P. Szperlich

Determination of energy band gap of nanocrystalline SbSI using diffuse reflectance spectroscopy

Twelve methods of determining energy band gap (E(g)) of semiconductors using diffuse reflectance spectroscopy have been applied in investigations of sonochemically produced antimony sulfoiodide (SbSI) consisting of nanowires. It has been proved that the best method of determining E(g) is based on simultaneous fitting of many mechanisms of absorption to the spectral dependence of Kubelka-Munk function evaluated from the diffuse reflectance data. It allows determining the values of indirect forbidden E(g), the Urbach energy, and the constant absorption/scattering of the examined semiconductor.

Ferroelectric properties of ultrasonochemically prepared SbSI ethanogel.

This article presents for the first time the electrical properties of sonochemically synthesised, high-surface-area SbSI ethanogel made up of large quantity nanowires with lateral dimensions of about 10-50 nm and lengths reaching up to several micrometers. The composition, morphology, dimensions, microstructures, and optical energy gap of the new form of SbSI were characterized. This material is a semiconducting ferroelectric as in the case of bulk SbSI crystals. The maximum of dielectric constant epsilon=1.6x10(4) is observed at Tc=292(1) K. The activation energies in temperature dependences of electric conductivity of SbSI ethanogel are different for ferroelectric and paraelectric phases during heating and cooling of the sample.

Sonochemical preparation of SbS1−xSexI nanowires

A sonochemical method for direct preparation of nanowires of SbS(1-x)Se(x)I solid solution has been established. The SbS(1-x)Se(x)I gel was synthesized using elemental Sb, S, Se and I in the presence of ethanol under ultrasonic irradiation (35kHz, 2W/cm(2)) at 50 degrees C for 2h. The product was characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray analysis, selected area electron diffraction, and optical diffuse reflection spectroscopy. The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 10-50nm and lengths reaching up to several micrometers and single-crystalline in nature. The increase of molar composition of Se affects linear decrease of the indirect forbidden optical energy gap as well as the distance between (121) planes of the SbS(1-x)Se(x)I nanowires.

Sonochemical growth of antimony sulfoiodide in multiwalled carbon nanotube.

This paper presents for the first time the nanocrystalline, semiconducting ferroelectrics antimony sulfoiodide (SbSI) grown in multiwalled carbon nanotubes (CNTs). It was prepared sonochemically using elemental Sb, S and I in the presence of methanol under ultrasonic irradiation (35kHz, 2.6W/cm(2)) at 323K for 3h. The CNTs filled with SbSI were characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, high-resolution transmission electron microscopy, selected area electron diffraction, and optical diffuse reflection spectroscopy. These investigations exhibit that the SbSI filling the CNTs is single crystalline in nature and in the form of nanowires. It has indirect forbidden energy band gap E(gIf)=1.871(1)eV.

Sonochemical preparation of SbSeI gel

A novel sonochemical method for direct preparation of nanocrystalline antimony selenoiodide (SbSeI) has been established. The SbSeI gel was synthesized using elemental Sb, Se, and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2W/cm(2)) at 50 degrees C for 2h. The product was characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 20-50 nm and lengths reaching up to several micrometers and single crystalline in nature.

Optical and photoelectrical properties of SbSI

The optical transmittance and reflectance of SbSI single crystals had been measured for photon energies from 1.5 to 2.6 eV in temperature range from 77 K to 343 K. The experimental data had been evaluated to determine anisotropic, spectral and temperature dependences of real part of refractive index and absorption coefficient of SbSI. The temperature dependence of the energy gap had been evaluated from the spectral characteristics of absorption of light with electric field parallel and perpendicular to the c axis of the SbSI. The phase transition had been determined from the temperature dependences of optical parameters as well as from the temperature dependence of the energy gap. The photoconductivity of the investigated crystals had been measured as a function of photon energy, illumination intensity and temperature.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Influence of the solvent on ultrasonically produced SbSI nanowires

The influence of the substitution of methanol in place of ethanol during the ultrasonic production of antimony sulfoiodide (SbSI) nanowires is presented. The new technology is faster and more efficient at temperatures greater than 314 K. The products were characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), optical diffuse reflection spectroscopy (DRS) and IR spectroscopy. The coexistence of Pna2(1) (ferroelectric) and Pnam (paraelectric) phases at 298 K was observed in the SbSI nanowires produced in methanol. The methanol decomposes during the sonication or due to the adsorption process on SbSI nanowires.

Sonochemical preparation of antimony subiodide

The substantiated isolation of the antimony subiodide (Sb(3)I) is presented for the first time. It has been prepared using elemental Sb and I in ethanol under ultrasonic irradiation at 323 K. Its composition was characterized using X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDAX). The scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) investigations exhibit that the samples are made up of large quantity of nanoparticles with diameters smaller than 20 nm and single crystalline in nature. The interplanar spacings in Sb(3)I that have been determined using powder X-ray diffraction (XRD), selected area electron diffraction (SAED) and HRTEM are very similar. Surprisingly, the registered XRD patterns are identical to the one reported earlier for Sb(4)O(5)I(2).

Using of sonochemically prepared SbSI for electrospun nanofibers

A novel polymeric, polyacrylonitrile (PAN) nanofibers containing ferroelectric and semiconducting antimony sulfoiodide (SbSI) have been made by electrospinning. SbSI nanowires, used as the filler, have been prepared sonochemically from antimony sulphide (Sb2S3) and antimony tri-iodide (SbI3) for the first time. Nanocrystalline SbSI has been fabricated in ethanol under ultrasonic irradiation (20kHz, 565W/cm2) at 323K within 2h. The products have been characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, high-resolution transmission electron microscopy, selected area electron diffraction and optical diffuse reflection as well as transmission spectroscopy. The good quality of the nanocrystals and their dispersion in the nanofibers volume is important because this material is attractive for nanogenerators due to its ferroelectric and piezoelectric properties. The amplitude of the voltage pulse, generated under shock pressure of 3.0MPa, has reached 180V in the prototype PAN/SbSI piezoelectric nanogenerator. The peak output voltage of about 0.2V was measured in bending/releasing conditions with the deformation frequency of 1Hz.

Addition of a small amount of multiwalled carbon nanotubes and flaked graphene to epoxy resin

The paper presents an attempt to evaluate the technically important properties of epoxy resin modified alternatively with multi-walled carbon nanotubes and flaked graphene. It is a presentation of experimental results supported by extensive referring to the professional literature. The nano-components were added in the amount which was economically justified and provides hope for a significant improvement of some of the properties of pure resin. Flowability, glass wettability, curing process and gelation time and curing shrinkage of the resin were evaluated. After the resin was cured, inner and outer hardness, thermal conductivity, flexural strength and impact resistance were measured. Glass fibre-reinforced laminates were also prepared with use of the nano-modified resin. The mechanical properties, interlaminar shear strength and flexural strength of the laminates, were evaluated for them. The obtained results showed either no effect or only technically slight effect of the nano-modification on the evaluated properties. Noticeable improvement in interlaminar shear strength and impact resistance for laminates containing resin filled with graphene can predestine this kind of modification as a method of increasing the delamination resistance of laminates.