Metal nanoparticles synthesis: An overview on methods of preparation, advantages and disadvantages, and applications

Diamondlike carbon (DLC) has been studied for many years as a wear-resistant material with low friction coefficient. Its tribological behavior is strongly affected by the tribotesting environment and is controlled by tribochemical effects, which may in turn be dependent on the technique used for the deposition of the films. New variations of DLC films, with various dopings, and new deposition methods have been investigated in recent years. The paper presents an updated review of the tribological properties of DLC and related materials, and discusses the mechanisms suggested for the explanation of the wear and friction behavior of these materials.

Tribology of diamondlike carbon and related materials: an updated review

Ferroelectrics and multiferroics have recently emerged as perspective materials for information technology and data storage applications. The combination of extremely narrow domain wall width and the capability to manipulate polarization by electric field opens the pathway toward ultrahigh (>10 TBit inch−2) storage densities and small (sub-10 nm) feature sizes. The coupling between polarization and chemical and transport properties enables applications in ferroelectric lithography and electroresistive devices. The progress in these applications, as well as fundamental studies of polarization dynamics and the role of defects and disorder on domain nucleation and wall motion, requires the capability to probe these effects on the nanometer scale. In this review, we summarize the recent progress in applications of piezoresponse force microscopy (PFM) for imaging, manipulation and spectroscopy of ferroelectric switching processes. We briefly introduce the principles and relevant instrumental aspects of PFM, with special emphasis on resolution and information limits. The local imaging studies of domain dynamics, including local switching and relaxation accessed through imaging experiments and spectroscopic studies of polarization switching, are discussed in detail. Finally, we review the recent progress on understanding and exploiting photochemical processes on ferroelectric surfaces, the role of surface adsorbates, and imaging and switching in liquids. Beyond classical applications, probing local bias-induced transition dynamics by PFM opens the pathway to studies of the influence of a single defect on electrochemical and solid state processes, thus providing model systems for batteries, fuel cells and supercapacitor applications.

https://iopscience.iop.org/article/10.1088/0034-4885/73/5/056502/pdf

Local polarization dynamics in ferroelectric materials

There has been a resurgence of complex oxides of late owing to their ferroelectric and ferromagnetic properties. Although these properties had been recognized decades ago, the renewed interest stems from modern deposition techniques that can produce high quality materials and attractive proposed device concepts. In addition to their use on their own, the interest is building on the use of these materials in a stack also. Ferroelectrics are dielectric materials that have spontaneous polarization in certain temperature range and show nonlinear polarization–electric field dependence called a hysteresis loop. The outstanding properties of the ferroelectrics are due to non-centro-symmetric crystal structure resulting from slight distortion of the cubic perovskite structure. The ferroelectric materials are ferroelastic also in that a change in shape results in a change in the electric polarization (thus electric field) developed in the crystal and vice versa. Therefore they can be used to transform acoustic wav...

Processing, Structure, Properties, and Applications of PZT Thin Films

Relaxor ferroelectrics were discovered in the 1950s but many of their properties are not understood. In this review, we shall concentrate on materials such as PMN (PbMg1/3Nb2/3O3), which crystallize in the cubic perovskite structure but with the Mg ion, charge 2+, and the Nb ion, charge 5+, randomly distributed over the B site of the perovskite structure. The peak of the dielectric susceptibility for relaxors is much broader in temperature than that of conventional ferroelectrics, while below the maximum of the susceptibility most relaxors remain cubic and show no electric polarization, unlike that observed for conventional ferroelectrics. Because of the large width of the susceptibility, relaxors are often used as capacitors. Recently, there have been many X-ray and neutron scattering studies of relaxors and the results have enabled a more detailed picture to be obtained. An important conclusion is that relaxors can exist in a random field state, as initially proposed by Westphal, Kleemann and Glinchuk, ...

Relaxing with relaxors: a review of relaxor ferroelectrics

The structural changes of porous silicon (PS) samples during oxidation are investigated and analyzed using various microscopy techniques and x-ray diffraction. It is found that the surface roughness of oxidized PS layers increases with the oxidation at 200–400°C and decreased at 600–800°C. At 800°C a partially fused surface is observed. The oxide formed on the wall of porous silicon skeleton is amorphous. The shifts of Si(400) peaks are observed in the x-ray diffraction patterns, which are correlated to the lattice deformation induced by thermal expansion coefficient mismatch between the grown SiO2 and the residual Si, and to the intrinsic stress caused by the Si–O bonds at the Si–SiO2 interface. These explanations are supported by thermomechanical modeling using three-dimensional finite element method.

Thermal oxidation of porous silicon: Study on structure

Dielectric anomalies observed in heterostructures of the epitaxial thin films of $({\mathrm{PbMg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}{)}_{0.68}{\ensuremath{-}(\mathrm{P}\mathrm{b}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}{)}_{0.32},$ fabricated by in situ pulsed laser deposition on ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{CoO}}_{3}/\mathrm{M}\mathrm{g}\mathrm{O}$ (100), and with metal top electrodes, were analyzed. The contribution of the film-electrode interfaces to the properties of the heterostructures was evaluated and the true properties of the films were reconstructed. Deviation from Curie-Weiss behavior, temperature evolution of the local order parameter, the V\"ogel-Fulcher relationship, and temperature evolution of the relaxation time spectrum were found in the films. The relaxor ferroelectric properties of the films were essentially similar to those of the single crystal. Also, it was shown that an apparent ``relaxorlike'' behavior in ferroelectric thin film heterostructures, evidenced only by a broad maximum and frequency dispersion of the dielectric permittivity, can be determined by the film-electrode interface rather than by the relaxor properties of the films.

Dielectric anomalies in epitaxial films of relaxor ferroelectric (PbMg 1/3 Nb 2/3 O 3 ) 0.68 -(PbTiO 3 ) 0.32

Tribological characterization of carbon-nitrogen coatings deposited by using vacuum arc discharge

Polarization state in epitaxial thin films of relaxor ferroelectric PbMg1∕3Nb2∕3O3 (PMN) was experimentally studied at the nanoscale using a piezoresponse force microscopy (PFM). In the absence of a dc bias applied to the PFM tip, no piezoelectric activity could be found on most of the surface of the film. Under a moderate voltage (>1.5–2V), a polar state with a nonzero piezoresponse could be induced. Longer poling resulted in a significant reduction of the initial piezoresponse. After removing the bias field, a long-term relaxation of the piezoelectric signal obeying a Kohlrausch-Williams-Watt dependence was observed.

Relaxation of induced polar state in relaxor PbMg1∕3Nb2∕3O3 thin films studied by piezoresponse force microscopy

The dielectric behavior of pulsed laser deposited ferroelectric (Pb1−xLax)(Zr0.65Ti0.35)O3 films (PLZT x/65/35, x=0–9.75 at. %) has been studied experimentally. Epitaxial stoichiometric PLZT films were formed on a pulsed laser deposited layer of La0.5Sr0.5CoO3 (LSCO) on MgO (100) single-crystal substrates. The dielectric permittivity and loss tangent of the resulting heterostructures were measured in the temperature range of 20–350 °C at a frequency of 100 Hz–1 MHz. A peak around 130–350 °C was observed in the dielectric permittivity versus temperature curves. The peak exhibited a relaxor type behavior. Its position was a nonmonotonic function of the La content and depended on the microstructure of the film. The broadening of the peak of the dielectric permittivity was larger than that in the ceramic PLZT and it also depended on the La content and microstructure of the film. The broadening depended on the temperature and frequency ranges: master curves of the normalized dielectric permittivity versus norm...

J. Levoska

Papers

Thermal oxidation of porous silicon: Study on structure

Dielectric anomalies in epitaxial films of relaxor ferroelectric (PbMg 1/3 Nb 2/3 O 3 ) 0.68 -(PbTiO 3 ) 0.32

Tribological characterization of carbon-nitrogen coatings deposited by using vacuum arc discharge

Relaxation of induced polar state in relaxor PbMg1∕3Nb2∕3O3 thin films studied by piezoresponse force microscopy

Relaxor behavior of pulsed laser deposited ferroelectric (Pb1−xLax)(Zr0.65Ti0.35)O3 films