Nahedh H.  Alwash, Raheem abed  Jeber, 
    The Effect of Zn<sup>+2</sup> Substitution on Properties of the System (M<sub>x</sub>Co<sub>1-x</sub>Fe<sub>2</sub>O<sub>4</sub>),
    Journal of Engineering and Applied Sciences,
    Volume 13,Issue 3,
    2018,
    Pages 619-623,
    ISSN 1816-949x,
    jeasci.2018.619.623,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2018.619.623)
    Abstract: The (co-precipitation) method is used to prepare two types of ferrite (CoCoFe<sub>2</sub>O<sub>4</sub> , ZnCoFe<sub>2</sub>O<sub>4</sub> ). Precursor materials (ZnCl<sub>2</sub> CoCl<sub>2</sub> .6H<sub>2</sub>O), mixed with iron chloride (FeCl<sub>3</sub>). The prepared powder of ferrites were primary sintered at 800&deg;C for 2 h XRD technique were used to study the structure of two types ferrite prepare. Then using these types of ferrite to prepare finely synthesis (Zn<sub>x</sub>Co<sub>1-x</sub>Fe<sub>2</sub>O<sub>4</sub>)                                             ) with (x = 0.2, 0.4, 0.6, 0.8) to be 8 samples halve of these were pressed as pellets (12.3 mm diameter, 5-4 mm thickness) then later halve as triodes (R<sub>in</sub> = 9.85 mm, R<sub>out</sub> = 19.4 mm) by hydraulic press at pressure (3-5 tons), all of them were sintered at in out (1100&deg;C) for 2 h. Bulks densities were measured, DC measurements were used to determine electrical resistivity (<i>p</i>), AC measurements real part and of dielectric constant, initial permeability (&epsilon;<sub>r</sub>&#146;, &mu; ) were calculated, the study r i is show that, the x increase lead to decrease the density. Electrical resistivity has minimum value for x = 0.4. Real part of dielectric constant decrease sharply with increasing frequency to reach 100 kHz then the decrease is reducing.
    Keywords: ferrites;Co-precipitation;permittivity;initial permeability;pressure;measurements