This laboratory supports a Scintag x-ray powder diffractometer as well as a variety of x-ray powder cameras and single crystal film cameras.

X-Ray Diffraction

The powder diffractometer employs a theta-theta goniometer. Its operation is controlled by a PC and generates complete Intensity vs. Scattering angle scans automatically as a basic function. Installed DMS 2000 software also allows pattern indexing, unit cell determination, precision lattice parameter determination, and Reitveld analysis as well as crystallite size determination. Sample identification can be performed through comparison with the content of the installed JCPDS powder diffraction database, as shown below.

Most users collect and process their own data. Instruction will be provided by Dr. Croft. In order to support the work of the laboratory, charges will be made for use, both for members of the Harvard community and those outside.

X-Ray Reflectometry

Analysis of thin films is important in both R&D and quality control. The properties of a thin film depend on film density, thickness and interfacial and surface roughness. These film parameters can all be studied by X-ray reflectometry, which is the study of X-ray intensity produced by the interference of X-rays reflected off the various interfaces (air:top surface, film:film or film:substrate). Constructive and destructive interference occurs to produce interference fringes as shown below. Computer programs are available to analyze this kind of data.

Most users collect and process their own data. Instruction will be provided by Dr. Croft. In order to support the work of the laboratory, charges will be made for use, both for members of the Harvard community and outside.

Other Apparatus

This laboratory is set up with a variety of x-ray powder cameras, including Gandolfi, Guinier, and a micro camera. Single crystal instruments, Weissenberg, Precession, and Laue cameras are also available.

Polarizing microscopes are available as well as standards for determining the refractive index of crystalline and non-crystalline materials. Precision density measurements can be made using the Berman Balance.