Hexagonal ferrites: A review of the synthesis, properties and applications of hexaferrite ceramics

In order to enable optical systems to operate with a high degree of compactness and reliability it is necessary to combine large number of optical functions in small monolithic structures. A development, somewhat reminiscent of that that took place in Integrated Electronics, is now beginning to take place in optics. The initial challenge in this emerging field, known appropriately as "Integrated Optics", is to demonstrate the possibility of performing basic optical functions such as light generation, coupling, modulation, and guiding in Integrated Optical configurations. The talk will review the main theoretical and experimental developments to date in Integrated Optics. Specific topics to be discussed include: Material considerations, guiding mechanisms, modulation, coupling and mode losses. The fabrication and applications of periodic thin film structures will be discussed.

Integrated optics

Electrophoretic deposition (EPD) is attracting increasing attention as an effective technique for the processing of biomaterials, specifically bioactive coatings and biomedical nanostructures. The well-known advantages of EPD for the production of a wide range of microstructures and nanostructures as well as unique and complex material combinations are being exploited, starting from well-dispersed suspensions of biomaterials in particulate form (microsized and nanoscale particles, nanotubes, nanoplatelets). EPD of biological entities such as enzymes, bacteria and cells is also being investigated. The review presents a comprehensive summary and discussion of relevant recent work on EPD describing the specific application of the technique in the processing of several biomaterials, focusing on (i) conventional bioactive (inorganic) coatings, e.g. hydroxyapatite or bioactive glass coatings on orthopaedic implants, and (ii) biomedical nanostructures, including biopolymer–ceramic nanocomposites, carbon nanotube coatings, tissue engineering scaffolds, deposition of proteins and other biological entities for sensors and advanced functional coatings. It is the intention to inform the reader on how EPD has become an important tool in advanced biomaterials processing, as a convenient alternative to conventional methods, and to present the potential of the technique to manipulate and control the deposition of a range of nanomaterials of interest in the biomedical and biotechnology fields.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2010.0156.focus

Electrophoretic deposition of biomaterials

With an ageing population, war, and sports related injuries there is an ever-expanding requirement for hard tissue replacement such as bone. Engineered artificial scaffold biomaterials with appropriate mechanical properties, surface chemistry and surface topography are in a great demand for enhancing cell attachment, cell growth and tissue formation at such defect sites. Most of these engineering techniques are aimed at mimicking the natural organization of the bone tissues and thereby create a conducive environment for bone regeneration. As the interaction between the cells and tissues with biomaterials at the tissue–implant interface is a surface phenomenon, surface properties play a major role in determining both the biological response to implants and the material response to the physiological condition. Hence surface engineering of biomaterials is aimed at modifying the material and biological responses through changes in surface properties while still maintaining the bulk mechanical properties of the implant. Therefore, there has been a great thrust towards development of Ca–P-based surface coatings on various metallic and nonmetallic substrates for load bearing implant applications such as hip joint prosthesis, knee joint prosthesis and dental implants. Typical coating methodologies like ion beam assisted deposition, plasma spray deposition, pulsed laser physical vapor deposition, magnetron sputtering, sol–gel derived coatings, electrodeposition, micro-arc oxidation and laser deposition are extensively studied at laboratory scale. In the present article, attempts are made to give an overview of the basic principles behind the coating techniques as well as advantageous features such as bioactivity and biocompatibility associated with these coatings. A strong emphasis will be given on laser-induced textured and bioactive coatings obtained by the author's research group [A. Kurella, N.B. Dahotre, Journal of Biomedical Applications 20 (2005) 5–50; A. Kurella, N.B. Dahotre, Acta Biomaterialia 2 (2006) 677–688; A. Kurella, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 58 (2006) 64–66; A. Kurella, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 17 (2006) 565–572; P.G. Engleman, A. Kurella, A. Samant, C.A. Blue, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 57 (2005) 46–50; R. Singh, A. Kurella, N.B. Dahotre, Journal of Biomaterials Applications 21 (2006) 46–72; S.R. Paital, N.B. Dahotre, Biomedical Materials 2 (2007) 274–281; S.R. Paital, N.B. Dahotre, 2009, Acta Biomaterialia, doi:10.1016/j.actbio.2009.03.004 ; R. Singh, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 18 (2007) 725–751.]. Since cells are sensitive to topographical features ranging from mesoscale to nanoscale, formation of these features by both pulsed and continuous wave Nd:YAG laser system will be highlighted. This can also be regarded as advancement towards third generation biomaterials which are bioinert, bioactive and which once implanted will stimulate cell adhesion, proliferation and growth at the interface. Further, an overview of various bio-implants and bio-devices and materials used for these kinds of devices, performance factors such as mechanical and corrosion behavior and surface science associated with these materials are also explained. As the present article is aimed at describing the multidisciplinary nature of this exciting field it also provides a common platform to understand this subject in a simple way for students, researchers, teachers and engineers in the fields ranging from medicine, dentistry, biology, materials science, biomedicine, biomechanics to physics.

Calcium phosphate coatings for bio-implant applications: Materials, performance factors, and methodologies

Friction stir welding/processing of metals and alloys: A comprehensive review on microstructural evolution

Evaluation of hot corrosion behaviors of Al2O3-YSZ composite TBC on gradient MCrAlY coatings in the presence of Na2SO4-NaVO3 salt

Improvement of planar perovskite solar cells by using solution processed SnO2/CdS as electron transport layer

Fabrication and characterization of low-cost freeze-gelated chitosan/collagen/hydroxyapatite hydrogel nanocomposite scaffold

Inconel alloys (IN738) have found a wide range of applications in industries such as high-temperature resistance materials. Furthermore, different surface treatments and coatings have been developed for improving the properties of Inconel alloys. In this study, Al 2 O 3 as a ceramic coating was deposited on the surface of the MCrAly as a ground coat layer on Ni-based super alloy, by cathodic plasma electrolytic deposition (CPED). The CPED process was carried out in Ethanol solution of Al (NO 3 ) 3 .9H 2 O (18 g/l). Several samples were obtained in different deposition conditions and analyzed using XRD, SEM and EDS. The XRD analysis shows the presence of Al 2 O 3 and Ni 3 Al phases. Based on thermal expansion, this is in agreement with the composition of the MCrAlY used as bond coat. SEM micrograph showed changes in microstructure of specimen by varying the pH of the solution in different PH of solutions.

Preparation and properties of ceramic Al2O3 coating as TBCs on MCrAly layer applied on Inconel alloy by cathodic plasma electrolytic deposition

Depth grating was inscribed into nonlinear optical (NLO) polymers functionalized with azo chromophores by a simple interferometric apparatus using a continuous wave laser within the absorption bands of NLO polymer. An attenuation of more than 99.5% with a full width at half maximum of ∼1.4nm was obtained for a single grating with a length of ∼1mm. By making use of the Pockels effect, the refractive index of the poled polymer was changed, and consequently the Bragg wavelength and filter transmission shifted. An ∼0.17nm shift in an applied field of about 116V∕μm was obtained in a weakly poled material.

Sirus Javadpour

Papers

Evaluation of hot corrosion behaviors of Al2O3-YSZ composite TBC on gradient MCrAlY coatings in the presence of Na2SO4-NaVO3 salt

Improvement of planar perovskite solar cells by using solution processed SnO2/CdS as electron transport layer

Fabrication and characterization of low-cost freeze-gelated chitosan/collagen/hydroxyapatite hydrogel nanocomposite scaffold

Preparation and properties of ceramic Al2O3 coating as TBCs on MCrAly layer applied on Inconel alloy by cathodic plasma electrolytic deposition

Grating based electro-optic switch with azo nonlinear optical polymers