Showing 3 results for Gel Auto
Ghobeiti Hasab M., Seyyed Ebrahimi S.a., Badaee A.,
Volume 2, Issue 2 (6-2005)
Abstract
In this research the sol-gel auto-combustion method was used to prepare strontium hexaferrite nanopowder. A solution of distilled water, ferric and strontium nitrates, citric acid, trimethylamine, and n-decyltrimethylammonium bromide cationic surfactant, was heated to form a viscous gel. The gel was heated and then ignited automatically. As-burnt powder was calcined at temperatures from 700 to 900?C in air to obtain SrO.6Fe2O3 phase. The influence of the calcination temperature on the phase composition of the products has been investigated. X-ray diffraction confirmed the formation of single-phase strontium hexaferrite nanopowder at temperature of 800?C.
Z. Ghiami, S. M. Mirkazemi, S. Alamolhoda,
Volume 12, Issue 2 (6-2015)
Abstract
trontium hexaferrite (SrFe
12
O
19
) nanosized powders were synthesized by sol-gel auto-combustion method
with and without cetyltrimethylammonium boromide (CTAB) addition in the sol with Fe/Sr ratio of 11 (using additional
Sr). The resultant powders were investigated by X-ray Diffraction (XRD), Transmission Electron Microscope (TEM),
Field Emission Scanning Electron Microscope (FESEM) and Vibration Sample Magnetometer (VSM) techniques.
Phase constituents of the synthesized samples which were heat treated at temperatures in the range of 700- 900 ◦C
were studied. XRD results revealed that CTAB addition facilitates the formation of single phase strontium hexaferrite
at 800 ◦C. Microstructural evaluations with FESEM represented that CTAB addition causes formation of larger
particles with a narrower size distribution. VSM results represented that the highest amount of intrinsic coercivity force
(
i
H
C
) was obtained in the sample without CTAB addition and with additional Sr, calcined at 800 ◦C for 1 h which was
equal to 5749.21 Oe, while the value of
i
H
C
was equal to 4950.89 Oe without additional Sr. The amount of maximum
magnetization (M
max
) was raised from 48.41 emu/g to 62.60 emu/g using CTAB and additional Sr. The microstructure
and magnetic properties of the samples have been explained
S. Alamolhoda, S. M. Mirkazemi, T. Shahjooyi, N. Benvidi,
Volume 13, Issue 1 (3-2016)
Abstract
Nano-sized NiFe2O4 powders were synthesized by sol–gel auto-combustion method using pH values from 7 to 9 in the sol. The effect of pH variations on complexing behavior of the species in the sol has been explained. Changes in phase constituents, microstructure and magnetic properties by changes in pH values were evaluated by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. Changes in pH value from 7 to 9 changes the amounts of NiFe2O4, FeNi3 and α-Fe2O3 phases. Calculated mean crystallite sizes are in the range of 44 to 51nm. FESEM micrographs revealed that increasing the pH value to 9 causes formation of coarse particles with higher crystallinity. Saturation magnetization was increased from 36.96emu/g to 39.35emu/g by increasing pH value from 7 to 8 which is the result of increased FeNi3 content. Using higher pH values in the sol reduces the Ms value.
