Sealing Glasses for Titanium and Titanium Alloys

Glass compositions containing calcium oxide, alumina, boric oxide, strontium oxide and barium oxide in various mole % combinations were studied. These compositions are capable of forming stable glass to metal seals with titanium and titanium alloys for use as seals for battery headers

Methods of Use and Manufacture of Silver-Doped, Nano-Porous Hydroxyapatite

A silver-doped, nano-porous hydroxyapatite material is provided that can be utilized to capture radioactive iodine, 129I. Methods of using the silver-doped, nano-porous hydroxyapatite material to remove radioactive iodine, and methods of manufacturing the material are also provided

Anomalous-diffusion Model of Ionic Transport in Oxide Glasses

The power-law frequency dependence of both the conductivity, (), and permittivity, (), of ion-conducting materials suggests that self-similar or scale-invariant behavior influences the transport of ions at high frequencies. Using an anomalous-diffusion model, we derive relevant power-law expressions for () and () and compare these with measurements performed on LiPO3 glass. Superior fits to the measured data are obtained compared to the commonly used Kohlrausch-Williams-Watts (KWW) description of the electrical modulus, most particularly in the notorious high-frequency regime. Evaluation of our results in terms of an anomalous-diffusion model suggests the dominance of interaction-based constraints to diffusion. © 1995 The American Physical Society

Two Contributions to the Ac Conductivity of Alkali Oxide Glasses

Although the frequency dependent conductivity of ion-containing glasses often displays scale invariant power law dispersion at high temperatures, the exponent increases to unity at lower temperatures. We report measurements of the conductivity of a series of alkali metaphosphate glasses including a mixed alkali composition and demonstrate that this temperature dependence results from the superposition of two power law dispersions originating from separate mechanism, and does not indicate any intrinsic change in scaling of the process which dominates at high temperatures. © 1995 The American Physical Society

Specific Heat and Transport “Anomalies” in Mixed Alkali Glasses

We show that changes in the relative mole fractions of Li2O and Na2O in alkali metaphosphate glasses lead to “anomalies” in the specific heat and structural relaxations. The heat capacity change between the liquid and glassy states, Δcp(Tg), at the calorimetric glass transition temperature, Tg, exhibits a minimum when the mole fractions of Li2O and Na2O are comparable. Moreover, systematic changes in the temperature dependence of the viscosity, η, i.e., changes in the “fragility” of the system, accompany these changes in mole fraction. This observed dependence of the “fragility” on the mixed alkali ion composition occurs in the absence of apparent changes in the covalent network connectivity which normally accounts for this behavior in glasses

Scaling Parallels in the Non-Debye Dielectric Relaxation of Ionic Glasses and Dipolar Supercooled Liquids

We compare the dielectric response of ionic glasses and dipolar liquids near the glass transition. Our work is divided into two parts. In the first section we examine ionic glasses and the two prominent approaches to analyzing the dielectric response. The conductivity of ion-conducting glasses displays a power law dispersion σ(ω)∞ωn, where n≈0.67, but frequently the dielectric response is analyzed using the electrical modulus M*(ω) = 1/ε*(ω), where ε*(ω) = ε(ω) - iσ(ω)/ω is the complex permittivity. We reexamine two specific examples where the shape of M*(ω) changes in response to changes in (a) temperature and (b) ion concentration, to suggest fundamental changes in ion dynamics are occurring. We show, however, that these changes in the shape of M*(ω) occur in the absence of changes in the scaling properties of σ(ω), for which n remains constant. In the second part, we examine the dielectric relaxation found in dipolar liquids, for which ε*(ω) likewise exhibits changes in shape on approach to the glass transition. Guided by similarities of M*(ω) in ionic glasses and ε*(ω) in dipolar liquids, we demonstrate that a recent scaling approach proposed by Dixon and co-workers for ε*(ω) of dipolar relaxation also appears valid for M*(ω) in the ionic case. While this suggests that the Dixon scaling approach is more universal than previously recognized, we demonstrate how the dielectric response can be scaled in a linear manner using an alternative data representation

Glass and Glass-Ceramic Sealant Compositions

A glass composition for use as a sealant or otherwise bonded to a fuel cell component, including from about 40 mol % to about 60 mol % RO; from about 2 mol % to about 10 mol % M2O3; and from about 35 mol % to about 45 mol % SiO2. R is selected from the group including strontium, calcium, magnesium and zinc and combinations thereof. M is selected from the group including aluminum, boron, lanthanum, iron and combinations thereof. The glass includes at least about 5 mol % ZnO. Upon heat treatment, the glass at least partially crystallizes with the formation of at least one alkaline earth-zinc pyrosilicate crystalline phases

Inorganic Biodegradable Substrates for Devices and Systems

Disclosed are biodegradable glass substrates that are useful as functional elements of solid-state devices. In particular, biodegradable glass substrates having a rapidly degradable glass and a slowly degradable glass provide a structural platform that completely dissolves following a desired operational lifetime of devices such as implanted electronic devices, implanted sensor devices, and optical fibers

Regarding the Correlation of Nuclear Spin Relaxation and Electrical Conductivity Relaxation in Ionic Glasses

Much attention has been focused recently on the apparent differences between ion dynamics in ion-containing glasses as probed by electrical conductivity relaxation (ECR) and by nuclear spin relaxation (NSR) techniques. In both relaxation processes, a power law frequency dependence is observed. Based upon fluctuation-dissipation arguments, the power law exponents should be equivalent. However, experimentally, it appears that the conductivity exponent is generally smaller than the NSR exponent. While an explanation for this discrepancy based upon fundamental differences in the correlation functions probed by the two techniques has been proffered, we show how this discrepancy may simply arise from differing analyses of the ac conductivity. We review several cases taken from the literature in which the conductivity exponent was obtained from analysis of the electrical modulus. We demonstrate how this analysis approach generally underestimates the conductivity exponent. When we instead determine the exponent directly from the ac conductivity, we find near equivalence between the NSR and ECR exponents