NIST SRM640g silicon powder

Main purpose:NIST SRM640g silicon powder Intended as a standard for calibrating the position and shape of diffraction lines, determined by powder diffraction method.

Packing Specification:NIST SRM640g silicon powder a bottleComposed of approximately 7.5 grams of silicon powder loaded under argon gas.

MaterialMade from ultra-high purity intrinsic silicon ingots, these ingots are crushed and jet milled with a median particle size of 4.1 μ m. Then, the obtained powder was annealed at 1000 ° C under argon gas for two hours [1] and bottled under argon gas. The analysis of X-ray powder diffraction data indicates that SRM material has uniform diffraction characteristics.

Authentication value:The certified lattice parameter at 22.5 ° C is 0.543 114 4 nm ± 0.000 008 nm

The interval defined by this value and its extended uncertainty (k=2) is mainly determined by Class B uncertainty, which is estimated from a technical understanding of the measurement data and its distribution. The NIST certification value is the value at which NIST has the highest confidence in its accuracy, as all known or suspected sources of bias have been investigated or considered. The certification value and uncertainty are calculated according to the methods described in ISO/JCGM guidelines [2]. The measured parameters are lattice parameters. Metrological traceability is the SI unit of length, expressed in nanometers.

Information value:The analysis of authentication data includes refining the full width at half maximum (FWHM) of the Lorentz distribution to illustrate the broadening caused by the sample. The angle dependence of the FWHM term with respect to 1/cos θ is explained as size induced broadening. The obtained value is consistent with an average volume weighted domain size of approximately 0.4 µ m. The term changes with tan θ and is interpreted as microstrain, refined to zero. The information values for calculating the peak position are given in Table 1. The typical particle size distribution determined by laser scattering is shown in Figure 1. The information value is considered to be a value of interest to SRM users, but insufficient information is available to evaluate the uncertainty associated with that value. Information values cannot be used to establish metrological traceability.

Certification expiration:The certification of NIST SRM 640f - Silicon Powder Standard is valid indefinitely within the specified uncertainty range, provided that the SRM is handled and stored in accordance with the instructions in this certificate (see "Storage Instructions"). There is no need for regular re certification of this SRM. If the SRM is damaged, contaminated, or otherwise modified, the certification is invalid.

Storage instructions:ambient temperature

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