Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Structural and Dielectric Properties of Manganese Ferrite Nanoparticles
Hashim Farooq, Muhammad Raza Ahmad, Yasir Jamil, Abdul Hafeez, Zeeshan Mahmood and Tahir Mahmood

http://dx.doi.org/10.6000/1927-5129.2012.08.02.53

Abstract: In this work, Manganese ferrite nanoparticles of various compositions were reproducibly synthesized via coprecipitation route. Variation in structural and dielectric properties was studied by varying the sintering temperature, sintering time and manganese to iron ratio. Structural, compositional and phase properties were investigated by X-ray diffraction (XRD) technique which confirmed the pure normal spinel structure with no other phase/impurity. Particle size, Lattice constant, measured bulk density, X-ray density, Specific Surface Area and Porosity were determined by the standard formulae. Responses of Capacitance and Dielectric constant were studied at room temperature in the frequency range of 600Hz to 1MHz by LCR meter which both showed the exponential decay at low frequency while both became nearly independent of frequency in higher frequency ranges.

Keywords: Nanoparticles, spinel structure, coprecipitation, dielectric constant.

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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