Phase identification in a scanning electron microscope using backscattered electron Kikuchi patterns

Goehner, R. P.; Michael, J. R.

doi:10.6028/jres.101.031

Cited by 90 publications

(60 citation statements)

References 18 publications

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“…EBSD had primarily been used as a tool for the mapping of the crystallographic orientation of a known polycrystalline sample [ 1,2]. A newer use of EBSD is for the identification of unknown crystalline phases in bulk specimens [3,4]. It is for this application that the use of higher order Laue zone (HOLZ) rings to determine the reciprocal lattice layer spacing may be most helpful [5].…”

Section: Introductionmentioning

confidence: 99%

“…This equation is correct for primitive unit cells, but it does not take into account extinctions that are caused by cell centering. Equation 4 will always provide the largest layer spacing and if there are extinctions present the measured value will always be related to the calculated value by an integer multiple. As an example, for the primitive hexagonal cell there are allowed reflections in each higher order Laue zone so there are no missing planes in the reciprocal lattice.…”

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confidence: 99%

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Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis

Michael

Eades

2000

Ultramicroscopy

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In the scanning electron microscope (SEM), using electron backscattered diffraction (EBSD), it is possible to measure the spacing of the layers in the reciprocal lattice. These values are of great use in confirming the identification of phases. The technique derives the layer spacing from the HOLZ rings which appear in patterns from many materials. The method adapts results from convergent-beam electron diffraction (CBED) in the transmission electron microscope (TEM). For many materials the measured layer spacing compares well with the calculated layer spacing. A noted exception is for higher atomic number materials. In these cases an extrapolation procedure is described that requires layer spacing measurements at a range of accelerating voltages. This procedure is shown to improves the accuracy of the technique significantly. The application of layer spacing measurements in EBSD is shown to be of use for the analysis of two polytypes of Sic.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis

Michael

Eades

2000

Ultramicroscopy

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“…Subsequently, these were replaced by various image intensified cameras giving the convenience of a live image of the pattern at the scintillator but with degraded pattern quality compared to that recorded using film [19]. Subsequently, scintillator coupled CCDs were introduced in the early 1990s [20,21]. In a limited number of examples tapered fiber-optic bundles have been used to couple the CCD to the scintillator with good results [20] but the alternative optical lens coupling has been adopted in the vast majority (> 95%) of instruments currently in use.…”

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confidence: 99%

“…Subsequently, scintillator coupled CCDs were introduced in the early 1990s [20,21]. In a limited number of examples tapered fiber-optic bundles have been used to couple the CCD to the scintillator with good results [20] but the alternative optical lens coupling has been adopted in the vast majority (> 95%) of instruments currently in use. Departures from these detection schemes have included an investigation of microchannel plates [22] and the adoption of a retarding electrostatic field for energy filtering [23].…”

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confidence: 99%

Direct Detection of Electron Backscatter Diffraction Patterns

et al. 2013

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We report the first use of direct detection for recording electron backscatter diffraction patterns. We demonstrate the following advantages of direct detection: the resolution in the patterns is such that higher order features are visible; patterns can be recorded at beam energies below those at which conventional detectors usefully operate; high precision in cross-correlation based pattern shift measurements needed for high resolution electron backscatter diffraction strain mapping can be obtained. We also show that the physics underlying direct detection is sufficiently well understood at low primary electron energies such that simulated patterns can be generated to verify our experimental data. DOI: 10.1103/PhysRevLett.111.065506 PACS numbers: 61.05.JÀ, 07.78.+s, 68.37.Hk Electron backscatter diffraction (EBSD) is a scanning electron microscope (SEM) based method in which diffraction of low-energy-loss electrons as they exit through the topmost few tens of nanometers leads to Kikuchi diffraction. In most EBSD studies the incident electron beam is stepped across a grid of points on the sample surface and the EBSD patterns analyzed in an automated way to determine crystal phase, orientation, or lattice strain variation. The EBSD method has evolved rapidly over the last two decades [1][2][3][4][5]. Most research has been directed to the application of this versatile tool to an ever increasing array of problems in materials characterization but the analysis methods themselves have also advanced, notably in three dimensional imaging using focused ion beam (FIB)-SEM [6-9] and in strain mapping [10][11][12][13][14]. However, the detector technology used to record EBSD patterns has essentially remained unchanged for over a decade and now limits performance in several application areas, such as strain resolution and low dose mapping, and prevents the development of new areas.The earliest EBSD patterns were recorded on film either exposed directly to the electrons in the chamber [15][16][17], or indirectly imaging a phosphor screen using a camera outside the vacuum [18]. Subsequently, these were replaced by various image intensified cameras giving the convenience of a live image of the pattern at the scintillator but with degraded pattern quality compared to that recorded using film [19]. Subsequently, scintillator coupled CCDs were introduced in the early 1990s [20,21]. In a limited number of examples tapered fiber-optic bundles have been used to couple the CCD to the scintillator with good results [20] but the alternative optical lens coupling has been adopted in the vast majority (> 95%) of instruments currently in use. Departures from these detection schemes have included an investigation of microchannel plates [22] and the adoption of a retarding electrostatic field for energy filtering [23].In other fields there have been significant advances in detectors directly exposed to the imaging beam for the detection of x rays [24,25] and medium energy electrons [26][27][28][29]. The current development of TEM instr...

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“…It is possible to identify the crystalline phase or polymorph and to determine the crystal orientation of the individual crystals from EBSD patterns (e.g., Dingley and Randle, 1992;Goehner and Michael, 1996). The combination of EBSD and SEM has several advantages when compared to ED in TEM, namely, easy sample preparation, a wide survey area, and superior perception of the crystal morphology or attitude.…”

Section: Introductionmentioning

confidence: 99%

Crystal orientation analyses of biominerals using Kikuchi patterns in TEM

Saruwatari

Akai

Fukumori

et al. 2007

Journal of Mineralogical and Petrological Sciences

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This paper shows that Kikuchi pattern analysis in a transmission electron microscope (TEM) using recent techniques is superior to conventional electron diffraction analysis for determining crystal orientation in an assemblage of small crystals such as those of biogenic origin. A CCD camera with a wide view and large dynamic range was used together with a dedicated program to analyze the patterns and enable real time and unique determination of crystal orientation. Convergent illumination of the incident beam was effective in enhancing the Kikuchi patterns and in improving spatial resolution. Two example biominerals are characterized by Kikuchi pattern analysis; one is spinel law twins in several tens of nanometers width magnetite crystals from magnetotactic bacteria. The other is crystal orientation and the alignment of calcite fragments in coccolith.

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Phase identification in a scanning electron microscope using backscattered electron Kikuchi patterns

Cited by 90 publications

References 18 publications

Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis

Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis

Direct Detection of Electron Backscatter Diffraction Patterns

Crystal orientation analyses of biominerals using Kikuchi patterns in TEM

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