Review on X-Ray Powder Diffraction Technique
Tushar D. Sonawane1*,
Dr. Rajesh Z. Mujoriya2, Harsha N. Nandre3
1Torrent Pharmaceutical Ltd, Bhat Village, Gandhinagar, Gujarat, India.
2Department of Pharmaceutics, Agnihotri College of Pharmacy, Wardha, India.
3Department of Physics, KSM’s Pratap College, Amalner, India
*Corresponding Author E-mail: tdsonawane@rediffmail.com
ABSTRACT:
The Review provides detail information regarding X-ray powder diffraction technique (XRPD). X-ray powder diffraction (XRPD) is innovative analytical technique used for determination of crystalline or amorphous nature of compound. XRPD technique is important for investigation of nanocrystalline form of the compound. XRPD techniques provide information about formation of polymorphs or hydrate under various environmental conditions. XRPD used in various fields and covered huge area of Academic and industrial research.
KEYWORDS: XRPD, Crystalline, Amorphous, Solvate, Hydrate, Polymorphs.
INTRODUCTION:
X-ray powder diffraction (XRPD) is ideal technique for screening of polymorphs. Different phases or polymorphs easily distinguished by this technique. Formation of crystalline form can be investigated. Determination of crystalline or amorphous nature of compound can be identified by using XRPD.
HISTORY:
Prof. Rontgen was found some invisible, unknown and highly penetrating rays emitted by the discharge tube on which cathode rays were incident, Prof. Rontgen investigated Xray (Prof. Rontgen 1895.)1 Discovery done for crystalline substances act as three-dimensional diffraction gratings for X-ray wavelengths and similar to the spacing of planes in a crystal lattice (Max von Laue, in 1912.)
PRINCIPLE:
XRPD technique based on the principle of constructive interference in which monochromatic X-rays and the crystalline sample. From cathode ray tube X-rays are generated. Filtered starts to produce monochromatic radiation, the collimated to concentrate the radiation, radiation fall on the sample. The interaction of the incident and the sample produces constructive interference at this time satisfy Bragg's Law (nλ=2d sin θ). Bragg’s law mentions the wavelength of electromagnetic radiation to the diffraction angle and lattice spacing in the crystalline sample. These diffracted X-rays are then identified and counted. Scanning of the sample done for the range of 2θangles, all diffraction directions of the lattice should be attained due to the random orientation of the powdered material.1
APPLICATIONS:
X-ray powder diffraction (XRPD) is most important and useful techniques in various fields like geology, environmental sciences, material sciences, engineering, biology, minerals, inorganic compound1 Asbestos, catalyst, ceramics, chemicals, clays & minerals, cement, composite, corrosion products, fly-ash, environmental studies, semiconductors, textiles, plastics, nanon-materials, pharmaceuticals, metals, alloys etc.2,3,4
1. After spray pyrolysis technique, Nanocrystalline material, crystal structure, elements of the constituents and grain sizes were studied from X-ray diffraction.5
2. XRPD used to determine physiochemical properties, morphology and structural features of Carbon nanotube, and carbon acts as a 3D optical diffractors.6
3. Effect of temperature and humidity on crystalline or no crystalline compound and Solid phase conversion process can be evaluated.7
4. Determining the size, shape and symmetry of the crystallographic unit cell from the crystalline component can be possible by XRPD. Identification of hydrate, solvate and co crystals can be possible.8
5. Multicomponent compounds can be identified such as Inclusion complex of drugs. Identification of Active Pharmaceutical Ingredients (API) from co crystals.9
6. Investigation of Interaction of drug excipient compatibility study.
7. To assessed effect of temperature and humidity on drug substances and dosage form.
8. This method distinguish allotropic modification of the same substances
9. Useful for determining complex structure of metal and alloys.
USES IN PHARMACEUTICAL INDUSTRY:
XRPD Technique is used for various reasons, for polymorphs screening, phase or polymorphs can be separated by its unique x-ray diffraction pattern, crystalline, nanocrystalline, and amorphous compound can be distinguished. Formation of solvate and hydrate in different environmental conditions can be identified; effect of temperature and humidity on conversion can be investigated. Provide information on drug excipient compatibility study.
USES IN MATERIAL SCIENCES:
Thin films samples characterize by XRPD, determining the thickness, roughness and density of the film using glancing incidence X-ray reflectivity measurements.1 From thin film nanocrystalline material, crystal structure, elements of the constituents and grain sizes studied by using X-ray powder diffraction technique.5
USES IN NANO MATEIALS:
Complete characterization of bulk carbon matters, unique properties of carbon based matters especially graphene, carbon nanotube, carbon nanobud, carbon nanofoam, dimond and activated carbon. XRPD is popular characterization method for nanoparticles7. X-Ray diffraction associated to calculations and is powerfull tool to study the nanoparticles such as structure, crystalline, particle size and size distribution, particle shape, homogeneity of the whole sample11.
USES IN GEOLOGY:
Mineral Can be characterized by its unique X-ray powder diffraction, characteristic crystal structure obtained by X-ray diffraction pattern, minerals identification carried out within a rock and soil sample4,12.
USES IN GLASS INDUSTRY:
XRPD Technique plays a vital role in glass industry. Glass is a example of amorphous solid. hence to Identification of constituent of glass XRPD technique used.
PARTS OF THE DIFFRACTOMETER:
Diffractometer consist of X-ray Tube, Incident-beam optics, the goniometer, Receiving-side optics, Detector. each part having its own function. X-ray Tube is the source of X Rays. Incident-beam optics placed in such position that X-ray beam before it hits the sample. The goniometer is the platform that holds and moves the sample, optics, detector, and or tube. The sample & sample holder. Receiving-side optics in such apposition that the X-ray beam after it has encountered the sample. Detector can count the number of X-rays scattered by the sample13
Advantages and Disadvantages of XRPD:
XRPD Technique having its own advantages and disadvantages.
1. Rapid non-destructive nature, high sensitivity, reliability, depth profiling (glancing incident angle) 10,
2. Rapid identification.
3. Size, shape and symmetry of the unit cell, the position of the molecule in the unit cell can be characterized.8
4. XRD can be used to look at single crystal or polycrystalline materials16
5. Determination of symmetry of single crystal14.
6. Laue method useful for Investigation of Prepared orientation sheets or fibers14.
Disadvantages:
1. Disadvantages like identification of mixed materials can be difficult its detection limit is ~ 2% of sample.
2. Determinations of unit cells indexing for non-isometric crystal systems is complicated.1
3. The main drawback to single crystal diffraction is the need to grow a sufficiently large and defect-free crystal for analysis, which is practically not possible for all crystal forms.8
Methods of X-ray Diffraction :
For crystal analysis three methods are used. Laue method, rotating crystal method and powder method.
1. Laue Method:
In Laue method single crystal is in a beam of X-ray of continuous wavelength. Source is producing X-ray wide range of wavelength. Wavelength is variable and angle θ is fixed. Arrangement done in such a way that source, Pin hole produces collimeter beam, gonimeter come in a same direction.16 (fig.1)
FIG.1 Laue Method
2. Rotating Crystal Method:
In the rotating crystal method a single crystal is rotated about a fixed axis in a beam of monochromatic x-ray. The variation of the angle θ brings the different atomic planes into position for reflection. The film is mounted in a cylindrical holder concentric with a rotating spindle crystal mount. The x-ray beam monochrimatized by a filter or by reflection from a real crystal. The beam is diffracted from a give plane. The wavelength is fixed and angle θ is variable by rotating crystal.16 (fig.2)
FIG.2 Rotating Crystal Method
3. Powder Method :
In this method the crystal sample need not be taken in large quantity(equal to 1 gm.)The experimental set up of powder method is shown in (fig.3) The X ray can be done monochromatic by using filter. The mono chromatic radiation strikes a fine powdered sample or a fine polycrystalline sample contained in a thin capillary tube, kept inside a deby sherraer camera diffracted rays go out from individual crystallites orientation. Diffracted angle making and angle 2θ with the direction of the original beam where θ is the Bragg angle. The wavelength is fixed and angle θ is variable due to random orientation of large number of polycrystalline powder.16
FIG.3 Powder method
DIFFREACTOGRAM AND INTERPRETATION15
(Images from How to analyze polymer using X ray diffraction, International centre for diffraction data)
Interpretation of results are commonly done as on peak positions at 2θ and X-ray counts (intensity) in the form of a table or an x-y plot. Intensity (I) is either reported as peak height intensity, that intensity or as integrated intensity, the area under the peak. The relative intensity is recorded as the ratio of the peak intensity to that of the most intense peak (relative intensity = I/I1 x 100.) As well as particle size can be determined by “Scherrer Formula.” Scherrer (1918) first observed that small crystallite size could give rise to line broadening. He derived a well known equation”17
Δ(2θ) or β = Kλ/{D cos θ}
CONCLUSION:
X-ray powder diffraction (XRPD) is novel analytical technique used for determination of crystalline and nanocrystaline compound. Now a day XRPD is ideal tool for solid state characterization and in future it provide tremendous scope for researchers.
REFERENCES:
1. Barbara L Dutrow, Christine M. Clark, X-ray Powder Diffraction (XRD).
2. Sharma BK (2000) Instrumental Methods of Chemical Analysis. Krishna Prakashan Media, Meerut, India, 514.
3. Dann SE (2002) Reactions and Characterization of Solids. Royal Society of Chemistry, USA, 10.
4. Skoog DA, Holler FJ, Crouch SR (2007) Principles of Instrumental Analysis.Sixth Edition, Thomson Brooks, USA.
5. R. H. Bari, Gas sensing performance of chemically deposited nanocrystalline Cu2S thin films, International Journal of Techno Chem Research, Vol.02, No.02, pp 133-140.
6. Rasel Das, Sharifah bee Abd Hamid, Md.Eaqub Ali, Carbon nanotube characterization by X-ray Powder diffraction – A review, current Nanoscience,Februvary 2015.
7. Rasel Das, Md. Eaqub Ali, Sharifah bee Abd Hamid, Current applications of X ray powder diffraction- A review, Rev. Adv. Mater. Sci.38 (2014)95-109.
8. Richard B. McClurg and Jared P. Smit, X-ray Powder Diffraction Pattern Indexing for Pharmaceutical Applications, Pharma. Tech.Eueope, Jan.2013.
9. Mino R.Caira, Currents Applications of Powder X-ray Diffraction in Drug Discovery and Development, American Pharmaceutical review.Feb.2014.
10. Chauhan A, Chauhan P, Powder XRD Technique and its Applications in Science and Technology. J Anal Bioanal Tech 5: 212. 2014.
11. Structural Characterization of Nanoparticles, Nicola Pinna, Max Planck Institute of Colloids and Interfaces.
12. Vogt FG, Williams GR (2010) Advanced approaches to effective solid-state analysis: X-ray diffraction, vibrational spectroscopy, and solid-state NMR. Am Pharm Rev 13: 58-65.
13. Basics of X-Ray Powder Diffraction, Scott A Speakman, Ph.D.
14. Measurement Techniques For Nanoparticles, University of Essex for Nanocap
15. How to analyze polymer using X ray diffraction, International centre for diffraction data.
16. Abhijit Nayak, Engineering Physics, 5 revised Edition, Publisher S K Kataria & Sons.
17. C. Prabakaran, Lecture 12, Nanotechnology- nano. blogspot.com/2012/09/lecture-12.html
Received on 13.06.2016 Modified on 29.06.2016
Accepted on 16.07.2016 ©A&V Publications All right reserved
Res. J. Pharm. Dosage Form. & Tech. 2016; 8(4): 292-295.
DOI: 10.5958/0975-4377.2016.00040.9