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Kiran Jain ¹, Rashmi ¹, S. T. Lakshmikumar ¹

Affiliations
1 Electronic Materials Division, National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012, IN

Abstract

Nanocrystalline tin oxide powders were prepared using a solution precipitation technique after adding the surfactants, Triton X-100 (TX-100) and Sodium Dodecyl Sulfate (SDS). Powders were characterized using XRD and FTIR studies. The gas sensitivity for surfactant added powders increased for LPG (Liquefied petroleum Gas) as well as CNG (Compressed Natural Gas), due to low degree of agglomeration. The LPG sensitivity increased by almost ten times using SDS.

Keywords

Nanocrysalline Tin Oxide, Semiconductor Gas Sensors, Gas Sensitivity, XRD, FTIR.

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V. K. Sankaranarayanan ¹, Om Prakash ¹, S. T. Lakshmikumar ¹

Affiliations
1 Electronic Materials Division, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, IN

Abstract

Co/Ag multilayers with 20 bilayers with the composition, Ti(5 nm) [Co(1 nm)/Ag(4 nm)]₂₀ Ti(5 nm), were deposited by electron beam evaporation in ultrahigh vacuum and annealed under vacuum to develop the discontinuous multilayer structure. The as-deposited and annealed multilayers show (111) texturing with both Co and Ag (111) peaks in the XRD. The magnetization curves have ferromagnetic behaviour which gradually change on annealing above 200°C to show a reduction of squareness and an increase in coercivity, a reflection of the microstructural changes involving breaking of layers to form the so called discontinuous multilayer (DML) structure. Magnetoresistance curves show increase in MR value with annealing that attains a constant value above 300°C presumably due to stagnation in growth of Co grains which are surrounded by Ag atoms.

Keywords

Giant Magnetoresistance, Co/Ag Multilayers, Discontinuous Multilayers, Magnetizations.

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