Tin sulphide (Sn,S,) thin films have been prepared on Pyrex glass substrates by the spray pyrolysis technique using tin chloride (SnCl,) and n, ndimethylthiourea (CH3NHCSNHCH3) as starting materials. The depositions were carried out in the range of substrate temperatures from 320 to 450 "C. From x-ray diffraction measurements and SEM micrographs, it is found that the values of x and y, which determine the type of deposited compound, depend on the substrate temperature. At lower substrate temperatures (320-360 "C), mixed phases such as SnpSs and y-SnzS3 are present. At intermediate substrate temperatures (370-390 "C), the SnS phase Is predominant. For substrate temperatures higher than 490 "C the deposited material is mainly Sn02. The optical reflectance and transmitfance of SnS were used in an iterative method to obtain the refractive index (n) and the extinction coefficient (k). These values of n and k were used to calculate the absorption coefficient (a) and the bandgap (&), giving the result EG = 1.27 eV. Measurements of the dark conductance (a) as a function of T were made and an activation energy of 0.54 eV was determined from the slope of a plot of In U versus 1 IT.

Ternary compound Sn II Sn IV S 3 thin films have been prepared on Pyrex glass substrates by the spray pyrolysis process using tin chloride (SnCl 2 ) and n, n-dimethylthiourea as starting materials. The depositions were carried out at a substrate temperature of 320 • C. The identification of the Sn 2 S 3 phase was achieved by means of x-ray diffraction measurements. The optical reflectance and transmittance of the prepared films were used to obtain the variation of the refractive index and the extinction coefficient as a function of the wavelength. These calculated values were used to find the absorption coefficient and the optical bandgap and gave E g = 1.16 eV. From measurements of the conductance as a function of T −1 , a dark activation energy was determined with a value of 1.02 eV.

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Europium doped Al2O3 photoluminescent coatings have been prepared by an ultrasonic spray pyrolysis process, using a solution of 0.05M of AlCl3 · 6H2O as starting material and EuCl3 as doping. These films were deposited on Pyrex glass substrates at atmospheric pressure using purified air as a carrier gas. All films were amorphous in structure. The photoluminescence spectra were measured at room temperature as a function of substrate temperature and doping concentration. For an excitation wavelength of 395 nm, all the photoluminescent spectra show bands located at 587, 600, 612 and 648 nm, characteristics of the trivalent europium ion. We observed a concentration quenching of the photoluminescence at values of activator concentration above 10 at% in the starting solution.

This Letter presents the fabrication of optical fiber refractometers based on indium tin oxide (ITO) coatings deposited by sputtering with response in the visible region. ITO thin films have been sputtered by means of a rotating mechanism that enables the fabrication of smooth and homogeneous coatings onto the optical fiber core. The ITO coating acts as a resonance supporting layer. This permits us to couple light from the waveguide to the ITO-coating/external medium region at specific wavelength ranges. The device is sensitive to external medium refractive index, which allows its utilization as a refractometer. The sensitivity is dependent on the coating thickness, ranging from 523.21 to 1221 nm/refractive index unit in the explored sensors. The sensor development process is time effective compared to other techniques such as dip coating or layer-by-layer self-assembly, which is interesting in terms of mass production.