Characteristics of pulse plated CdxZn1−xSe films

K.R. Murali,M. Balasubramanian 한국물리학회 2010 Current Applied Physics Vol.10 No.3

CdxZn1-xSe films (0≤ x ≤ 1) were deposited for the first time by the pulse plating technique at different duty cycles in the range 6–50% at room temperature from an aqueous bath containing zinc sulphate, cadmium sulphate and selenium oxide. To the author’s knowledge this is the first report on pulse plated CdxZn1-xSe films. The deposition potential was 0.9 V (SCE). The as deposited films exhibited cubic structure. Composition of the films was estimated by Energy Dispersive Analysis of X-ray studies. X-ray photoelectron spectroscopy studies indicated the binding energies corresponding to Zn(2p3/2), Cd(3d5/2 and 3d3/2) and Se(3d5/2 and 3d3/2). Optical band gap of the films varied from 1.72 to 2.70 eV as the composition varied from CdSe to ZnSe side. Atomic force microscopy studies indicated grain size in the range of 20–150 nm.

Synthesis, luminescence properties, and growth mechanisms of YF₃:Yb³⁺/Er³⁺ nanoplates

Murali, G.,Lee, Byeong Hoon,Mishra, R. K.,Lee, Jae Myeong,Nam, Sang-Hwan,Suh, Yung Doug,Lim, Dong-Kwon,Lee, Joong Hee,Lee, Seung Hee The Royal Society of Chemistry 2015 Journal of Materials Chemistry C Vol.3 No.39

<▼1><P>Anisotropically structured upconversion nanocrystal is a promising new class of high performance optical materials.</P></▼1><▼2><P>Anisotropically structured upconversion nanocrystals capable of exhibiting bright upconversion emission properties are a promising new class of high performance optical materials. In this study, we investigate a facile synthetic method for the new nanoplate structure of YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> with enhanced luminescence intensity. The shape of YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> nanocrystals can be controlled by changing the synthesis conditions of the NaOH concentration, reaction time, and surfactant. The concentration of NaOH determines the final structure of YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP>. By increasing the NaOH concentration from 0.25 mmol to 2.5 mmol, YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> nanoplates transform into NaYF4:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> nanoparticles; in the absence of NaOH, the nanoplate structure of YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> changes to particles. The YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> nanoplates show luminescence efficiency much greater than that of the spherical YF3:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> nanocrystals.</P></▼2>

Aspect-Ratio Controlled Synthesis and Tunable Luminescence of YF₃:Yb³⁺/Er³⁺ Upconversion Nanocrystals

Murali, G.,Mishra, R. K.,Lee, Jae Myeong,Chae, Young Cheol,Kim, Jongwoo,Suh, Yung Doug,Lim, Dong-kwon,Lee, Seung Hee The American Chemical Society 2017 CRYSTAL GROWTH AND DESIGN Vol.17 No.6

<P>We report a facile synthetic method for high-aspect-ratio YF3:Yb3+/Er3+ nanocrystals by controlling-the composition of the precursor and' saltsto manipulate the structures-of YF3:Yb3+/Er3+ nanocrystals. A controlled aspect ratio is attained by tufting the-molar:ratio of NH4+/RE3+ (NH4+ is the counterion- released from the fluoride precursor (NH4F) and RE3 indicates the total amount of Y, Yb, and Er)-and the presence of specific inorganic salts. A low molar ratio of NH4+/RE3+ induced the production of high-aspect-ratio YF3:Yb3+/Er3+ nanocrystals, while a high molar ratio of NH4+/RE3+ induced the formation of irregular=nanoplates. The selection of the inorganic salt as an additive is critical in controlling the aspect ratio and crystallinity-of YF3:Yb3+/Er3+ nanocrystals. The cation showed limited control over the aspect 'ratio, but the anions, Cl- and Br-, induced the production of the highest aspect ratio for YF3:Yb3+/Er3+ nanocrystals. We round that the aspect ratio affected the luminescence properties of YF3:Yb3+/Er3+ nanocrystals. The green emission from nanorod structures changed to orange when the morphology is transformed to nanoplates.</P>

Two Statistical Scrutinize of Impact Strength and Strength Reliability of Steel Fibre-Reinforced Concrete

G. Murali,R. Gayathri,V. R. Ramkumar,K. Karthikeyan 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.1

The variations in impact strength of steel Fibre Reinforced Concrete (FRC) were statistically, commanded in this research. For this purpose, the experimental impact test results of earlier researchers were investigated using two statistical approaches. Firstly, normality test was carried out on first crack strength (N1) and failure strength (N2) using distribution plot and its accuracy was verified with Kolmogorov-Smirnov, Shapiro-Wilk and Chen-Shapiro test. Secondly, strength reliability analysis was carried out using two parameter Weibull distribution and their Weibull parameters were determined using three methods viz., Empherical Method of Justus (EMJ), Method of Moments (MOM) and Empherical Method of Lysen (EML). Results suggested that, if three samples are used to determine the N1 value for researchers’ data, at 95% levels of confidence, then the error in the measured value is about 50%. The 0.1 reliability level of the impact strength values of EMJ, EML and MOM were 153, 120 and 153 respectively in case of N1 and were 198, 156, and 198 respectively in case of N2 based on earlier researcher’s data.

SnO2 quantum dots decorated on RGO: a superior sensitive, selective and reproducible performance for a H2 and LPG sensor.

Mishra, R K,Upadhyay, S B,Kushwaha, Ajay,Kim, Tae-Hyung,Murali, G,Verma, Ranjana,Srivastava, Manish,Singh, Jay,Sahay, P P,Lee, Seung Hee RSC Pub 2015 Nanoscale Vol.7 No.28

<P>We report the H2 and LPG gas sensing behavior of RGO/SnO2 QDs synthesized by a surfactant assisted hydrothermal method. The RGO/SnO2 QD based sensor shows a high response of 89.3% to H2 and 92.4% to LPG for 500 ppm test gas concentration at operating temperatures of 200 C and 250 C, respectively. Further, the RGO/SnO2 QD based sensor shows good selectivity for H2 and LPG in the presence of other interfering gases such as ammonia, chloroform, toluene, benzene, acetone, n-butylacetate, acetic acid and formic acid. We observed that the gas response to H2 is 29.8 times higher than that to acetic acid whereas the gas response to LPG is 17.8 times higher than that to formic acid. Long-term analyses have also been performed to demonstrate the reproducible nature of the RGO/SnO2 QD based sensor over passing time which shows excellent reproducibility.</P>

Analysis of flexural fatigue failure of concrete made with 100% coarse recycled and natural aggregates

G. Murali,T. Indhumathi,K. Karthikeyan,V.R. Ramkumar 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.3

In this study, the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA) and 100% Coarse Natural Aggregates (NA) were statistically commanded. For this purpose, the experimental fatigue test results of earlier researcher were investigated using two parameter Weibull distribution. The shape and scale parameters of Weibull distribution function was evaluated using seven numerical methods namely, Graphical method (GM), Least-Squares (LS) regression of Y on X, Least-Squares (LS) regression of X on Y, Empherical Method of Lysen (EML), Mean Standard DeviationMethod (MSDM), Energy Pattern FactorMethod (EPFM) andMethod of Moments (MOM). The average of Weibull parameters was used to incorporate survival probability into stress (S)-fatigue life (N) relationships. Based on the Weibull theory, as single and double logarithm fatigue equations for RCA and NA under different survival probability were provided. The results revealed that, by considering 0.9 level survival probability, the theoretical stress level corresponding to a fatigue failure number equal to one million cycle, decreases by 8.77% (calculated using single-logarithm fatigue equation) and 6.62%(calculated using double logarithm fatigue equation) in RCAwhen compared to NAconcrete.

Dip Coated Indium Oxide Films and Their Optical Constants

G. Ramanathan,K. R. Murali 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.5

Metal oxide play very important role in the field of semiconductors. Metals have high reflectivity for the light radiation in the range of infrared and visible range and low reflectivity in the ultraviolet and higher frequency range. Indium oxide thin films were successfully deposited by the sol gel dip coating method. The envelope method was used to evaluate the optical parameters and thickness. Resistivity, mobility and carrier concentration were obtained from Hall measurements. The dispersion energy was obtained from the single effective oscillator model. The energy band gap values estimated from Tauc’s plot and the static refractive index estimated from the Cauchy’s curve fi tting agree well with single effective oscillator model. Optical characteristics of materials are determined by the interaction of the electromagnetic radiation with the valence electron of the materials which lies within or near visible range of electromagnetic spectrum. The other optical parameters like optical conductivity and the dielectric constants were also evaluated.

Degradation of Methylene Blue Dye by TiO2 Nanoparticles Biologically Synthesized Using Leaf Extract of Citrus Aurantifolia

D. Vishali,B. Manikandan,Rita John,K. R. Murali 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.5

A viable alternative approach fir the synthesis of metal and oxide nanmaterials is the low cost nontoxic biosynthesis method. In this study, TiO 2 nanoparticles were synthesized using the lemon leaf extract. Calcining the synthesized powder at 150–450 °C resulted in single phase anatase spherical particles (6–14 nm) of titania and band gap decreased from 3.34 to 3.29 eV. Raman studies exhibit the prominent bands assignable to the anatase phase. MB blue dye degraded by 94% in 180 min (pH-11). The nanoparticles could be reused for eight cycles with a 4% decrease in the degradation efficiency.