{"id":1000,"date":"2021-11-22T12:12:07","date_gmt":"2021-11-22T12:12:07","guid":{"rendered":"http:\/\/www.calm-ebsd.com\/?page_id=1000"},"modified":"2021-12-10T21:03:03","modified_gmt":"2021-12-10T21:03:03","slug":"false-bands","status":"publish","type":"page","link":"https:\/\/www.calm-ebsd.com\/index.php\/how-to-start\/false-bands\/","title":{"rendered":"False bands"},"content":{"rendered":"\n

It can happen that, by chance<\/strong>, exactly where a band could be, an intensity accumulation <\/strong>occurs that actually looks<\/strong> like<\/strong> a band profile<\/strong>.
To make matters worse, most band profiles<\/strong> do not look as ideal as is commonly thought, but have a rather atypical<\/strong> shape<\/strong>. With CALM, you can inspect any profile after defining the band positions. <\/em><\/p>\n\n\n\n

Of course, it can also happen that single strong bands<\/strong> of another pattern<\/strong> become visible in one pattern because both superimpose<\/span><\/a><\/strong> in the image. These bands are usually easy to identify<\/strong> and are automatically ignored because they do not match the other bands, neither in direction nor in width.
The situation becomes more difficult when crystallographic intergrowths<\/span><\/a> occur<\/strong> (e.g. single or multiple twinning) and such patterns overlap. There a separation can become difficult, especially if by chance both lattices generate a superlattice.<\/em><\/p>\n\n\n\n

Wrong [hkl]* selected in a pattern from anatase (TiO2<\/sub>)<\/p>\n\n\n\n

It is not very difficult to describe a band position [hkl]*j<\/sub> by another very close [hkl]*i<\/sub>, e.g. by [3hi<\/sub> 3ki<\/sub> (3li<\/sub>+1)]*. Depending on the (unknown) lattice parameters, the angular distance<\/strong> of [hkl]*i<\/sub> and [hkl]*j<\/sub> can be<\/strong> as small as a few tenths of a degree<\/strong> only.
Please consider:<\/span> During definition<\/strong> of the trace positions the indexing<\/strong> is totally unknown<\/strong>. High and low indexing of [hkl]* is later decided by their bandwidth. However, by visual inspection of the circles around [hkl]* you can predict how likely the defined pole might be, or whether there is another connection of two narrow bands (small circles) which might match better.<\/em><\/p>\n\n\n\n

Such an example is described in the following. In the left image below the uper right quarter of the Funk transformation of a Kukichi pattern from anatase is shown. Beside several ten poles one pole<\/strong> is displayed as red dot<\/strong>. It is defined by the intersection of two great circle. The one containing many [hkl]* is certainly reasonable. The other one, connecting one pole without and one with an intermediate band width (circle diameter) is only possibly reasonable <\/p>\n\n\n\n