V. R. K. Murthy

Bio: V. R. K. Murthy is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Dielectric & Rietveld refinement. The author has an hindex of 27, co-authored 162 publications receiving 2595 citations. Previous affiliations of V. R. K. Murthy include VIT University & Indian Institute of Science.

Dielectric relaxation behaviour of glycine in aqueous solution medium in the microwave frequency region

Abstract: A study on the dielectric properties of glycine in aqueous solution medium in the microwave frequency region (130 MHz-20 GHz) is curried out using the open-ended coaxial probe technique. Dielectric parameters such as dielectric constant, dielectric loss of various weight percentage levels of glycine in double distilled aqueous medium such as water are determined. It is observed that the real part of dielectric permittivity decreases and imaginary part of the dielectric permittivity increases with increase in the weight percentage level of glycine in water. From these parameters we calculated the relaxation time and its behaviour is analysed. Dipole moment value is calculated from the optimized geometrical structure of the glycine molecule from the AM 1 , PM 3 , and MNDO ab initio quantum mechanical calculations using the Argus Lab chemical modeling Software 2004.

13C NMR and dielectric relaxation studies of methanol+nitrile systems

Abstract: 13C NMR studies for both spin-lattice relaxation time (T 1 ) and chemical shifts were obtained for two systems namely methanol+acetonitrile and methanol+acrylonitrile. The dielectric dispersion data was also obtained for these systems. The 1 3 C NMR and dielectric dispersion data with a view to understand the conformation of these systems and also to understand the basic mechanisms of relaxation in the same have been presented. A correlation between the rotational correlation time from NMR and the dielectric relaxation time for the two systems have been reported. The confirmation of the ring-like conformer for methanol+acetonitrile system using 1 3 C NMR chemical shift data.

Dielectric Studies on Fe3O4 Nanodoped --Alkyloxybenzoic Acids

Abstract: The stability of phase transition temperatures and textural changes for thermotropic pure and nanodoped --alkyloxybenzoic acid mesogens were aimed to study at considerable time periods Frequency and temperature dependent dielectric constant and dielectric loss for the pure and nanodoped liquid crystals were carried out Significant anomalies in dielectric studies were observed near phase transitions when dielectric constant and dielectric loss had been measured as a function of temperature and frequency Changes in dielectric constant and loss were observed and there were no apparent changes at high frequencies instead maintaining constant values The variations in conductivity, activation energy, and relaxation times had also been studied in the nematic and smectic phases The temperature dependent dielectric constant stability (temperature coefficient of dielectric constant ) had shown shift in the observed frequency range of thermotropic liquid crystals corresponding to the change in the dielectric constant values

Study of one dimensional photonic band gaps at microwave frequencies for microwave filters

Abstract: There has been a great deal of interest in periodic dielectric structures that exhibit photonic band gaps. Periodicity in dielectric constant results in a range of frequencies within which transmission is forbidden, known as Photonic Band Gaps (PBG). PBG structures can be used as tunable filters whose bandwidth can be varied depending on the periodicity, dielectric constant etc. It is possible to construct PBG structures with one-dimensional periodicity. In this paper, we report the experimental observation of the band gaps between 10 and 20 GHz for a structure made of lossy glass slabs (ϵ r ′ = 6.1, ϵ r ” = 0.06). This paper also presents the results on the numerical computation using transfer matrix method for the above structure for comparison. The nature of the band gaps is also investigated with respect to the spacing between the dielectric slabs and dielectric constant.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Photonic crystals

Abstract: The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

Ferromagnetic materials

Abstract: In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Magnetic and electric properties of transition-metal-doped ZnO films

Abstract: 3d-transition-metal-doped ZnO films (n-type Zn1−xMxO (x=005–025): M=Co, Mn, Cr, Ni) are formed on sapphire substrates using a pulsed-laser deposition technique, and their magnetic and electric properties are examined The Co-doped ZnO films showed the maximum solubility limit Some of the Co-doped ZnO films exhibit ferromagnetic behaviors with the Curie temperature higher than room temperature The magnetic properties of Co-doped ZnO films depend on the concentration of Co ions and carriers

Wide band gap ferromagnetic semiconductors and oxides

Abstract: Recent advances in the theory and experimental realization of ferromagnetic semiconductors give hope that a new generation of microelectronic devices based on the spin degree of freedom of the electron can be developed. This review focuses primarily on promising candidate materials (such as GaN, GaP and ZnO) in which there is already a technology base and a fairly good understanding of the basic electrical and optical properties. The introduction of Mn into these and other materials under the right conditions is found to produce ferromagnetism near or above room temperature. There are a number of other potential dopant ions that could be employed (such as Fe, Ni, Co, Cr) as suggested by theory [see, for example, Sato and Katayama-Yoshida, Jpn. J. Appl. Phys., Part 2 39, L555 (2000)]. Growth of these ferromagnetic materials by thin film techniques, such as molecular beam epitaxy or pulsed laser deposition, provides excellent control of the dopant concentration and the ability to grow single-phase layers. T...