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The magnetic and magnetooptical properties of CeFe[O.sub.3] (CFO) and YCeCoFe[O.sub.6] (YCFCO) films grown by pulsed laser deposition onto MgO or SrTi[O.sub.3](100) substrates at ~[10.sup.-5] Torr or at 6 mTorr [O.sub.2] are studied. Faraday rotation hysteresis loops were obtained at the 1.55-[micro]m wavelength, yielding a saturation of ~0.6 deg/[micro]m in all CFO films and ~0.25 deg/[micro]m in the YCFCO film grown under vacuum. Optical measurements give a refractive index of 2.9 and an optical absorption of 1.8 dB/[micro]m at the same wavelength. The corresponding saturation magnetization in CFO films reaches 45 emu/[cm.sup.3] at room temperature. Interpretation of the magnetic and magnetooptical properties is based on the electronic structure and optical transitions of [Ce.sup.3+] in an iron garnet or orthoferrite lattice. Index Terms--Laser ablation, magnetooptic films, optical isolators.

Magnetic garnets with Bi3+ are the standard media of discrete Faraday rotation isolators for IR-laser/fiber-optical transmission at 1.55 μm wavelength. For monolithic integration with semiconductors, perovskites of generic formula A[B]O3 offer promising alternatives that involve combinations of select transition-metal ions in octahedral B sites. In this paper, two concepts are described. In both cases, the 180° B–O–B bonding of the perovskite lattice could provide superexchange fields large enough to maintain spin ordering at room temperature. One model proposes a quasiferrite arrangement with antiferromagnetic alignment between Fe3+ and Ni2+ charge ordered in the double perovskite compound {A3+A′4+}[Fe3+Ni2+]O6. The other concept relies on ferromagnetism through delocalization superexchange with the composition A23+[Mn4+Ni2+]O6. Where appropriate to enhance Faraday rotation, Bi3+ can be used for A3+. [ABSTRACT FROM AUTHOR]

We extensively studied serigraphic screen-printed commercial silver flake inks loaded with silicon inclusions in order to achieve pinning at the grain boundaries. Based on grain size measurements using electron backscattered diffraction (EBSD), commercial silver ink with silicon microparticle content of 5 wt.% shows significant grain growth retardation compared to pristine silver ink, which stabilizes electrical conductivity up to 700 °C via a Zener pinning mechanism. The modified silicon-loaded silver ink experiences a two-times increase in grain size when heated up to 700 °C, compared to a seven-times increase for pristine silver ink. In turn, this enables operation temperatures significantly higher than the conventional operational window of microparticle-based silver inks, which are usually limited to 400 °C. Using isothermal exposures of 10 min up to 4 h, this phenomenon is observed at temperatures ranging from 250 °C to 900 °C. The electrical conductivity stability, grain size evolution and oxide contents were studied up to 4 h. The activation energy of silver ink with silicon inclusions is 54% lower than for pristine silver ink due to the pining effect, which retards grain growth via the Zener mechanism. Most importantly, the electrical resistivity remains stable up to 700 °C, which is more than twice the operation limit for off-the-shelf screen-printable silver flake inks. Hence, we demonstrate that adding controlled amounts of silicon particles to silver inks for grain structure engineering can open new vistas of possibilities for screen-printed metallic inks.

Printed electronic devices are attracting significant interest due to their versatility and low cost; however, quality control during manufacturing is a significant challenge, preventing the widespread adoption of this promising technology. We show that terahertz (THz) radiation can be used for the in situ inspection of printed electronic devices, as confirmed through a comparison with conventional electrical conductivity methods. Our in situ method consists of printing a simple test pattern exhibiting a distinct signature in the THz range that enables the precise characterization of the static electrical conductivities of the printed ink. We demonstrate that contactless dual-wavelength THz spectroscopy analysis, which requires only a single THz measurement, is more precise and repeatable than the conventional four-point probe conductivity measurement method. Our results open the door to a simple strategy for performing contactless quality control in real time of printed electronic devices at any stage of its production line.