# Talk:Europium

 Europium has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
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WikiProject Elements (Rated GA-class, Mid-importance)
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Article changed over to new Wikipedia:WikiProject Elements format by schnee. Elementbox converted 11:19, 10 July 2005 by Femto (previous revision was that of 13:44, 9 July 2005).

If so, it can't be 'moderately hard' - that's a contradiction in terms.

### Information Sources

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Europium. Data for the table WERE obtained from the sources listed on the subject page and Wikipedia:WikiProject Elements but was reformatted and converted into SI units.

## Source needed

"A salt of Europium is a component of the newer phosphorescent powders and paints, some of which will glow for days after a few minutes of exposure to light." I don't think this is possible (allthough it may be). I have commented it out in article page (< !-- -->). Please find some relevant source. --Borislav Dopudja 16:09, 14 September 2006 (UTC)

How is Europium used in screening for Down's Syndrome?--Syd Henderson 17:54, 1 October 2006 (UTC)

In a very generic way: by tagging, with europium, the antibodies for a relevant protein; reacting the antibodies with a serum sample; and then testing for presence of europium. Fortunately, the concentration of various proteins at specific times in pregnancy give a statistical signal for Down's syndrome. See (PDF): [1]. At any rate, it's very misleading to give such attention to Down's syndrome and this whole sentence is clumsy. Also United Nuclear appears to proudly sell a new line of Europium glow powder/paint with a shine-time of 12 hours: [2]--Tteravai (talk) 03:38, 27 August 2008 (UTC)

## Vague Phraseology

What is meant by the comment: "...deliveries of the metal element in solid form..." in the Characteristics section? I'm certain that the author can come up with a better way of phrasing this. R N Talley (talk) 19:06, 23 December 2008 (UTC)

I've changed "deliveries" to "samples". --Itub (talk) 20:22, 23 December 2008 (UTC)

## Water is a liquid

H2O (g) is probably a typo.

While it is possible that H2O (aq) (i.e. water vapor in a solution of water) may be what actually reacts in the 2 Eu + 6 H2O, I suspect that 2 Eu (s) + 6 H2O (l) → ... would suffice.

Water vapor dissolved in water? Heh... never heard of that. Wouldn't it just condense immediately? Anyway, fixed all the lanthanoid articles that had this error (it is clearly stated that it's cold water and hot water, so I'm assuming that it can't be referring to steam -- besides, the point was that these metals are quite reactive towards water, which wouldn't be the case if they required > 100°C to react). The joys of copy-n-paste... —Tetracube (talk) 03:40, 18 September 2009 (UTC)

## Infobox

Infobox says it's silvery white. Pictures indicate it's not. Was probably copied from somewhere else and not changed. Anyone know how to properly describe it? --Jinman11 (talk) 08:57, 13 May 2010 (UTC)

From what I can tell, it is silvery white, but is almost impossible to observe pure, since it oxidizes in seconds (like calcium). The samples pictured here appear to be slightly oxidized; even a thin layer can drastically change the appearance. As with other metals (like bismuth, niobium, titanium, and aluminum), the oxide thickness determines the apparent color of the sample, which can vary widely. Here is a more heavily oxidized piece of Eu that appears dark bluish-green: [3] and here is one that looks more light green: [4]. Stonemason89 (talk) 18:18, 15 May 2010 (UTC)
Infobox changed to reflect the fact that Eu is rarely seen without an oxide coat. Stonemason89 (talk) 18:23, 15 May 2010 (UTC)
Yeah, it is definitely silvery-white, but oxidizes inconveniently quickly. Does anybody have a CC-BY-SA compatible picture of the oxide? - 2/0 (cont.) 19:10, 15 May 2010 (UTC)
Sure, we have File:Eu2O3.powder.jpg, and it is white and there is no doubt about it (pale red color of some powders might be due to strong luminescence of Eu oxide powder under UV light). There is also little doubt that pure Eu is white. The Eu in images is handled in Ar, but I this won't save from surface oxidation. I don't have a good answer and will search for it when time permits. An explanation is welcome.

UV 'light'? Oh, dear ...

Materialscientist (talk) 01:22, 16 May 2010 (UTC)

The oxide is white in bulk (as are many other oxides) but sufficiently thin layers of it can and do display colors. See anodizing for more information, specifically the sections on titanium and niobium. Any transparent material can display such colors if it is deposited in sufficiently thin layers. The underlying principle is the same as that used in manufacturing dielectric mirrors. Stonemason89 (talk) 18:50, 16 May 2010 (UTC)
I thought about that, but my concern was the rough surface of the material which would suppress interference (angle change constantly and thus reflected color). Yes, it should be related to the color of the oxide, and the color changes on those chunks, but I'm not sure it is just thin film interference. Materialscientist (talk) 22:29, 16 May 2010 (UTC)
Yes, but even for rough surfaces there's still an average angle of reflection, so the overall apparent color might be related to this average angle? Maybe I'm just grasping at straws here. For what it's worth, the image description for Eu-block.jpg says that it is polycrystalline, which would imply that its surface is not truly rough but is rather made up of many tiny, but smooth, facets.Stonemason89 (talk) 00:03, 17 May 2010 (UTC)

It shouldn't be THAT difficult to observe in a vacuum glass container, surely? Isn't that what one of the pictures shows? — Preceding unsigned comment added by 92.2.221.112 (talk) 19:13, 1 February 2014 (UTC)

## Error in vapor pressure?

In the info box, shouldn't the vapor pressure at 1796K, which is nearly the boiling point, be closer to 100kPa ~1atm than 1kPa?Wikimedes (talk) 09:57, 10 June 2011 (UTC)

There was a typo in the code of the infobox that messed up the pressure scale of the table. Fixed. Thanks! Materialscientist (talk) 10:30, 10 June 2011 (UTC)

## References

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--Stone (talk) 21:01, 13 June 2011 (UTC)

## GA Review

Reviewer: 05:02, 25 July 2011 (UTC)

Woohoo. Back from the GOCE's drive, I have this thing to review. 05:02, 25 July 2011 (UTC)

### Review

GA review – see WP:WIAGA for criteria

1. Is it reasonably well written?
A. Prose quality:
Particularly for this, the sections should have as few distinct paragraphs as possible. This thing needs cohesion.
B. MoS compliance for lead, layout, words to watch, fiction, and lists:
2. Is it factually accurate and verifiable?
A. References to sources:
B. Citation of reliable sources where necessary:
C. No original research:
3. Is it broad in its coverage?
A. Major aspects:
Although that suffices, I would like a coverage of the compounds and precautions as in-depth as samarium.
B. Focused:
4. Is it neutral?
Fair representation without bias:
5. Is it stable?
No edit wars, etc:
6. Does it contain images to illustrate the topic?
A. Images are copyright tagged, and non-free images have fair use rationales:
B. Images are provided where possible and appropriate, with suitable captions:
The only issue here is the captions: two of them are wrongly formatted. dendritic sublimated Eu handled in a glovebox (~300 g; purity 99.998%) and Europium sulfate, Eu2(SO4)3 (top), fluoresces red under ultraviolet light (bottom).
7. Overall:
Pass or Fail:

### Issues

#### 2b

• Divalent europium is, however, a mild reducing agent, oxidizing in air to Eu(III) compounds. Under anaerobic, and particularly under geothermal conditions, the divalent form is sufficiently stable such that it tends to be incorporated into minerals of calcium and the other alkaline earths. This ion-exchange process is the basis of the "negative europium anomaly", the low europium content in many lanthanide minerals such as monazite, relative to the chondritic abundance. Bastnäsite tends to show less of a negative europium anomaly than does monazite, and hence is the major source of europium today. The development of easy methods to separate europium from the other trivalent lanthanides made europium accessible even when present in low concentration, as it usually is. (Eu2+ vs. Eu3+)
• Europium is commonly included in trace element studies in geochemistry and petrology to understand the processes that form igneous rocks (rocks that cooled from magma or lava). The nature of the europium anomaly found is used to help reconstruct the relationships within a suite of igneous rocks. (Occurrence)
• The most outstanding examples of this originated around Weardale, and adjacent parts of northern England, and indeed it was this fluorite that gave its name to the phenomenon of fluorescence, although it was not until much later that europium was discovered or determined to be the cause. (Occurrence)
• Europium has continued in use in the TV industry ever since, and, of course, also in computer monitors. Californian bastnäsite now faces stiff competition from Bayan Obo, China, with an even "richer" europium content of 0.2%. (History)
• Relative to most other elements, commercial applications for europium are few and rather specialized. Almost invariably, they exploit its phosphorescence, either in the +2 or +3 oxidation state. (Applications)
• One more problem that is not immediately obvious: the refs are bunched up together. Try and space them out, one for every statement. 03:48, 27 July 2011 (UTC)

#### 1b

• The lead section is lacking on the area of applications.
• The precautions section discusses things in an unacceptable wording: "were" (reporter's point) instead of "have been" (encyclopedic point).
• In the section on Eu as a nuclear fission product, the two tables are misaligned and don't look good. Is there a way to fix it? If so, do it. 01:44, 29 July 2011 (UTC)
• Not done I'm not sure how to do it --Lanthanum-138 (talk) 07:54, 10 August 2011 (UTC)

#### 1a

• Europium is a chemical element with the symbol Eu and atomic number 63, which was named after the continent of Europe. Redundant wording.
• Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3; however, europium compounds with the oxidation state +2 are also common, and all of them are slightly reducing. Repeated ideas within a sentence are not so good.
• Characteristics
• Physical properties
• Europium becomes a superconductor when it is cooled below 1.8 K and compressed to above 80 GPa that was explained as follows. Europium is divalent in the metallic state, and the applied pressure converts it into the trivalent state. In the divalent state, the strong local magnetic moment (J = $7 \over 2$) suppresses the superconductivity, which is induced by eliminating this local moment (J = 0 in Eu3+). Reads more like a story than a piece of an encyclopedia.
• Eu2+ versus Eu3+
• The +2 state has a configuration 4f7, the half-filled f-shell being known to confer stability. Reword this since it may be confusing to people.
• In terms of size and coordination number, europium(II) and barium(II) are similar. For example, the sulfates of both barium and europium(II) are also highly insoluble in water. Generally, when two short sentences share a similar idea, it is better to put them together with a semicolon than just leaving them alone.
• Divalent europium is, however, a mild reducing agent, oxidizing in air to Eu(III) compounds. Under anaerobic, and particularly under geothermal conditions, the divalent form is sufficiently stable such that it tends to be incorporated into minerals of calcium and the other alkaline earths. More repeats.
• Isotopes
• While 153Eu is stable, 151Eu was recently found to be unstable to alpha decay with half-life of 5+11
−3
× 1018 year (in reasonable agreement with theoretical predictions), giving about 1 alpha decay per two minutes in every kilogram of natural europium.
Grammar errors.
• The primary decay mode before the most abundant stable isotope, 153Eu, is electron capture, and the primary mode after is beta minus decay. Since the sentence regards 153Eu only, the bolded segment should be removed.
• Occurence
• The nature of the europium anomaly found is used to help reconstruct the relationships within a suite of igneous rocks. Replace with help.
• Divalent europium (Eu2+ in small amounts is the activator of the bright blue fluorescence of some samples of the mineral fluorite (CaF2). Bad bracket and repeated ideas.
• The most outstanding examples of this originated around Weardale, and adjacent parts of northern England, and indeed it was this fluorite that gave its name to the phenomenon of fluorescence, although it was not until much later that europium was discovered or determined to be the cause. Redundant punctuation and words. 07:48, 29 July 2011 (UTC)
• Production
• Europium is associated with the other rare earth elements and therefore is mined together with them. Swapped words.
• Which of the methods is used is based on the concentration and composition of the ore and on the distribution of the individual lanthanides in the resulting concentrate.[clarification needed]
• Roasting the ore and subsequent acid and basic leaching is used mostly to produce a concentrate of lanthanides. They go together, like Latias and Latios, so: Comma Please.
• If cerium is the dominant lanthanide then it is converted from cerium(III) to cerium(IV) and than precipitated. Another comma, please, and correct the spelling error.
• The Bayan Obo iron ore deposit contains significant amounts of bastnäsite and monazite and is with an estimated 36 million tonnes of rare earth element oxides the largest known deposit. Two commas needed.
• Compounds
• Halides
• This route gives white europium(III) fluoride (EuF3), yellow europium(III) chloride (EuCl3), and gray europium(III) bromide (EuBr3), and colorless europium(III) iodide (EuI3). Europium also forms the corresponding dihalides including yellow-green europium(II) fluoride (EuF2), colorless europium(II) chloride (EuCl2), colorless europium(II) bromide (EuBr2), and green europium(II) iodide (EuI2). Redundant words.
• Chalcogenides and pnictides
• Otherwise the following are the main chalcogenide with the formulae EuX (X = S, Se, Te), all three of which are black solids. EuS is prepared by sulfiding the oxide at temperatures sufficiently high to decompose the Eu2S3: Some people may not understand the first bolded section. The second is actually contradictory to the equation that follows, and should be replaced by Eu2O3.
• History
• Although europium is present in most of the minerals containing the other rare elements, due to the difficulties in separating the elements it wasn't until the late 1800s that the element was isolated. No contractions.
• Europium was first found by Paul Émile Lecoq de Boisbaudran in 1890, who obtained basic fraction from samarium-gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium; however, the discovery of europium is generally credited to French chemist Eugène-Anatole Demarçay, who suspected samples of the recently discovered element samarium were contaminated with an unknown element in 1896 and who was able to isolate europium in 1901. Split this sentence into two and correct the grammar error. The last issue here should be replaced by isolated it.
• When the europium-doped yttrium orthovanadate red phosphor was discovered in the early 1960s, and understood to be about to cause a revolution in the color television industry, there was a scramble for the limited supply of europium on hand among the monazite processors. (Typical europium content in monazite is about 0.05%.) Merge the two sentences together.
• Frank Spedding, celebrated for his development of the ion-exchange technology that revolutionized the rare earth industry in the mid-1950s once related the story of how, in the 1930s, he was lecturing on the rare earths when an elderly gentleman approached him with an offer of a gift of several pounds of europium oxide. The commas are wrong.
• Applications
• One of the more common persistent after glow phosphors besides copper doped zinc sulfide is europium doped strontium aluminate. Is it better to hyphenate these two words? 03:29, 31 July 2011 (UTC)

Done All done --Lanthanum-138 (talk) 07:35, 10 August 2011 (UTC)

#### 6b

Done Lanthanum-138 (talk) 07:39, 10 August 2011 (UTC)

## looks like some people were interested, but not TOO interested

Eu complexes (some details!) in the euro notes Double sharp (talk) 02:58, 25 June 2013 (UTC)