الفهرس 
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Abstract
The effect of Fe-doping on Bi2-xFexSe3 (x = 0, 0.6, 1.0 and 1.4), Bi0.6Fe1.4Se2.5Y0.5Prx (x = 0.0, 0.1, 0.2 and 0.3) and Bi0.6Fe1.4Se2.5Y0.5Dyx (x = 0.0, 0.1, 0.2 and 0.3) nano-crystallites was experimentally prepared and investigated. All samples were successfully prepared by acidic Sol-gel method. X-ray diffraction (XRD) results showed a polycrystalline structure for all samples. SEM and TEM microscopies confirmed the existing of a combination of nanorods and nanospheres in soft accumulation of the samples with an average particle nano-size nearly 30–33 nm for Fe-ions doped samples, 33-25 nm for Pr-ions doped samples and 33-3.42 nm for Dy-ions doped samples. Thermal analysis for all samples have been recorded and exhibited a weight loss at 500°C corresponds to the crystallisation of all samples. Also, the ratio of the weight loss was about (8%) of the sample indicating high thermal stability of all samples.In addition, magnetic moment-field dependence confirmed an antiferromagnetic state in the Fe-ions and Y-ion at room temperature while adding Pr-ions or Dy-ions to Bi0.6Fe1.4Se2.5Y0.5 converted it to paramagnetic behavior state. Experimental data confirmed that adding Fe-ions, Y-ion, Pr-ions and Dy-ions can creates a magnetic state in an insulator Bi2Se3 for applications of the next-generation of electronic devices including; spintronics, topological quantum computation and dissipation less topological electronics. Dielectric-dependence temperature and frequency results confirmed the doping of Fe-ions, Y-ion, Pr-ions and Dy-ions exhibited the transition between insulator/semiconductor/metal states.