# US 10,309,912 B2 · Methods and apparatus for x-ray diffraction

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- Number: US 10,309,912 B2
- Document ID: US10309912B2
- Status: Granted
- Kind: B2
- Application number: 15/919,496
- Filed: 2018-03-13
- Published: 2018-07-19
- Granted: 2019-06-04
- Earliest claimed: 2012-04-19
- Assignees: University of Leicester
- Applicants: University of Leicester
- Inventors: Graeme Mark Hansford
- Web page: https://patentgrep.com/patent/US10309912B2

## CPC

- G01N 23/20091: Measuring the energy-dispersion spectrum [EDS] of diffracted radiation
- G01N 23/203: Measuring back scattering
- G01N 23/223: by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence
- G01N 2223/076: X-ray fluorescence
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Methods and apparatus are provided for performing back-reflection energy-dispersive X-ray diffraction (XRD). This exhibits extremely low sensitivity to the morphology of the sample under investigation. As a consequence of this insensitivity, unprepared samples can be analyzed using this method. For example, in a geological context, whole rock samples become amenable to analysis. A composite diffraction spectrum can be produced using information from different recorded spectra in different energy sub-ranges. The composite spectrum excludes fluorescence signals that would otherwise obscure the diffraction signals.

## Claims

### Claim 1

A method of inspecting a material sample by X-ray diffraction, the method comprising:
irradiating the material sample with a beam of X-ray radiation from a source with a range of photon energies;
obtaining at least one energy-resolved spectrum from radiation diffracted substantially back toward the source at diffraction angles greater than 155°; and
processing the at least one energy-resolved spectrum to obtain information on spacing of crystal planes in the material sample, the obtained information being substantially independent of sample distance or morphology.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein a plurality of energy-resolved spectra are obtained using different settings of source energy, whereby at least one spectrum of the plurality of energy-resolved spectra excludes a fluorescence signal that is present in another spectrum of the plurality of energy-resolved spectra and the plurality of energy-resolved spectra are processed together to obtain information on the spacing of crystal planes in the material sample over a wider range of spacings than can be obtained from any one spectrum of the plurality of energy-resolved spectra on its own.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the material sample is non-prepared rocks in their natural form.

### Claim 4

An apparatus for use in performing energy-dispersive X-ray diffraction to determine characteristics of a material sample, the apparatus comprising:
a source arrangement for irradiating the material sample with a beam of radiation with a range of photon energies;
a detector for detecting radiation diffracted from a sample in a direction substantially back towards the source arrangement at diffraction angles greater than 155°;
a processor configured to:
resolve radiation detected by the detector into at least one energy-resolved spectrum; and
process the at least one energy-resolved spectrum to obtain information on spacing of crystal planes in the material sample, the information on spacing of crystal planes in the material sample being substantially independent of sample distance or morphology.

### Claim 5 (depends on 4)

The apparatus as claimed in claim 4, wherein the source arrangement is located behind the detector, such that the beam of radiation passes beside the detector or through and aperture in the detector to reach the material sample.

### Claim 6 (depends on 4)

The apparatus as claimed in claim 4, wherein the source arrangement comprises a source of X-ray radiation that is controllable to restrict the maximum photon energy of radiation to different selected values.

### Claim 7 (depends on 6)

The apparatus as claimed in claim 6, comprising a controller for automatically controlling the source arrangement and the detector to record a plurality of spectra using different maximum photon energies.

### Claim 8 (depends on 4)

The apparatus as claimed in claim 4, wherein the detector substantially or completely surrounds a path of the beam of radiation.

### Claim 9 (depends on 4)

The apparatus as claimed in claim 4, comprising:
an X-ray source;
a collimator comprising an aperture for passage of the beam of radiation; and
an energy-resolving detector adjacent the aperture, the energy-resolving detector configured to receive diffracted radiation.

### Claim 10 (depends on 4)

The apparatus as claimed in claim 4, comprising:
an X-ray source;
a collimator comprising an aperture for passage of the beam of radiation; and
an energy-resolving detector that surrounds the aperture, the energy-resolving detector configured to receive diffracted radiation.