23 Ni Addition Induced Changes in Structural, Magnetic, and Cationic. . .
359
of Zn 0.7-x Ni x Mg 0.2 Cu 0.1 Fe 2 O 4 (x = 0.0–0.7) nano-ferrite is presented in [24]. The
magnetic properties M s (43.2–69.9 Am 2 /kg) and n B
N (1.74–2.86 μ B ) increase up
to x = 0.42, but at higher values of Ni content (0.42 < x ≤ 0.70) M s and n B
N
decrease, but coercivity (16.3–131.1 Oe) increases constantly with increasing Ni
content. Zero values of Yafet-Kittel angle (α Y-K ) suggest the presence of Néel-type
magnetic ordering in Zn 0.7−x Ni x Mg 0.2 Cu 0.1 Fe 2 O 4 .
The above available literature [16, 19–24] on Zn-/Mg-doped mixed Zn-Ni-MgCu SF explains the variation of magnetization with the doping content on the basis
of Néel’s two-sub-lattice model of ferrimagnetism, but up till now no literature on
Ni-doped Zn-Mg-Cu SF is available which shows the presence of Yafet-Kittel threesub-lattice model. Some reports are available [25–30] which shows the presence of
Y-K type of magnetic ordering for high doping content. Thus, magnetic ordering
also depends on the effect of doping concentration of the cation as also observed in
[25–30]. Hence, it becomes important to study the effect of dopant on the structural,
magnetic properties of SF.
Therefore, the aim of the present work is to look into the effect of Ni content
on structural, magnetic properties of Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4 ferrite, synthesized by sol-gel auto-combustion.
23.2 Materials and Methods
23.2.1 Materials
AR-grade zinc nitrate, Zn(NO 3 ) 2 .6H 2 O; nickel acetate, Ni(CH 3 COO) 2 .4H 2 O; magnesium acetate, Mg(CH 3 COO) 2 ·4H 2 O; copper nitrate, Cu(NO 3 ) 2. 3H 2 O; and ferric
nitrate, Fe(NO 3 ) 3 .9H 2 O, were used for the synthesis of Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4
(x = 0.00, 0.15, 0.30, 0.45, 0.60, and 0.75) spinel ferrite.
23.2.2 Material Synthesis
Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4 ferrites were synthesized by sol-gel autocombustion method. Stoichiometric amounts of citrate-nitrate/acetate precursors
were mixed with citric acid (in the molar ratio 1:1). Citric acid has a dual function:
initially it acts as a chelator and then as a fuel [31]. Synthesis was done by
dissolving all the precursors in stoichiometric ratio in deionized water, and then
ammonia solution (NH 4 OH) was added to maintain the pH at 7 by continuous
stirring. Now the solution was heated at 120 ◦ C in air till the loose powder (fluffy)
was formed called as “dry gel or as-burnt powder” which was then annealed at
500 ◦ C for 3 h in air.
359
of Zn 0.7-x Ni x Mg 0.2 Cu 0.1 Fe 2 O 4 (x = 0.0–0.7) nano-ferrite is presented in [24]. The
magnetic properties M s (43.2–69.9 Am 2 /kg) and n B
N (1.74–2.86 μ B ) increase up
to x = 0.42, but at higher values of Ni content (0.42 < x ≤ 0.70) M s and n B
N
decrease, but coercivity (16.3–131.1 Oe) increases constantly with increasing Ni
content. Zero values of Yafet-Kittel angle (α Y-K ) suggest the presence of Néel-type
magnetic ordering in Zn 0.7−x Ni x Mg 0.2 Cu 0.1 Fe 2 O 4 .
The above available literature [16, 19–24] on Zn-/Mg-doped mixed Zn-Ni-MgCu SF explains the variation of magnetization with the doping content on the basis
of Néel’s two-sub-lattice model of ferrimagnetism, but up till now no literature on
Ni-doped Zn-Mg-Cu SF is available which shows the presence of Yafet-Kittel threesub-lattice model. Some reports are available [25–30] which shows the presence of
Y-K type of magnetic ordering for high doping content. Thus, magnetic ordering
also depends on the effect of doping concentration of the cation as also observed in
[25–30]. Hence, it becomes important to study the effect of dopant on the structural,
magnetic properties of SF.
Therefore, the aim of the present work is to look into the effect of Ni content
on structural, magnetic properties of Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4 ferrite, synthesized by sol-gel auto-combustion.
23.2 Materials and Methods
23.2.1 Materials
AR-grade zinc nitrate, Zn(NO 3 ) 2 .6H 2 O; nickel acetate, Ni(CH 3 COO) 2 .4H 2 O; magnesium acetate, Mg(CH 3 COO) 2 ·4H 2 O; copper nitrate, Cu(NO 3 ) 2. 3H 2 O; and ferric
nitrate, Fe(NO 3 ) 3 .9H 2 O, were used for the synthesis of Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4
(x = 0.00, 0.15, 0.30, 0.45, 0.60, and 0.75) spinel ferrite.
23.2.2 Material Synthesis
Zn 0.75−x Ni x Mg 0.15 Cu 0.1 Fe 2 O 4 ferrites were synthesized by sol-gel autocombustion method. Stoichiometric amounts of citrate-nitrate/acetate precursors
were mixed with citric acid (in the molar ratio 1:1). Citric acid has a dual function:
initially it acts as a chelator and then as a fuel [31]. Synthesis was done by
dissolving all the precursors in stoichiometric ratio in deionized water, and then
ammonia solution (NH 4 OH) was added to maintain the pH at 7 by continuous
stirring. Now the solution was heated at 120 ◦ C in air till the loose powder (fluffy)
was formed called as “dry gel or as-burnt powder” which was then annealed at
500 ◦ C for 3 h in air.