Analytical study of radionuclide concentration and radon exhalation rate in market available building materials of Ramsar

Bavarnegin Elham, Vahabi-Moghaddam Masoud, Babakhani Asad, Fathabadi, Fathabadi Nasrin

Description

Samples of structural and covering market available building materials from Ramsar, a northern city of Iran, were analyzed for their radon exhalation rate using an active radon gas analyzer with an emanation container. The radon exhalation rate varied from below the minimum detection limit of 0.01 to 0.31 Bq·m −2 ·h −1 with an average of 0.08 Bq·m −2 ·h −1 . The 226 Ra, 232 Th, and 40 K contents were also measured using a high resolution HPGe gamma-ray spectrometer system. The radionuclides contents varied from below the minimum detectable activity up to 73.5, 169, and 1,350 Bq.kg −1 , with the average value of 16 ± 6, 25 ± 11, and 280 ± 101 Bq.kg −1 , respectively. It was concluded from the results that some granite samples along with the block sample were the main source of radon exhalation rate, and the mean values of 226 Ra, 232 Th, and 40 K in building material samples are below the world average values. Therefore, the use of these market available building materials in construction of Ramsar dwellings is considered to be safe for human habitation.

Sujets

• Building material
• Gamma spectroscopy
• Ramsar
• Isotopes of radon
• PACS

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 9
• Langue: English

Extrait

Moteet al. Journal of Theoretical and Applied Physics2012,6:6 http://www.jtaphys.com/content/22517235/6/1/6

R E S E A R C H

WilliamsonHall analysis in estimation of strain in nanometersized ZnO particles 1 2 1* VD Mote , Y Purushotham and BN Dole

Open Access

lattice

Abstract ZnO nanoparticles were prepared by coprecipitation method at 450°C. Xray diffraction result indicates that the sample is having a crystalline wurtzite phase. Transmission electron microscopy (TEM) result reveals that the ZnO sample is spherical in shape with an average grain size of about 50 nm. Xray peak broadening analysis was used to evaluate the crystalline sizes and lattice strain by the WilliamsonHall (WH) analysis. All other relevant physical parameters such as strain, stress, and energy density values were also calculated using WH analysis with different models,viz, uniform deformation model, uniform deformation stress model and uniform deformation energy density model. The root mean square strain was determined from the interplanar spacing and strain estimated from the three models. The three models yield different strain values; it may be due to the anisotropic nature of the material. The mean particle size of ZnO nanoparticles estimated from TEM analysis, Scherrer’s formula and WH analysis is highly intercorrelated. Keywords:Nanostructured materials, Chemical synthesis, Crystal structure, TEM, WH analysis PACS:81.07.b, 81.07.Bc, 68.37.d, 68.37.Lp, 73.63.Bd

Background Semiconductor research is a very important field in the ongoing research activity across the world. As the semiconductor particles exhibit sizedependant proper ties like scaling of the energy gap and corresponding change in the optical properties, they are considered as the front runners in the technologically important materials. Zinc oxide is a IIVI semiconductor with a large bandgap (E g = 3.37 eV) and high exciton binding energy (60 meV). It is widely used in a number of applications like photocatalysis, gas sensors, varistors, and lowvoltage phosphor materials [14]. ZnO is the richest family of nanostructures among all semicon ducting materials, both in structures and in properties due to its unique properties [5,6]. A perfect crystal would extend in all directions to infinity, so no crystals are perfect due to their finite size. This devi ation from perfect crystallinity leads to a broadening of the

* Correspondence: [e-mail] 1 Department of Physics, Materials Research Laboratory, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431 004, India Full list of author information is available at the end of the article

diffraction peaks. The two main properties extracted from peak width analysis are (a) crystallite size and (b) lattice strain. Crystallite size is a measure of the size of a coher ently diffracting domain. The crystallite size of the particles is not generally the same as the particle size due to the pres ence of polycrystalline aggregates [7]. The most common techniques used for the measurement of particle size rather than the crystallite size are BET, light scattering, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Lattice strain is a measure of the distribu tion of lattice constants arising from crystal imperfections, such as lattice dislocation. The other sources of strain are the grain boundary triple junction, contact or sinter stresses, stacking faults, coherency stresses, etc. [8]. Xray line broad ening is used for the investigation of dislocation distribution. Apart from crystallite size reduction and alloying, mechanical alloying induces a large amount of strain in the powders [9]. Xray profile analysis is a simple and powerful tool to estimate the crystallite size and lattice strain [10]. Among the available methods to estimate the crystallite size and lattice strain are the pseudo Voigt function, Rietveld refinement, and Warren

© 2012 Mote et al; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.