provided is a toner external additive including: a strontium titanate particle which has a hydrophobized surface, in which an average primary particle diameter is 10 nm or more and 100 nm or less, and a specific volume resistivity R1 is 11 or more and 14 or less in terms of a common logarithm value log R1.

A carrier core material is provided that is formed with ferrite particles which can uniformly adhere a coupling agent to the entire surface. A carrier core material is formed with ferrite particles, and the powder pH of the ferrite particles is equal to or more than 9. Here, the ferrite particles are preferably formed of Mn ferrite or MnMg ferrite. The ferrite particles preferably contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer disposed on the conductive substrate, wherein when time that takes for a current value to reach the maximum after beginning of application of a square wave voltage to the electrophotographic photoreceptor is T.sub.1 and time that takes for the current value to reach the maximum after the beginning of the application of the square wave voltage and then decrease to one fifth of the maximum is T.sub.2, T.sub.2 is approximately from 3.2 to 11.0 times as large as T.sub.1.

An electrostatic charge image developer contains a toner including toner particles that contain a binder resin and a carrier including magnetic particles and a resin layer that adheres to a surface of the magnetic particles, in which, in a dynamic viscoelasticity measurement of the toner, in a case where a loss tangent tan? at a temperature of 90? C. and a strain of 1% is represented by D1 (90), a loss tangent tan? at a temperature of 90? C. and a strain of 50% is represented by D50 (90), a loss tangent tan? at a temperature of 150? C. and a strain of 1% is represented by D1 (150), and a loss tangent tan? at a temperature of 150? C. and a strain of 50% is represented by D50 (150), each of D1 (90), D50 (90), D1 (150), and D50 (150) is 0.5 or more and 2.5 or less, a value of D50 (150)?D1 (150) is less than 1.5, and a value of D50 (90)?D1 (90) is less than 1.0, and in the surface of the magnetic particles, an average unevenness interval Sm and an arithmetic mean roughness Ra satisfy 0.5 ?m? Sm?2.5 ?m and 0.3 ?m? Ra?1.2 ?m.

An electrostatic image developing toner contains: toner particles, first silica particles having an average equivalent circle diameter of 10 nm to 120 nm and second silica particles having a compressive agglomeration degree of 60% to 95%, a particle compression ratio of 0.20 to 0.40 and an average equivalent circle diameter being greater than the average equivalent circle diameter of the first silica particles.

An object of the present invention is to provide a carrier in which decrease in specific gravity is achieved and a volatile organic compound (VOC) is reduced and to provide an electrophotographic developer using the carrier. There is provided a carrier including a core material coated with a resin, the core material including a magnetic component and a nonmagnetic component, wherein the sum total of volatile organic compounds is 1 ppb or more and 1.5 ppm or less. There is also provided an electrophotographic developer using the carrier.

An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer disposed on the conductive substrate, wherein when time that takes for a current value to reach the maximum after beginning of application of a square wave voltage to the electrophotographic photoreceptor is T.sub.1 and time that takes for the current value to reach the maximum after the beginning of the application of the square wave voltage and then decrease to one fifth of the maximum is T.sub.2, T.sub.2 is approximately from 3.2 to 11.0 times as large as T.sub.1.