XRD is based on the optical interferences produced when a monochromatic radiation cross a split of similar thickness to the wave length of the radiation. The x-ray wave length is around Angstroms, it means they are at the same order than inter atomic distances of the crystal structures. When the sample to be analyzed is irradiated with x-rays, these are diffracted with angles that are depending of the inter-atomic distances. The Powder Diffraction Method (or Debye-Scherrer method) consists in the radiation of a powder sample. The sample is formed by many small crystals oriented in all possible directions. In this case, the diffraction obeys to the Bragg law (nλ = 2dsenθ), where 'd' is the distance between inter atomic planes.
XRD is a non-destructive, high technology method for the analysis of a broad range of materials, metals, minerals, polymers, catalysts, plastics, pharmaceutical products, fine thin recovered materials, ceramics and semi-conductors, even fluids. The main application is the qualitative identification of crystallographic phases in a crystalline sample.
Other applications are, the quantitative analysis of crystalline compounds, the determination of many parameters like crystal size, coefficient of thermal expansion, etc, as well as, determine the crystal symmetry, the assignation of distances of some family planes and the calculation of crystallographic parameters.
Furthermore, one diffraction system can be configured for the following applications:
- SAX, this function allows acquiring information about the material structure, such as particles size and shape.
- Thin Films Analysis by X-ray reflectometry and low angle diffraction.
- Micro-diffraction with possibility of a spot analysis with a 100μm spatial resolution.
- Transmission diffraction analysis without capillaries. Sample is placed between two mylar sheets to get a higher irradiated sample volume. This configuration has a focusing mirror to ensuring high quality and resolution measures.
- Measurements under non-ambient conditions. Measure phase changes and composition under controlled atmosphere and temperature (up to 900ºC).
Bruker D8-Advance with mirror Goebel (non-planar samples) with high temperature Chamber (up to 900°C), with a generator of x-ray KRISTALLOFLEX K 760-80F (power: 3000W, voltage: 20-60KV and current: 5-80mA) with a tube of RX with copper anode. Available from the database of the ICDD (International Center for Diffraction Data).
PANalytical Empyrean multi-functional system for analysis by X-ray diffraction. The basic configuration has a goniometer with an X-ray tube cathode Cu K α, and a 3D Pixcel detector. The configuration allows the installation of different modules (SAX, reflectometry, etc.) easy to install with prefix positions. The system has a reaction chamber for analysis of the phase change material during heating to a maximum temperature of 900 ° C. The ICDD (International Center for Diffraction Data) and the COD (Crystallography Open Database) databases are available for the determination of minerals and compounds.
- The samples must be delivered properly labelled, packaged and upgraded to ensure your identification, integrity and conservation during transport and ensure the safety of personnel responsible for performing it.
- For best results, sample must be representative and homogeneous total set part to analyze.
- Necessary sample quantities for analysis are:
- Ground sample: quantity equivalent to the contents of a teaspoon, with 15 µm average particle size.
- Not ground sample: dimensions compatible with the sample holder (4 cm in diameter and 0.6 cm in height).
- For reflectometry analysis, the sample must have a flat suitable shape for this kind of experiments (low roughness –less than 1 nm- and thicknesses less than 1 micron) and the dimensions must be 1cm x 1cm or bigger.
- For SAX measures, samples with equal particle morphology (spherical, cylindrical, etc.) are required, that is to say, polymorphic samples cannot be analysed. The analysis particle range goes from 10 to 100nm.
- High Temperature Chamber:
- For ground samples the quantity should be equivalent to the contents of a teaspoon, with 15 micron average particle size.
- For unground samples, dimensions should be compatible with the sample holder (1.4 cm in diameter and 0.1 cm height).
- Low angle diffraction: it should be a flat sample with dimensions greater than 1cm x 1cm.
- Microdiffraction. It should be solid samples (not powdered) depending on the morphology.
- Transmission analysis is aimed at hazardous and environmental sensitive samples, slightly absorbent or transparent to radiation (organic compounds, pharmaceuticals, etc.).