Talk:Material properties of diamond/GA2

GA Review

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Hi, I'll be performing this GA review. My usual routine lately is to go through the article twice, first time to copyedit and boldly fix any non-contentious errors (but feel free to revert or discuss if you feel otherwise); and then a second time focusing more on content and references. Will take a few days to do this, as I must balance reviewing duties with the dozens of other things that are fun to spend time on here :) Sasata (talk) 20:45, 23 June 2009 (UTC)

Initial comments: Sasata (talk) 16:58, 24 June 2009 (UTC)

Lede

• "...and it could be as high as 90-225 GPa depending on crystal direction." Crystal direction is not explained and is likely to be confusing to many readers (including me). I also wasn't able to find this explained in the article... and of course anything that's in the lede must be in the article as well.

  Fixed (direction → orientation) , and explained in the main text. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "Scientists classify diamonds into two main types, I and II, and four subtypes (Ia, Ib, IIa and IIb)," There's no context given for what these types and subtypes mean, so perhaps it's not necessary to list the names of the types in the lede.

  Deleted from the lead. Materialscientist (talk)

• "Trace impurities substitutionally replacing carbon atoms in a diamond's crystal lattice, and in some cases structural defects, are responsible for the wide range of colors seen in diamond." Why the link to substitution reactions? I didn't read anything about substitution reactions (i.e. Sn1 or Sn2) in the article.

  Wrong wikilink fixed. This has nothing to do with chemical substitutional reactions - one atom substitute another in the lattice. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• there's still a cite-needed tag in the lede.

  Deleted that trivia. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Hardness and crystal structure

• "Known to the ancient Greeks as adamas ("tame'sles" or "bridleless")" source?

  Added. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "It has been shown[2][3] that diamond aggregates having nanometer grain size could be harder and tougher than conventional large diamond crystals, thus they perform better as abrasive material." I think that unless it's totally necessary, the cites should be at the end of the sentence

  Indeed. Moved. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "...thus they perform better as abrasive material." Did the source actually test its use as an abrasive material, or is this a conjecture? If so, it may be better to write "they may perform better" If they did, change the "could" ("could be harder and tougher -> are harder and tougher))

  The tricky part was "some diamonds". Fixed. The applied hardness test was actually simulation of abrasion, thus the claim is valid. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "A (111) surface (normal to the largest diagonal of a cube)" this sentence will be confusing to those who don't understand what "normal" means in this context. And the (111) is jargon as well - I'm assuming this is crstallographic notation?

  Yes. Fixed. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

  Much better. I see some of the notations are bounded by () and some by [], please make this consistent. Also, it would be nice if there was a link somewhere in there so the reader could find out more info about what this notation means (how about Crystal system). Sasata (talk) 15:52, 25 June 2009 (UTC)

  Linked. To Crystallography#Notation (easy version). If you glance there you'll understand why it causes headache to most young scientists - there are four types of brackets (but brave X-ray diffraction people bluntly deny all rules and omit all brackets in their literature :). Each has its strict meaning, which is often neglected. For example, you can define a direction as a vector <111>, or as a "line" perpendicular to a plane (111) - in some situations those definitions are different, in some almost same, but we have to follow the bracket rules. In short - I would not explain those symbols but leave to those interested to dig in the links. I use only [] in the present version. Materialscientist (talk) 00:03, 26 June 2009 (UTC)

• Am getting a bit confused by the terminology... hardness is scored from 1 to 10, so how can a pure diamond have a hardness value of 167 GPa? Does this number refer to tensile strength?

  Not only you :) but we can't fix the situation in that science field here - there are so many terms for hardness. The Mohs scale (1 to 10) relates to "scratch hardness" and thus is proportional to the "Vickers hardness", "Brinell hardness", "Indentation hardness" or simply "hardness" (compression or scratch like). "Tensile strength" refers to twisting and bending and is another parameter (related, but not always proportional). Thus 167 GPa value is "hardness" Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "...which means that they have four Planes" is planes supposed to be capitalized?"

  No. Typo. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Toughness

• "The toughness of natural diamond has been measured as 2.0 MPa m^1/2" according to the toughness page, the units normally used are not the same as the one used here.

  Wrong WP article :) I relinked to the "right one". J/m3 units are academic (for theorists), not practical. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "The culet, which is a facet (parallel to the table) given to the pavilion of cut diamonds," I do not understand this phrase

  Deleted this unnecessary jargon. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "Solid foreign crystals are commonly present in diamond." Could this be elaborated slightly? What kind of foreign crystals might be found?

  Elaborated. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Optical properties

• "Diamonds occur in a restricted variety of colors..." is it a "wide range" (lede) or a "restricted variety" (here)?

  Blunder. Fixed. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "..knocking carbon atoms out of place and producing color centers." Color centers is linked to a region of the human brain

  Wrong wikilink fixed. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Luster

• "...although the body color of fancy diamonds may hide their fire to some degree." what is meant by fancy?

  Explained. Unfortunately, the term is all around the world, but is never defined. Just unusual colors. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "Many other minerals have higher dispersion than diamond:" higher dispersions? higher dispersion ratios? not sure which is correct

  No it is correct; not ratio, but difference. I added a primitive definition. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "synthetic rutile 0.330 ![18]" - not sure if the exclam was meant to be there but it looks awkward

  Deleted "!" Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Thermal conductivity

• units are given as W/cm•K, but as W/m•K in the thermal conductivity article... is there a standard unit that should be used?

  Same point as exclusive use of either meters or centimeters. There was a standartization attempt in the past to use only meters, which was quickly trashed. Most people use W/cm•K. I haven't got to some physics WP articles yet :) Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Thermal stability

• "Being a form of carbon, diamond graphitizes in the presence of oxygen" is graphitizes really a word? How about "turns into graphite"?

  graphitizes is very normal in science, but I changed to your version. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• "The fact that diamonds are combustible bears further examination because it is related to an interesting fact about diamonds." Not encylopedic - shouldn't be telling the reader what's interesting or worth further examination, just present the facts

  Indeed. Cut off trivia. Materialscientist (talk) 00:48, 25 June 2009 (UTC)

• the references could also use some cleanup, as they are inconsistent with regards to formatting... but I won't be too picky as it's only GA!

  At the time of rewriting this article, I haven't moved to cite templating yet. I have reformatted most refs now.

Thank you for careful reading ! Materialscientist (talk) 00:48, 25 June 2009 (UTC)

Comments about references: Sasata (talk) 15:52, 25 June 2009 (UTC)

• I checked some random references, and most of them were fine, i.e. the article accurately reflected what the source said. Just two concerns:

• "Being a form of carbon, diamond turns into graphite in the presence of oxygen if heated over 800 °C." The source abstract (didn't access the article) says that diamond "oxidizes in dry O2 in a vacuum furnace at temperatures up to 800 °C" Can you confirm this means the same thing, or that it's in the source somewhere? Also, the abstract qualifies the type of diamond (lightly textured (100) chemical vapour deposited (CVD) diamond), whereas the article just says "diamond", which looks misleading.

  I actually skipped the abstract :). (i) "turns into graphite" → "oxidizes" (my mistake; those two are closely related, but latter is what was actually measured). (ii) 800 → 700 (it depends what weight loss do you take for start of oxidation. The threshold is broad, but 700 C seems more representative); (iii) "lightly textured (100) chemical vapour deposited (CVD) diamond" = diamond. Those words only mean diamond was grown by CVD (but it is same good old diamond), and that its crystallographic orientation was [100]. A purist would say that orientation is important, but Table 1 of that paper compares results for different orientation and the dependence is weak. The reason I chose that specific article is it honestly measures weight loss. Most others do not provide quantitative values. Materialscientist (talk) 00:03, 26 June 2009 (UTC)

• "Blue emission from type IIa and IIb diamonds is reliably identified with dislocations by directly correlating the emission with dislocations in an electron microscope.[22]" The article abstract suggests that X-ray topography was used, not electron microscopy (but again I haven't read the whole article).

  Science trick. The abstract and article itself focuses on cathodoluminescence, which is light emission (from dislocations in that case) induced by electron beam (of electron microscope), i.e. it is a thorough topographical study; X-ray topography was supplemental. Thank you for careful reading. Any skepticism stimulates me to question the claims. Materialscientist (talk) 00:03, 26 June 2009 (UTC)

1. It is reasonably well written.

   a (prose): b (MoS):

Prose is fine; article largely complies with MOS (refs will still need some detail work if FAC is planned).

1. It is factually accurate and verifiable.

   a (references): b (citations to reliable sources): c(OR):

   Well-referenced. I checked a few random refs that were available on-line and they were fine. A couple of claims in the article need checking.

2. It is broad in its coverage.

   a (major aspects): b (focused):

   Coverage is broad (but I'm not an expert in the field).

3. It follows the neutral point of view policy.

   Fair representation without bias:

4. It is stable.

   No edit wars etc.:

5. It is illustrated by images, where possible and appropriate.

   a (images are tagged and non-free images have fair use rationales): b (appropriate use withsuitable captions):

   All images have appropriate free use licenses.

6. Overall:

   Pass/Fail:

   Pending last few revisions.

In my opinion, article is up to GA standards. Thanks for your contribution(s)! Sasata (talk) 05:36, 26 June 2009 (UTC)