Dinesh Patidar

Structural, optical and electrical properties of CdZnS thin films

The thin films of Cd1-x Zn x S (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) have been prepared by the vacuum evaporation method using a mechanically alloyed mixture of CdS and ZnS. The structural, optical and electrical properties have been investigated through the X-ray diffractometer, spectrophotometer and Keithley electrometer. The X-ray diffraction patterns of these films show that films are polycrystalline in nature having preferential orientation along the (002) plane. In the absorption spectra of these films, absorption edge shifts towards lower wavelength with the increase of Zn concentration. The energy band gap has been determined using these spectra. It is found that the energy band gap increases with increasing Zn concentration. The electrical conductivity of so prepared thin films has been determined using a I–V characteristic curve for these films. The result indicates that the electrical conductivity decreases with increasing Zn content and increases with temperature. An effort has also been made to obtain activation energy of these films which increases with increasing Zn concentration in CdS.

Optical properties of CdS sintered film

Chemical method has been used to prepare cadmium sulphide by using cadmium, hydrochloric acid and H2S. The reflection spectra of covered and uncovered sintered films of CdS have been recorded by ‘Hitachi spectrophotometer’ over the wavelength range 300–700 nm. The energy band gaps of these films have been calculated from reflection spectra. It is found that the energy band gap of both films is same as 2.41 eV. It is indicated that energy band gap of these films does not change. This value of band gap is in good agreement with the value reported by other workers. The measurement of photocurrent has also been carried out using Keithley High Resistance meter/ Electrometer. This film shows the high photosensitivity and high photocurrent decay. Thus so obtained films are suitable for fabrication of photo detectors and solar cells.

Glass transition temperature and thermal stability of ZnS/PMMA nanocomposites

In this article, ZnS nanoparticles were prepared by wet chemical precipitation method using zinc sulphate (ZnSO4), sodium sulphide (Na2S) and thio-glycerol. These nanoparticles were characterized through X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The solution-based processing was used to prepare Poly methyl methacrylate (PMMA) nanocomposites with different weight percents (0, 2, 4, 6 and 8) of ZnS nanoparticles. The obtained ZnS/PMMA nanocomposites were characterized through XRD, scanning electron microscope and TEM measurements. The dynamic mechanical analyzer was used to obtain the storage modulus and glass transition temperature (T g) of the nanocomposites. The apparent activation energy of the glass transition region was also determined using the Vogel–Fulcher–Tammann equation. The results indicated that the thermal stability of ZnS/PMMA nanocomposites was higher than PMMA and 6 wt. % of ZnS nanoparticles in PMMA matrix showed the maximum activation energy, which indicated that this nanocomposite had higher thermal stability than other composites.

Electrical Properties of CdS/Polyaniline Heterojunction

Conducting polyaniline (PANI) has been synthesized using Sol-gel technique with chemical oxidation process. Chemically prepared cadmium sulphide has been printed on pellet of conducting polyaniline using screen-printing technique. I-V characteristics of conducting polyaniline and CdS printed conducting polyaniline have been recorded at room temperature using Keithley Electrometer. The results indicated that I-V of conducting polyaniline shows non-ohmic behaviour and I-V characteristic of CdS printed PANI, a CdS/ PANI heterojunction, shows the rectification effect and confirms that a diode can be fabricated by using simple technique.

Storage modulus and glass transition behaviour of CdS/PMMA nanocomposites

The storage modulus and glass transition temperature (T g) of CdS/PMMA nanocomposites have been evaluated as a function of concentration of CdS nanoparticles. CdS particles have been synthesised via chemical route using cadmium acetate, thiourea and dimethylformamide. The solution-based processing has been used to prepare PMMA composites with CdS nanoparticles at different filler concentration. Size and shape of CdS nanoparticles in PMMA have been determined with the help of small angle X-ray scattering and transmission electron microscope measurements. Dynamical mechanical analysis was carried out on the CdS/PMMA nanocomposites to study storage modulus and tan δ. It is observed that CdS nanoparticles enhance the storage modulus and T g for composites. The storage modulus and T g show the maximum value of 6 wt.% of CdS nanoparticles embedded PMMA composite. The results indicate that the 6 wt.% of CdS nanoparticles in PMMA matrix provides more stability to the composite over the other composites.

Monodispersed ZnO Nanoparticles and Their Use in Heterojunction Solar Cell

Monodispersed ZnO nanoparticles have been synthesised in ethylene glycol medium using zinc acetate and sodium hydroxide at room temperature through ultrasonic treatment. The monodispersed ZnO nanoparticles were characterized by XRD, TEM, SEM, and optical spectroscopy. The results indicate that ZnO shows the hexagonal wurtzite structure having 8 nm average particle size with the band gap of 3.93 eV. ZnO nanoparticles blended with P3HT show the improvement in the interchains and intrachains ordering as compared to pure P3HT. The power conversion efficiency of P3HT/ZnO solar cell is found to be 0.88%, which is comparable with the result obtained by other researchers.

Effect of nano CdS dispersion on thermal conductivity of PS/PVC and PS/PMMA polymeric blend nanocomposites

The effect of dispersion of CdS nano-filler particles in respective PS/PVC and PS/PMMA polymer blend matrices on the effective thermal conductivity has been studied through Hot Disk Thermal Constant Analyzer based on transient plane source (TPS) technique. The thick film samples have been prepared by dispersing nano-filler particles of CdS (6 wt%) in respective PS/PVC and PS/PMMA binary blend matrices. The nanocomposite nature of prepared samples ascertained through small angle X-ray scattering (SAXS) as well as transmission electron microscopy (TEM) measurements. It is observed that at room temperature nano CdS dispersed polymeric blend samples offer higher effective thermal conductivity.

Investigation of temperature-dependent mechanical properties of CdS/PMMA nanocomposites

Nanoparticles of chemically synthesized CdS with the different weight percents (0, 2, 4, 6, and 8 wt%) have been embedded into poly(methyl methacrylate) (PMMA) by solution casting method. The obtained CdS/PMMA nanocomposites are characterized through small-angle X-ray scattering and transmission electron microscope measurements. Temperature-dependent mechanical properties of CdS/PMMA nanocomposites have been studied at different temperatures (30, 50, 70, and 90°C) using stress–strain behavior through dynamic mechanical analyzer. Results indicate that CdS nanoparticles are uniformly distributed at low weight percent, and agglomeration of particles is observed at high weight percent and all the quantities obtained from stress–strain relations, i.e., Young’s modulus, tensile strength, and fracture energy increase up to 6 wt.% of CdS nanoparticles and then decrease for further increase of weight percent of CdS nanoparticles.

Investigation of Thermo‐mechanical Properties of PMMA

The present paper reports the investigation of thermo‐mechanical properties of Poly(methyl methacrylate) or PMMA. The film of PMMA has been prepared by solution casting method taking tetrahydrofuran (THF) as solvent. So prepared film has been used for the measurement of mechanical properties such as storage modulus, loss modulus, Tan δ and stress strain relation employing Dynamic Mechanical Analyzer (DMA). The glass transition temperature of pure PMMA sample has also been obtained in order to determine its physical state and its influence in other properties such as toughness and stiffness. An effort has also been made to study the storage modulus (E’), loss modulus (E”) and Tan δ in a temperature range from 32°C to 140°C by DMA. It has been observed that storage modulus decreases with temperature due to thermal expansion of films. On the other hand Tan δ increases up to glass transition temperature beyond which it shows decreasing trend towards melting. Glass transition temperature (Tg) is found to be 82...

Electrical conduction mechanism in GeSeSb chalcogenide glasses

Electrical conductivity of chalcogenide glassy system Ge30−xSe70Sbx (x = 10, 15, 20 and 25) prepared by melt quenching has been determined at different temperatures in bulk through the I–V characteristic curves. It is quite evident from results that Poole–Frenkel conduction mechanisms hold good for conduction in these glasses in a given temperature range. The variation in electrical conductivity with composition was attributed to the Se–Sb bond concentration in the Se–Ge–Sb system. Results indicated that Ge5Se70Sb25 showed the minimum resistance. In view of this the composition Ge5Se70Sb25 may be coined as ‘critical composition’ in the proposed series. Also the activation energies of conduction of these glassy alloys have been calculated in higher and lower temperature range using the Arrhenius equation.