Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

Functionalization Of Carbon Nanotubes With Metal Phthalocyanine For SELECTIVE Gas Sensing Application

Abstract: Composites of hydroxylated single-walled carbon nanotubes and copper phthalocyanine (CuPc) has been obtained. Phthalocyanines get noncovalently adsorbed onto CNTs surface by π–π stacking. Conversion of β-form of phthalocyanine to α-form gives clear evidence of composite formation. Only carboxyl and hydroxyl CNTs react with phthalocyanine while no reaction occurs for amided CNTs. High selectivity in the thin film resistors of SWNT–OH + CuPc composites toward NOx gases is observed. The response for NOx is 10 times and 100 times more then that of ammonia and Sox, respectively. This makes the SWNT–OH + CuPc composite a candidate for detection of NOx—a common pollutant.

The seed stimulant effect of nano iron pyrite is compromised by nano cerium oxide: regulation by the trace ionic species generated in the aqueous suspension of iron pyrite

Abstract: A brief seed pretreatment of 12 hours, in an aqueous suspension of synthesized nano iron pyrite (FeS2), significantly increases the yield of spinach and other crops. The effector mechanism is not clear. An aqueous suspension of FeS2, produces very trace amounts of H2O2, Fe2O3, FeS, FeSO4, Fe(SO4)3, SO2, S and H+ ionic species. Thus for 12 hours, seeds are exposed to this complex aqueous suspension. Among these trace species, H2O2 and Fe2O3 are known seed stimulants and plant growth promoters respectively. In this work, an attempt has been made to quench one of these trace compounds generated in the aqueous suspension of FeS2, viz., H2O2; and the long-term effect on the mature plant was monitored. To test this, along with FeS2, an agriculturally relevant inorganic peroxide scavenger viz., nano cerium oxide (CeO2) was introduced into this system. Four seed pretreatment regimens were followed for the spinach viz., (i) control (water), (ii) FeS2 + water, (iii) CeO2 + water, (iv) FeS2 + CeO2 + water; and growth was monitored for the next 80 days. It was found that, at maturity, CeO2 and FeS2 + CeO2, resulted in significantly smaller leaves, as compared to the control and FeS2; furthermore, FeS2 resulted in leaves with increased chlorophyll and carbohydrate. Thus, the data indicates that by quenching the H2O2, the seed-stimulant effect of FeS2 is compromised. So, while the FeS2 + water suspension functions as a seed vigor enhancer, CeO2 + water on the contrary, functions as a ‘seed vigor reducer’. It is noteworthy, that CeO2 is used by Chinese farmers, as a micro-nutrient to increase crop production. Current data indicates that, it delays germination of seeds, whereas FeS2 hastens germination. Thus such an approach could be used for hastening or delaying germination, manipulating weed population, seed storage in critical conditions, timing the life-cycle of a plant and developing more energy-efficient plants, especially in regions, where there is limited sunlight during significant parts of the year.

Graphene nanoribbons: Relevance of etching process

Abstract: Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely, O2 plasma ashing and O2 + Ar reactive ion etching (RIE). O2 plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused by more or larger localized states at the edges of the ashed device compared to the RIE defined device.

Dielectric and piezoelectric properties of La doped lead zinc niobate–lead zirconium titanate ceramics prepared from mechano-chemically activated powders

Abstract: Lead zinc niobate–lead zirconium titanate, 0.3Pb(Zn 1/3 Nb 2/3 )O 3 –0.7Pb(Zr 0.51 Ti 0.49 )O 3 (PZN–PZT), ceramics doped with different amounts of lanthanum (La) were prepared by mechano-chemical alloying (MCA) method accompanied by sintering. The results of X-ray diffraction suggest that all the ceramics crystallize into a single-phase pervoskite structure. The SEM analysis of the ceramic samples reveals a dense microstructure with homogeneous distribution of grains. The bulk density of the ceramics increases with the increase of La content. The effects of the La doping on the dielectric and piezoelectric properties of the ceramics were systematically examined. An increase in La concentration causes the Curie temperature ( T c ) to decrease and the phase transition to become more diffused. The piezoelectric charge co-efficient ( d 33 ) and electromechanical coupling constant ( k p ) show improvement with the increase of La doping level in the ceramic system. The d 33 , k p and percentage strain of the 3 mol%-La doped PZN–PZT ceramic were observed to be 575 pC/N, 64 and 22%, respectively.