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第1行:
{{noteTA
|T=zh-cn:镎; zh-tw:錼; zh-hk:鎿;
|G1=Chemistry
|G2=Unit
}}
{{Elementbox
第18行:
|series color=ff99cc
|phase color=
|image name= neptunium21g of neptunium metal.jpg
|appearance=銀色的金屬光澤
|atomic mass= ([237) ]
|electron configuration= &#91;[[氡|Rn]]&#93; 5f<sup>4</sup> 6d<sup>1</sup> 7s<sup>2</sup>
|electrons per shell= 2, 8, 18, 32, 22, 9, 2
第28行:
|melting point C=637
|melting point F=1179
|boiling point K=4273 4447
|boiling point C=4000 4174
|boiling point F=72327545
|boiling point comment=外推
|heat fusion= 3.20
|heat vaporization= 336
第52行 ⟶ 第53行:
|thermal conductivity= 6.3
|CAS number= 7439-99-8
|isotopes={{infobox neptunium isotopes}}
{{Elementbox_isotopes_decay | mn=235 | sym=Np
| na=[[放射性同位素|人造]] | hl=396.1 天
| dm1={{衰變|α}} | de1=5.192 | pn1=231 | ps1=鏷
| dm2={{衰變|電子捕獲}} | de2=0.124 | pn2=235 | ps2=鈾}}
{{Elementbox_isotopes_decay | mn=236 | sym=Np
| na=人造 | hl=1.54&times;10<sup>5</sup> 年
| dm1={{衰變|電子捕獲}} | de1=0.940 | pn1=236 | ps1=U
| dm2={{衰變|β-}} | de2=0.940 | pn2=236 | ps2=鈈
| dm3=α | de3=5.020 | pn3=232 | ps3=Pa}}
{{Elementbox_isotopes_decay | mn=237 | sym=Np
| na=[[痕量放射性同位素|痕量]] | hl=2.144&times;10<sup>6</sup> 年
| dm1={{衰變|自發裂變}}、 {{衰變|α}} | de1=4.959 | pn1=233 | ps1=Pa}}
{{Elementbox_isotopes_decay | mn=239 | sym=Np
| na=痕量 | hl=2.356 天
| dm1={{衰變|β-}} | de1=0.218 | pn1=239 | ps1=Pu}}
|isotopes comment=
|discovered by=[[埃德溫·麥克米倫]]和[[菲力普·艾貝爾森]]
|discovery date=1940
}}
{{地區用詞2|zh-cn='''{{zy|-{zh-hans:镎;zh-hant:鎿;}-|ná|ㄋㄚˊ|naa4}}'''|zh-tw='''{{zy|-{錼}-|nài|ㄋㄞˋ|noi6}}'''|equiv-hk=cn|as=譯|start=({{lang-en|Neptunium}};}},是一種[[化學元素]],其[[化學符號]]为'''{{化學式|鎿}}''',[[原子序數]]为93。屬於[[錒系元素]],且是首個[[超鈾元素]],於1940年由[[勞倫斯柏克萊國家實驗室|柏克萊輻射實驗室]]的[[埃德温·麦克米伦]]和[[菲力普·艾貝爾森]]首次合成出來,並參照以[[天王星]]({{lang|en|Uranus}})為名的[[鈾]],將其以[[海王星]]({{lang|en|Neptune}})命名。
'''錼'''('''Neptunium''',-{zh-tw:中國大陸、港澳譯作'''鎿''';zh-hk:台灣譯作'''錼''';zh-cn:台湾译作'''錼''';}-)是一種[[化學元素]],符號為'''Np''',[[原子序]]為93。錼是首個[[超鈾元素]],屬於[[錒系元素|錒系]]金屬。錼具有放射性,其最穩定的[[同位素]]<sup>237</sup>Np是[[核反應爐]]和[[鈈]]生產過程的副產品,能夠用於製造中子探測儀。由於[[核嬗變]]反應,[[鈾]]礦當中存在著微量錼元素。<ref name=CRC>{{cite book| author = C. R. Hammond |title = The Elements, in Handbook of Chemistry and Physics 81st edition| publisher =CRC press| isbn = 0-8493-0485-7| year = 2004}}</ref>
 
錼是一種堅硬、有[[延展性]]的高[[密度]][[金屬]],是所有錒系元素中密度最大的,在所有天然元素中密度第五高,僅次於[[錸]]、[[鉑]]、[[銥]]和[[鋨]]。錼金屬外觀為銀白色,暴露在空氣中表面會氧化而失去光澤。錼有三種[[同素異形體]],且在水溶液中能表現出+3到+7共五種[[氧化態]],其中以+5最為穩定。錼具有[[放射性]],其最穩定的[[同位素]]為<sup>237</sup>Np,半衰期為214萬年。由於錼有放射性、有毒,在粉末狀態下能自燃,且攝入人體後會在[[骨骼]]中積聚,因此處理錼元素具有一定的危險性。
 
現時絕大多數的錼是[[核燃料]]中的鈾吸收[[中子]]后產生的,為[[核反應爐]]和[[鈈]]生產過程常見的副產品。雖然镎本身目前沒有商業用途,但它被用作生產[[鈽-238|<sup>238</sup>Pu]]的母體,而<sup>238</sup>Pu是航天和軍事上的[[放射性同位素熱電機]]中常用的熱源。镎也被用於高能中子探測儀。
 
由於[[核嬗變]]反應,天然[[鈾]]礦當中存在著[[痕量同位素|痕量]]錼元素,故錼是少數存在於自然界中的超鈾元素。<ref name=CRC>{{cite book| author = C. R. Hammond |title = The Elements, in Handbook of Chemistry and Physics 81st edition| url = https://archive.org/details/crchandbookofche81lide | publisher =CRC press| isbn = 0-8493-0485-7| year = 2004}}</ref>
 
==歷史==
[[德米特里·门捷列夫]]於1870年代出版的[[元素週期表]]在鈾之後的位置顯示的是一條橫線「-」,其他當時未發現的元素亦然。1913由[[卡西米爾·法揚斯]]出版的已知放射性同位素列表中,也同樣在鈾之後留了空格。<ref>{{cite journal | last1 = Fajans | first1 = Kasimir | title = Die radioaktiven Umwandlungen und das periodische System der Elemente | journal = Berichte der deutschen chemischen Gesellschaft | volume = 46 | pages = 422 | year = 1913 | doi = 10.1002/cber.19130460162}}</ref>
 
===誤報===
第81行 ⟶ 第73行:
 
===實際發現===
[[File:Berkeley 60-inch cyclotron.gifjpg|thumb|left|upright|伯克利加州大學勞倫斯伯克利國家實驗室的1.5米直徑迴旋加速器,攝於1939年8月]]
在93號元素被發現之前,當時的元素週期表還沒有錒系這一行,因此釷、鏷和鈾分別位於鉿、鉭和鎢之下,93號元素也在錸之下。根據這一排位推測,93號元素的特性應該與錳和錸相似。這意味著這一元素不可能從礦石中提取出來,儘管人們於1952年在鈾礦中探測到了錼元素。<ref>{{cite journal | last1 =Peppard | first1 =D. F. | last2 =Mason | first2 =G. W. | last3 =Gray | first3 =P. R. | last4 =Mech | first4 =J. F. | journal =Journal of the American Chemical Society | volume =74 | pages =6081 | year =1952 | doi =10.1021/ja01143a074 | issue =23}}</ref>
 
第91行 ⟶ 第83行:
| image1 = Mcmillan postcard.jpg
| alt1 = A photo of Edwin McMillan
| image2 = Philip Hauge Abelson.jpg
| alt2 = A photo of Philip Abelson
}}
費米相信對[[鈾]]進行中子撞擊,再經β衰變後,可產生93號元素。實驗產物具有短半衰期,因此費米於1934年宣佈發現了新元素,<ref name="Fermi">{{cite journal | doi =10.1038/133898a0 | title =Possible Production of Elements of Atomic Number Higher than 92 | year =1934 | author =Fermi, E. | journal =Nature | volume =133 | pages =898 | bibcode=1934Natur.133..898F | issue =3372}}</ref>然而這卻是錯誤的。後來人們猜測<ref>{{cite journal|author=Ida Noddack|authorlink=Ida Noddack|year=1934|pages=653|title=Über das Element 93|volume=47|journal=Zeitschrift für Angewandte Chemie|url=http://www.chemteam.info/Chem-History/Noddack-1934.html|doi=10.1002/ange.19340473707|issue=37|access-date=2013-05-26|archive-date=2017-12-11|archive-url=https://web.archive.org/web/20171211223522/http://www.chemteam.info/Chem-History/Noddack-1934.html}}</ref>並證實,<ref>{{cite journal|last1=Meitner|first1=Lise|last2=Frisch|first2=O. R.|doi=10.1038/143239a0|title=Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction|year=1939|pages=239|volume=143|journal=Nature|url=http://www.nature.com/physics/looking-back/meitner/index.html|bibcode=1939Natur.143..239M|issue=3615|access-date=2013-05-26|archive-date=2019-04-28|archive-url=https://web.archive.org/web/20190428141914/http://www.nature.com/physics/looking-back/meitner/index.html|dead-url=no}}</ref>當時的產物是中子導致鈾進行[[核裂變]]所產生的。[[奧托·哈恩]]在1930年代末進行的<sup>239</sup>U衰變實驗中,產生了少量的錼。Hahn的團隊通過實驗生產並證實了<sup>239</sup>U的屬性,但未成功分離和探測到錼。<ref>{{cite journal|url=http://www.crownedanarchist.com/emc2/discovery_of_fission.doc|title=Discovery of fission|author=Otto Hahn|journal=Scientific American|year=1958}}{{dead link|access-date=2018年5月 2013-05-26|botarchive-date=InternetArchiveBot 2010-12-24|fixarchive-attemptedurl=https://web.archive.org/web/20101224154146/http://www.crownedanarchist.com/emc2/discovery_of_fission.doc|dead-url=yes }}</ref>
 
[[埃德温·麦克米伦]]和[[菲力普·艾貝爾森]]於1940年在[[伯克利加州大學]]的伯克利輻射實驗室正式[[化學元素發現年表|發現]]了錼。錼(Neptunium)以[[海王星]](Neptune)命名,它的前一元素鈾(Uranium)則以[[天王星]](Uranus)命名。研究團隊以低速中子撞擊[[鈾]],生成了錼[[同位素]]<sup>239</sup>Np([[半衰期]]為2.4天)。錼是首個被發現,也是首個人工合成的[[錒系元素|錒系]][[超鈾元素]]。<ref name="EL93">{{cite journal| doi =10.1103/PhysRev.57.1185.2| title =Radioactive Element 93| year =1940| author =Mcmillan, Edwin| journal =Physical Review| volume =57| pages =1185| last2 =Abelson| first2 =Philip| issue =12|bibcode = 1940PhRv...57.1185M }}</ref>
第100行 ⟶ 第92行:
:<math>\mathrm{^{238}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow \ ^{239}_{\ 92}U\ \xrightarrow[23 \ min]{\beta^-} \ ^{239}_{\ 93}Np\ \xrightarrow[2.355 \ d]{\beta^-} \ ^{239}_{\ 94}Pu}</math>
 
==存量物理特性==
錼是銀色、有[[延性]]的[[放射性]][[金屬]],在[[元素周期表]]中位于[[铀]]和[[钚]]之间,[[镧系元素]][[钷]]的下面。{{sfn|Yoshida et al.|2006|pp=718}}镎较硬,体积模量118&nbsp;[[帕斯卡|GPa]],与[[锰]]相近。<ref>{{cite journal |last1=Dabos |first1=S. |last2=Dufour |first2=C. |last3=Benedict |first3=U. |last4=Pagès |first4=M. |date=1987 |title=Bulk modulus and P–V relationship up to 52&nbsp;GPa of neptunium metal at room temperature |journal=Journal of Magnetism and Magnetic Materials |volume=63–64 |pages=661–3 |doi=10.1016/0304-8853(87)90697-4|bibcode = 1987JMMM...63..661D }}</ref>镎暴露于空气时会形成一层氧化层,该反应在高温下更迅速。{{sfn|Yoshida et al.|2006|pp=718}}镎在639±3&nbsp;°C下就会融化。它的低熔点和旁边的钚(熔点639.4&nbsp;°C)一样源自5f和6d轨道的[[轨道杂化|杂化]]及金属间有方向性的金属键。<ref name="Yu. D. Tretyakov" />镎的沸点还未经实验得知,通过[[蒸汽压]]数值外推出来的沸点是4174&nbsp;°C。如果属实,镎会有所有元素間最高的液態溫度區間,其熔點和沸點溫度差為3535&nbsp;[[開氏度|K]]。{{sfn|Yoshida et al.|2006|pp=718}}<ref name="Gray" />
最穩定的錼同位素是<sup>237</sup>Np,半衰期為200萬年。這比[[地球年齡]]短得多,因此所有[[原始核素|原始]]的錼元素,也就是地球形成時就存在的錼,至今已衰變殆盡了。然而在[[鈾礦]]中,自然[[核嬗變]]反應會產生[[衰變產物]],當中含有微量的錼-237至錼-240。<ref name=CRC/><ref name = "Nature's Building Blocks"/>
 
要產生<sup>237</sup>Np金屬,須將<sup>237</sup>NpF<sub>3</sub>與液態[[鋇]]或[[鋰]]在1200 °[[攝氏度|C]]高溫下反應。含錼的反應原料可從[[乏核燃料]]中作為[[鈈]]生產過程的副產品提取出來,單次提取量有數公斤。<ref name = "Nature's Building Blocks"/>
 
錼具有三種[[同素異形體]]: <ref name=CRC/>
:2 {{chem|NpF|3}} + 3 Ba → 2 Np + 3 {{chem|BaF|2}}
 
依重量計,錼-237產量是鈈產量的5%,或所有乏核燃料的0.05%。<ref>{{cite web| format=PDF| url = http://www.isis-online.org/publications/fmct/book/New%20chapter%205.pdf| title = Separated Neptunium 237 and Americium| accessdate = 2009-06-06}}</ref>不過錼的年產量仍然超過50噸。<ref name="rsc">http://www.rsc.org/chemistryworld/podcast/interactive_periodic_table_transcripts/neptunium.asp</ref>
 
==特性==
錼是一種[[金屬]],外表呈銀色,化學活性很高。錼具有三種[[同素異形體]]: <ref name=CRC/>
* α型:屬於[[正交晶系]],密度20.45 g/cm<sup>3</sup>;<ref name = "alo">{{cite journal | last1 = Lee | first1 = J | last2 = Mardon | first2 = P | last3 = Pearce | first3 = J | last4 = Hall | first4 = R | title = Some physical properties of neptunium metal IIA study of the allotropic transformations in neptunium | journal = Journal of Physics and Chemistry of Solids | volume = 11 | pages = 177 | year = 1959 | doi = 10.1016/0022-3697(59)90211-2 | issue = 3–4|bibcode = 1959JPCS...11..177L }}</ref>
* β型:出現於280 °C以上,屬於[[四方晶系]],313 °C時密度19.36 g/cm<sup>3</sup>;<ref name = "alo"/>
* γ型:出現於577 °C以上,屬於[[立方晶系]],600 °C時密度18 g/cm<sup>3</sup>。<ref name = "alo"/>
 
有声称发现了镎的第四种同素异形体,但仍未证实。{{sfn|Yoshida et al.|2006|pp=718}}锕系元素都有很多同素异形体。[[镤]]、铀、镎、钚的[[晶体结构]]不像镧系元素,更像第4周期的[[过渡金属]]。<ref name="Yu. D. Tretyakov">{{cite book|editor=Yu. D. Tretyakov|title = Non-organic chemistry in three volumes| place =Moscow|publisher = Academy|date = 2007|volume = 3|series = Chemistry of transition elements|isbn = 978-5-7695-2533-9}}</ref>
錼的液態溫度區間是所有元素間最高的,其熔點和沸點溫度差為3363 [[開氏度|K]]。
 
錼是所有錒系元素中密度最高的,在所有產生的元素中密度第五高,仅次于[[锇]]、[[铱]]、[[铂]]、[[铼]]。<ref name="Gray">Theodore Gray. ''The Elements''. Page 215</ref>錼不存在没有生物作用,但會被消化系統吸收。如果注射到身體裏,錼會累積在[[骨骼]]當中,並慢慢減少。
 
==化學特性==
[[File:Np_ox_st.jpg|thumb|350px|right|溶液中的錼離子]]
錼的化學活性很高。在溶液中具有4種離子[[氧化態]]:
* Np<sup>3+</sup>(淡紫色),相似於稀土元素離子Pm<sup>3+</sup>
* Np<sup>4+</sup>(黃綠色)
* {{chem|NpO|2|+}}(藍綠色)
* {{chem|NpO|2|2+}}(淡粉紅色)
 
氫氧化錼(III)不溶於水和過鹼溶液中。錼(III)在空氣中會氧化為錼(IV)。<ref>{{cite book | url = http://books.google.de/books?id=1lArAAAAYAAJ | title = Radiochemistry of neptunium | author1 = Burney, G. A | author2 = Harbour, R. M | author3 = Subcommittee On Radiochemistry, National Research Council (U.S.) | author4 = Technical Information Center, U.S. Atomic Energy Commission | year = 1974 | access-date = 2013-05-26 | archive-date = 2015-04-15 | archive-url = https://web.archive.org/web/20150415205351/http://books.google.de/books?id=1lArAAAAYAAJ }}</ref><ref>{{cite book | url =http://books.google.de/books?id=UnQ_NQAACAAJ | title =The migration chemistry of neptunium | isbn =978-87-550-1535-7 | author1 =Nilsson, Karen | year =1989 | access-date =2013-05-26 | archive-date =2015-04-15 | archive-url =https://web.archive.org/web/20150415205400/http://books.google.de/books?id=UnQ_NQAACAAJ }}</ref>
 
錼可以形成三[[鹵化物]]和四鹵化物,如NpF<sub>3</sub>、NpF<sub>4</sub>、NpCl<sub>4</sub>、NpBr<sub>3</sub>和NpI<sub>3</sub>等,以及類似於鈾氧化合物系統的各種[[氧化物]],包括Np<sub>3</sub>O<sub>8</sub>和[[二氧化錼|NpO<sub>2</sub>]]。
 
[[六氟化錼]](NpF<sub>6</sub>)是一種類似於[[六氟化鈾]]的揮發性物質。
 
錼和鏷、鈾、鈽和[[鋂]]一樣,能夠形成線形二氧錼芯(NpO<sub>2</sub><sup>n+</sup>),其中的錼原子呈5+或6+氧化態。錼會與[[氧]]、[[蒸汽]]和[[酸]]產生劇烈反應,但不被[[鹼]]侵蝕。<ref name = "Nature's Building Blocks"/>
 
* NpO<sub>2</sub>(OH)<sub>2</sub><sup>–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sup>–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sub>2</sub><sup>3–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub><sup>5–</sup>
 
==同位素==
{{Main|錼的同位素}}
已知的錼同位素有19種,全部都具有[[放射性]]。其中最穩定的包括:<sup>237</sup>Np,[[半衰期]]214萬年;<sup>236</sup>Np,半衰期152,000年;以及<sup>235</sup>Np,半衰期396.1天。所有剩餘的[[放射性同位素]]半衰期都在4.5天以下,大部分甚至在50分鐘以下。錼還有4種[[同核異構體]],最穩定的是<sup>236m</sup>Np,半衰期22.5小時。
 
錼同位素的[[原子量]]在225.0339 [[原子質量單位|u]](<sup>225</sup>Np)和244.068 u(<sup>244</sup>Np)之間。質量比最穩定的<sup>237</sup>Np低的同位素以[[電子捕獲]]的[[衰變模式|模式]]衰變(一部分也進行[[α衰變]]),比它高的同位素則進行[[β衰變]]。前者的衰變產物是鈾的各種同位素,後者則衰變為鈈同位素。
 
<sup>237</sup>Np能夠進行[[核裂變]]。<ref name="critical" />它衰變後最終穩定物是[[鉈|<sup>205</sup>Tl]]-205,但,而其他重原子核的[[衰變鏈]]末端終點都是[[鉛的同位素]]。<sup>237</sup>Np的特殊衰變鏈稱為[[錼衰變系]]。此外,<sup>237</sup>Np能夠進行[[核裂變]]。<ref name="critical" />
 
==存量==
最穩定的錼同位素是<sup>237</sup>Np,半衰期為200萬年。這比[[地球年齡]]短得多,因此所有[[原始核素|原始]]的錼元素,也就是地球形成時就存在的錼,至今已衰變殆盡了。然而在[[鈾礦]]中,自然[[核嬗變]]反應會產生[[衰變產物]],當中含有微量的錼-237至錼-240,因此錼是少數存在於自然界中的超鈾元素。<ref name=CRC/><ref name = "Nature's Building Blocks"/>
 
要產生<sup>237</sup>Np金屬,須將<sup>237</sup>NpF<sub>3</sub>與液態[[鋇]]或[[鋰]]在1200 °[[攝氏度|C]]高溫下反應。含錼的反應原料可從[[乏核燃料]]中作為[[鈈]]生產過程的副產品提取出來,單次提取量有數公斤。<ref name ="Nature's Building Blocks"/>
 
<chem>2 NpF3 + 3 Ba -> 2 Np + 3 BaF2</chem>
 
依重量計,錼-237產量是鈈產量的5%,或所有乏核燃料的0.05%。<ref>{{cite web| format = PDF| url = http://www.isis-online.org/publications/fmct/book/New%20chapter%205.pdf| title = Separated Neptunium 237 and Americium| accessdate = 2009-06-06| archive-date = 2011-08-22| archive-url = https://www.webcitation.org/618balVfw?url=http://www.isis-online.org/publications/fmct/book/New%20chapter%205.pdf| dead-url = yes}}</ref>不過錼的年產量仍然超過50噸。<ref name="rsc">{{Cite web |url=http://www.rsc.org/chemistryworld/podcast/interactive_periodic_table_transcripts/neptunium.asp |title=存档副本 |access-date=2013-05-26 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304000859/http://www.rsc.org/chemistryworld/podcast/interactive_periodic_table_transcripts/neptunium.asp }}</ref>
 
==合成==
要製成錼金屬,須在1200 °C高溫下用鋇或鋰對三氟化錼(NpF<sub>3</sub>)進行[[氧化還原反應|還原]]。<ref name=CRC/>大部分的錼都是在核反應中產生的:
* [[鈾-235]]原子在捕獲一顆中子後,會變為[[鈾-236]]的激化態。這些激化了的原子核有大約81%會進行裂變,剩餘的衰變為<sup>236</sup>U的基態,並釋放[[伽馬射線]]。再次[[中子捕獲|捕獲中子]]後,<sup>236</sup>U會變為<sup>237</sup>U,其半衰期為7天,並且會快速經[[β衰變]]形成<sup>237</sup>Np。在β衰變過程中,激化的<sup>237</sup>U原子核釋放一顆電子,[[弱交互作用]]再把一顆[[中子]]轉變為一顆[[質子]],從而產生<sup>237</sup>Np。
 
第139行 ⟶ 第154行:
較重的錼同位素迅速衰變,而較輕的錼同位素則無法通過[[中子捕獲]]形成,因此從乏核燃料中化學提取出的錼幾乎完全由<sup>237</sup>Np組成。
 
要製成純的錼金屬,須在1200°C高溫下用[[鋇]]或[[鋰]]對[[三氟化錼]](NpF<sub>3</sub>)進行[[氧化還原反應|還原]]。<ref name=CRC/>
==化學特性==
[[File:Np_ox_st.jpg|thumb|350px|right|溶液中的錼離子]]
錼在溶液中具有4種離子[[氧化態]]:
* Np<sup>3+</sup>(淡紫色),相似於稀土元素離子Pm<sup>3+</sup>
* Np<sup>4+</sup>(黃綠色)
* {{chem|NpO|2|+}}(藍綠色)
* {{chem|NpO|2|2+}}(淡粉紅色)
 
氫氧化錼(III)不溶於水和過鹼溶液中。錼(III)在空氣中會氧化為錼(IV)。<ref>{{cite book | url = http://books.google.de/books?id=1lArAAAAYAAJ | title = Radiochemistry of neptunium | author1 = Burney, G. A | author2 = Harbour, R. M | author3 = Subcommittee On Radiochemistry, National Research Council (U.S.) | author4 = Technical Information Center, U.S. Atomic Energy Commission | year = 1974}}</ref><ref>{{cite book | url =http://books.google.de/books?id=UnQ_NQAACAAJ | title =The migration chemistry of neptunium | isbn =978-87-550-1535-7 | author1 =Nilsson, Karen | year =1989}}</ref>
 
錼可以形成三[[鹵化物]]和四鹵化物,如NpF<sub>3</sub>、NpF<sub>4</sub>、NpCl<sub>4</sub>、NpBr<sub>3</sub>和NpI<sub>3</sub>等,以及類似於鈾氧化合物系統的各種[[氧化物]],包括Np<sub>3</sub>O<sub>8</sub>和[[二氧化錼|NpO<sub>2</sub>]]。
 
{{link-en|六氟化錼|Neptunium hexafluoride}}(NpF<sub>6</sub>)是一種類似於[[六氟化鈾]]的揮發性物質。
 
錼和鏷、鈾、鈈和[[鋂]]一樣,能夠形成線形二氧錼芯(NpO<sub>2</sub><sup>n+</sup>),其中的錼原子呈5+或6+氧化態。錼會與[[氧]]、[[蒸汽]]和[[酸]]產生劇烈反應,但不被[[鹼]]侵蝕。<ref name = "Nature's Building Blocks"/>
 
* NpO<sub>2</sub>(OH)<sub>2</sub><sup>–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sup>–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sub>2</sub><sup>3–</sup>
* NpO<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub><sup>5–</sup>
 
==應用==
第169行 ⟶ 第165行:
 
===武器===
錼可進行[[核裂變]],理論上可用作[[快中子反應爐]]或[[核武器]]的燃料,其[[臨界質量]]大約為60公斤。<ref name="rsc" />1992年,[[美國能源部]]解密部分文件,其中包括「錼-237可用於製造核子爆炸裝置」一句。<ref name="RDD-7">[http://www.fas.org/sgp/othergov/doe/rdd-7.html "Restricted Data Declassification Decisions from 1946 until Present"] {{Wayback|url=http://www.fas.org/sgp/othergov/doe/rdd-7.html |date=20110628194940 }}, accessed Sept 23, 2006</ref>沒有證據顯示歷史上曾出現過含錼核武器。截至2009年,商業核發電反應爐所產生的-237每年超過臨界質量的1000倍,然而要將該同位素從燃料中萃取出來卻需要巨大的規模和技術。
 
2002年9月,美國的[[洛斯阿拉莫斯國家實驗室]]短暫地創造了首個達到臨界質量的含錼物體,當中還含有[[濃縮鈾]]([[鈾-235]])。實驗發現,用錼-237製造的裸露球體的臨界質量在60公斤左右,<ref name="critical1"/>用作炸彈用途的話,並不比鈾-235優勝很多。<ref name="critical">{{cite web|last = Weiss|first = P.|title = Little-studied metal goes critical – Neptunium Nukes?| publisher = [[Science News]] |date = October 26, 2002|url = http://www.findarticles.com/p/articles/mi_m1200/is_17_162/ai_94011322|accessdate = 2006-09-29|archive-date = 2006-12-01|archive-url = https://web.archive.org/web/20061201120103/http://www.findarticles.com/p/articles/mi_m1200/is_17_162/ai_94011322}}</ref>
 
===物理應用===
第179行 ⟶ 第175行:
 
==作為核廢料==
[[File:Neptunium2.jpg|thumb|錼-237]]
錼-237是受[[深地質處置]]的[[錒系元素]]中可動性最高的。<ref>{{cite web| url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818052.pdf| title= Yucca Mountain| accessdate = 2009-06-06}}</ref>因此它需要和[[鋂-241]]一起通過[[核嬗變]]轉化為其他污染性較弱的同位素。<ref>{{cite journal| doi =10.1016/S0029-5493(03)00034-7| title =Deep-Burn: making nuclear waste transmutation practical| year =2003| author =Rodriguez, C| journal =Nuclear Engineering and Design| volume =222| pages =299| issue =2–3| last2 =Baxter| first2 =A.| last3 =McEachern| first3 =D.| last4 =Fikani| first4 =M.| last5 =Venneri| first5 =F.}}</ref>家居[[電離室]][[煙霧探測器]]含有的鋂-241(一般有0.2[[微克]])會衰變成錼。鋂-241的半衰期為432年,因此在20年後有3%變為錼,100年後則有15%變為錼。
錼-237是受[[深地質處置]]的[[錒系元素]]中可動性最高的。<ref>{{cite web| url = http://www.fas.org/sgp/othergov/doe/lanl/pubs/00818052.pdf| title = Yucca Mountain| accessdate = 2009-06-06| archive-date = 2021-01-18| archive-url = https://web.archive.org/web/20210118014809/https://fas.org/sgp/othergov/doe/lanl/pubs/00818052.pdf}}</ref>因此它需要和[[鋂-241]]一起通過[[核嬗變]]轉化為其他污染性較弱的同位素。<ref>{{cite journal| doi =10.1016/S0029-5493(03)00034-7| title =Deep-Burn: making nuclear waste transmutation practical| year =2003| author =Rodriguez, C| journal =Nuclear Engineering and Design| volume =222| pages =299| issue =2–3| last2 =Baxter| first2 =A.| last3 =McEachern| first3 =D.| last4 =Fikani| first4 =M.| last5 =Venneri| first5 =F.}}</ref>家居[[電離室]][[煙霧探測器]]含有的鋂-241(一般有0.2[[微克]])會衰變成錼。鋂-241的半衰期為432年,因此在20年後有3%變為錼,100年後則有15%變為錼。
 
錼的半衰期很長,所以它在一萬年以內會是核廢料中輻射的主要來源。為了避免日後(數千年後)廢料容器破裂時造成的大範圍核污染,錼需要先從廢料中提取出來。<ref>{{cite web|url = http://newscenter.lbl.gov/feature-stories/2005/11/29/getting-the-neptunium-out-of-nuclear-waste/|date = 2005-11-29| title = Getting the Neptunium out of Nuclear Waste|first = Lynn|last = Yarris|publisher = Berkeley laboratory, U.S. Department of Energy|accessdate = 05-12-2008|archive-date = 2013-06-06|archive-url = https://web.archive.org/web/20130606053322/http://newscenter.lbl.gov/feature-stories/2005/11/29/getting-the-neptunium-out-of-nuclear-waste/}}</ref><ref>{{cite web|url = http://www.pnl.gov/main/publications/external/technical_reports/PNNL-14307.pdf|title = Existing Evidence for the Fate of Neptunium in the Yucca Mountain Repository|author = J. I. Friese; E. C. Buck; B. K. McNamara; B. D. Hanson; S. C. Marschman|date = January 06-2003-01-06|publisher = Pacific northwest national laboratory, U.S. Department of Energy|accessdate = 05-12-2008|archive-date = 2017-01-01|archive-url = https://web.archive.org/web/20170101092133/http://www.pnl.gov/main/publications/external/technical_reports/PNNL-14307.pdf}}</ref><!--{{doi|10.1002/anie.200501281}}--><!--annual production 4.6 tonnes http://books.google.de/books?hl=de&lr=&id=oFtPmEPqjCgC&oi=fnd&pg=PA79-->
 
==參考資料==
第189行 ⟶ 第186行:
* ''Guide to the Elements – Revised Edition'', Albert Stwertka, (Oxford University Press; 1998) ISBN 978-0-19-508083-4
* Lester R. Morss, Norman M. Edelstein, Jean Fuger (Hrsg.): ''The Chemistry of the Actinide and Transactinide Elements'', Springer-Verlag, Dordrecht 2006, ISBN 978-1-4020-3555-5.
* {{cite journal|author=Ida Noddack|authorlink=Ida Noddack|year=1934|pages=653|title=Über das Element 93|volume=47|journal=Zeitschrift für Angewandte Chemie|url=http://www.chemteam.info/Chem-History/Noddack-1934.html|doi=10.1002/ange.19340473707|issue=37|access-date=2013-05-26|archive-date=2017-12-11|archive-url=https://web.archive.org/web/20171211223522/http://www.chemteam.info/Chem-History/Noddack-1934.html}}
* Eric Scerri, A Very Short Introduction to the Periodic Table, Oxford University Press, Oxford, 2011, ISBN 978-0-19-958249-5.
*{{cite book |last1=Yoshida |first1 = Zenko|first2 = Stephen G.|last2 = Johnson|first3 = Takaumi|last3 = Kimura|first4 = John R.|last4=Krsul|ref=CITEREFYoshida et al.2006|contribution = Neptunium|title = The Chemistry of the Actinide and Transactinide Elements|editor1-first = Lester R.|editor1-last = Morss|editor2-first = Norman M.|editor2-last = Edelstein|editor3-first = Jean|editor3-last = Fuger|edition = 3rd|date = 2006|volume = 3|publisher = Springer|location = Dordrecht, the Netherlands|pages = 699–812|url = http://radchem.nevada.edu/classes/rdch710/files/neptunium.pdf|doi = 10.1007/1-4020-3598-5_6|archive-url=https://web.archive.org/web/20180117190715/http://radchem.nevada.edu/classes/rdch710/files/neptunium.pdf|archive-date=January 17, 2018|isbn = 978-1-4020-3555-5}}
 
==外部連結==
{{Commons|Neptunium}}
{{Wiktionary|neptunium}}
{{Elements.links|neptunium}}
* [http://www.periodicvideos.com/videos/093.htm Neptunium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [http://www.periodicvideos.com/videos/093.htm Neptunium] {{Wayback|url=http://www.periodicvideos.com/videos/093.htm |date=20201122194522 }} at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [http://www.eurekalert.org/features/doe/2001-08/danl-lbw060502.php Lab builds world's first neptunium sphere], [[U.S. Department of Energy]] Research News
* [http://www.eurekalert.org/features/doe/2001-08/danl-lbw060502.php Lab builds world's first neptunium sphere] {{Wayback|url=http://www.eurekalert.org/features/doe/2001-08/danl-lbw060502.php |date=20060925064716 }}, [[U.S. Department of Energy]] Research News
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+neptunium,+radioactive NLM Hazardous Substances Databank – Neptunium, Radioactive]
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+neptunium,+radioactive NLM Hazardous Substances Databank – Neptunium, Radioactive] {{Wayback|url=http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+neptunium,+radioactive |date=20190710172746 }}
* [http://www.ead.anl.gov/pub/doc/neptunium.pdf Neptunium: Human Health Fact Sheet]
* [http://www.ead.anl.gov/pub/doc/neptunium.pdf Neptunium: Human Health Fact Sheet] {{Wayback|url=http://www.ead.anl.gov/pub/doc/neptunium.pdf |date=20081219162631 }}
* [http://pubs.acs.org/cen/80th/neptunium.html C&EN: It's Elemental: The Periodic Table – Neptunium]
* [http://pubs.acs.org/cen/80th/neptunium.html C&EN: It's Elemental: The Periodic Table – Neptunium] {{Wayback|url=http://pubs.acs.org/cen/80th/neptunium.html |date=20190413082303 }}
 
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