G. Padeletti - Academia.edu (original) (raw)

Papers by G. Padeletti

MRS Proceedings, 1992

ABSTRACTAir and UV/ozone exposure have been used for growing sacrificial thin oxide layers on HCl... more ABSTRACTAir and UV/ozone exposure have been used for growing sacrificial thin oxide layers on HCl etched GaAs (100) surfaces. Passive films have been then desorbed by vacuum thermal cleaning in order to prepare suitable surfaces for molecular beam epitaxy (MBE) growth. Structure, thickness and chemical composition of passive films and desorbed surfaces have been studied by ellipsometry and angle dependent X-ray photoelectron spectroscopy (ADXPS). The results have indicated an increased chemical reactivity of both arsenic and gallium during UV/ozone exposure, compared to that of air exposure, that produces Ga (III) oxide enriched films. Furthermore, XPS results have also shown that the thermal desorption behavior are different. In particular, GaAs (100) after short term UV/ozone exposure and oxide film desorption, has an As/Ga surface atomic ratio close to unity and a level of carbon contamination below the XPS detectability. On the contrary, air exposed surfaces never have a stoichi...

Surface and Interface Analysis, 1994

The iron ore deposit of Kerry (north‐western Syria) has been sampled; by means of the combined us... more The iron ore deposit of Kerry (north‐western Syria) has been sampled; by means of the combined use of small‐area x‐ray photoelectron spectroscopy (SA‐XPS), small‐area x‐ray induced Auger electron spectroscopy (SA‐XAES), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA), the smelting process of the most iron‐rich ore has been studied under a CO atmosphere up to 1570 K. Attention has been focused on the chemical aspects involvéd during the reduction of the iron ore and on the chemical composition of the non‐metallic compounds, i.e. the slags, that result from the smelting process. Furthermore, this information has been compared with that obtained from early iron metallurgy slags and artefacts found in north‐western Syria in order to locate the geographical source of the iron ore exploited during the early Iron Age in this region.

Journal of Physics: Conference Series, 2008

Cellulose, 2013

A simple, environmentally benign and energy efficient process for fabricating single faced superh... more A simple, environmentally benign and energy efficient process for fabricating single faced superhydrophilic/hydrophobic cotton fabrics by controlling surface texture and chemistry at the nano/ microscale is reported here. Stable ultra-hydrophobic surfaces with advancing and receding water droplet contact angles in excess of 146°as well as extreme superhydrophilic surfaces are obtained. Hydrophobic water-repellent cotton fabrics were obtained following plasma treatment through diamond-like carbon (DLC) coating by plasma enhanced chemical vapour deposition. The influence of changing different precursor's plasma pre-treatments such as H 2 , Ar or O 2 on the properties of DLC coatings is also evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and analysed in terms of contact angle measurements. Because of the DLC coating, the coated fabric showed to endure its superhydrophobic character even after 12 months.

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1998

Single wavelength ellipsometry was used to monitor the growth of Si(1−x)Gex alloys obtained by ul... more Single wavelength ellipsometry was used to monitor the growth of Si(1−x)Gex alloys obtained by ultrahigh vacuum chemical vapor deposition (CVD) at 570 °C on Si and to evaluate the effect of sample irradiation by KrF excimer laser pulses at an energy density above the threshold for surface melting. Laser irradiation was performed during or after the CVD growth. When the Si(1−x)Gex alloys were grown without laser assistance, the recorded ellipsometric curves indicated the presence of pronounced surface roughness, which was confirmed by atomic force microscopy analysis. On line ellipsometry during multiple pulse postgrowth irradiations showed a sudden increase of the ellipsometric angles Ψ and Δ corresponding to the first laser pulse. This behavior attested to the smoothing of the surface microroughness induced by the melt–recrystallization cycle. The excimer laser assisted CVD growth of Si(1−x)Gex alloy layers was also followed. By changing the ratio between the thermal growth rate an...

Surface and Interface Analysis, 1994

Sensors and Actuators B: Chemical, 2005

Smart (Nano) materials with biosensing functions posses enormous potential in the development of ... more Smart (Nano) materials with biosensing functions posses enormous potential in the development of new generation stable biosensors, chemical sensors, and actuators. Recently, there is a considerable interest in using TiO 2 nanostructured materials as a film-forming material since they have high surface area, optical transparency, high bio-compatibility, and relatively good conductivity. In this work, TiO 2 oxides were used as nanoporous electrodes to study the electron transfer mechanisms of H 2 O 2 , and many interesting biological molecules, as 3,4-dihydroxyphenylacetic acid (DOPAC), ascorbic acid, guanine, l-tyrosine, acetaminophen, and ␤-NADH, in order to assemble a new generation of chemical sensors and biosensors. A kinetic study was also reported in this paper, which demonstrated high performances towards electrocatalytic processes, obtained at nanostructured TiO 2 -modified electrodes.

Sensor Letters, 2010

ABSTRACT The paper reports a simple one-step procedure to synthesize Single Walled Carbon Nanotub... more ABSTRACT The paper reports a simple one-step procedure to synthesize Single Walled Carbon Nanotubes (SWCNTs) decorated with gold nanoparticles (AuNps). The method involves the reaction between HAuCl4 aqueous solution and sodium citrate, used as reducing-dispersing agent, in an aqueous dispersion of SWCNTs. An accurate purification of commercial SWCNTs has been achieved, before use, according to the literature methods. Using sodium citrate as reducing agent, 10 nm in size gold nanoparticles can be obtained and an interaction between SWCNTs and AuNps could be observed by UV-Vis measurements. Gold nanoparticles size and nanocomposite morphology have been studied by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) observations. SWCNTs/AuNps nanocomposite has been used to modify conventional Glassy Carbon electrode (GCE), by dip coating technique. The SWCNTs-AuNps modified electrode was used for an electrochemical study of neurotransmitters, such as dopamine and catechol by cyclic voltammetry.

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997

... Y.Uchiyama and K. Tanaka, Wear, 58,223 (1980). CM Pooley and D. Tarbor, Proc. R. SOC. London ... more ... Y.Uchiyama and K. Tanaka, Wear, 58,223 (1980). CM Pooley and D. Tarbor, Proc. R. SOC. London A. m, 251 (1972). P. Maltese, F. Campoli, A. d'Alessandro, V. Foglietti, A. Galbato, A. Galloppa, G. Rafaelli and M. Wnek, Ferroelectrics. m, 153 (1996). ...

Materials Science in Semiconductor Processing, 2002

ABSTRACT In the last years, zirconium titanate thin films ZrxTi1−xO4 (ZT) turned out to have very... more ABSTRACT In the last years, zirconium titanate thin films ZrxTi1−xO4 (ZT) turned out to have very interesting dielectric properties, which suggests a use in microwave integrated systems. In this work, the synthesis and characterization of ZrxTi1−xO4 (ZT) thin films grown via MOCVD are described, giving emphasis to the study of their structural, chemical and physical properties, with relation to the different process parameters applied. All samples analysed by XRD, AFM, SEM and EDS, show a great dependence on substrate temperature and reactor pressure on the kinetic of growth as well as on the chemical, crystallographic, morphological and microstructural features.

Materials Science and Engineering: C, 2007

Diamond-like carbon (DLC) films have been largely studied for their excellent mechanical properti... more Diamond-like carbon (DLC) films have been largely studied for their excellent mechanical properties and their high potential in many industrial applications. Although DLC films have poorer physical properties than diamond films, their lower thermal stability and high internal residual stress can be avoided with the incorporation of other elements, such as silicon, nitrogen and some metals.

Materials Science and Engineering: C, 2006

The functionalisation of solid electrodes with thin films of biocompatible materials revealed ver... more The functionalisation of solid electrodes with thin films of biocompatible materials revealed very attractive for the development of biosensors on miniaturized platforms, since this configuration could provide a rapid translation of the biological processes occurring on the surface to electronic outputs. In this study, the realization of functionalised TiO 2 thin films on Si substrates for the immobilization of several enzymes and biological molecules is reported. Deposition parameters were found to affect the chemical and microstructural features of the films, which influenced the protein immobilization. Glucose oxidase and horseradish peroxidase immobilized onto TiO 2 -based nanostructured surfaces exhibited a pair of well-defined and quasi-reversible voltammetric peaks. The electron exchange between the enzyme and the electrodes was greatly enhanced in the TiO 2 nanostructured environment. The electrocatalytic activity of HRP and GOD embedded in TiO 2 electrodes toward H 2 O 2 and glucose, respectively, may have a potential perspective in the fabrication of third-generation biosensors based on direct electrochemistry of enzymes. D 2005 Published by Elsevier B.V.

Materials Science and Engineering: B, 2005

Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices. The basi... more Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices. The basic compound, ZrTiO 4 , has long been known to have a low temperature coefficient of the dielectric permittivity, while the compound Zr 0.8 Sn 0.2 TiO 4 has optimal properties at microwave frequencies (ε r ∼ 38, T cc = 0 ppm • C −1 and tan δ ≈ 1 × 10 −4 ). Thin films of these materials appear as very promising dielectric layers for the integration in MIM and MIS structures. In this work we describe the pulsed laser deposition of zirconium titanate based materials on Pt/TiO 2 /SiO 2 /(1 0 0)Si substrates. The influence of the different processing parameters on film orientation, microstructure and chemical composition is discussed. Surface roughness, chemical composition and microstructural features of the films were optimised to achieve the most suitable dielectric properties. A laser fluence J ≈ 4.5 J/cm 2 , a substrate temperature T s ≈ 550-600 • C and 5 × 10 −2 mbar of oxygen atmosphere are required to achieve highly oriented and crystalline films. The departure from these optima deposition conditions causes variations on the film composition, microstructure and residual strains. The permittivity of the films is affected by the presence of foreign crystalline phases. Crystalline and single phase thin films having a dense columnar structure is a fundamental requirement to achieve low loss dielectric films.

Materials Science and Engineering: B, 2004

In this work the synthesis and characterisation of Zr x Ti 1−x O 2 (ZT) grown via a non conventio... more In this work the synthesis and characterisation of Zr x Ti 1−x O 2 (ZT) grown via a non conventional MOCVD apparatus on both silicon and platinum coated substrates are described. The samples have been chemically, morphologically and structurally characterised by AFM, XRD, SEM + FEG and XPS. Also high and low frequencies electrical characterisation has been performed to evaluate a possible application of such materials as high-k dielectrics.

Langmuir, 2013

A stable and improved control of the wettability of textiles was obtained by using a coating of d... more A stable and improved control of the wettability of textiles was obtained by using a coating of diamond like carbon (DLC) films on cotton by PECVD. By controlling different plasma pretreatments of argon, oxygen, and hydrogen on the cotton fibers' surface, we have shown that the pretreatments had a significant impact on wettability behavior resulting from an induced nanoscale roughness combined with an incorporation of selected functional groups. Upon subsequent deposition of diamond like carbon (DLC) films, the cotton fibers yield to a highly controlled chemical stability and hydrophobic state and could be used for self-cleaning applications. By controlling the nature of the plasma pretreatment we have shown that the oxygen plasma pretreatment was more effective than the argon and hydrogen for the superhydrophilic/ ultra hydrophobic properties. The chemical and morphological changes of the cotton fibers under different treatments were characterized using X-ray photoelectron and Raman spectroscopy, AFM, and water contact angle measurements. The mechanism underlying the water-repellent properties of the cotton fibers provides a new and innovative pathway into the development of a range of advanced self-cleaning textiles.

Journal of the European Ceramic Society, 2005

Ferroelectric thin films have been investigated intensely by many researchers over the past decad... more Ferroelectric thin films have been investigated intensely by many researchers over the past decade, but some important phenomena that influence the electrical properties have been overlooked. This work addresses the lead enrichment, which is observed on the surface of lead zirconate titanate films.

Journal of Structural Chemistry, 1989

X~ and multiple-scattering methods have been used with atomic photoionization amplitudes (MSAA) t... more X~ and multiple-scattering methods have been used with atomic photoionization amplitudes (MSAA) to calculate photoionization cross sections and asymmetry parameters for valency molecular levels in fluoromethanes. The partial cross sections show a nonmonotonic behavior near threshold, which shows that there are quasistationary states in the continuum. Photoabsorption measurements agree best with the MSAA approximation.

Journal of Nanoparticle Research, 2009

Gold colloidal nanoparticles (AuNps), synthesized by gold chloride hydrate (HAuCl 4 ) chemical re... more Gold colloidal nanoparticles (AuNps), synthesized by gold chloride hydrate (HAuCl 4 ) chemical reduction were used to realize a modified glassy carbon electrode (GCE). Different shapes and sizes were observed, varying the molar ratio of HAuCl 4 and polyvinylpyrrolidone (PVP). The electrochemical behaviour of different neurotransmitters and molecules of biological interest (dopamine, caffeic acid, catechol, uric acid, epinephrine and serotonin) were investigated by cyclic voltammetry (CV) at the AuNps modified GCE and a dependence of the electrochemical response on the size and the shape of the particles was observed. The electrochemical responses were stable during time with a generic decreasing of the peak current after 10 days ranging from 5-10% for catechol, uric acid and serotonine to 10-15% for the other analytes. A study on the electrochemical interface of modified electrodes was also carried out by means of electrochemical impedance spectroscopy (EIS).

Journal of Electroceramics, 2000

Reliability issues have hampered the adoption of ferroelectric thin films by the microelectronics... more Reliability issues have hampered the adoption of ferroelectric thin films by the microelectronics industry. One of these is imprint, an important problem affecting the performance of ferroelectric non-volatile memories. This paper presents the effects of the low temperature pyrolysis step on the chemical and physical properties of SrBi 2 Ta 2 O 9 films. A comparison of the hysteretic properties and composition profiles shows that control of the oxidising conditions during pyrolysis is critical to the dielectric properties. Data from this work and from the literature have been used to construct a model that explains the origin of surface depletion and segregation, self poling and as-grown imprint in ferroelectric films.

MRS Proceedings, 1992

ABSTRACTAir and UV/ozone exposure have been used for growing sacrificial thin oxide layers on HCl... more ABSTRACTAir and UV/ozone exposure have been used for growing sacrificial thin oxide layers on HCl etched GaAs (100) surfaces. Passive films have been then desorbed by vacuum thermal cleaning in order to prepare suitable surfaces for molecular beam epitaxy (MBE) growth. Structure, thickness and chemical composition of passive films and desorbed surfaces have been studied by ellipsometry and angle dependent X-ray photoelectron spectroscopy (ADXPS). The results have indicated an increased chemical reactivity of both arsenic and gallium during UV/ozone exposure, compared to that of air exposure, that produces Ga (III) oxide enriched films. Furthermore, XPS results have also shown that the thermal desorption behavior are different. In particular, GaAs (100) after short term UV/ozone exposure and oxide film desorption, has an As/Ga surface atomic ratio close to unity and a level of carbon contamination below the XPS detectability. On the contrary, air exposed surfaces never have a stoichi...

Surface and Interface Analysis, 1994

The iron ore deposit of Kerry (north‐western Syria) has been sampled; by means of the combined us... more The iron ore deposit of Kerry (north‐western Syria) has been sampled; by means of the combined use of small‐area x‐ray photoelectron spectroscopy (SA‐XPS), small‐area x‐ray induced Auger electron spectroscopy (SA‐XAES), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA), the smelting process of the most iron‐rich ore has been studied under a CO atmosphere up to 1570 K. Attention has been focused on the chemical aspects involvéd during the reduction of the iron ore and on the chemical composition of the non‐metallic compounds, i.e. the slags, that result from the smelting process. Furthermore, this information has been compared with that obtained from early iron metallurgy slags and artefacts found in north‐western Syria in order to locate the geographical source of the iron ore exploited during the early Iron Age in this region.

Journal of Physics: Conference Series, 2008

Cellulose, 2013

A simple, environmentally benign and energy efficient process for fabricating single faced superh... more A simple, environmentally benign and energy efficient process for fabricating single faced superhydrophilic/hydrophobic cotton fabrics by controlling surface texture and chemistry at the nano/ microscale is reported here. Stable ultra-hydrophobic surfaces with advancing and receding water droplet contact angles in excess of 146°as well as extreme superhydrophilic surfaces are obtained. Hydrophobic water-repellent cotton fabrics were obtained following plasma treatment through diamond-like carbon (DLC) coating by plasma enhanced chemical vapour deposition. The influence of changing different precursor's plasma pre-treatments such as H 2 , Ar or O 2 on the properties of DLC coatings is also evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and analysed in terms of contact angle measurements. Because of the DLC coating, the coated fabric showed to endure its superhydrophobic character even after 12 months.

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1998

Single wavelength ellipsometry was used to monitor the growth of Si(1−x)Gex alloys obtained by ul... more Single wavelength ellipsometry was used to monitor the growth of Si(1−x)Gex alloys obtained by ultrahigh vacuum chemical vapor deposition (CVD) at 570 °C on Si and to evaluate the effect of sample irradiation by KrF excimer laser pulses at an energy density above the threshold for surface melting. Laser irradiation was performed during or after the CVD growth. When the Si(1−x)Gex alloys were grown without laser assistance, the recorded ellipsometric curves indicated the presence of pronounced surface roughness, which was confirmed by atomic force microscopy analysis. On line ellipsometry during multiple pulse postgrowth irradiations showed a sudden increase of the ellipsometric angles Ψ and Δ corresponding to the first laser pulse. This behavior attested to the smoothing of the surface microroughness induced by the melt–recrystallization cycle. The excimer laser assisted CVD growth of Si(1−x)Gex alloy layers was also followed. By changing the ratio between the thermal growth rate an...

Surface and Interface Analysis, 1994

Sensors and Actuators B: Chemical, 2005

Smart (Nano) materials with biosensing functions posses enormous potential in the development of ... more Smart (Nano) materials with biosensing functions posses enormous potential in the development of new generation stable biosensors, chemical sensors, and actuators. Recently, there is a considerable interest in using TiO 2 nanostructured materials as a film-forming material since they have high surface area, optical transparency, high bio-compatibility, and relatively good conductivity. In this work, TiO 2 oxides were used as nanoporous electrodes to study the electron transfer mechanisms of H 2 O 2 , and many interesting biological molecules, as 3,4-dihydroxyphenylacetic acid (DOPAC), ascorbic acid, guanine, l-tyrosine, acetaminophen, and ␤-NADH, in order to assemble a new generation of chemical sensors and biosensors. A kinetic study was also reported in this paper, which demonstrated high performances towards electrocatalytic processes, obtained at nanostructured TiO 2 -modified electrodes.

Sensor Letters, 2010

ABSTRACT The paper reports a simple one-step procedure to synthesize Single Walled Carbon Nanotub... more ABSTRACT The paper reports a simple one-step procedure to synthesize Single Walled Carbon Nanotubes (SWCNTs) decorated with gold nanoparticles (AuNps). The method involves the reaction between HAuCl4 aqueous solution and sodium citrate, used as reducing-dispersing agent, in an aqueous dispersion of SWCNTs. An accurate purification of commercial SWCNTs has been achieved, before use, according to the literature methods. Using sodium citrate as reducing agent, 10 nm in size gold nanoparticles can be obtained and an interaction between SWCNTs and AuNps could be observed by UV-Vis measurements. Gold nanoparticles size and nanocomposite morphology have been studied by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) observations. SWCNTs/AuNps nanocomposite has been used to modify conventional Glassy Carbon electrode (GCE), by dip coating technique. The SWCNTs-AuNps modified electrode was used for an electrochemical study of neurotransmitters, such as dopamine and catechol by cyclic voltammetry.

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997

... Y.Uchiyama and K. Tanaka, Wear, 58,223 (1980). CM Pooley and D. Tarbor, Proc. R. SOC. London ... more ... Y.Uchiyama and K. Tanaka, Wear, 58,223 (1980). CM Pooley and D. Tarbor, Proc. R. SOC. London A. m, 251 (1972). P. Maltese, F. Campoli, A. d'Alessandro, V. Foglietti, A. Galbato, A. Galloppa, G. Rafaelli and M. Wnek, Ferroelectrics. m, 153 (1996). ...

Materials Science in Semiconductor Processing, 2002

ABSTRACT In the last years, zirconium titanate thin films ZrxTi1−xO4 (ZT) turned out to have very... more ABSTRACT In the last years, zirconium titanate thin films ZrxTi1−xO4 (ZT) turned out to have very interesting dielectric properties, which suggests a use in microwave integrated systems. In this work, the synthesis and characterization of ZrxTi1−xO4 (ZT) thin films grown via MOCVD are described, giving emphasis to the study of their structural, chemical and physical properties, with relation to the different process parameters applied. All samples analysed by XRD, AFM, SEM and EDS, show a great dependence on substrate temperature and reactor pressure on the kinetic of growth as well as on the chemical, crystallographic, morphological and microstructural features.

Materials Science and Engineering: C, 2007

Diamond-like carbon (DLC) films have been largely studied for their excellent mechanical properti... more Diamond-like carbon (DLC) films have been largely studied for their excellent mechanical properties and their high potential in many industrial applications. Although DLC films have poorer physical properties than diamond films, their lower thermal stability and high internal residual stress can be avoided with the incorporation of other elements, such as silicon, nitrogen and some metals.

Materials Science and Engineering: C, 2006

The functionalisation of solid electrodes with thin films of biocompatible materials revealed ver... more The functionalisation of solid electrodes with thin films of biocompatible materials revealed very attractive for the development of biosensors on miniaturized platforms, since this configuration could provide a rapid translation of the biological processes occurring on the surface to electronic outputs. In this study, the realization of functionalised TiO 2 thin films on Si substrates for the immobilization of several enzymes and biological molecules is reported. Deposition parameters were found to affect the chemical and microstructural features of the films, which influenced the protein immobilization. Glucose oxidase and horseradish peroxidase immobilized onto TiO 2 -based nanostructured surfaces exhibited a pair of well-defined and quasi-reversible voltammetric peaks. The electron exchange between the enzyme and the electrodes was greatly enhanced in the TiO 2 nanostructured environment. The electrocatalytic activity of HRP and GOD embedded in TiO 2 electrodes toward H 2 O 2 and glucose, respectively, may have a potential perspective in the fabrication of third-generation biosensors based on direct electrochemistry of enzymes. D 2005 Published by Elsevier B.V.

Materials Science and Engineering: B, 2005

Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices. The basi... more Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices. The basic compound, ZrTiO 4 , has long been known to have a low temperature coefficient of the dielectric permittivity, while the compound Zr 0.8 Sn 0.2 TiO 4 has optimal properties at microwave frequencies (ε r ∼ 38, T cc = 0 ppm • C −1 and tan δ ≈ 1 × 10 −4 ). Thin films of these materials appear as very promising dielectric layers for the integration in MIM and MIS structures. In this work we describe the pulsed laser deposition of zirconium titanate based materials on Pt/TiO 2 /SiO 2 /(1 0 0)Si substrates. The influence of the different processing parameters on film orientation, microstructure and chemical composition is discussed. Surface roughness, chemical composition and microstructural features of the films were optimised to achieve the most suitable dielectric properties. A laser fluence J ≈ 4.5 J/cm 2 , a substrate temperature T s ≈ 550-600 • C and 5 × 10 −2 mbar of oxygen atmosphere are required to achieve highly oriented and crystalline films. The departure from these optima deposition conditions causes variations on the film composition, microstructure and residual strains. The permittivity of the films is affected by the presence of foreign crystalline phases. Crystalline and single phase thin films having a dense columnar structure is a fundamental requirement to achieve low loss dielectric films.

Materials Science and Engineering: B, 2004

In this work the synthesis and characterisation of Zr x Ti 1−x O 2 (ZT) grown via a non conventio... more In this work the synthesis and characterisation of Zr x Ti 1−x O 2 (ZT) grown via a non conventional MOCVD apparatus on both silicon and platinum coated substrates are described. The samples have been chemically, morphologically and structurally characterised by AFM, XRD, SEM + FEG and XPS. Also high and low frequencies electrical characterisation has been performed to evaluate a possible application of such materials as high-k dielectrics.

Langmuir, 2013

A stable and improved control of the wettability of textiles was obtained by using a coating of d... more A stable and improved control of the wettability of textiles was obtained by using a coating of diamond like carbon (DLC) films on cotton by PECVD. By controlling different plasma pretreatments of argon, oxygen, and hydrogen on the cotton fibers' surface, we have shown that the pretreatments had a significant impact on wettability behavior resulting from an induced nanoscale roughness combined with an incorporation of selected functional groups. Upon subsequent deposition of diamond like carbon (DLC) films, the cotton fibers yield to a highly controlled chemical stability and hydrophobic state and could be used for self-cleaning applications. By controlling the nature of the plasma pretreatment we have shown that the oxygen plasma pretreatment was more effective than the argon and hydrogen for the superhydrophilic/ ultra hydrophobic properties. The chemical and morphological changes of the cotton fibers under different treatments were characterized using X-ray photoelectron and Raman spectroscopy, AFM, and water contact angle measurements. The mechanism underlying the water-repellent properties of the cotton fibers provides a new and innovative pathway into the development of a range of advanced self-cleaning textiles.

Journal of the European Ceramic Society, 2005

Ferroelectric thin films have been investigated intensely by many researchers over the past decad... more Ferroelectric thin films have been investigated intensely by many researchers over the past decade, but some important phenomena that influence the electrical properties have been overlooked. This work addresses the lead enrichment, which is observed on the surface of lead zirconate titanate films.

Journal of Structural Chemistry, 1989

X~ and multiple-scattering methods have been used with atomic photoionization amplitudes (MSAA) t... more X~ and multiple-scattering methods have been used with atomic photoionization amplitudes (MSAA) to calculate photoionization cross sections and asymmetry parameters for valency molecular levels in fluoromethanes. The partial cross sections show a nonmonotonic behavior near threshold, which shows that there are quasistationary states in the continuum. Photoabsorption measurements agree best with the MSAA approximation.

Journal of Nanoparticle Research, 2009

Gold colloidal nanoparticles (AuNps), synthesized by gold chloride hydrate (HAuCl 4 ) chemical re... more Gold colloidal nanoparticles (AuNps), synthesized by gold chloride hydrate (HAuCl 4 ) chemical reduction were used to realize a modified glassy carbon electrode (GCE). Different shapes and sizes were observed, varying the molar ratio of HAuCl 4 and polyvinylpyrrolidone (PVP). The electrochemical behaviour of different neurotransmitters and molecules of biological interest (dopamine, caffeic acid, catechol, uric acid, epinephrine and serotonin) were investigated by cyclic voltammetry (CV) at the AuNps modified GCE and a dependence of the electrochemical response on the size and the shape of the particles was observed. The electrochemical responses were stable during time with a generic decreasing of the peak current after 10 days ranging from 5-10% for catechol, uric acid and serotonine to 10-15% for the other analytes. A study on the electrochemical interface of modified electrodes was also carried out by means of electrochemical impedance spectroscopy (EIS).

Journal of Electroceramics, 2000

Reliability issues have hampered the adoption of ferroelectric thin films by the microelectronics... more Reliability issues have hampered the adoption of ferroelectric thin films by the microelectronics industry. One of these is imprint, an important problem affecting the performance of ferroelectric non-volatile memories. This paper presents the effects of the low temperature pyrolysis step on the chemical and physical properties of SrBi 2 Ta 2 O 9 films. A comparison of the hysteretic properties and composition profiles shows that control of the oxidising conditions during pyrolysis is critical to the dielectric properties. Data from this work and from the literature have been used to construct a model that explains the origin of surface depletion and segregation, self poling and as-grown imprint in ferroelectric films.