Piezo Engineering at nano scale
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Recent papers in Piezo Engineering at nano scale
Nowadays, nanoelectroctronic, electro-nanotechnologies environmental friendly products become the roadmap in industry. Hence, nanoscale of reinforcement into lead-free solder becomes more popular rather than the micro size of... more
Nowadays, nanoelectroctronic, electro-nanotechnologies environmental friendly products become the roadmap in industry. Hence, nanoscale of reinforcement into lead-free solder becomes more popular rather than the micro size of reinforcement. In this paper, Cobalt nanoparticles-reinforced Sn-Ag-Cu composite solders were prepared by thoroughly blending 0.75 wt% of cobalt nanoparticles with near eutectic cement tended to suppress the growth of Cu 3Sn intermetallic layer. However, upon addition of Co nanoparticles, the growth of Cu6Sn5 was enhanced. The distribution of the Co nanoparticles was observed by the elemental mapping which was carried out by using electron micro probe analysis (EPMA) and transmission electron microscopy which equipped together with electron-dispersive X-ray spectroscopy (TEM-EDX). There was no Co detected in the Cu3Sn, it only presented in Cu 6Sn5. The interdiffusion coefficient was increased with the ageing temperature. Upon additionof Co nanoparticles, the interdiffusion coefficient for the formation of Cu3Sn intermetallic layer was reduced, but the interdiffusion coefficient for the formation of Cu 6Sn5 layer was increased. The activation energy for the formation of Cu3Sn was also increased with the Co addition.
https://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5702678&tag=1
https://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5702678&tag=1
Piezoresistive polymeric composites were prepared by melt mixing of polypropylene (PP) with expanded graphite (EG) (10-15 wt%) and/or multiwalled carbon nanotubes (MWCNTs) (1-2 wt%). The composites were extruded at a temperature of 185°C,... more
Piezoresistive polymeric composites were prepared by melt mixing of polypropylene (PP) with expanded graphite (EG) (10-15 wt%) and/or multiwalled carbon nanotubes (MWCNTs) (1-2 wt%). The composites were extruded at a temperature of 185°C, by adopting screw speeds in the 2.5-10 rpm range, and fibres with diameters of 0.2, 1.5 and 3 mm, were obtained. An integrated piezoresistive sensor device was obtained by hot pressing the extruded fibres into two sandwiched PP panels.
Structure and morphology of the carbon fillers (EG and MWCNTs) and of the fibres, were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (conventional and conductive SEM) and atomic force microscopy. Piezoelectric properties of fibres and sensor devices were detected through a set up made by a dynamometer, a potentiometer and a digital multimeter. It was shown, that mechanical deformations, due to applied loads, affect remarkably the resistivity of the materials.
An integrated piezoresistive sensor device was obtained by hot pressing the extruded fibres into two sandwiched PP panels.
Structure and morphology of the carbon fillers (EG and MWCNTs) and of the fibres, were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (conventional and conductive SEM) and atomic force microscopy. Piezoelectric properties of fibres and sensor devices were detected through a set up made by a dynamometer, a potentiometer and a digital multimeter. It was shown, that mechanical deformations, due to applied loads, affect remarkably the resistivity of the materials."
Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive fibres Piezoresistive fibers, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive graphene, piezoresistive graphene, Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,), Piezoresistive fibers, few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, extrusion rate, extrusion rate,extrusion rate,
nanostructured hybrid composites have attracted an increasing attention. playing with sizes, aspect-ratio, porosity/surface area, energy-gap and composition of nanodomains, many properties of the final material can be suitably tailored, including the catalytic, the electrochemical, the electric, the mechanical, the optical and the magnetic ones. As for the polymer based composites, fillers made by inorganic compounds (ZnS, SnO2, ZnO), or by carbon based materials (graphene (GR), nanographite (NG), carbon nanofibres (CNFs) or nanotubes (CNTs) are of special interest. In fact, depending on the polymer matrix structure and on the peculiar treatments (i.e. UV-Vis). More in detail, the excellent electrical and mechanical properties of CNTs make them ideal fillers for making conductive polymer composites. However, there is a limit in the CNTs industrial-scale use, due to their production costs. Otherwise the use of other high aspect-ratio carbon-based fillers (GRs, NGs, etc.) alone or in addition to CNTs could be a good way to improve electrical properties with limited costs. Electric conductivity of CNT/polymer composites, a made by the percolation theory. Following this theory, the material exhibits an abrupt insulator-to-conductor transition at a specific concentration of the conductive filler (percolation threshold), due to the formation of a continuous conductive network. It has been reported, that conductive networks have been recently obtained along segregated paths into the bulk or at the surface of CNT/polymer composites, by the laser-stimulated percolation of CNTs. Moreover it is known, that the simultaneous use of different types of conductors (i.e. 1D, 2D and 3D) can help in reducing the electric percolation threshold, as consequence of synergic effects.
Further interest in CNT/polymer composites comes from their piezoresistive capability, which is strongly dependent on loading type (tension, compression), loading history and then on the matrix mechanical behaviour. This property has been observed in reinforced polymer matrices or wearable textiles [20, 21] as well as in many composites, including carbon nanofibres (CNFs)/PP [22], MWCNT/polyimides (PI), MWCNT/rubbers [23-25] and in hybrid CNTs/EG sheets [26].
Along these themes, MWCNTs/PP, PP/EG and MWCNTs/EG/PP fibres have been investigated with the aim to develop stress-strain sensors to be integrated in composite materials. Polypropilene (PP - HIFAX EP3080G, Lyondell Basell, MFI = 11 g/10 min), Expanded Graphite (EG-TIMREX C-THERM001, TimcalMultiwall Carbon Nanotubes (MWCNTs - Nanocyl NC7000) were obtained from (5% wt) MWCNTs - PP masterbatches. Polymer fibres and carbon-based composite fibres were prepared according to the following steps: i) melt blending of the raw materials (PP, EG and/or MWCNTs masterbatch) in a mixer with horizontal counter rotating screws (HAAKE PolyLab QC) to obtain homogeneous pellets, ii) extrusion of the composite in a single screw extruder (HAAKE PolyLab QC). Some efforts were made to find more suitable conditions, afterwards the following was selected: a) temperature values: 185°C; b) EG percentages: 5 wt%, 10 wt% and 15 wt%; MWCNTs percentages: 1 wt% and 2 wt%; c) fibres diameters: 0.2 mm, 1.5 mm and 3 mm; d) screw speeds in the 2,5-10 rpm range. A sensor device was fabricated via hot pressing (165°C, 100 bar for 5 minutes) of two piezoresistive fibres between two sandwiched PP fabrics 8x4x0.3 cm in size (Propex Curve C100A). For this, fibres 1.5 mm and 3 mm in diameters were chosen, as they can be more easily embedded inside polymer panels or in any devises. (see Supporting Information for details). The morphology of the samples has been investigated by means of: i) Zeiss Evo50 SEM equipped with an energy dispersive X-ray detector (EDAX), ii) AFM (Park Systems XE-100). Conductivity profiles on cross-sections of the extruded samples were obtained by a secondary electron (SE) detector of a Zeiss Evo50 SEM operating at low acceleration voltage (0.5 KeV). More in details, edge effects on the samples due to secondary-electrons were reduced by working on “flat” sections of the material obtained by means of the ultramicrotome. Specifically, samples, embedded in epoxy resin to fill voids, were then cross sectioned using a regular glass knife. Microtome slices 0.1-1 µm in thickness, representing the cross-section area along the sample length, were obtained. The cross-section slices, contacted on the back sides with conductive Ag paste, were then imaged by low voltage SEM and by conductive AFM as well. Optical images of cross-section slices were also acquired by Leica DFC290 HD digital camera. X-Ray Diffraction patterns on samples have been collected with a diffractometer (PANalytical PW3050/60 X'Pert PRO MPD) by using a Ni-filtered Cu anode and working with reflectance Bragg–Brentano geometry for EG and MWCNTs fillers and in the capillary configuration for fibres. Electrical resistance of the samples was measured by using a digital multimeter (Keithley 2420) via two points probe method, whose probes were contacted with Ag conducting electrodes (1 cm apart) to ensure good electrical contacts as well a dynamometer (Instron 5544), a potentiometer and a digital multimeter (Keithley 2700E). The dynamometer, by enabling the application of loads from 0 N to 2000 N, allows to make either traction, flexion and compression tests. Upon several cycles of mechanical deformation (that is traction of 1 mm, 2 mm and 3 mm of the wires, or flexion of 0.5 mm, 1 mm, 1.5 mm of the panel) the stress-strain curves and the piezoresistive properties of samples were obtained. The morphology of EG and of MWCNTs fillers is shown. High aspect ratio EG flakes, ranging in 5-30 μm interval and with domains 25-30 nm in thickness, corresponding to about 60-90 graphene layers, show an irregularly layered structure A dense network of entangled MWCNTs, 15 μm in lengths and 1520 nm in diameters is shown Due to the high length and flexibility of the MWCNTs nanofilaments, which gives rise to highly interconnected bundles, the percolation threshold can be achieved at low loadings. XRD patterns of MWCNTs and of EG flakes, are compared. In this figure, the narrow (002) graphite peak, together the weak and broad feature due to MWCNTs, the last one shifting towards smaller diffraction angles, are observed. From this, it results that MWCNTs show a much lower crystallinity, as compared to that of EG flakes
Structure and morphology of the carbon fillers (EG and MWCNTs) and of the fibres, were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (conventional and conductive SEM) and atomic force microscopy. Piezoelectric properties of fibres and sensor devices were detected through a set up made by a dynamometer, a potentiometer and a digital multimeter. It was shown, that mechanical deformations, due to applied loads, affect remarkably the resistivity of the materials.
An integrated piezoresistive sensor device was obtained by hot pressing the extruded fibres into two sandwiched PP panels.
Structure and morphology of the carbon fillers (EG and MWCNTs) and of the fibres, were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (conventional and conductive SEM) and atomic force microscopy. Piezoelectric properties of fibres and sensor devices were detected through a set up made by a dynamometer, a potentiometer and a digital multimeter. It was shown, that mechanical deformations, due to applied loads, affect remarkably the resistivity of the materials."
Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive fibres Piezoresistive fibers, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive graphene, piezoresistive graphene, Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,), Piezoresistive fibers, few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, Piezoresistive fibres, piezoresistive wires, multiwalled carbon nanotubes (MWCNTs,) few-layer graphene, expanded graphite, metal-free conductive wires, synergistic effect, low potential SEM, conductive mapping, maps of conductivity, atomic force microscopy (AFM), Scanning Probe Force Microscopy (SPFM), piezoresistivity, electrical measurements, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, carbon-based polymer nanocomposites, extrusion rate, extrusion rate,extrusion rate,
nanostructured hybrid composites have attracted an increasing attention. playing with sizes, aspect-ratio, porosity/surface area, energy-gap and composition of nanodomains, many properties of the final material can be suitably tailored, including the catalytic, the electrochemical, the electric, the mechanical, the optical and the magnetic ones. As for the polymer based composites, fillers made by inorganic compounds (ZnS, SnO2, ZnO), or by carbon based materials (graphene (GR), nanographite (NG), carbon nanofibres (CNFs) or nanotubes (CNTs) are of special interest. In fact, depending on the polymer matrix structure and on the peculiar treatments (i.e. UV-Vis). More in detail, the excellent electrical and mechanical properties of CNTs make them ideal fillers for making conductive polymer composites. However, there is a limit in the CNTs industrial-scale use, due to their production costs. Otherwise the use of other high aspect-ratio carbon-based fillers (GRs, NGs, etc.) alone or in addition to CNTs could be a good way to improve electrical properties with limited costs. Electric conductivity of CNT/polymer composites, a made by the percolation theory. Following this theory, the material exhibits an abrupt insulator-to-conductor transition at a specific concentration of the conductive filler (percolation threshold), due to the formation of a continuous conductive network. It has been reported, that conductive networks have been recently obtained along segregated paths into the bulk or at the surface of CNT/polymer composites, by the laser-stimulated percolation of CNTs. Moreover it is known, that the simultaneous use of different types of conductors (i.e. 1D, 2D and 3D) can help in reducing the electric percolation threshold, as consequence of synergic effects.
Further interest in CNT/polymer composites comes from their piezoresistive capability, which is strongly dependent on loading type (tension, compression), loading history and then on the matrix mechanical behaviour. This property has been observed in reinforced polymer matrices or wearable textiles [20, 21] as well as in many composites, including carbon nanofibres (CNFs)/PP [22], MWCNT/polyimides (PI), MWCNT/rubbers [23-25] and in hybrid CNTs/EG sheets [26].
Along these themes, MWCNTs/PP, PP/EG and MWCNTs/EG/PP fibres have been investigated with the aim to develop stress-strain sensors to be integrated in composite materials. Polypropilene (PP - HIFAX EP3080G, Lyondell Basell, MFI = 11 g/10 min), Expanded Graphite (EG-TIMREX C-THERM001, TimcalMultiwall Carbon Nanotubes (MWCNTs - Nanocyl NC7000) were obtained from (5% wt) MWCNTs - PP masterbatches. Polymer fibres and carbon-based composite fibres were prepared according to the following steps: i) melt blending of the raw materials (PP, EG and/or MWCNTs masterbatch) in a mixer with horizontal counter rotating screws (HAAKE PolyLab QC) to obtain homogeneous pellets, ii) extrusion of the composite in a single screw extruder (HAAKE PolyLab QC). Some efforts were made to find more suitable conditions, afterwards the following was selected: a) temperature values: 185°C; b) EG percentages: 5 wt%, 10 wt% and 15 wt%; MWCNTs percentages: 1 wt% and 2 wt%; c) fibres diameters: 0.2 mm, 1.5 mm and 3 mm; d) screw speeds in the 2,5-10 rpm range. A sensor device was fabricated via hot pressing (165°C, 100 bar for 5 minutes) of two piezoresistive fibres between two sandwiched PP fabrics 8x4x0.3 cm in size (Propex Curve C100A). For this, fibres 1.5 mm and 3 mm in diameters were chosen, as they can be more easily embedded inside polymer panels or in any devises. (see Supporting Information for details). The morphology of the samples has been investigated by means of: i) Zeiss Evo50 SEM equipped with an energy dispersive X-ray detector (EDAX), ii) AFM (Park Systems XE-100). Conductivity profiles on cross-sections of the extruded samples were obtained by a secondary electron (SE) detector of a Zeiss Evo50 SEM operating at low acceleration voltage (0.5 KeV). More in details, edge effects on the samples due to secondary-electrons were reduced by working on “flat” sections of the material obtained by means of the ultramicrotome. Specifically, samples, embedded in epoxy resin to fill voids, were then cross sectioned using a regular glass knife. Microtome slices 0.1-1 µm in thickness, representing the cross-section area along the sample length, were obtained. The cross-section slices, contacted on the back sides with conductive Ag paste, were then imaged by low voltage SEM and by conductive AFM as well. Optical images of cross-section slices were also acquired by Leica DFC290 HD digital camera. X-Ray Diffraction patterns on samples have been collected with a diffractometer (PANalytical PW3050/60 X'Pert PRO MPD) by using a Ni-filtered Cu anode and working with reflectance Bragg–Brentano geometry for EG and MWCNTs fillers and in the capillary configuration for fibres. Electrical resistance of the samples was measured by using a digital multimeter (Keithley 2420) via two points probe method, whose probes were contacted with Ag conducting electrodes (1 cm apart) to ensure good electrical contacts as well a dynamometer (Instron 5544), a potentiometer and a digital multimeter (Keithley 2700E). The dynamometer, by enabling the application of loads from 0 N to 2000 N, allows to make either traction, flexion and compression tests. Upon several cycles of mechanical deformation (that is traction of 1 mm, 2 mm and 3 mm of the wires, or flexion of 0.5 mm, 1 mm, 1.5 mm of the panel) the stress-strain curves and the piezoresistive properties of samples were obtained. The morphology of EG and of MWCNTs fillers is shown. High aspect ratio EG flakes, ranging in 5-30 μm interval and with domains 25-30 nm in thickness, corresponding to about 60-90 graphene layers, show an irregularly layered structure A dense network of entangled MWCNTs, 15 μm in lengths and 1520 nm in diameters is shown Due to the high length and flexibility of the MWCNTs nanofilaments, which gives rise to highly interconnected bundles, the percolation threshold can be achieved at low loadings. XRD patterns of MWCNTs and of EG flakes, are compared. In this figure, the narrow (002) graphite peak, together the weak and broad feature due to MWCNTs, the last one shifting towards smaller diffraction angles, are observed. From this, it results that MWCNTs show a much lower crystallinity, as compared to that of EG flakes
In this study, boron doped calcium stabilized bismuth cobalt oxide nanocrystalline ceramic powders were successfully prepared from aqueous boric acid containing calciumbismuth-cobalt acetate/poly(vinyl alcohol) hybrid precursor polymer... more
In this study, boron doped calcium stabilized bismuth cobalt oxide nanocrystalline ceramic powders were successfully prepared from aqueous boric acid containing calciumbismuth-cobalt acetate/poly(vinyl alcohol) hybrid precursor polymer solutions. Then, obtained ceramic powders were characterized via FT-IR, XRD, and SEM techniques.
According to X-ray results, fcc and bcc phases coexist in the samples of the nanocrystalline ceramic powders. fcc peaks became sharper and bcc peak decreased with increasing boron content. Structural parameters for face centered cubic structure were calculated using Scherrer equation. Moreover, dislocation densities and microstrain values were calculated for the nanocrystalline powder samples.
According to X-ray results, fcc and bcc phases coexist in the samples of the nanocrystalline ceramic powders. fcc peaks became sharper and bcc peak decreased with increasing boron content. Structural parameters for face centered cubic structure were calculated using Scherrer equation. Moreover, dislocation densities and microstrain values were calculated for the nanocrystalline powder samples.
Relaxor ferroelectric single-crystal materials PMN-PT and PZN-PT are currently of interest to the scientific community due to their enhanced properties and possible role as next-generation piezoelectric transducers in applications such as... more
Relaxor ferroelectric single-crystal materials PMN-PT and PZN-PT are currently of interest to the scientific community due to their enhanced properties and possible role as next-generation piezoelectric transducers in applications such as sonar and medical ultrasound. One key phenomenon affecting both the properties and the mechanical integrity of these materials is the ferroelectric domain structure within the material. In this work we examine the morphology and behavior of domain structures in PMN-29%PT. In order to do this we first present details of the construction and testing of a working piezo-response force microscope (PFM), and then use the PFM to verify a new domain observation technique called “relief polishing”. Relief polishing is shown to reveal surface domains in the same manner as acid etching, preserving domain details as small as 0.5um.
Using these two techniques, we then determine that cutting and polishing strongly affect the surface and subsurface ferroelectric domain structures in PMN-29%PT. Specifically, we show that saw cutting can create characteristic striated domain structures as deep as 130um within a sample, while straight polishing creates a characteristic domain structure known as the “fingerprint” pattern to a depth proportional to the size of the polishing grit, on the order of 0--12um for grits as large as 15um. We hypothesize that most samples contain these “skin effect” domain structures. In consequence, it is suggested that researchers presenting experimental results on domain structures should report the physical treatment history of the samples along with the experimental data.
Using these two techniques, we then determine that cutting and polishing strongly affect the surface and subsurface ferroelectric domain structures in PMN-29%PT. Specifically, we show that saw cutting can create characteristic striated domain structures as deep as 130um within a sample, while straight polishing creates a characteristic domain structure known as the “fingerprint” pattern to a depth proportional to the size of the polishing grit, on the order of 0--12um for grits as large as 15um. We hypothesize that most samples contain these “skin effect” domain structures. In consequence, it is suggested that researchers presenting experimental results on domain structures should report the physical treatment history of the samples along with the experimental data.
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