http://nopr.niscair.res.in/handle/123456789/2619 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2713 Title: ⁵⁷Fe Mössbauer studies of pseudo-binary alloy system Fe₁₋yCrySb₂ for 0 ≤y ≤ 0.97 at 300 K <br/> <br/>Authors: Sharma, R K; Sharma, Y K <br/> <br/>Abstract: ⁵⁷Fe Mössbauer and X – ray powder diffraction (XRD) of the alloy system Fe₁₋yCrySb₂ for 0 ≤y ≤ 0.97 at 300K have been studied. XRD patterns of all specimens recorded using FeKα radiation at 300K suggest the presence of single phase orthorhombic crystal structure for this alloy series. The lattice parameters and the unit cell volume increase with the increase in chromium concentration. The ⁵⁷Fe Mössbauer spectra for all the compositions analyzed as a single quadrupole split doublet reveal the paramagnetic character. The increase in the isomer shift and the decrease in the quadrupole splitting with the increase in chromium concentration y for the alloy series have been correlated with the observed structural and bonding properties of the series compositions. <br/> <br/>Page(s): 846-850 Fri, 28 Sep 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2712 Title: Magnetization and Mössbauer studies of Ni₃₋xCuxFe alloys in nano-crystalline state <br/> <br/>Authors: Sharma, M P; Prashant, B L; Krishnamurthy, Anjali; Srivastava, Bipin K <br/> <br/>Abstract: The iron-nickel alloys, commonly known as permalloys, known for atomic disorder, have been studied due to their interesting magnetic properties. Nano-particle samples have been prepared for three compositions in the series Ni₃₋xCuxFe. ⁵⁷Fe Mössbauer studies are reported on the three nano-particle samples which are found to be ferromagnetic. The value of Tc goes down from 880K in N₃Fe to 800K in Ni₂CuFe. The introduction of Cu causes the saturation moment to decrease and lowering of temperature cause an increase in atomic disorder. <br/> <br/>Page(s): 842-845 Fri, 28 Sep 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2687 Title: Mössbauer study of nano-particles of spinel ferrites LixFe₃₋xO₄ <br/> <br/>Authors: Chander, Subhash; Sharma, M P; Krishnamurthy, Anjali; Srivastava, Bipin K <br/> <br/>Abstract: Mössbauer spectra have been recorded on three nano-particle samples in the series LixFe₃₋xO₄ (for x = 0.1, 0.2 and 0.3) at 300K and 80K. Spectra could be resolved into two doublets attributed to two crystalline sites, viz., tetrahedral site and octahedral site. Li occupies the octahedral site with a complete preference as in the bulk particle size state. Analysis of Mössbauer spectra shows that electron hopping manifests at temperatures down to 80K implying the absence of a Verwey type transition. Magnetization measurements support this inference and are suggestive of no such transition occurring down to 20K. <br/> <br/>Page(s): 816-820 Fri, 28 Sep 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2686 Title: FTIR and Mössbauer spectroscopy applied to study of archaeological artefacts from Maligaimedu, Tamil Nadu, India <br/> <br/>Authors: Manoharan, C; Venkatachalapathy, R; Dhanapandian, S; Deenadayalan, K <br/> <br/>Abstract: Archaeological potteries belonging to 300 BC collected from Maligaimedu (11°48’Lat.N; 79°35’Long.E) Tamil Nadu, India were subjected to FTIR, XRD and Mössbauer spectroscopic studies in order to characterise the clay minerals associated, their origin and technology of firing adopted by artisans. To determine the firing temperature of the potteries and to find any phase change in magnetic minerals, the pottery samples were refired to different temperatures. From FTIR studies, it is observed that these pottery samples were made up of disordered kaolinite type clay with appreciable amount of iron with a firing temperature of about 800ºC. The minerals like quartz, anorthite, orthoclase and hematite were identified using XRD. No change in the Mössbauer parameters are observed in the case of sample MGM-2 during laboratory firing up to 800°C, which indicates that original firing temperature is above 800°C. Changes in the Mössbauer spectra of sample MGM-5 during laboratory firing reveal that the laboratory firing atmosphere differs from original firing atmosphere. The presence of Fe²⁺ ion in as-received state spectra of black pottery (MGM-5) indicates that the sample was fired under reduced atmospheric condition during manufacturing. The colour of the potteries also reflects the above results. <br/> <br/>Page(s): 860-865 Fri, 28 Sep 2007 22:58:59 GMT