Nanocomposites and nanomaterials

Influence of aluminum ion substitution on dielectric properties of nanosized lithium ferrite
Kaykan L.S.1, Mazurenko J.S.2
1 Vasyl Stefanyk Precarpathian National University, Shevchenko street, 57, 76018, Ivano-Frankivsk, Ukraine.
E-mail: larysa.kaykan@gmail.com
2 Ivano-Frankivsk National Medical University, Halytska street, 2, 76000, Ivano-Frankivsk, Ukraine

Lithium and substituted lithium ferrites play an important role in microwave technology and memory cells due to the high Curie temperature, high saturation magnetization, excellent hysteresis loops, and low voltage sensitivity [1]. Lithium ferrites behave as an n-type semiconductor with an inverse spinel structure, have a high electrical resistance (105 - 106 Ohm∙cm) and a high Curie temperature (913 – 950K), and can be used in gas sensors due to the high active surface area.

Substitution by trivalent cations that provide charge neutrality is one of the important areas of structure modification. Such mixed lithium ferrites are unique because they do not contain any divalent cations.
Figure shows the change in the dielectric constant of nanosized ferrite samples of the composition Li0.5AlxFe2.5-xO4 (0.0≤x≤1.0) with a frequency of 0.1 Hz to 100 kHz at room temperature.
In our measurements ε' is a very large, comparable to 105 order in pure and Al-substituted nanocrystalline Li0.5Fe2.5O4 ferrites. A decrease in the value of the dielectric constant with increasing frequency is a normal dependence observed in most ferromagnetic materials. 

1.	Uhorchuk, O.M., Uhorchuk, V.V., Lithium ferrite as the cathode of the electrochemical power sources: The perspectives of sol-gel synthesis method // J. Nano- Electron. Phys.-2015.-7(2).-P. 02012-1 - 02012-7