Papers by Author: Shahid Ameer

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Authors: Shahid Ameer, Asghari Maqsood
Abstract: The compound Dy2Si2O7 exists in two polymorphs, the low temperature triclinic phase (type B) and a high temperature orthorhombic phase (type E).The dc and ac electrical conductivities of E-Dy2Si2O7 are measured in the temperature range 290-510 K and frequency range 1 kHz to 1 MHz . The dc electrical transport data are analyzed according to Motts variable-range hopping model. The disorder parameter (To) and density of states at fermi level are obtained. The ac conductivity σac (ω) is obtained through the dielectric parameters. The ac conductivity can be expressed as σac (ω) =B ω s , where s is slope and it decreases with increase in temperature. The conduction mechanism in the compound is discussed in low and high temperature regions in the light of theoretical models.
Authors: Ahmad Faraz, Asghari Maqsood, Nasir M. Ahmad, Fazal Ur-Rehman, Shahid Ameer
Abstract: Spinel Nanoferrites of Composition Mg0.50Cu0.5-XNixFe2O4 (0.00≤x≤0.50) Were Synthesized by Chemical Co-Precipitation Method. the Structural, Morphological and Magnetically Changes due to Varying Concentrations of Metal Ions of Cu and Ni in the Prepared Nanoferrites Were Studied. XRD Confirmed the Formation of Single Phase Spinel Ferrite with Crystalline Sizes in between 16-29 Nm, and the Lattice Parameter (a) Found to Decreases with Increase of Ni Concentration. Electrical Resistivity of the Prepared Nanoferrites with Varying Nickel and Copper Concentrations X Observed to Follow Arrhenius Relation and Also Exhibited the Semiconductor Behavior. the Magnetic Hysteresis Curves Clearly Indicate the Soft Nature of the Prepared Samples. Saturation Magnetization (Ms) Increases with Ni Content. This Effect Is Related to the Magnetic Moments of Ni+2 Ions. the Y-K Angles Increase with Increasing Ni Content, and Suggest a Non Collinearity Néel Type of Ordering of the Y-K Type. the Increase in the Y-K Angles Also Suggests the Increase in Triangular Spin Arrangements on B Sites, which Subsequently Lead to Increment in A-B Interactions.
Authors: Shahid Ameer, Ahmad Faraz, Asghari Maqsood, Nasir M. Ahmad
Abstract: The Polymorphic Er2Si2O7 Is Synthesized by Solid State Double Sintering Method. Structural and Morphological Characterizations Have Been Performed Using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The Electrical Characterization Has Been Performed by Two Probe Method as a Function of Temperature. the Dielectric Spectroscopic Measurements of Polymorphic Er2Si2O7 Are Performed in the Temperature Range 300-555 K and Frequency Range 3 kHz to 1 MHz. the dc Electrical Transport Data Are Analyzed According to Mott’s Variable-Range Hopping. The ac Conductivity σac(ω) Is Obtained through the Dielectric Spectroscopic Measurements. the ac Conductivity Obeys Power Law which Can Be Expressed as σac (ω) = B ωs, where S Is Slope and it Determines the ac Electrical Transport Phenomenon. the ac Electrical Transport Data and its Variation with Temperature in this Rare Earth Formulation Are Well Discussed. the Magnetic Behavior of Synthesized Material Is Analyzed and Confirmed that Material Have Non-Magnetic Behavior with Coercivity (Hc) 842 Oe. while the Values of Magnetic Saturation (MS) and Remanace (Mr) Were Found in Range 3.90emu/g and 1.07emu/g.
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