Respirable Alpha Quartz

(Quantitative X-Ray Powder Diffraction Standard)

This Standard Reference Material (SRM) is intended for use in preparation of calibration standards for quantitative analyses of a-quartz by X-ray powder diffraction in accordance to National Institute for Occupational Safety and Health (NIOSH) Analytical Method 7500 [1] (or equivalent). A unit of SRM 1878a consists of approximately 5 g

of powder bottled in an argon atmosphere.

Material Description: The SRM material was prepared from electronic grade, single crystal nodules of Brazilian quartz obtained from the National Defense Stockpile, which were crushed and jet milled to a median particle size of

1.6 mm. The resulting powder was then washed in hydrofluoric acid and hydrochloric acid, rinsed, ignited at 500

°C, and bottled.

An analysis of the quantitative results from Rietveld analyses of X-ray powder diffraction data indicated that the

SRM material was homogeneous with respect to diffraction properties.

Certified Value and Uncertainty: The certified phase purity of the material expressed as a mass fraction is:

93.7 % ± 0.21 % (crystalline a-quartz)

The interval defined by a value and its uncertainty is expressed as a 95 % confidence interval in the absence of systematic error [2,3].

Expiration of Certification: The certification of this SRM is valid indefinitely within the stated uncertainties, provided the SRM is stored and handled in accordance with the “Storage” section of this certificate. This material degrades with exposure to humidity. If excessive exposure is suspected, discontinue use.

Maintenance of SRM Certification: NIST will monitor this SRM over the period of its certification. If substantive changes occur that affect the certification before the expiration of this certificate, NIST will notify the purchaser. Registration (see attached sheet) will facilitate notification.

The material preparation, measurements, and data analysis leading to the certification of this SRM were provided by

J.P. Cline of the NIST Ceramics Division and R.B. Von Dreele of Argonne National Laboratory, Argonne, IL. The

jet milling operation was performed by D. Ramsey and J. McLaurin, NIOSH, Cincinnati, OH. Statistical analysis was performed by J.J. Filliben of the NIST Statistical Engineering Division.