The NIST WWW High Temperature Superconductors database (WebHTS) provides evaluated thermal, mechanical, and superconducting property data for oxide superconductors. The range of materials covers the major series of compounds derived from the Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Tl-Sr-Ca-Cu-O, and La-Cu-O chemical families, along with numerous other variants of the cuprate and bismuthate materials that are known to have superconducting phases. The materials are described by specification and characterization information that includes processing details and chemical compositions. Physical characteristics such as density and crystal structure are given in numeric tables. All measured values are evaluated and supported by descriptions of the measurement methods, procedures, and conditions. In all cases, the sources of the data are fully documented in a comprehensive bibliography.

The NIST WWW Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics. These materials tend to have low mass densities and high strengths and tend to be resistant to corrosion. These characteristics form the basis for applications of these materials in high-temperature, energy-efficient heat exchangers, advanced engine designs, bearings, wear resistant parts, and stable electronic substrates and electronic packaging.

The range of materials covers the major series of compounds derived from the ceramic oxide, carbide, nitride, boride, and oxynitride chemical families. The materials are described by specification and characterization information that includes processing details and chemical compositions. Physical characteristics such as density and crystal structure are given in numeric tables. All measured values are evaluated and supported by descriptions of the measurement methods, procedures, and conditions. In all cases, the sources of the data are fully documented in a detailed bibliography.

Property Data Summaries

Property Data Summaries are collections of property values derived from surveys of published data. These collections typically focus on either one material or one particular property. Studies of specific materials typically include thermal, mechanical, structural, and chemical properties, while studies of particular properties survey one property across many materials. The property values may be typical, evaluated, or validated. Values described as typical are derived from values for nominally similar materials.

CAUTION! Typical values are only representative of trends of values commonlyfound for a general class of materials and are not necessarily the best or most appropriate valuesfor any particular material.

Data Evaluation Levels

The data evaluation levels used throughout the NIST Ceramics WebBook are:

• Certified (standard reference values)
• Validated (confirmed via correlations and models)
• Evaluated (basic acceptance criteria satisfied)
• Commercial (manufacturer's data)
• Typical (derived from surveys)
• Research (preliminary values; work in progress)
• Unevaluated (all other data)

Use of Commercial Names

Certain commercial equipment, instruments, or materials are identified in this document to specify adequately the experimental procedures and conditions. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

All solid materials can deform, stretch, compress, bend, flex, shear, twist, or otherwise deviate from their original unstressed sizes and shapes when subjected to external forces or internal thermal stresses. This propensity of materials to deform under exerted forces is a critically important consideration in the design of any mechanical component whose operation depends on its ability to sustain loads or to maintain dimensions within specified tolerances. Especially important is the condition known as elastic deformation.

The deformation produced by an external force acting on a solid is said to be elastic when removing the external force returns the solid to its original undeformed state.

The present compilation of elastic moduli data for polycrystalline oxide ceramics includes Young's modulus, shear modulus, bulk modulus, and Poisson's ratio. The data have been collected from the technical literature, either as reported in textual or tabular formats or as digitized from graphical formats. Special attention has been given to the dependence of the moduli on porosity and temperature.