The transition of amorphous alumina to aalumina was studied by X-ray diffraction, electron diffraction, DTA, TGA, and microscopic observation. The amorphous alumina was prepared by condensing vapor from evaporating molten alumina in vacuo onto the glass envelope of the vacuum chamber. The amorphous alumina was transformed to a poorly crystalline material by heating for 16 hr between 570° and 670OC. Between 670° and 1200°C, the poorly crystalline alumina was converted to a-alumina via two parallel series of transition aluminas. The principal series was ?-alumina to 6-alumina to a-alumina. A minor amount of &alumina developed from the initial crystallization and persisted throughout the duration of the principal series as a parallel path. Some conversion of 6-to 6alumina was detected above 900°C. DTA produced an unexplained exothermic peak at 320°C and a second exothermic peak at 860°C which corresponded to formation of metastable aluminas. 574Library, Microreproduction Service Room 14-0551.

The following fifteen reference patterns of boride, silicide and oxide ceramics represent the first group of ceramic phases measured at the National Bureau of Standards under the project “High Quality Reference Patterns and Total Digital Powder Patterns of Technologically Important Ceramic Phases”. The support and interest of the JCPDS-ICDD in this project is gratefully acknowledged.The general methods of producing these X-ray powder diffraction reference patterns are described in this journal, Vol. 1, No. 1, pg. 40(1986).

The following fourteen reference patterns of carbide, nitride, telluride, and oxide ceramics are reported. Included in the fourteen reference patterns are data for three high Tc superconducting oxide related phases (Ba2CuO3, CuSrO2, and Ba2Cu3YO6). The general methods of producing these X-ray powder diffraction reference patterns are described in this journal, Vol. 1, No. 1, pg. 40 (1986).Samples were mixed with one or two internal standards: silicon (SRM640a), silver, tungsten, or fluorophlogopite (SRM675). Expected 2θ values for these internal standards are specified in the methods described (ibid.). Data were measured with a computer controlled diffractometer. The POWDER-PATTERN system of computer programs was used to locate peak positions, to calibrate the patterns, and to perform variable indexing and least-squares cell refinement. A check on the overall internal consistency of the data was also provided by a computer program.

The following sixteen reference patterns of boride, silicide, nitride and oxide ceramics represent the second group of reference patterns measured at the National Bureau of Standards under the project “High Quality Reference Patterns and Total Digital Powder Patterns of Technologically Important Ceramic Phases”. Included in the sixteen reference patterns are data for two high Tc superconducting oxide phases (CuSr0.2La1.8O4 and Ba2Cu3YO7) plus one related phase (BaCuY2O5). In addition to these new phases, five other patterns represent phases previously not contained in the PDF and eight represent major corrections to data in the file. The general methods of producing these X-ray powder diffraction reference patterns are described in this journal, Vol. 1, No. 1, pg. 40 (1986).

Standard Reference Materials (SRM) are stable materials which have one or more properties certified by the National Bureau of Standards. A general introduction is given to the types of SRM's and their certification. SRM's for X-ray diffraction are described in detail, including their intended use and their certified and other properties. New SRM's are under consideration as quantitative standards, intensity and line shape standards, and materials properties standards.