NOPR Collection:

Nanosize dependent electrical and magnetic properties of NiFe₂O₄ ferrite

2012-10-01T00:00:00Z

Title: Nanosize dependent electrical and magnetic properties of NiFe₂O₄ ferrite Authors: Singh, Sukhdeep; Ralhan, N K; Kotnala, R K; Verma, Kuldeep Chand Abstract: The effect of nanosize particles on dielectric and magnetic properties of NiFe₂O₄ (NF) ferrite has been studied. NF nanoferrites were prepared by a chemical combustion route followed by annealing temperatures from 400° to 700°C. The X-ray diffraction (XRD) shows minor amorphous behaviour of NF at 400°C. However, spinel ferrite structure has been observed with higher annealing in the temperature range 500-700°C. The average particles size is measured using Debye-Scherer’s relation. The particle's size is also measured by transmission electron microscopy and the average value is at nm scale. Room temperature dielectric properties viz.; dielectric constant (ε) and loss (tanδ) for all the specimens have been studied as a function of applied frequency in the range 100 Hz-20 MHz. These studies indicate that the values of ε and tanδ depend on the size of particles. The cole-cole plot of impedance spectroscopy has been used to find the grain size and boundary effect on electrical properties of NF nanograins. The magnetic measurements show the value of saturation magnetization (M_s) is 0.003, 44.95, 38.83, 45.26 emu/g, respectively, observed at 400°, 500°, 600° and 700°C. Page(s): 739-743

Pressure derivatives of bulk modulus for materials at extreme compression

2012-10-01T00:00:00Z

Title: Pressure derivatives of bulk modulus for materials at extreme compression Authors: Singh, P K; Dwivedi, A Abstract: The method based on the calculus of indeterminates for demonstrating that all the physically acceptable equations of state satisfy the identities for the pressure derivatives of bulk modulus of materials at extreme compression, has been developed. The specific examples of the Birch-Murnaghan finite strain equation, the Poirier-Tarantola logarithmic equation, the Rydberg-Vinet potential energy equation, the Keane K-primed equation and the Stacey reciprocal K-primed equation, have been considered. Expressions for the bulk modulus and its pressure derivatives have been derived and reduced to the limit of infinite pressure. The expressions thus obtained are useful for further analysis of higher derivative thermoelastic properties. Page(s): 734-738

Interdependence of nano grain size, alloying effects and magnetic properties of Ni-Cu-Al alloys

2012-10-01T00:00:00Z

Title: Interdependence of nano grain size, alloying effects and magnetic properties of Ni-Cu-Al alloys Authors: Karar, N; Srivastava, A K; Kotnala, R K Abstract: The remarkable modification in physical and magnetic properties of ternary Ni, Cu and Al based ensemble of ball milled nanoparticle alloys and their crystalline shape with grain size and composition has been studied in the present paper. The onset of crystalline changes have been correlated to grain size and alloying content. A sharp decrease in ferromagnetism maintaining the cubic symmetry with grain size and alloying was also revealed. These alloys show two phase transitions, one near room temperature and the other near 80°C compared to 200°C for similar bulk compositions. Such observations have been explained and their possible usage is being explored. Page(s): 727-733

Molecular structure, vibrational spectra and theoretical NBO, HOMO-LUMO analysis of N-benzoyl glycine by DFT and ab-initio HF methods

2012-10-01T00:00:00Z

Title: Molecular structure, vibrational spectra and theoretical NBO, HOMO-LUMO analysis of N-benzoyl glycine by DFT and ab-initio HF methods Authors: Rui-Zhou, Zhang; Xiao-Hong, Li; Xian-Zhou, Zhang Abstract: The vibrational frequencies of N-benzoyl glycine in the ground state have been calculated using density functional method (B3LYP) by using 6-311++G(d,p) basis set. Theoretical vibrational spectra have been interpreted by means of potential energy distribution (PEDs) using MOLVIB program. The equilibrium geometry and the thermodynamic functions of the title compound have been performed at HF/6-31G(d,p)/6-311++G(d,p) and B3LYP/6-31G(d,p)/ 6-311++G(d,p) levels of theory. A detailed interpretation of the infrared spectra is reported. The theoretical spectrograms for IR and Raman spectra have been constructed. The natural bond orbital analysis has been carried out to explain the charge transfer or delocalization of charge due to the intra-molecular interactions. Energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) have been predicted. Page(s): 719-726

NOPR Collection:

Nanosize dependent electrical and magnetic properties of NiFe2O4 ferrite

Pressure derivatives of bulk modulus for materials at extreme compression

Interdependence of nano grain size, alloying effects and magnetic properties of Ni-Cu-Al alloys

Molecular structure, vibrational spectra and theoretical NBO, HOMO-LUMO analysis of N-benzoyl glycine by DFT and ab-initio HF methods

Nanosize dependent electrical and magnetic properties of NiFe₂O₄ ferrite