Function Of Dopant Concentration Research Articles

Refractive indices and extinction coefficients of p-type doped Germanium wafers for photovoltaic and thermophotovoltaic devices

Our work is primarily driven by the absence of optical parameters for p-type Ge wafers, adaptable to any specific doping value, and, at the same time, able to cover any application from infrared to ultraviolet regime. To address this, we have determined the complex refractive indices of p-type commercial Ge wafers through a wide spectral range (200–25000 nm) employing spectroscopic ellipsometry and transmittance measurements. The doping levels in these wafers vary between 1015 and 1018 cm−3, which are most commonly used in photovoltaic, thermophotovoltaic and optoelectronic applications. Our data fitting procedure resulted in a dielectric function that successfully reproduces not only the critical points associated with interband transitions above the bandgap, but also absorption features below the bandgap connected to intraband processes. Consequently, we obtained the complex refraction indices of these Ge wafers as a function of dopant concentration, and these have been corroborated through experimental reflectance and transmittance measurements. Additionally, we achieved a successful validation of these refractive indices by simulating the external quantum efficiency of Ge single-junction solar cell with two different thickness fabricated on a Ge wafer with a different doping level than those analyzed in this study.

Facile synthesis of PVA-formamide based solid state electrolyte membrane: A combined experimental and computational studies

For ever-growing energy demand, it is the imperative of time to develop advanced electrolyte materials which are compatible with Li + ion mobility in Lithium based batteries. In this study, polyvinyl alcohol (PVA)-LiNO3-Formamide (PLF) membrane complex has been developed for cost effective and mass fabrication of Li ion based energy storage devices. Improved Li + ion conducting PVA based polymer electrolytes in seven different PVA and LiNO3 blend compositions were prepared and characterized. Incorporation of Formamide (0.5 g) as plasticizer in the PVA-LiNO3 polymer matrix leads to a remarkable improvement in ionic conductivity (4.18 × 10−4 Scm−1) for a 0.27 g of LiNO3 concentration at ambient temperature. Improvement in Li conductivity is due to change in crystalline nature as a consequence of PVA O-H---O intra/inter molecular H-bonding destabilization. Investigation on the trend of activation energy as a function of dopant concentration indicates that the activation energy decreases up to 0.27 g of LiNO3. Lowest activation energy 0.21 eV is observed for this concentration. More interestingly, improved Lithium Transference Number (LITN) of 0.437 is obtained through Bruce-Vincent approach for the plasticized optimum conducting membrane (PLF4–0.27 g LiNO3 concentration) which is better than that of the commercially available Li batteries. Underlying molecular level interactions in the models of PVA and its complexes were explored using M05-2×/6–31 + G (d,f) levels of theory and NCI analysis. From the least interaction energy of PVA-Formamide complex, it is inferred that metal-Oxygen coordination contributes much for the stabilization of PVA-LiNO3-Formamide, PVA-LiNO3, Formamide-LiNO3 complexes.

Concentration quenching mechanism of dysprosium(III) ions in silicate-substituted fluorapatite

Silicon-substituted apatite doped with Dy3+ ions was obtained by using microwave assisted hydrothermal techniques. The general formula of obtained samples is related to Ca10-xDyx(PO4)2(SiO4)4F2, where x = 0.05; 0.1; 0.2; 0.5. The structural, and morphological features of the obtained materials were determined by using XRD (X-ray powder diffraction) and SEM imaging (Scanning Electron Microscopy). The Rietveld refitment was used for estimation of unit-cell parameters. The photoluminescence of the Dy3+ ions was detected and analysed as a function of dopant concentration. The particular attention was focused on the concentration quenching of Dy3+ ion luminescence as well as the critical transfer radius was calculated. The chromaticity diagram, emission colour and correlated colour temperature (CCT) were evaluated.

Fabrication, structural characteristics, and influence of Bi3+ doping concentration on UV-vis spectra of Bi3+:SnO2 nanocomposite materials

The authors report the characteristics and optical properties of Bi3+-doped SnO2 quantum dots prepared bysol-gel and hydrothermal methods. The structure and morphology of the materials as a function of dopingconcentration were studied and analysed by X-ray diffraction (XRD) and scanning electron microscope(SEM). The structure of the material was assigned to the tetragonal crystal structures of the SnO2 rutile phase,reported in JCPDS Card No. 41-1445. With the increase of Bi3+ doping, the crystallinity of Bi-doped SnO2worsened. The average sizes of the SnO2 nanocrystals were within 3-8 nm. The effect of Bi3+ ion concentrationon the absorbance properties of the materials was investigated by UV-Vis absorption spectra. The absorbancedecreased with increasing the concentration of Bi3+ dopant in the SnO2 lattice. The bandgap width decreasedwith Bi3+ dopant concentration. All Bi3+-doped SnO2 samples presented an enlargement of the light absorptionrange due to a bandgap width decrease.

Investigation of n-type co-doping in barium stannate nanoparticles

Barium stannate (BaSnO3) has recently emerged as an ideal candidate for use as a transparent electrode, especially when appropriately doped. Whilst research has been conducted on the effects of using various elements to dope BaSnO3, to date there has been no systematic study into the role of two separate elements doping both sites at once. Here, were present an in-depth investigation into the optical and crystallographic effects of simultaneously doping the barium stannate crystal at both cationic sites. A wet chemical methodology to synthesize BaSnO3 nanoparticles that enables tunable doping with lanthanum (at the Ba site) and/or antimony (at the Sn site) is developed. Doping is validated via energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and absorption spectroscopy in the visible and near infrared range. Through high-resolution X-ray diffraction (XRD) and transmission electron microscopy (TEM) we assessed the effect of doping on the crystal size and strain, and then evaluated the role of each dopant in affecting the plasmonic properties of the BaSnO3 nanoparticles as a function of dopant concentration and annealing temperature. We show that doping across both sites results in less lattice strain, less defects, and overall larger particles, and through a systematic study we provide design rules to synthesize high-quality BaSnO3-based nanomaterials.

Thermoluminescent response of LaAlO3:Pr3+ under X-ray beams effect

Thermoluminescent (TL) dosimeters are the most used, since they can store information, due to exposure to radiation. Rare earth doped lanthanum aluminate (LaAlO3) ceramic has attracted great attention in recent years for many applications because it shows excellent properties such as thermal stability, color light emission as well as high thermoluminescent intensity. In the present work, TL glow curve under diagnostic X-ray beam was obtained. According to the literature, procedures in interventional cardiology are Thermoluminescent glow curve was analyzed using a Harshaw 3500 TL reader coupled to a personal computer for storage information and future analysis. For irradiation processes was used a diagnostic X-ray source Siemens 256-slice computed tomography (CT) Somaton drive model. TL response of trivalent praseodymium doped lanthanum aluminate as a function of dopant concentration was increasing as concentrations of Pr3+ ion in LaAlO3 was increased. The increase in TL glow peak sensitivity was increased up to 2 % concentration of Pr3+ ion. This TL glow curve exhibited a broad peak centered at 190°C and little shoulder which is consider as the second peak centered at 260°C respectively. The nature of the glow curve form in samples is attributed to at least one type of the trap with relates at least one type of the defect. After experimental results LaAlO3:Pr3+ can be used as thermoluminescent material for diagnostic X-ray beams measurements.

Oxidation states and occupation sites of Fe and Cu ions in the Y3Fe5−xCuxO12, (0.00 ≤ x ≤ 0.05) compound synthesized via sol gel method

This paper presents an experimental and theoretical study on the oxidation states and occupation sites of Fe and Cu ions in the Y 3 Fe 5−x Cu x O 12 , (0.00 ≤ x ≤ 0.05) compound synthesized via sol gel method. Transmission electron microscopy images showed agglomerated coral-shaped particles, while selected area electron diffraction analysis confirmed the formation of YIG cubic structure, since the bright points correspond to the (004), (123), (024), (224), (022), and (112) YIG family planes. Fourier transform infrared and Raman spectroscopies testified the YIG crystal structure formation and suggest that the Fe by Cu replacement occurs in the octahedral sites. The cation distribution and reticular energy were estimated theoretically, revealing that the more probable valence state combination corresponds to Cu + -Fe 2+ doped YIG configuration. The experimental study by X-ray Photoelectron Spectroscopy certified the elements valence states and confirmed that Y, Fe and Cu are mainly in the Y 3+ , Fe 3+ , Fe 2+ and Cu + oxidation states. The oxygen vacancies formation was also identified through the deconvolution of XPS spectra for the oxygen region. Finally, the dopant occupation probability per site as function of dopant concentration per unit formula was calculated using a phenomenological model and suggested that Cu + and Fe 2+ cations prefer to occupy the octahedral sites in the YIG crystal structure. • Cu-doped YIG nanoparticles were synthesized by the sol gel method. • Fe ions were found in the oxidation states 3 + and 2 + . • Cu + ions were discovered in Cu- doped YIG. • The cation distribution and reticular energy were estimated theoretically. • Cu + and Fe 2+ cations are in the a -sites of YIG.

Iron(III) Dopant Counterions Affect the Charge-Transport Properties of Poly(Thiophene) and Poly(Dialkoxythiophene) Derivatives.

This study investigates the charge-transport properties of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(ProDOT-alt-biEDOT) (PE2) films doped with a set of iron(III)-based dopants and as a function of dopant concentration. X-ray photoelectron spectroscopy measurements show that doping P3HT with 12 mM iron(III) solutions leads to similar extents of oxidation, independent of the dopant anion; however, the electrical conductivities and Seebeck coefficients vary significantly (5 S cm-1 and + 82 μV K-1 with tosylate and 56 S cm-1 and +31 μV K-1 with perchlorate). In contrast, PE2 thermoelectric transport properties vary less with respect to the iron(III) anion chemistry, which is attributed to PE2 having a lower onset of oxidation than P3HT. Consequentially, PE2 doped with 12 mM iron(III) perchlorate obtained an electrical conductivity of 315 S cm-1 and a Seebeck coefficient of + 7 μV K-1. Modeling these thermoelectric properties with the semilocalized transport (SLoT) model suggests that tosylate-doped P3HT remains mostly in the localized transport regime, attributed to more disorder in the microstructure. In contrast perchlorate-doped P3HT and PE2 films exhibited thermally deactivated electrical conductivities and metal-like transport at high doping levels over limited temperature ranges. Finally, the SLoT model suggests that PE2 has the potential to be more electrically conductive than P3HT due to PE2's ability to achieve higher extents of oxidation and larger shifts in the reduced Fermi energy levels.

Concentration Dependent Improved Spectroscopic Characteristics and Near White Light Emission in Boro Phosphate Glasses Doped with Holmium

The physical, structural, thermal, and optical properties of heavy metal (Ho3+) oxide incorporated lithium-boro-phosphate glass prepared utilizing melt quenching process are presented in this paper as a function of dopant concentration. To support the findings of the FTIR and DSC studies, many theoretical, experimental, physical, and optical parameters were calculated. XRD and FTIR measurements revealed the prepared glasses’ amorphous nature and the presence of significant borate functional groups. The optical band gap, Urbach energy, and steepness characteristics were tested to validate the structural results. The emission spectrums were recorded in the prepared glasses for an excitation of 450 and 550 nm to find powerful emission color. The color co-ordinates (0.33, 0.41) were found to be quite comparable to white light color co-ordinates. The present glasses can, therefore, be ideal candidates for possible applications with light-emitting diodes.

The structural and optical properties of combustion synthesized Ag doped ZnO nanoparticles

We report the combustion synthesis of Ag (1 to 5 mol%) doped ZnO nanoparticles and their structural and optical characteristics as a function of dopant concentration in this work. The phase, purity, structure, and optical characteristics of the produced samples were thoroughly investigated using XRD and UV-Visible spectroscopy methods. The production of polycrystalline nanoparticles in their as-synthesized condition is confirmed by XRD findings. To estimate the different structural parameters and examine the structure of the produced samples, Rietveld refinement was used. The optical properties were evaluated using Tauc’s plots (band gap energy). With increasing dopant concentration, the band gap was determined to be increasing.

On the quantification of Auger recombination in crystalline silicon

Quantification of Auger recombination in crystalline silicon is usually challenging because it requires distinguishing Auger recombination from extrinsic recombination processes, especially at the surface. In this work we exploit the known injection dependence of surface recombination at surfaces passivated by highly charged dielectric films to assess the value of the ambipolar Auger coefficient Camb in crystalline silicon from carefully calibrated photoconductance decay measurements of high-lifetime Si wafers. A value of Camb = (2.11±0.02) × 10−30 cm6 s−1 is determined for both n- and p-type Si, independent of the dopant concentration for moderately doped samples near 300 K. Furthermore, by exploiting the expected equality of the surface saturation current density J0s for identically processed n- and p-type substrates, we are able to estimate the relative contributions of ehh and eeh Auger processes to Camb under the same doping and injection regime. The resulting ratio Cn/Cp=2.81 is in close agreement with the value of 2.91 derived from the data of Dziewior and Schmid at high dopant concentrations, which we reassess in light of modern mobility models. Based on our own data and literature data at higher concentrations, we offer a revised parameterisation of the Auger recombination rate in c-Si as a function of dopant concentration and injection level which is consistent with these findings. This revised parameterisation is also shown to be consistent with the most recent record lifetimes reported by other authors. Finally, we suggest experimental considerations relevant for future efforts to further refine the Auger parameterisation.

Effects of strain, disorder, and Coulomb screening on free-carrier mobility in doped cadmium oxide

The interplay of stress, disorder, and Coulomb screening dictating the mobility of doped cadmium oxide (CdO) is examined using Raman spectroscopy to identify the mechanisms driving dopant incorporation and scattering within this emerging infrared optical material. Specifically, multi-wavelength Raman and UV-vis spectroscopies are combined with electrical Hall measurements on a series of yttrium (X = Y) and indium (X = In) doped X:CdO thin-films. Hall measurements confirm n-type doping and establish carrier concentrations and mobilities. Spectral fitting along the low-frequency Raman combination bands, especially the TA+TO(X) mode, reveals that the evolution of strain and disorder within the lattice as a function of dopant concentration is strongly correlated with mobility. Coupling between the electronic and lattice environments was examined through analysis of first- and second-order longitudinal–optical phonon–plasmon coupled modes that monotonically decrease in energy and asymmetrically broaden with increasing dopant concentration. By fitting these trends to an impurity-induced Fröhlich model for the Raman scattering intensity, exciton–phonon and exciton–impurity coupling factors are quantified. These coupling factors indicate a continual decrease in the amount of ionized impurity scattering with increasing dopant concentration and are not as well correlated with mobility. This shows that lattice strain and disorder are the primary determining factors for mobility in donor-doped CdO. In aggregate, the study confirms previously postulated defect equilibrium arguments for dopant incorporation in CdO while at the same time identifying paths for its further refinement.

Pressure induced phase transitions in Sm-doped BiFeO3 in the morphotropic phase boundary

Sm-doped BiFeO3 compacted powders with composition across the morphotropic phase boundary region were prepared by sol-gel method. Crystal structure, morphology and magnetic state of the compounds were analyzed as a function of dopant concentration, temperature and external pressure using synchrotron and laboratory X-ray diffraction, electron microscopy, Raman and Mössbauer spectroscopy. Application of external pressure shifts the phase transition from the rhombohedral structure to the nonpolar orthorhombic structure towards lower concentration of the dopant content, wherein the amount of the anti-polar orthorhombic phase notably decreases. Raman and Mössbauer spectroscopy data provides additional information about the structural distortion on local scale level which testifies faster formation of nonpolar orthorhombic phase and associated modification in the magnetic state in the compounds subjected to high pressure. Temperature increase leads to the structural transition to the nonpolar orthorhombic phase regardless the structural state at room temperature; furthermore, application of external pressure decreases the phase transition temperature.

Assessing the structural and interaction behaviour of Pr@Gd2O3 nanoparticles with biological entities

The current work focuses on accessing the potential aptitude of the rare-earth-doped Gadolinium oxide (Gd2O3) nanoparticles as a function of dopant concentrations with biological entities in aqueous media. A series of Pr@Gd2O3 NPs were synthesized by fast and economically viable microwave-assisted methodology. Various high end techniques such as high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), vibrating sample magnetometric studies, thermal gravimetric analysis and scanning electron microscopy (SEM), were employed to characterize the prepared particles. The optical, magnetic and thermal properties of Pr-doped Gd2O3 (doping percentage = 5, 10 and 15%) were scrutinized in relationship with their optical band gap, spectroscopic properties, defect states and thermal stability. In order to access the effect of different concentrations of dopant on the biocompatibility of Gd2O3, in vitro biocompatibility studies on the bacterial and fungal stains have been performed. These variables were on the basis of dopant amount (5, 10 and 15% of Pr) and initial concentration (10, 50, 100 ppm). The outcomes of in-vitro blood compatibility assay showed the biocompatible aptitude of effect of Pr@Gd2O3 NPs as a function of initial concentration ranging from 10, 50, 100 ppm. The relative effect on the chromosomal aberrations in root meristems of A. cepa shown the reduction of 20%, 23%, 8% in mitotic index (MI), correlative mitotic index (CMI) and index of phase (PI) values with increase in Pr doping amount. The high biocompatibility was observed for 10 ppm of Pr@Gd2O3 NPs. Collectively; the outcomes of the present study exemplify the various properties of Pr@Gd2O3 NPs with potential biomedical efficacies.

Enhancing Li-Ion Charge Storage in Disordered Vanadium Ferrite Aerogels via Multivalent Substitution

We have developed a family of vanadium ferrite (VFe2Ox) aerogels that exhibit promising performance for Li-ion storage [1]. These materials are synthesized by a simple epoxide-driven sol–gel route that yields aerogels with high surface area (200–300 m2 g–1) and no discernible crystallinity by powder X-ray diffraction. Subsequent calcination at 300°C is required to decompose residual organics from the synthesis, but even after such thermal treatment, the VFe2Ox aerogels retain their disordered nature. Because of their high surface area and lack of defined crystal structure, VFe2O x aerogels exhibit the electrochemical characteristics of pseudocapacitive materials―broad voltammetric envelopes and sloping discharge curves; fast charge–discharge response; and low charge–discharge voltage hysteresis―but with capacity levels commensurate with many battery-type materials. We find that substituting ~10 at% of the V sites with nominally electroinactive Al3+ enhances specific capacity by >25% from 100 mAh g–1 for VFe2Ox to 128 mAh g–1 for Al-VFe2Ox , while also improving capacity retention at high current density. X-ray photoelectron spectroscopy (XPS) shows that incorporation of Al3+ induces the formation of V4+ sites that likely increase local electronic conductivity in Al-VFe2Ox. Ex-situ XPS analysis of materials electrochemically conditioned to various charge–discharge states reveals distinct differences in the utilization of V and Fe redox sites for VFe2Ox versus Al-VFe2Ox. First principles modeling shows the effect of Al-doping on V and Fe oxidation as a function of dopant concentration and site location within the amorphous material. Lessons learned from this paper will inform future studies on rational substituents and targeted defective compositions for high-rate lithium-ion charge storage. Chervin, Christopher N., et al. "Defective by design: vanadium-substituted iron oxide nanoarchitectures as cation-insertion hosts for electrochemical charge storage." Journal of Materials Chemistry A22 (2015): 12059-12068.Chervin, Christopher N., et al. "Enhancing Li-ion capacity and rate capability in cation-defective vanadium ferrite aerogels via aluminum substitution.” RSC Adv., under review, March 2021.

Optical Properties of Non-Crystalline Fluorine Doped Hematite Fe<sub>2</sub>O<sub>3</sub> Thin Films Deposited by Chemical Spray Pyrolysis Technique

By using the spray pyrolysis technique, un-doped and Fluorine highly doped iron oxide Fe2O3 thin films were deposited on a glass substrate at a temperature of 380 oC and at different dopant concentrations (10, 15, and 20) %. The crystal structure and optical characterization of the deposited thin film were performed by x-ray diffraction and UV-Vis spectrophotometer. The XRD results revealed that the presence of a very wide peak in-between (15-35) o angles, this gives evidence that un-doped and F-doped Fe2O3 thin films have very low crystallinity and amorphous structures. The optical absorbance edge was shifted towards short wavelengths (blue shift) and the absorbance was reduced with the increase of Fluorine dopant content. The optical constants such as absorption, extinction coefficients, and the optical conductivity of the deposition films were investigated as a function of dopant content. The optical energy band gap of un-doped and Fe2O3:F thin films was found to be increased when increasing of the Fluorine content and exhibited a direct allowed energy gap (Eg) from (2.55 to 2.7) eV which can related to the Burstein-Moss effect.

Mass specific performance of potassium tetrabromoaurate as a carbon nanotube dopant

Improvements in carbon based conductors can impact the development of a variety of new electronic and optoelectronic devices, and may offer significant weight savings (over copper), important in mass sensitive applications such as aircraft design. Published experimental work indicates that chemical doping offers the most likely route to high specific conductivity carbon-based wiring. Interpretation of the test data on potassium tetrabromoaurate, the most successful carbon nanotube dopant tested to date, is complicated by the possibility that the nominal dopant molecule and the ‘in situ’ configuration of the dopant species may differ, due to disassociation, ionization, or other chemical effects. Ab initio modeling of KAuBr4 doping, in both molecular and disassociated forms, allows for the theoretical isolation of molecular, molecular fragment, and atomic dopant effects on metallic and semiconducting tubes, as a function of dopant concentration. The modeling results suggest that the dopant is most effective in a disassociated form, but that KAuBr4 doping is not likely to produce high specific conductivity CNT wiring.

Thermodynamics of order and randomness in dopant distributions inferred from atomically resolved imaging

Exploration of structure-property relationships as a function of dopant concentration is commonly based on mean field theories for solid solutions. However, such theories that work well for semiconductors tend to fail in materials with strong correlations, either in electronic behavior or chemical segregation. In these cases, the details of atomic arrangements are generally not explored and analyzed. The knowledge of the generative physics and chemistry of the material can obviate this problem, since defect configuration libraries as stochastic representation of atomic level structures can be generated, or parameters of mesoscopic thermodynamic models can be derived. To obtain such information for improved predictions, we use data from atomically resolved microscopic images that visualize complex structural correlations within the system and translate them into statistical mechanical models of structure formation. Given the significant uncertainties about the microscopic aspects of the material’s processing history along with the limited number of available images, we combine model optimization techniques with the principles of statistical hypothesis testing. We demonstrate the approach on data from a series of atomically-resolved scanning transmission electron microscopy images of MoxRe1-xS2 at varying ratios of Mo/Re stoichiometries, for which we propose an effective interaction model that is then used to generate atomic configurations and make testable predictions at a range of concentrations and formation temperatures.

Continuous trap distribution and variation of optical properties with concentration in oxi-fluoroborate glass doped with Nd3+

Alkaline earth borate glasses are being studied due to their interesting structure and properties. Here, the optical properties of some barium oxyfluoride glasses are reported. The absorption spectra by means of Judd Ofelt theory, the room temperature luminescence, and the thermoluminescence (TL) response as a function of dopant concentration were studied. The effect of the concentration on the thermal stability and the glass structure was also analyzed. The incorporation of Nd 3+ affects not only the optical properties but also the thermal ones. From Raman spectroscopy, no great differences were observed among undoped and doped glass samples. Judd-Ofelt parameters are lower or comparable to other borate and silicate systems. The temperature of the maximum intensity on the TL curve does not change with the irradiation dose, indicating samples follow a first-order kinetic model. However, the detailed TL analyses evidenced a continuous distribution of the activation energy and the signal stability after irradiation was also studied and interpreted in the same way. The results presented here indicate that the oxy-fluoride borate glasses are promising materials for TL applications.

Evaluation of physical properties and bactericidal efficacy of chemically developed undoped and Mn (5, 10, 15wt%) doped ZnO nanoparticles

ABSTRACT Chemical precipitated and followed by calcinations is a versatile process for synthesising undoped ZnO and Mn (5, 10 and 15 wt%) doped ZnO nanoparticles at pH-10 and calcinations temperature of 450°C for 2 hours were followed for synthesising all the samples. The structural properties evaluated via XRD pattern revealed the hexagonal wurzite phase and with the grain size of 19 to 9 nm. Variation in the microstructural properties as function of dopant concentration was attributed using standard relations. The morphological and cross verification of structural properties were made via HRTEM analysis. Wide, direct allowed band gap property and narrow size distributed particles nature were confirmed through UV-visible absorption spectra with blue shifted peaks. The bandgap values got increased on increasing the dopant concentration. The presences of functional groups of the prepared samples were also confirmed by FTIR. Bands below 700 cm−1 assigns the Metal-oxygen framework of the sample. The antibacterial efficiency of the prepared nanoparticles was evaluated for gram positive bacterial strains namely Staphylococcus aureus and Bcaillus subtilis.