Annealing of laser patterned PMMA coated with gold and gallium

Poly(methyl methacrylate) (PMMA) surface was patterned by laser scanning and Ga and Au layers of different thicknesses were sputtered onto modified polymer surface. The metal/PMMA structures were annealed at 160 °C for 1 h and the changes in the surface morphology were examined by AFM and STM techniques. It was found that sufficiently thick and continuous metal coverage protect the underlying pattern structure.     

Porphyrin migration and aggregation in a poly(methylmethacrylate) matrix

The aging of thin polymer films is interesting for the development of nonlinear optical media. In this study, the optical properties of porphyrin‐doped poly(methylmethacrylate) (PMMA) films are investigated before and after annealing. Both absorption and luminescence spectroscopies were used to characterize the changes that occurred during the thermal treatment. The surface and bulk characteristics of the doped films were also measured using atomic force microscopy, X‐ray‐induced photoelectron spectra, and DSC. We found that the aging of the thin polymer films led the porphyrin molecules to diffuse in the direction of the polymer surface. This led to the random formation of porphyrin aggregates on the surface, followed by absorption band shift and little luminescence quenching. These results suggest that porphyrin‐doped PMMA films could be used as long‐term stable active optical materials. POLYM. COMPOS., 35:665–670, 2014. © 2013 Society of Plastics Engineers     

The properties of free-standing epoxy polymer multi-mode optical waveguides

The paper reports on the fabrication and characterisation of free-standing multimode optical epoxy polymer waveguides consisting of a core made of EpoCore and EpoClad polymer cladding and cover protection layers. The 50 × 50 μm² rectangular waveguides are intended for short-reach optical interconnection and optimised for an operating wavelength of 850 nm. The waveguides of the proposed shapes were fabricated by a standard photolithography process on a silicon substrate provided with a Poly(vinyl alcohol) thin layer. The free-standing structure was then achieved by peeling the deposited EpoClad/EpoCore/EpoClad structures of that substrate. The optical scattering losses of the created planar waveguides, measured by the fibre probe technique at 632.8 and 964 nm, were 0.30 dB cm⁻¹ at 632.8 nm and 0.17 dB cm⁻¹ at 964 nm. Propagation optical loss measurements for rectangular waveguides were performed by the cut-back method and the best samples had optical losses below 0.55 dB cm⁻¹ at 850 and 1310 nm.

     

Inorganic–organic hybrid polymer optical planar waveguides for micro-opto-electro-mechanical systems (MOEMS)

The paper reports on the fabrication and characterisation of three types of OrmoClear, OrmoClear^®HI01 XP and OrmoClear^®FX hybrid polymer optical planar waveguides deposited on glass substrate. The design of the optical planar waveguides was done using a modified dispersion equation; waveguiding properties and refractive indices were measured by dark mode spectroscopy at five wavelengths: 473, 632.8, 964, 1311 and 1552 nm; the measurement showed that the OrmoClear HI01 XP had a higher refractive index value (1.582 at 1552 nm) than the OrmoClear polymer (1.537 at 1552 nm). Optical scattering losses of the waveguides were measured by the fibre scanning method; the measurement showed that the average values of the optical losses of the OrmoClear HI01 XP (0.48 dB/cm) were lower than those of the OrmoClear FX (0.64 dB/cm) and the OrmoClear polymer (0.76 dB/cm) for the measured wavelengths 964, 1311 and 1552 nm. Our measurement showed that the OrmoClear HI01 XP would allow the implementation of the MOEMS structures with higher integration density also in the case of such commonly used substrates as e.g. silica-on-silicon and that our approach would make possible to use low-cost and feasibly elaborated hybrid-polymer-based structures instead of the widely used semiconductor approach.

     

Rapid pressure-less and spark plasma sintering of (Ba0.85Ca0.15Zr0.1T0.9)O3 lead-free piezoelectric ceramics

This work shows for the first time the possibility to sinter BCZT powder compacts by rapid heating rates within one hour of sintering, while achieving good piezoelectric properties. The sintering was performed by rapid (heating rates 100 and 200 °C/min) pressure-less sintering (PLS) at 1550 °C/5-60 min and by SPS sintering (100 °C/min, 1450 °C/5?60 min and 1500 °C/15?45 min). The rapid PLS samples reached a relative density up to 94 % and grain sizes of 17–36 μm acquiring d₃₃ up to 414 pC/N. Although the SPS samples reached full density at 1450 °C, their piezoelectric properties worsened due to smaller grains (10?15 μm) as well as formation of cracks at dwell times > 30 min. At elevated SPS temperature of 1500 °C/30 min, the d₃₃ increased to 360 pC/N sustaining full density. Even higher increase in d₃₃ (424 pC/N) of SPS samples was achieved by post-rapid PLS at 1550 °C/60 min resulting from further expansion in grain size.     

Optical properties of PMMA doped with erbium(III) and ytterbium(III) complexes

In this article, we report the fabrication and optical/spectroscopic properties of polymethylmethacrylate (PMMA) doped with rare earth (RE) (Er³⁺ and Er³⁺/Yb³⁺) ions. Infrared spectroscopy revealed only very weak O? H stretching vibration peaks in the samples, which is important if satisfactory photoluminescence is to be observed at 1530 nm. Measurement of transmission spectra in the wavelength ranges from 300 to 700 nm for Er³⁺‐doped samples and from 900 to 1050 nm for Yb³⁺‐doped samples enabled us to observe the ⁴G_11/2 (377 nm) and ²H_11/2 (519 nm) transmission bands typical for Er³⁺‐doped samples, as well as the ²F_5/2 (975 nm) band typical for Yb³⁺‐doped samples. Under excitation at 980 nm, at room temperature, the characteristic Er³⁺ emission at 1530 nm was also observed with improving trend when the higher RE concentrations were applied. The results indicate that the PMMA reveals very low tendency to the RE clustering, which together with low cost and easy fabrication make it a material with a great potential in the active photonics devices. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

The manipulation of carbon nanotubes on a polymer surface using a laser beam

Controlled noninvasive manipulation of porphyrin-doped single-walled carbon nanotubes (SWCNT) by laser beam is described. SWCNT/porphyrin complexes have been deposited on a polymer surface and irradiated by a scanning beam of laser light with the wavelength of 405 nm. Laser energy was absorbed by the porphyrin and converted into heat through an energy transfer within the complexes. This led to periodical deformation of the initially flat polymer surface. As a result of the surface deformation the SWCNTs or SWCNT bundle move in the direction given by the laser scanning. It was proved that SWCNTs can be moved to a desired position using the focused laser beam.     

Composition driven (Ba,Ca)(Zr,Ti)O3 lead-free ceramics with large quality factor and energy harvesting characteristics

A comprehensive study on energy harvesting characteristics as well as electro-mechanical properties of lead-free (1−x)(BaZr_0.2Ti_0.8)O₃—x(Ba_0.7Ca_0.3Ti)O₃ ceramics were systematically carried out. Raman and Rietveld analyses show a formation of rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary region between 4/6 BZT/BCT and 6/4 BZT/BCT compositional range. Raman modes shift toward lower frequencies with increased Zr/Ca stoichiometric ratio attributed to asymmetric Ti-O phonon vibrations, which caused local disorder, widening of energy band and reduced Curie temperature. The large mechanical quality factor Q_m = 556 is related to the hardening effect and significantly high energy conversion efficiency η = 96% was discovered for 3/7 BZT/BCT composition. Largely, the noblest electro-mechanical properties were retrieved for 5/5 BZT/BCT ceramics, in which d₃₃ = 500 pC/N (from quasi-static d₃₃ meter), d₃₃ = 540 pm/V (from field-dependent d₃₃ curves) indicating that the both methods are analogous with a deviation of 8%. The outstanding energy harvesting characteristics such as voltage constant g₃₃ = 27 × 10⁻³ Vm/N, transduction coefficient d₃₃ × g₃₃ = 13 301 × 10⁻¹⁵ m²/N, figure of merit under off-resonance conditions FOM_off = 12.1 × 10⁻¹⁰ m²/N and fairly large η of 94% were attained again for 5/5 BZT/BCT ceramics. These outstanding characteristics were ascribed to the R-O-T phase boundary region that comprises a low energy barrier, consequently facilitated easy polarization rotation and triggered an increased electro-mechanical conversion. These characteristics outperform other lead-free and even most commercially available lead-based ceramics, and thus suitable for sensors, actuators, resonators, and energy harvesting applications.     

Abnormal grain growth in DC flash sintered 3-mol% yttria-stabilized zirconia ceramics

The origin of nonuniform microstructure and abnormal grain growth (AGG) was investigated in flash sintered 3 mol% yttria-stabilized zirconia (3YSZ) ceramics. The microstructural homogeneity decreased with increasing direct current (DC) density and with dwell time in a flash state, eventually resulting in AGG in the specimen core, the first observation of AGG in 3YSZ. Abnormal grains up to 100 μm in size emerged when the DC density was ≥160 mA/mm², and the specimen's density exceeded 99% of theoretical, starting from the cathode and propagating toward the anode. The results are discussed by comparison with established mechanisms and previous experimental evidence concerning AGG in oxides, focusing on the possible effects of the electrochemical reduction at the cathode end of the specimen.     

Optical properties of bi-doped epoxy novolak resin containing Ce,Dy, and Y ions

In this article, we report on the optical properties of Bismuth doped Epoxy Novolak Resin (ENR) co-doped with Dysprosium, Cerium, and Yttrium ions. The polymer layers containing 1.0 to 20.0 at % of Bismuth were fabricated by spin-coating onto silicon or quartz substrates. The properties of the material were studied using several methods with special regards to its potential utilization in photonics devices. Transmission spectra were taken in the range from 350 to 1600 nm, while photoluminescence spectra around 1300 nm were recorded by using excitation of semiconductor lasers operating at 808 nm and at 980 nm (E_x = 250 mW). Optical properties of the samples were evaluated on the bases of the concentration of the Bismuth ions as well as on the concentrations of the co-doping ions and showed close relations between concentration of the dopants and intensity of the luminescence band at 1300 nm. Our results proved that the Bismuth doped ENR has a strong potential for application in active photonics structures, as it has excellent optical properties and very easy and not demanding fabrication procedures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012