| 1. |
- Vomiero, Alberto, et al.
(författare)
-
Application of ion beam analysis to the selective sublimation processing of thin films for gas sensing
- 2006
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 249:1-2 SPEC. ISS., s. 302-305
-
Tidskriftsartikel (refereegranskat)abstract
- Ion beam analysis was successfully applied to a novel technique, named selective sublimation process (SSP), for deposition of nanostructured gas-sensing films through reactive sputtering. The method consists of the co-deposition of a mixed oxide, one of which has a relatively low sublimation temperature. Annealing at suitable temperature causes the sublimation of the most volatile compound, leaving a layer with adjustable composition. The appropriate choice of thermal treatments and the consequent tailoring of the composition play a crucial role in the determination of the microstructural properties. We developed a model based on diffusion equations that provides a useful guide to control the deposition and processing parameters and we applied the model on the systems TiO2-WO3 and TiO2-MoO3. Rutherford backscattering (RBS) was demonstrated to be effective for the characterization of the diffusion and sublimation processes during SSP. Experimental results fully agree with theoretical prediction, and allowed the calculation of all the parameters involved in SSP. © 2006 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Vomiero, Alberto, et al.
(författare)
-
Composition and resistivity changes of reactively sputtered W-Si-N thin films under vacuum annealing
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:3, s. 1-3
-
Tidskriftsartikel (refereegranskat)abstract
- W-Si-N layers about 200 nm thick with different nitrogen content were reactively sputtered from a W5 Si3 target on oxidized silicon substrates. The thermal stability of the films' composition and resistivity was studied with ion beam analysis and four-point probe measurements. Upon vacuum annealing from 600 to 980 °C for 1.5 h, a sample with an initial 56 at. % of nitrogen gradually loses nitrogen down to 36%. This composition lies close to the W- Si3 N4 tie line. Concurrently, the room temperature resistivity decreases from 4.7 to about 2 mΩ cm. The composition changes only a little for a sample whose initial composition is near the W- Si3 N4 tie line and the resistivity changes significantly less than for the nitrogen-rich film. Interpretations are discussed. © 2006 American Institute of Physics.
|
|
| 3. |
- Comini, E., et al.
(författare)
-
Influence of iron addition on ethanol and CO sensing properties of tin oxide prepared with the RGTO technique
- 2006
-
Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 115:2, s. 561-566
-
Tidskriftsartikel (refereegranskat)abstract
- Effects of iron introduction in RGTO prepared tin oxide gas sensors are presented. The films were deposited by sputtering from a tin target with the introduction of an adjustable number or iron inset. Iron content was varied in the range 0-7%. The thin films are investigated by the volt-amperometric technique for electrical and gas-sensing properties. The layers are capable of sensing CO and ethanol, no evidence of surface poisoning is detected, and recovery of the resistance is complete. The response of the sensors is stable and reproducible at all operating temperatures tested (200-500 °C) during 3 months of operation. © 2005 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Guidi, V., et al.
(författare)
-
Characterization of crystals for steering of protons through channelling in hadronic accelerators
- 2006
-
Ingår i: EPAC 2006. - Edinburgh : European Physical Society Accelerator Group (EPS-AG). - 9290832797 ; , s. 1523-1525
-
Konferensbidrag (refereegranskat)abstract
- Channeling of relativistic particles through a crystal may be useful for many applications in accelerators, and particularly for collimation in hadronic colliders. Efficiency proved to be dependent on the state of the crystal surface and hence on the method used for preparation. We investigated the morphology and structure of the surface of the samples that have been used in accelerators with high efficiency. We found that crystal fabrication by only mechanical methods (dicing, lapping, and others) leads to a superficial damaged layer, which is correlated to performance limitation in accelerators. A planar chemical etching was studied and applied in order to remove the superficial damaged layer. RBS channeling analysis with low-energy protons and 4He + highlighted better crystal perfection at surface, as a result of the etching. A protocol for preparation and characterization of crystal for channelling has been developed, which may be of interest for reliable operation with crystals in accelerators.
|
|
| 5. |
- Quaranta, A., et al.
(författare)
-
Analysis of art objects by means of ion beam induced luminescence
- 2006
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 41:1, s. 543-546
-
Tidskriftsartikel (refereegranskat)abstract
- The impact of energetic ions on solid samples gives rise to the emission of visible light owing to the electronic excitation of intrinsic defects or extrinsic impurities. The intensity and position of the emission features provide information on the nature of the luminescence centers and on their chemical environments. This makes ion beam induced luminescence (IBIL) a useful complement to other ion beam analyses, like PIXE, in the cultural heritage field in characterizing the composition and the provenience of art objects. In the present paper, IBIL measurements have been performed on inorganic pigments for underlying the complementary role played by IBIL in the analysis of artistic works. Some blue and red pigment has been presented as case study. © 2006 IOP Publishing Ltd.
|
|
