Nanocrystalline Yttria-Stabilized Zirconia Ceramics for Cranial Window Applications.

Transparent yttria-stabilized zirconia (YSZ) ceramics are promising for cranial window applications because of their good mechanical and optical properties as well as biocompatibility. YSZ discs with different yttria concentrations were either processed via current-activated pressure-assisted densification (CAPAD) using commercial nanoparticles or densified via spark plasma sintering (SPS) using pyrolysis-synthesized nanoparticles in-house. This study provided critical results to screen composition, processing, microstructure, and cytocompatibility of transparent YSZ discs for cranial window applications.

Processing and Thermal Conductivity of Bulk Nanocrystalline Aluminum Nitride.

Producing bulk AlN with grain sizes in the nano regime and measuring its thermal conductivity is an important milestone in the development of materials for high energy optical applications. We present the synthesis and subsequent densification of nano-AlN powder to produce bulk nanocrystalline AlN. The nanopowder is synthesized by converting transition alumina (δ-AlO) with <40 nm grain size to AlN using a carbon free reduction/nitridation process.

Iron oxide-based nanostructured ceramics with tailored magnetic and mechanical properties: development of mechanically robust, bulk superparamagnetic materials.

Nanostructured iron-oxide based materials with tailored mechanical and magnetic behavior are produced in bulk form. By applying ultra-fast heating routines spark plasma sintering (SPS) to supercrystalline pellets, materials with an enhanced combination of elastic modulus, hardness and saturation magnetization are achieved. Supercrystallinity - namely the arrangement of the constituent nanoparticles into periodic structures - is achieved through self-assembly of the organically-functionalized iron oxide nanoparticles.

Characterization of ageing resistant transparent nanocrystalline yttria-stabilized zirconia implants.

The "Window to the Brain" is a transparent cranial implant under development, based on nanocrystalline yttria-stabilized zirconia (nc-YSZ) transparent ceramic material. Previous work has demonstrated the feasibility of this material to facilitate brain imaging over time, but the long-term stability of the material over decades in the body is unknown. In this study, the low-temperature degradation (LTD) of nc-YSZ of 3, 6, and 8 mol % yttria is compared before and after accelerated ageing treatments following ISO standards for assessing the ageing resistance of zirconia ceramics.

Gain in polycrystalline Nd-doped alumina: leveraging length scales to create a new class of high-energy, short pulse, tunable laser materials.

Traditionally accepted design paradigms dictate that only optically isotropic (cubic) crystal structures with high equilibrium solubilities of optically active ions are suitable for polycrystalline laser gain media. The restriction of symmetry is due to light scattering caused by randomly oriented anisotropic crystals, whereas the solubility problem arises from the need for sufficient active dopants in the media. These criteria limit material choices and exclude materials that have superior thermo-mechanical properties than state-of-the-art laser materials.

Retraction: A photon thermal diode.

This corrects the article DOI: 10.1038/ncomms6446.

Novel Cranial Implants of Yttria-Stabilized Zirconia as Acoustic Windows for Ultrasonic Brain Therapy.

Therapeutic ultrasound can induce changes in tissues by means of thermal and nonthermal effects. It is proposed for treatment of some brain pathologies such as Alzheimer's, Parkinson's, Huntington's diseases, and cancer. However, cranium highly absorbs ultrasound reducing transmission efficiency.

Evaluation of laser bacterial anti-fouling of transparent nanocrystalline yttria-stabilized-zirconia cranial implant.

Background And Objective: The development and feasibility of a novel nanocrystalline yttria-stabilized-zirconia (nc-YSZ) cranial implant has been recently established. The purpose of what we now call "window to the brain (WttB)" implant (or platform), is to improve patient care by providing a technique for delivery and/or collection of light into/from the brain, on demand, over large areas, and on a chronically recurring basis without the need for repeated craniotomies. WttB holds the transformative potential for enhancing light-based diagnosis and treatment of a wide variety of brain pathologies including cerebral edema, traumatic brain injury, stroke, glioma, and neurodegenerative diseases.

Unprecedented Electro-Optic Performance in Lead-Free Transparent Ceramics.

A high-performance lead-free electro-optic (EO) transparent material is introduced and used in an EO device operating up to 10 kHz. The BZT-BCT ceramic, named as BXT, has an effective DC EO coefficient, r = 530 pm V , which is higher than state-of-the-art materials such as LiNbO . The high EO response can be leveraged for miniaturization and/or reduction of the operating voltage of EO devices.

A 3 omega method to measure an arbitrary anisotropic thermal conductivity tensor.

Previous use of the 3 omega method has been limited to materials with thermal conductivity tensors that are either isotropic or have their principal axes aligned with the natural cartesian coordinate system defined by the heater line and sample surface. Here, we consider the more general case of an anisotropic thermal conductivity tensor with finite off-diagonal terms in this coordinate system. An exact closed form solution for surface temperature has been found for the case of an ideal 3 omega heater line of finite width and infinite length, and verified numerically.

A photon thermal diode.

A thermal diode is a two-terminal nonlinear device that rectifies energy carriers (for example, photons, phonons and electrons) in the thermal domain, the heat transfer analogue to the familiar electrical diode. Effective thermal rectifiers could have an impact on diverse applications ranging from heat engines to refrigeration, thermal regulation of buildings and thermal logic. However, experimental demonstrations have lagged far behind theoretical proposals.

Transparent nanocrystalline yttria-stabilized-zirconia calvarium prosthesis.

Unlabelled: Laser-based diagnostics and therapeutics show promise for many neurological disorders. However, the poor transparency of cranial bone (calvaria) limits the spatial resolution and interaction depth that can be achieved, thus constraining opportunity in this regard. Herein, we report preliminary results from efforts seeking to address this limitation through use of novel transparent cranial implants made from nanocrystalline yttria-stabilized zirconia (nc-YSZ).

Thermal conductivity of nanocrystalline silicon: importance of grain size and frequency-dependent mean free paths.

The thermal conductivity reduction due to grain boundary scattering is widely interpreted using a scattering length assumed equal to the grain size and independent of the phonon frequency (gray). To assess these assumptions and decouple the contributions of porosity and grain size, five samples of undoped nanocrystalline silicon have been measured with average grain sizes ranging from 550 to 64 nm and porosities from 17% to less than 1%, at temperatures from 310 to 16 K. The samples were prepared using current activated, pressure assisted densification (CAPAD).

Ultralow-temperature superplasticity in nanoceramic composites.

We report the successful demonstration for low-temperature and high-strain-rate superplastic forming of nanoceramic composites for the first time. Porous preforms of nanoceramic composites that were partially densified at low temperatures were superplastically deformed by SPS at the record low temperatures of approximately 1000 to 1050 degrees C, which are comparable to those of Ni-based superalloys. The maximum strain rate achieved is over 10(-2) s(-1), and a compressive strain over 200% can be obtained without cracking.