Ruchika Yadav

Order-disorder phase transition and multiferroic behaviour in a metal organic framework compound (CH3)2NH2Co(HCOO)3

We have investigated the multiferroic and glassy behaviour of metal-organic framework (MOF) material (CH3)2NH2Co(CHOO)3. The compound has perovskite–like architecture in which the metal–formate forms a framework. The organic cation (CH3)2NH2+ occupies the cavities in the formate framework in the framework via N–H···O hydrogen bonds. At room temperature, the organic cation is disordered and occupies three crystallographically equivalent positions. Upon cooling, the organic cation is ordered which leads to a structural phase transition at 155 K. The structural phase transition is associated with a para-ferroelectric phase transition and is revealed by dielectric and pyroelectric measurements. Further, a PE hysteresis loop below 155 K confirms the ferroelectric behaviour of the material. Analysis of dielectric data reveal large frequency dispersion in the values of dielectric constant and tanδ which signifies the presence of glassy dielectric behaviour. The material displays a antiferromagnetic ordering belo...

Magnetic frustration and dielectric relaxation in insulating Nd2NiMnO6 double perovskites

We have investigated structural, dielectric, and magnetic properties of polycrystalline double perovskite Nd2NiMnO6 compound. The compound crystallizes in monoclinic P21∕n symmetry and is partially B-site disordered depending on the synthesis conditions. It undergoes second-order ferromagnetic transition at 192 K and shows glassy behaviour at low temperature. The glassy phase is due to anti-site disorder within the homogeneous sample. Temperature and frequency dependent dielectric measurements reveal colossal values of dielectric constant and is best interpreted using Maxwell-Wagner interfacial polarization model. Impedance spectroscopy has been used to analyse the intrinsic dielectric response. This enabled us to differentiate the conduction process at the grain and grain boundaries. Arrhenius behaviour is favoured at the grain boundary, while variable range hopping mechanism is considered most suitable within the grain region. dc conductivity measurements corroborate variable range hopping conduction.

Investigation of dielectric relaxation, Jahn-Teller distortion, and magnetic ordering in Y substituted Pr1−xYxMnO3 (0.1 ≤ x ≤ 0.4)

We report structural, magnetic, and dielectric properties of the perovskite compound Pr1-xYxMnO3 (0.1 <= x <= 0.4) studied using dc magnetization, ac susceptibility, neutron powder diffraction, and dielectric techniques. These compounds crystallize in orthorhombic space group (Pnma) in the temperature range 5-300 K. The Mn-O-Mn bond angle decreases with the Y substitution along with an increase in the Jahn-Teller distortion. The Jahn-Teller distortion for Pr0.9Y0.1MnO3 shows an anomalous change near 50 K, below which it falls sharply. Neutron powder diffraction patterns of all reported compositions at low temperature constitute additional magnetic Bragg peaks that suggest magnetic ordering. Magnetic reflections were indexed in the nuclear lattice with the propagation vector k = (0, 0, 0). Rietveld refinement of powder patterns conform to A type antiferromagnetic ordering where moments are aligned ferromagnetically in a-c plane and coupled nearly antiferromagnetically along b-axis resulting in a net ferromagnetic component along the b-direction. The antiferromagnetic transition temperature was deduced from dc magnetization and ac susceptibility data. The transition temperature decreases by nearly 22 K (from 81 K to 59 K) as yttrium content (x) increases from 0.1 to 0.4. Measurements reveal strong frequency dispersion in dielectric constant and dielectric loss. Activation energy and relaxation time are estimated from the Arrhenius plot. It is further shown that relaxation behaviour is altered with yttrium doping concentration

To Study the Socio-Economic Back Ground of Basmati Rice Growers in Saharanpur District, India

Rice is the lifeline for Asians as it is not only a dominant food crop but also an important crop in the national economy. It accounts for a major share of cereal consumption, ranging from 40% in India to 97% in Myanmar. Rice contributes 30–76% of total daily calorie intake by Hossain and Pingali (1998). Therefore, boosting rice production and making rice available to consumers at affordable prices is always at the top of the political agenda for national governments for economic growth, social security, and political stability of the continent. Recent food inflation further alerted Asian countries to keep rice development strategy and policy as a top priority in order to sustain food International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 7 (2017) pp. 2817-2823 Journal homepage: http://www.ijcmas.com

Study on Personal Socio-Agro-Economic, Psychological and Communicational Characteristics of the Vegetable Growers in Western Uttar Pradesh, India

India is the second largest producers of vegetables in the world next to china with 2.8 per cent of total cropped area under vegetables. The total cultivated area of vegetables in India was 9542.23 thousand ha and production was of 169478.23 thousand million tones in 2014-15. Our country has progressed significantly during the past six decades in developing high yield verities/hybrids of different vegetables with their improved qualities and standardized agro techniques suitable for different agro-climatic conditions. Out per capita consumption has increased from 80-175 g/day.

Study of lattice dynamics in yttrium doped NdMnO3 using Raman spectroscopy

A systematic study of Raman spectra on Yttrium doped NdMnO3 polycrystalline samples was undertaken to understand the lattice dynamics in this compound. Raman active phonons were analyzed and the observed peak were assigned to elucidate various phonon modes in the range (200 - 800) cm−1. It was observed that at 325 cm−1 phonon frequency shifts upward as much as upto 4 % with increase in Yttrium content. Lattice distortions manifest themselves by frequency shifts in both bending and tilt modes of MnO6 octahedra, resulting in increase of Raman band line-widths.