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| Natura: | Artículo científico |
| Lingua: | en |
| Pubblicazione: |
Sociedade Brasileira de Física
2016
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| Accesso online: | https://www.redalyc.org/articulo.oa?id=46445584003 |
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Sommario:
- AC Dielectric Properties and Positron Annihilation Study on Co and Ti Substitution Effect on Ca–Sr M-Hexaferrites K. R. Mahmoud M. R. Eraky Física, Astronomía y Matemáticas Dielectric Hexaferrites AC conductivity Polycrystalline Positron annihilation lifetime spectroscopy t The dependence of AC conductivity σAC, dielectric constant έ, and dielectric loss tangent tan δ on frequency and composition have been investigated at room temperature for polycrystalline Ca0.5Sr0.5CoxTixFe12 − 2xO19 (where 0.0 ≤ x ≤ 0.8) hexaferrites. It was found that the parameters σAC, ε′ , and tan δ have maximum values at x= 0.4 of the Co and Ti substitution. The behavior of σAC, ε′ , and tan δ with frequency and composition was explained on the basis of the hopping conduction mechanism and the Koops model. Positron annihilation lifetime spectroscopy (PALS) was used to investigate the defects and changes in electron density for hexaferrite samples. The PAL parameters (τ1, I1, τ2, I2, and mean lifetime) show that altering the doping percentage of the Co and Ti ions affects the size and concentration of defects. The results reveal that there are some large voids in the studied samples. The obtained results indicate the high sensitivity of the PALS technique to the enhanced structure changes with changing composition of the investigated samples and correlate the results with the measured electrical parameters. 2016 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46445584003 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.3 Vol.46