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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Ceramic substrate including thin film multilayer surface conductor

A ceramic substrate comprises a plurality of ceramic sheets, a plurality of inner conductive layers, a plurality of vias, and an upper conductive layer. The ceramic sheets are stacked one on top of another and include a top ceramic sheet. The inner conductive layers include electrically conductive material that forms electrically conductive features on an upper surface of each ceramic sheet excluding the top ceramic sheet. The vias are formed in each of the ceramic sheets with each via being filled with electrically conductive material. The upper conductive layer includes electrically conductive material that forms electrically conductive features on an upper surface of the top ceramic sheet. The upper conductive layer is constructed from a stack of four sublayers. A first sublayer is formed from titanium. A second sublayer is formed from copper. A third sublayer is formed from platinum. A fourth sublayer is formed from gold.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Metal-ceramic composite powders

A process for manufacturing metal-ceramic composite material powder comprising ball milling metal powder and ceramic nanoparticles to yield a metal-ceramic composite powder comprising ceramic nanoparticles embedded in a metal matrix powder particles; wherein the ball milling is performed using a ceramic milling media and a milling vessel having a ceramic interior surface. Metal matrix nanocomposite powders comprising ceramic nanoparticles imbedded in metal matrix powder particles; wherein the metal matrix powder particles have a spherical shape; wherein there is uniform distribution the ceramic nanoparticles; wherein the nanocomposite powders have good flowability.

Chen, Lianyi↗
DOE OSTI2015

Preparation and characterization of novel foamed porous glass-ceramics

Foamed glass-ceramics without using foaming agent have been synthesized in a novel glass system of SrO-CaO-Al{sub 2}O{sub 3}-TiO{sub 2}-B{sub 2}O{sub 3}-SiO{sub 2}-P{sub 2}O{sub 5}-M{sub x}O{sub y} (where M = Ba, Mg, La, Ce and Ni) by a simple process of powder sintering. The glass and glass-ceramics are characterized by dilatometry, differential scanning calorimetry (DSC), heating stage microscopy (HSM), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), optical microscopy and Fourier transformed infrared spectroscopy (FTIR). All the glasses formed are amorphous and the glass transition temperature and dilatometric softening temperature of these glasses are found to be in the range 673–678 °C and 706–728 °C respectively. The glasses are highly stable as indicated by the DSC evaluated glass stability parameters of the range 195–240 °C. Quantitative sintering study of glass powder compacts revealed swelling in the samples with NiO and CeO{sub 2} corresponding to a geometry change of 75 and 108% around 900 °C respectively. With reference to this finding the glass powder compacts are heated to 900 °C and the foamed glass-ceramics are obtained. Characteristic crystalline silicate phases have been identified in the XRD studies and their microstructures are recorded by FESEM. Optical microscope study of the foamed samples revealed formation of bigger foamed cavity with residual pores in samples with NiO and CeO{sub 2} in comparison to samples with BaO, MgO and La{sub 2}O{sub 3}. The mean pore diameters of the samples with NiO and CeO{sub 2} are determined to be 43 and 32 μm, and their respective porosities are 2.34 and 1.82 cm{sup 3}/g respectively. Thus NiO and CeO{sub 2} are found to be very effective to obtain foamed glass-ceramics without using foaming agent by the viscous flow sintering of fine glass powder compacts along with the reduction of the respective polyvalent ions. - Highlights: • Synthesis of foamed porous glass-ceramics without foaming agent by sintering method • Only powder compact yielded foamed porous glass-ceramics but bulk glass did not. • Glasses containing NiO and CeO{sub 2} exhibited significant foaming efficiency. • Bloating of entrapped gas during viscous flow sintering is the origin of foaming. • Residual void created pores in the sintered glass-ceramics as evidenced in FESEM.

36 MATERIALS SCIENCE↗
DOE OSTI2013

High energy storage density performance of Ba, Sr-modified lead lanthanum zirconate titanate stannate antiferroelectric ceramics

Graphical abstract: Polarization hysteresis (P–E) loops of the (Pb{sub 0.85}Ba{sub 0.08}Sr{sub 0.03}La{sub 0.03}) (Zr{sub 0.74}Sn{sub 0.22}Ti{sub 0.04}) samples: (a) measured at different applied electric-field and (b) measured at different temperatures is shown. It is typical antiferroelectrics whose remnant polarization is zero. As the remnant polarization of AFE is small and the ceramics are accompanied by the formation of the anti-parallel domain structure, energy stored in PLZST can be effectively released. Thus we calculated the energy density from the P–E loop and obtained the power density was up to 1.2 J/cm{sup 3} at 55 °C, and at 45 °C the energy density was ∼1.24 J/cm{sup 3}. As usual, for bulk ceramics, the switching between the AFE and FE states occurs at lower field. This value is much higher than that reported previously for the PLZT bulk ceramic (0.4 J/cm{sup 3}). - Highlights: • Ba{sup 2+}, Sr{sup 2+} co-doping caused the T{sub c} of PLZST moved to the lower temperature (T{sub c} ≈ 40 °C). • The ΔE was so smaller, E{sub AF} ≈ 90 kV/cm and E{sub FA} ≈ 85 kV/cm. • Ba, Sr co-doped PLZST ceramic exhibited slanted P–E loops with a large breakdown field (100 kV/cm). • A high energy density was up to 1.2 J/cm{sup 3}. - Abstract: (Pb{sub 0.85}Ba{sub 0.08}Sr{sub 0.03}La{sub 0.03})(Zr{sub 0.74}Sn{sub 0.22}Ti{sub 0.04}) (Ba, Sr co-doped PLZST) co-doping antiferroelectric (AFE) ceramics with orthorhombic perovskite structure were prepared by the traditional solid state reaction process. It was observed that the doping of barium and strontium caused the Curie temperature of PLZST move to the lower temperature (T{sub c} ≈ 40 °C). Ba, Sr co-doped PLZST AFE ceramics exhibited excellent electrical properties, the AFE to ferroelectric (FE) transition occurred at field E{sub AF} ≈ 90 kV/cm, and the transition from FE to AFE occurred at E{sub FA} ≈ 85 kV/cm. The maximum relative permittivity was about 4800, occurring at a field near the AFE to FE transition point, with a dielectric loss of 0.006. The samples exhibited small ΔE and slanted hysteresis loops with a large breakdown field of 100 kV/cm due to Ba, Sr co-doping ceramics, and a high energy density of 1.2 J/cm{sup 3}.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Structure and ferroelectric studies of (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.9}Zr{sub 0.1})O{sub 3} piezoelectric ceramics

Graphical abstract: - Highlights: • (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.9}Zr{sub 0.1})O{sub 3} (BCTZO) ceramic was synthesized by the ceramic method. • In situ XRD and Raman spectra showed the phase transition of BCTZO around 360 K. • The ceramics showed a tunability of 82% at 40 kV cm{sup −1} electric field. • BCTZO exhibited good quality factor of 111 at microwave frequencies. • Piezoforce microscopy studies indicated the switchability of ferroelectric domains. - Abstract: We have synthesized and studied the structural and ferroelectric properties of lead-free 0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}–0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} ceramics in the temperature region of its ferroelectric transition. The synthesized material showed high dielectric constant, low loss and good pyroelectric figure of merit. From the temperature dependent X-ray diffraction measurements, we determined the tricritical point to be in the temperature range of 303–400 K. The dielectric measurements indicate a diffuse ferroelectric phase transition (DPT) around 360 K in agreement with the X-ray measurements. We studied the evolution of Raman spectra with temperature to understand the nature of phase transition in BaTiO{sub 3} (BTO) and the BCTZO. The results indicates that the transition of ferroelectric–paraelectric state is not sharp as in the case of BTO and the polar state persists through the paraelectric state. In general, our study indicates that there are ferroelectric domains of nanometer size beyond the commonly defined transition temperature. The observation of local piezoelectric hysteresis loop indicated the existence of intrinsic ferroelectric property of the ceramic at the nanoscale. The ceramics exhibited electric field tunable dielectric properties with a tunability of 82% at an applied DC field of 40 kV cm{sup −1}, low dielectric loss of 0.001 and room temperature pyroelectric coefficient of 6 × 10{sup −8} C cm{sup −2} K{sup −1} and the detectivity of 1.9 × 10{sup −8} C cm{sup −1} J{sup −1}; larger than those reported for other BaTiO{sub 3}-based materials. Overall, our results indicate that BCTZO ceramics with coexistence of rhombohedral–tetragonal phases is a promising candidate for lead-free ferroelectric applications.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructure and dielectric properties of BaTiO{sub 3} ceramic doped with yttrium, magnesium, gallium and silicon for AC capacitor application

Graphical abstract: Core–shell structure can be obtained in BaTiO{sub 3} ceramics co-doped with Y–Mg-Ga-Si. Y-Mg-Ga-Si co-dopant can obviously reduce dielectric loss, improve AC breakdown voltage and flatten temperature dependence of capacitance curve. - Highlights: • Y-Mg-Ga-Si co-doped BaTiO{sub 3} ceramics with core-shell structure were prepared. • Y{sup 3+}, Mg{sup 2+}, and Ga{sup 3+} dissolved in the lattice BaTiO{sub 3} replacing Ba{sup 2+} site or Ti{sup 4+} site. • Y{sup 3+} and Ga{sup 3+} tended to remain close to the grain boundaries as a shell maker. • Y-Mg-Ga-Si co-doped BaTiO{sub 3} ceramics show high AC breakdown voltage and low tanδ. - Abstract: The microstructures and dielectric properties of Y-Mg-Ga-Si co-doped barium titanate ceramics were investigated. Y{sup 3+} dissolved in the lattice of BaTiO{sub 3} replacing both Ba{sup 2+} site and Ti{sup 4+} site, and Mg{sup 2+} replaced Ti{sup 4+} site. The replacements of Y{sup 3+} and Mg{sup 2+} inhibit the grain growth, cause tetragonal-to-pseudocubic phase transition, reduce the dielectric loss, and flatten the temperature dependence of capacitance curve. The incorporation of Ga{sup 3+} can improve sintering and increase permittivity. Y{sup 3+} and Ga{sup 3+} tended to remain close to the grain boundaries, and play an important role as a shell maker in the formation of the core–shell structure in the co-doped BaTiO{sub 3} ceramics. Excellent dielectric properties: ϵ{sub r} = ∼2487, tanδ = ∼0.7% (at 1 kHz), ΔC/C{sub 25} < ∼6.56% (from −55 °C to 125 °C) and alternating current breakdown voltage E < ∼4.02 kV/mm can be achieved in the BaTiO{sub 3}–0.02Y{sub 2}O{sub 3}–0.03MgO–0.01Ga{sub 2}O{sub 3}–0.005SiO{sub 2} ceramics sintered at 1380 °C. This material has a potential application in alternating current multilayer ceramic capacitor.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Spectroscopic analysis on the basis Judd–Ofelt theory of Nd{sup 3+} in (Y{sub 0.985}Nd{sub 0.015}){sub 2}O{sub 3}: A transparent laser-host ceramic

Highlights: • Transparent Y{sub 2}O{sub 3} ceramic with 1.5 atm% doping of neodymium (Nd) was fabricated and its spectroscopic properties were investigated using Judd–Ofelt theory. • The Judd–Oflet parameters, computed from the absorption bands of Nd{sup 3+} ion, are Ω{sub 2} = 8.84 × 10{sup −20} cm{sup 2}, Ω{sub 4} = 9.82 × 10{sup −20} cm{sup 2} and Ω{sub 6} = 4.44 × 10{sup −20} cm{sup 2}. These parameters were used to determine absorption line strength, radiative transition probabilities, fluorescence branch ratio and radiative lifetime for different transitions of Nd{sup 3+}. • The branching ratios for {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transition are 0.548 and 0.389, respectively. The spectroscopic quality factor was determined to be 2.21, which is higher than 1.0 atm% neodymium doped Y{sub 2}O{sub 3} ceramic. A calculated radiation decay time (τ = 140 μs) is reasonably close to the experimentally measured life time (153 μs). The life time for 1.5 mol% Nd doped Y{sub 2}O{sub 3} ceramic which is lower than that of 1.0 atm% neodymium doped ceramic. The lowering of life time was attributed to the presence of concentration quenching effects. • The room temperature emission cross-section for individual Stark bands of {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transitions was determined. The total emission cross section for {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transition was found to be 25.49 × 10{sup −20} and 37.04 × 10{sup −20} cm{sup 2}, which is significantly higher than 1.0 atm% Nd{sup 3+} doped Y{sub 2}O{sub 3}ceramic. - Abstract: Spectroscopic investigation of 1.5 atm% Nd{sup 3+} doped Y{sub 2}O{sub 3} transparent ceramic was performed for different emission wavelengths. Judd–Oflet parameters, computed from the absorption bands of Nd{sup 3+} ion, are Ω{sub 2} = 8.84 × 10{sup −20} cm{sup 2}, Ω{sub 4} = 9.82 × 10{sup −20} cm{sup 2} and Ω{sub 6} = 4.44 × 10{sup −20} cm{sup 2}. These parameters were used to determine absorption line strength, radiative transition probabilities, fluorescence branch ratio and radiative lifetime for different transitions of Nd{sup 3+}. The branching ratios for {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transition are 0.548 and 0.389, respectively. The calculated radiative lifetime (140 μs) is in good agreement with the measured lifetime (153 μs). The room temperature emission cross-section of individual Stark bands of {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transitions was determined. The total emission cross section for {sup 4}F{sub 3/2} → {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} transition was found to be 25.49 × 10{sup −20} and 37.04 × 10{sup −20} cm{sup 2}, which is significantly higher than 1.0 atm% Nd{sup 3+} doped Y{sub 2}O{sub 3}ceramic.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Preparation and microwave dielectric properties of Li{sub 3}(Mg{sub 0.92}Zn{sub 0.08}){sub 2}NbO{sub 6}–Ba{sub 3}(VO{sub 4}){sub 2} composite ceramics for LTCC applications

Highlights: • Microwave properties of ϵ{sub r} ∼ 16.3, Q × f ∼ 50,084 GHz and τ{sub f} ∼ 1.5 ppm/°C are achieved. • The τ{sub f} value of the LMZN ceramic can be adjusted to near zero by adding BV. • The LMZN–BV composite ceramic can be well sintered at a relatively low temperature. • The composite ceramic has a good chemical compatibility with Ag electrode. - Abstract: In this work, the (1 − x)Li{sub 3}(Mg{sub 0.92}Zn{sub 0.08}){sub 2}NbO{sub 6}–xBa{sub 3}(VO{sub 4}){sub 2} (x = 0.1–0.35) ceramics were prepared via a conventional solid state reaction route. The phase composition, microstructure and microwave dielectric properties were investigated by an X-ray diffractometer (XRD), a scanning electron microscope and a network analyzer. The XRD results indicated that the Li{sub 3}(Mg{sub 0.92}Zn{sub 0.08}){sub 2}NbO{sub 6} and Ba{sub 3}(VO{sub 4}){sub 2} phases could well coexist without forming any secondary phases. The dielectric constant (ϵ{sub r}) and quality factor (Q × f) values of the Li{sub 3}(Mg{sub 0.92}Zn{sub 0.08}){sub 2}NbO{sub 6} ceramic decreased with the addition of Ba{sub 3}(VO{sub 4}){sub 2} phase, however its temperature coefficient of resonant frequency (τ{sub f}) value was improved significantly. Excellent microwave dielectric properties of ϵ{sub r} ∼ 16.3, Q × f ∼ 50,084 GHz (at 8.64 GHz) and τ{sub f} ∼ 1.5 ppm/°C were achieved for the x = 0.3 sample when sintered at 950 °C for 4 h. The chemical compatibility with Ag electrode indicated that the 0.7Li{sub 3}(Mg{sub 0.92}Zn{sub 0.08}){sub 2}NbO{sub 6}–0.3Ba{sub 3}(VO{sub 4}){sub 2} composite ceramic would be a promising material for the low temperature cofired ceramic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Influence of sintering conditions on the microstructure and optical properties of Eu: CaF{sub 2} transparent ceramic

Highlights: • Eu: CaF2 ceramics sintering at different conditions were fabricated by HP method. • The results show that the temperatures have great effect on the microstructure. • The ceramic sintered at 600 °C/30 MPa has high transmittance and pore-free structure. • The diffusion and densification process mainly occurs between 350 °C and 500 °C. • The optical losses in ceramic were caused by structure defects and polishing damage. - Abstract: Nanopowders of the 5 at.% Eu doped CaF{sub 2} have been synthesized by co-precipitated method. X-ray diffraction (XRD) indicated that the samples corresponds to the cubic CaF{sub 2} phase and scanning electron microscopy (SEM) showed that the morphology of nanopowders were approximately spherical. The Eu: CaF{sub 2} transparent ceramics were fabricated by hot-pressing (HP) method at different P-T conditions in a vacuum environment. The fracture surface, the relative density, average grain size and shrinkage displacements were also studied to analysis the influence of sintering conditions on Eu: CaF{sub 2} ceramic. In comparison with other samples, the proper sintering temperature and pressure was 600 °C/30 MPa. The transmittance of ceramic was up to 79.7% and 88.85% at the wavelength of 760 nm and 2400 nm. Furthermore, the emission spectra of Eu: CaF{sub 2} transparent ceramics under 393.5 nm excitation was also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Correlation between structure and microwave dielectric properties of low-temperature-fired Mg2SiO4 ceramics

Highlights: • Mg{sub 2}SiO{sub 4}–xLiF ceramics could be sintered at 900 °C. • The microwave dielectric properties were significantly dependent on the structure. • The following optimum properties were achieved in the x = 8 wt% ceramics. • Temperature stability of Mg{sub 2}SiO{sub 4}–8 wt% LiF–6.0vol% CaTiO{sub 3} ceramics was obtained. • These ceramics also exhibited excellent chemical compatibility with Ag. - Abstract: Mg{sub 2}SiO{sub 4}–LiF ceramics were fabricated via a conventional solid-state process and sintered at 900 °C. The secondary phase, Li{sub 2}SiO{sub 3}, was observed with ≤6 wt% LiF, and the Li{sub 2}MgSiO{sub 4} phase was detected with ≥8 wt% LiF. The relative density and secondary phase can account for the decrease in the ε{sub r} with an increase in LiF. The degree of crystallization, unit cell volume, secondary phase, and microstructure correlated with the Q × f values. The value of the τ{sub f} was related to the distortions in the Mg(1)O{sub 6} octahedron and the secondary phase. The sample exhibited excellent properties for Mg{sub 2}SiO{sub 4}–8 wt% LiF with ε{sub r} = 6.1, Q × f = 109719 GHz, and τ{sub f} = − 61 ppm/°C. The temperature stability of the Mg{sub 2}SiO{sub 4}–8 wt%LiF–6 vol%CaTiO{sub 3} ceramics was obtained with ε{sub r} = 7.1, Q × f = 31091 GHz and τ{sub f} = − 2.0 ppm/°C. Mg{sub 2}SiO{sub 4}–LiF–CaTiO{sub 3} ceramics provide excellent chemical compatibility with Ag.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Influence of Erbium doping on the electrical behaviour of CaCu3Ti4O12 ceramics probed by impedance spectroscopy analysis

Highlights: • Influence of Er doping on the electrical behaviour of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics was reported. • Powder XRD analysis reveals that addition of Er did not affect the crystallinity. • High dielectric constant (ε{sub r} = 26,749) was found for Er doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics. • Nyquist plot suggest the negative temperature coefficient of resistance behaviour. - Abstract: Herein, the preparation and impedance spectroscopic investigation of pure and Er doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics is reported. FTIR spectroscopy and powder XRD analysis elucidate the surface functionality and crystalline nature of the products respectively. Scanning Electron Microscopy images substantiate the homogenous formation of nanoparticles and the EDS analysis confirms the elemental composition of the products. A relatively high dielectric constant (ε{sub r} = 26,749) is found for Er doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics than that of pure CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics (ε{sub r} = 5885) at 10 Hz (at 800 K). Nyquist plot of pure and Er doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics indicates the presence of a non-Debye type of relaxation phenomenon, which is further validated from the electrical modulus analysis. The variation of temperature dependent relaxation time of pure and Er doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics is estimated from both the imaginary part of impedance and electrical modulus analysis.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Twisted-layer boron nitride ceramic with high deformability and strength

Moiré superlattices formed by twisted stacking in van der Waals materials have emerged as a new platform for exploring the physics of strongly correlated materials and other emergent phenomena. However, there remains a lack of research on the mechanical properties of twisted-layer van der Waals materials, owing to a lack of suitable strategies for making three-dimensional bulk materials. Here we report the successful synthesis of a polycrystalline boron nitride bulk ceramic with high room-temperature deformability and strength. This ceramic, synthesized from an onion-like boron nitride nanoprecursor with conventional spark plasma sintering and hot-pressing sintering, consists of interlocked laminated nanoplates in which parallel laminae are stacked with varying twist angles. The compressive strain of this bulk ceramic can reach 14% before fracture, about one order of magnitude higher compared with traditional ceramics (less than 1% in general), whereas the compressive strength is about six times that of ordinary hexagonal boron nitride layered ceramics. The exceptional mechanical properties are due to a combination of the elevated intrinsic deformability of the twisted layering in the nanoplates and the three-dimensional interlocked architecture that restricts deformation from propagating across individual nanoplates. The advent of this twisted-layer boron nitride bulk ceramic opens a gate to the fabrication of highly deformable bulk ceramics.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Luminescent properties of Eu{sup 2+}-doped BaGdF{sub 5} glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

Eu{sup 2+} doped transparent oxyfluoride glass ceramics containing BaGdF{sub 5} nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd{sup 3+} ions at 312 nm excited with 275 nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu{sup 2+} doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions, the energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu{sup 2+} doped BaGdF{sub 5} glass ceramics may be used as a potential blue-emitting phosphor for UV-LED.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Porosity and mechanical properties of zirconium ceramics

Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO{sub 2}(MgO), ZrO{sub 2}(Y{sub 2}O{sub 3}) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO{sub 2} powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO{sub 2} grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Fabrication and characterization of spark plasma sintered Ce:LuAG ceramic for scintillation application

Rare earth Cerium doped Lutetium Aluminum Garnet (Ce:LuAG) ceramics are widely used as phosphor material in medical imaging and high-energy physics. Due to its technological importance, an attempt has been made to fabricate Ce:LuAG ceramics by using spark plasma sintering (SPS) technique. XRD patterns of SPS sintered Ce:LuAG ceramics reveals a mixed LuAG and CeO{sub 2} (antisite defect) phases. The microstructures of SPS sintered Ce:LuAG ceramics shows limited densification, inappropriate compaction of particles and existence of residual pores, voids between the grain boundaries affects the transparency of Ce:LuAG ceramics. Relative density and hardness of post sintered Ce:LuAG ceramic is also determined. The effect of Ce{sup 3+} doping concentration and sintering temperature on optical luminescence behavior of Ce:LuAG ceramic is presented.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Additive Manufacturing of Porous Ceramics With Foaming Agent

The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, and the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. In this work, a set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity three-dimensional (3D) printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Improved Stability and Cyclability of Ceramic Solid Electrolyte by Coating Polymer

Rechargeable all-solid-state lithium (Li) metal batteries show better safety and energy density compared to commercial Li-ion batteries using liquid electrolyte. As the key component of Li metal batteries, ceramic solid-state electrolyte has attracted great interest because of its high ion conductivity and great potential in interfacing with Li metal. Ceramic electrolyte has a more stable interface with Li metal than liquid electrolyte, but chemical reaction and Li dendrite growth at the electrolyte/Li interface are still significant, which causes device degradation and failure by cycling of Li plating and stripping. Unlike ceramic electrolyte, polymer electrolyte has a relatively stable interface with Li metal and better mechanical flexibility. Therefore, we introduced a polymer electrolyte coating to protect the ceramic electrolyte from direct contact with Li metal. The galvanotactic cycling Li plating/striping data on the devices with (without) the coating illustrates increased (decreased) overall conductivity and cyclability of the test cell by the cycling. Nanometer-scale ionic-transport imaging, based on atomic force microscopy, shows that cycling degrades the ceramic-only electrolyte by partially blocking ionic transport in areas; in contrast, cycling on the polymer-coated electrolyte improves ionic conductivity. Compared with the ceramic-only electrolyte, this novel polymer electrolyte coating on ceramic electrolyte shows less degradation when in contact with Li metal.

25 ENERGY STORAGE↗
DOE OSTI2015

Characterization and corrosion behavior test of glass ceramic waste form

The research conducted in this work package is to collect data in support of future development of glass ceramic waste forms and to help develop the next generation high performance waste management technologies. This work package collaborates closely with the work conducted under “Glass Ceramic – Pacific Northwest National Laboratory (PNNL) - (FT-15PN030704)” and “CCIM Test with Glass Ceramic – Idaho National Laboratory (INL) – (FT-15IN030707)”. The Los Alamos National Laboratory (LANL) is focusing on characterization, testing procedures on glass ceramics from the test matrix and melter testing to further develop and mature the glass ceramic waste form for immobilization of high level waste (HLW) raffinate stream. In Fiscal Year 2015, we are mainly working on multi-phase glass ceramic waste forms. Various characterization and testing techniques (including X-ray diffraction, transmission electron microscopy/scanning transmission electron microscopy, scanning electron microscopy, synchrotron X-ray, nano-indentation) were used to characterize and investigate the corrosion behavior of glass ceramics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗