Mr. Rawanduzy,

There are not disadvantages of the single crystal XRD structural analysis up to 100 atoms. There are variations in the analytical instrumentation associated with single crystal X-ray diffraction. Or there are instrumental schemes for structural analysis of small molecules, and in parallel there are diffractometers for single crystal X-ray diffraction of macromolecular objects (for protein research, for example).

In context your comments regarding the crystal size and quality, it should be mentioned, here, that the crystallographic analysis of macromolecules can be carried out using a single crystalline object with dimensions about 10E-3 mm3. On the other hand there are set different techniques for crystallization of small molecular single crystalline objects; and set independent techniques for obtaining of single crystalline objects from proteins, for example. So, question about "quality"/"size" of a single crystalline object often cannot be regarded as disadvantage to the XRD method. It is rather associated with skills/techniques for crystallization and crystal growth, which themselves can vary for crystallization/growth of organics, inorganics and metalorganics even within the framework of single crystal XRD analysis of small molecules.

Towards your central question for the difference between single crystal XRD and the powder XRD (in terms "phenomenology"), perhaps a short common answer would be given on the base on the content of the discussions below.

Towards the analytical instrumentation - both single crystal and powder XRD have different instrumental schemes for hkl data collection, in context "methodological instrumental developments", thus producing different results from an analytical scientific (even not only chemical) point of view. In the first case (single crystal XRD) there is obtained a discrete function of the intensity of the analytical signal as a function of the diffraction angle. While in powder XRD there is a continuous function.

In this context here are differences associated with elaboration of the data processing algorithms/softwares (or contributions to the "computational chemistry" and "chemometrics", in a general context). In the first case (single crystal XRD) there is determination of the atomic positions on the base on the electron density map evaluating the intensities of the hkl reflections of an isolated unique unit cell. In the second case the mentioned continuous function of unknown compound is treated comparing with database of powder XRD patterns of known compounds.

In other words the analytical structural information by the single crystal XRD is "unambiguous" and in parallel an "absolute" one, thus directly determining the structure and the chemical content of unknown compound/sample "without" application to any standard XRD pattern/data of a "known" sample. By contrast to powder XRD, where the analytical information is not "absolute" and even it can be not "unambiguous" one. Few details in context of the latter paragraph, about spontaneous crystallization of polymorphs and/or non-stoichiometric compositions of substances you can find in the second discussion (below).

In parallel, the analytical information by powder XRD cannot be even treated as "structural" analytical information. Because of largest part of this information has qualitative character without to provide quantitative data/quantities of the geometry parameters like bond lengths and angles of the molecule.

So, this can be regarded, as well as, like difference between the powder and single crystal XRD in terms "analytical structural information" of the matter. In context...what kind information, associated with the molecular structure, this method (powder XRD), in fact, provides to the "Chemistry".

Discussions:

https://www.researchgate.net/post/What_is_the_difference_between_XRD_Data_of_polycrystalline_and_Single_crystal

https://www.researchgate.net/post/Why_do_I_get_a_the_same_XRD_spectrum_after_crystallization

Single-crystal X-ray diffraction is regarded to be the most powerful technique for elucidating crystal structures. For structures with less than 100 atoms in the asymmetric unit, single-crystal techniques are always guaranteed to be successful with accurate parameters of cell dimensions. However, many materials cannot be prepared in the form of single-crystal of sufficient size or stability for investigation using single-crystal X-ray diffraction techniques. Even if the single-crystal can be obtained, culturing single-crystal can be very time consuming. Therefore, applying powder X-ray diffraction techniques becomes essential to studying the structural properties of certain materials. Although structure determination by powder X-ray diffraction may not be as accurate as that by single-crystal X-ray diffraction, improvements will likely be achieved through future advancements in instrumentation and algorithm development.

Why do you ask a question and then give an answer (which is actually not an answer since you did not say anything about the difference between both techniques but why both are necessary)?

I must ask the same question as Gert Nolxe - why ask a question and then answer it yourself and then not even answer the question.  

Mr. Rawanduzy,

There are not disadvantages of the single crystal XRD structural analysis up to 100 atoms. There are variations in the analytical instrumentation associated with single crystal X-ray diffraction. Or there are instrumental schemes for structural analysis of small molecules, and in parallel there are diffractometers for single crystal X-ray diffraction of macromolecular objects (for protein research, for example).

In context your comments regarding the crystal size and quality, it should be mentioned, here, that the crystallographic analysis of macromolecules can be carried out using a single crystalline object with dimensions about 10E-3 mm3. On the other hand there are set different techniques for crystallization of small molecular single crystalline objects; and set independent techniques for obtaining of single crystalline objects from proteins, for example. So, question about "quality"/"size" of a single crystalline object often cannot be regarded as disadvantage to the XRD method. It is rather associated with skills/techniques for crystallization and crystal growth, which themselves can vary for crystallization/growth of organics, inorganics and metalorganics even within the framework of single crystal XRD analysis of small molecules.

Towards your central question for the difference between single crystal XRD and the powder XRD (in terms "phenomenology"), perhaps a short common answer would be given on the base on the content of the discussions below.

Towards the analytical instrumentation - both single crystal and powder XRD have different instrumental schemes for hkl data collection, in context "methodological instrumental developments", thus producing different results from an analytical scientific (even not only chemical) point of view. In the first case (single crystal XRD) there is obtained a discrete function of the intensity of the analytical signal as a function of the diffraction angle. While in powder XRD there is a continuous function.

In this context here are differences associated with elaboration of the data processing algorithms/softwares (or contributions to the "computational chemistry" and "chemometrics", in a general context). In the first case (single crystal XRD) there is determination of the atomic positions on the base on the electron density map evaluating the intensities of the hkl reflections of an isolated unique unit cell. In the second case the mentioned continuous function of unknown compound is treated comparing with database of powder XRD patterns of known compounds.

In other words the analytical structural information by the single crystal XRD is "unambiguous" and in parallel an "absolute" one, thus directly determining the structure and the chemical content of unknown compound/sample "without" application to any standard XRD pattern/data of a "known" sample. By contrast to powder XRD, where the analytical information is not "absolute" and even it can be not "unambiguous" one. Few details in context of the latter paragraph, about spontaneous crystallization of polymorphs and/or non-stoichiometric compositions of substances you can find in the second discussion (below).

In parallel, the analytical information by powder XRD cannot be even treated as "structural" analytical information. Because of largest part of this information has qualitative character without to provide quantitative data/quantities of the geometry parameters like bond lengths and angles of the molecule.

So, this can be regarded, as well as, like difference between the powder and single crystal XRD in terms "analytical structural information" of the matter. In context...what kind information, associated with the molecular structure, this method (powder XRD), in fact, provides to the "Chemistry".

Discussions:

https://www.researchgate.net/post/What_is_the_difference_between_XRD_Data_of_polycrystalline_and_Single_crystal

https://www.researchgate.net/post/Why_do_I_get_a_the_same_XRD_spectrum_after_crystallization

I just like to know if you have any other opinions on my answer. May you know more in their techniques or the limitations in using as a crystal than a powder.

The straightforward and broad explanation of your question is a) single crystal must have only one plane and its same orientation throughout in bulk crystals too as the long range order. XRD pattern must have only one peak. b) While for powder, it will show many plane and different orientation with short range order. XRD pattern would show several peaks with varying intensity.

Dear colleagues:

I'm afraid I do not understand the statements:

(1) " give an answer (which is actually not an answer....." and

(2)  "why ask a question and then answer it yourself and then not even answer the question?".

Either Kasim answered his own question or he didn't. One cannot have it both ways.

I hope this discussion has been helpful, Kasim.

I just want to add the words of one clever man: “If you have single crystal in your hands, do not crush it to powder to solve its structure”.

Brian Lent, I really did not mean to insult anyone and I apologize if I did, but this particular posting did trouble me for a couple of reasons.  First, and perhaps quite cynically, by posting a question and then posting a response can be viewed as a way of artificially increasing one's ResearchGate score.  This score may be used at some institutions as a quality indicator and artificially inflating it may be an improper use.  I cannot conclude this is what happened but the way it was done still puzzles me.  Second, the issue is not "answering ones own question" but making a post that attempts to answer without really answering the question.  So, yes, it is possible to have it both ways in that context.    

The original poster could have perhaps rephrased the original post to "I would like to start a discussion on the advantages and disadvantages of powder vs single crystal x-ray diffraction."  The original post could then give the poster's view and then waited for others to respond and then a reasonable discussion could be started in that manner.

I hope this clarifies my point 

To investigate the structure of a glass (to know if its crystal or non-crystalline amorphous) we must make it powder before test it in the XRD....can we test it without crash it to powder?

Technically, a glass always refers to an amorphous material so neither powder nor single crystal xray diffraction will do anything for those other than to confirm they are amorphous.  Sometimes there are materials with a glassy appearance that might be crystalline and so you could tell the crystallinity of those.

Powder XRD at its simplest can be used to easily identify a known material since the diffraction pattern can be compared either to previously published powder patterns or to simulated powder patterns from single crystal data.   Single crystal data is the only tool that can readily provide not only direct identification of the material but also clear quantification of bond distances and angles.  Obviously, for the latter, a single crystal is needed but the techniques to obtain them have become pretty sophisticated.

Dattatray:

Would you kindly clarify your comment that a single crystal "must have only one plane"? I can only visualize this as a monolayer of atomic species with a repeating motif throughout the whole 2-dimensional specimen (such as a graphene film, for example). As soon as a second monolayer begins to form and the sample becomes a 3-dimensional single crystal there will be many planes in the sample, limited only by the sample dimensions relative to the lattice parameter. For example, consider a simple cubic material and a hypothetical  initial (111) plane. Add a second monolayer and we will also have (112), (113), (114) .... planes - lots of them (and also planes of any other combination of Miller indices) and we still have a single crystal.

Dear Sir,

Similar opinion as you stated --- Would you kindly clarify your comment that a single crystal "must have only one plane"? I can only visualize this as a monolayer of atomic species with a repeating motif throughout the whole 2-dimensional specimen

Sir, I have provided typical XRD patterns of substrate and its powder of the InSb detached Ingot. We have grown 72 Ingots varying dimensions (d= 10-18mm, L=65-75 mm) by vertical directional solidification (VDS) all the detached ingots growth with high crystallinity and good physical properties similar to the space grown crystals ( see our publication in ResearchGate). For illustration, in our experimental measurements,  InSb crystals grown by VDS showed highest mobility (60.2K) for crystal grown ever. The XRD patterns are same along the entire InSb ingot and typical detached ingot is shown in attached file

Dear Dattatray:

 The results you show on your InSb specimen explain (to me) what you meant in your comment about “only one plane”. However, I do not think that it will be at all obvious to our fellow members who are less-experienced in XRD methods. You are implying but do not state that the Laue back-scattering pattern was from the face of a slice cut normal to the crystal axis (which in this case would also be the growth axis) at some position along the crystal length. If similar cuts are made normal to the crystal axis at different positions along the axis the Laue patterns for those faces will be the same if the specimen is a single crystal. If the Laue patterns show different symmetries then the sample is not a single crystal.

A single crystal does not have only one plane but a plane which is normal to any direction within the sample will have the same crystallographic orientation (and the same Laue diffraction pattern) at all positions along that direction. And of course the diffractometer (2Theta) scans will also be the same at all positions along any arbitrary direction in a single crystal sample.

With reference to some of the earlier answers to this question, our younger and less-experienced colleagues deserve encouragement and support for their enthusiasm and desire to learn from those members who have been in the field longer. I do not think that they deserve to be criticized for what is more likely to be some difficulty in expressing themselves in a foreign language than some hypothetical attempt to elevate their “status” via a rather silly (and irrelevant?) rating system.

Dear Briant Lent

Thank you for valuable interpretation!

Dattatray,

   Brian has given you an excellent answer.  Your back scattering profile shows exactly what he indicates.   Your sample is not the "typical" single crystal as usually discussed for many molecular (or even mineral) samples and so you do get the same pattern if you always scatter from the plane cut normal to the growth axis.  In more commonly described single crystal x-ray diffraction, a small (mm x mm x mm or so) is mounted so that ALL planes can be brought into the diffraction condition and position and intensity measured.   In that way, the full electron density map (and thus the molecular structure) can be obtained.

Dear Brian Lent, and Joseph S Merola

 I would like to thank you for your valuable comments; these comments are explained here --

 The detached ingots were cut transverse to the growth direction i.e. growth axis on different regions along growth direction (c-axis). The XRD and typical detached ingot was shown in earlier discussion. Some ingots were also cut longitudinal to the growth direction for compositional analysis (not studied XRD) . In brief, we have grown 35 ingots (InSb) and 37 ingots (GaSb) doped and undoped bulk crystals with various dopant materials. The ingots were grown by VDS into indigenous designed and fabricated vertical furnace into quarts ampoule of varying dimensions (attached file in earlier discussion) in a crystal growth chamber. Ingots have been grown without seed (seedless), without contact (contactless), without ampoule coating inside and without external fields (magnetic or gas pressure). However, 10% ingots showed preferential (111), (331) and (422) ingots growth direction, while 90% ingots showed preferential (220) ingots growth direction. The growth direction depends on the vertical position of quartz ampoules into growth chamber of the vertical furnace. The devices made on these substrates (220) showed enhanced characteristics and performance. Detached ingot growth mechanism in VDS and its physics concept has been reported elsewhere. However, in depth study of detached growth using VDS in terrestrial lab (on earth) and physics behind, it is in the process. The correlations, if any, with the detached crystals growths in space will also be analylized.