This is definitely true about the so-called grain boundary dislocations in ceramics because the refractive index around the grain boundaries is lower than that of the bulk. Therefore, light scattering due to dislocations induced changes in refractive index may indeed occur in ceramics. For more discussion, see the attached paper.
As it is written in the attached paper: "Many dislocations exist around the grain boundaries in ceramic, and the refractive index around the grain boundaries is lower than that of the average value of the bulk ceramic." But question still is open, can disslocations in bulk also act as light scattering source? In grain boundary there is high concentration of different point and extended defects.
The question is actually about the effect of a single dislocation line in a bulk. Since the amount of light scattering depends on the wavelength of the incident light, for a visible light with a wavelength scale of the order of hundreds of nanometers, scattering centers should have dimensions on a similar scale. So, to observe any light scattering by dislocations, you will need quite significant amount of them, pile ups or created by dislocations twinning boundaries (inevitably present in any single crystal). But in ceramics, these intragranular effects will be smeared by intergranular grain boundary scattering. Hence, to definitely distinguish between the two scattering centers (intra and inter), you need high quality single crystals with controlled number of dislocations.
It should be true - single disslocation is too small to scatter the light. Interesting, that nanopowder with particles even smaller than 10 nm scatter the light - in this case light is scatterd by particle agglomerates?
It ie known fact that scattering of light is due to dislocations (point defects, line defect and plane defect) and dosent matter the materials is transparent ceramic but is with say with dislocation/defects which will lead to scattering of light.
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