A systematic measurement of radon/thoron concentration by using pin-holes dosimeter and their decay products by deposition based progeny sensors have been carried out in indoor environment of ...district Palwal, Southern Haryana, India. LR-115 type-II of cellulose nitrate with thick polyester base film was used as detectors. A total 150 locations were selected for measurements over a period of 40 days. In this paper, results of winter season are reported and compared with results of summer and rainy season. The measured average indoor thoron gas concentration (34.6 ± 1.5) is about 3.5 times higher than the world average value (10 Bq m
−3
). The average values for radon concentration, EERC, and EETC is found below the world average values of 40 Bq m
−3
for radon, 15 Bq m
−3
for EERC, and 0.5 Bq m
−3
for EETC. The average annual effective dose inhaled by humans was estimated and compared with recommended limits of ICRP and WHO.
This paper describes radon mass exhalation rate (
J
m
)
and thoron surface exhalation rate (
J
s
) of 46 soil samples of district Faridabad, Southern Haryana, India. Scintillation detector based ...SMART RnDuo (AQTEK System, India) coupled with exhalation chamber was used. Outdoor gamma exposure rate was measured by GM counter based survey meter.
J
m
of one sample and
J
s
of 95% samples were found higher than world average values of 57 mBq kg
−1
h
−1
and 3600 Bq m
−2
h
−1
for
J
m
and
J
s
respectively reported by UNSCEAR 2000. No significant correlation was observed between radon/thoron exhalation rates with outdoor gamma exposure rate.
ZnO is a wide band gap semiconductor and is very attractive because of its fundamental and technological importance. It is extensively used in research due to its properties viz. excellent chemical & ...thermal stability, large exciton binding energy, anti-corrosion and heat resistance. It is a promising material for optoelectronic devices in both UV and Visible regions. In the present investigation, ZnO nano powder was synthesized by single step Sol-gel technique using zinc acetate dihydrate as a precursor and ethanol as a medium. The synthesized ZnO nano powder was characterized using UV–Vis, FTIR, XRD, RAMAN, Photoluminescence (PL), Nano-particle size analyzer, SEM and EDX techniques. UV–Vis spectra gives intense peak at 372 nm wavelength showing the presence of absorption band due to ZnO nano powder. The chemical bonding among Zn and O can be clearly observed from FTIR spectrum. XRD spectra displays sharp peaks which indicates the crystalline nature of ZnO. It also shows homogeneity and size consistency of prepared nanoparticles. The crystallite size of ZnO nano powder were calculated using Scherrer's formula. The morphology and elemental analysis have been studied via SEM and EDX techniques. All the characterization results have been correlated with each other.
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•The band gap energy for ZnO is approximately 3.3 eV (using UV–Visible) and 3.18 eV (using PL).•Raman peaks at 335 and 582 cm−1 confirms the structural defects present in ZnO nanopowders.•The average size of synthesized nanorods is 70.9 nm and of nanoflowers is 458.6 nm.•The average crystallite size of nano powder is 18.22 nm and bond length is 1.9798 Å (calculated from XRD data).•The atomic percentage of Zn and O in ZnO is 41.18% and 58.82% respectively.
Electrical, optical and morphological properties of polymer nanocomposite materials are quite interesting to investigate due to their innovative characteristics and applications. Temperature ...dependent dc conductivity using different charge transport mechanisms like ionic hopping, Schottky and Poole-Frankel emissions has been investigated for pristine PS and PS/ZnO (at different wt% of ZnO) nanocomposite films in this research report. Non-ohmic conduction behaviour of these films developed an interest to carry out bulk and electrode limited conduction mechanisms. Ionic jump distance ‘a’ and conduction coefficient ‘βexp’ values for these films were calculated at various temperatures from the slopes of log I vs E and log I vs E1/2 plots respectively. The increase in dc conductivity of an order of 108 was observed by increasing the doping concentration up to 20 wt% of ZnO. The change in their ac conductivity was observed from 10−9 S/m to 10−6 S/m by varying the frequency from 1 to 300 kHz.
•Anomalous behaviour of ionic jump distance ‘a’ and conduction coefficient ‘β’ hasbeen correlated with Tg.•DC conductivity of PS/ZnO nanocomposite films was increased to an order of 108 withdoping concentration.•10wt% ZnO doped PS nanocomposite film indicates percolation threshold occurs with 10wt% concentration of nanofiller.•A change of the order of 103 S/m in ac conductivity has been observed by changing thefrequency from 1 kHz to 300 kHz.
Thermally stimulated depolarization current studies of pristine and ZnO doped nanocomposite films (at 5, 10, 15 & 20 wt% of ZnO) have been investigated at different poling temperatures and polarizing ...fields. Peaks corresponding to glass transition temperature (α1 and α2-peaks) relaxation, space-charge relaxation (ρ-peaks) and γ-relaxation were observed in thermograms of pristine and doped films. The change in peak height and peak positions with increase in doping concentration and poling parameters i.e., EP & TP results to the trapping or detrapping of the charge carriers. The anomalous behaviour of PS/ZnO nanocomposite films towards TSD current spectra observed near the glass transition temperature indicates the phase transitions. Changes in different relaxations may be attributed to the structural deformation of the samples due to doping and supported by FTIR and SEM results. Moreover, some molecular parameters like activation energy (Ea) and relaxation times (τ) were estimated.
•Effect of different poling temperatures and polarizing fields on TSDC spectrums of pristine PS and PS/ZnO nanocomposite films.•Different relaxation phenomenon like glass transition temperature (corresponding to α1 & α2 peaks), space-charge (ρ-peaks) and water absorption (γ-peaks) relaxations were investigated by varying ZnO concentration.•Structural deformation of samples during TSDC analysis were correlated with the results of FTIR, SEM and DSC techniques.•Activation energies of pristine and ZnO doped PS nanocomposite films were estimated at 323K and 383K polarizing temperatures.
Organic–inorganic nanocomposites have endured our interest in research, as they possess unique physical and chemical properties in various fields of application. In the present investigation, ZnO ...nanoparticles and polystyrene/zinc oxide nanocomposite films were successfully synthesized by sol–gel and solution-mixing techniques, respectively. These thin films were prepared with varying concentrations of ZnO, i.e., from 0 to 20 wt%. The thickness of these synthesized films was measured experimentally. These films were characterized to investigate the structural, morphological and thermal properties using Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques. The roughness of film surfaces has been calculated from Nanoscope analysis software and correlated to the SEM images. The glass transition temperature of pristine and nanocomposite films is observed from the analysis of DSC data.
In the present work, pristine and ZnO-doped polystyrene (PS) nanocomposite films were synthesized using solution-mixing technique. These films have been synthesized with different concentrations of ...ZnO, i.e. 5, 10, 15 and 20 wt% to PS matrix. The main emphasis of this study is to investigate the effect of ZnO nanopowder on the dielectric properties of PS matrix. Dielectric constant/loss of these PS nanocomposite films was examined as a function of frequency (from 100 Hz to 300 kHz) and temperature (from 293 to 443 K). Overall increase in dielectric constant, i.e. from 7.5 to 9.3 (at room temperature) and 7.7 to 9.5 (at 443 K), and dielectric loss, i.e. from 0.08 to 0.18 (at room temperature), was observed after the incorporation of ZnO in PS matrix. Change in dielectric constant and loss values of nanocomposite films is attributed to the increased water absorption capability and defects/traps arise in nanocomposite films. These configurational changes were confirmed by different characterization techniques, viz. Fourier transform infrared and photoluminescence techniques. Cole–Cole distribution function has been employed to investigate the variation in dielectric relaxation phenomenon due to the insertion of ZnO in PS matrix. Different parameters like mean relaxation time, molecular relaxation time, dipolar relaxation strength and dielectric strength are calculated from the experimental data. Significant changes in dipolar relaxation strength, i.e. from 0.13 to 0.51 and 0.36 to 0.69, were observed at 293 K and 443 K temperature, respectively, with the increase in wt% of ZnO.
Graphical abstract
Forty soil samples from district Palwal of Southern Haryana, India were collected to estimates the radon/thoron exhalation rate using scintillation detector-based SMART RnDuo out of which twenty ...samples were tested to estimate the activity of
226
Ra,
232
Th and
40
K using high purity germanium (HPGe) gamma-ray spectrometry. The radon mass exhalation rate (mBqkg
−1
h
−1
) was observed as {range (mean)} {16 ± 1-48 ± 3 (28 ± 8)} and thoron surface exhalation rate (Bqm
−2
h
−1
) was observed as {1800 ± 198-6331 ± 205 (3850 ± 850)}. Activities of radium (
226
Ra), thorium (
232
Th) and potassium (
40
K) were {range (mean)} observed as {28.4-48.4 (40.0 ± 1.4)}, {49.7-75.0 (62.7 ± 1.6)} and {432-698 (522.9 ± 17.6)}, respectively. It is observed that the radium in 75% samples while thorium and potassium in all samples were found to higher than the world's average values of 35, 30 and 400 Bqkg−
1
, respectively, as reported by UNSCEAR. Average of radon mass exhalation and thoron surface exhalation rates exceeded the world's mean value 57 mBq kg
−1
h
−1
and 3600 Bq m
−2
h
−1
, respectively. Health hazard index is well below the unity (< 1), which indicates that there are no gamma radiation hazards associated with samples collected from the study region.
Abstract
Scintillation-detector-based SMART RnDuo (AQTEK System, India) and LED fluorimeter (Quantalase Instrument, India) were used for measurements of radon and uranium concentration in 54 ...groundwater samples collected from different locations in the Palwal district of Haryana (India). Radon in 26% and uranium in 54% of samples were found to be at higher levels than the maximum contamination limit (11 Bq l−1) for drinking water recommended by US Environmental Protection Agency and provisional guideline level (30 μg l−1) stated by World Health Organization.
A systematic measurement of radon/thoron concentration by using pin-holes dosimeter and their decay products by deposition based progeny sensors have been carried out in indoor environment of ...district Palwal, Southern Haryana, India. LR-115 type-II of cellulose nitrate with thick polyester base film was used as detectors. A total 150 locations were selected for measurements over a period of 40 days. In this paper, results of winter season are reported and compared with results of summer and rainy season. The measured average indoor thoron gas concentration (34.6 ± 1.5) is about 3.5 times higher than the world average value (10 Bq m.sup.-3). The average values for radon concentration, EERC, and EETC is found below the world average values of 40 Bq m.sup.-3 for radon, 15 Bq m.sup.-3 for EERC, and 0.5 Bq m.sup.-3 for EETC. The average annual effective dose inhaled by humans was estimated and compared with recommended limits of ICRP and WHO.
