Editing Barium oxide (section)

==Uses==
Barium oxide is used as a coating for [[hot cathode]]s, for example, those in [[cathode-ray tube]]s. It replaced [[lead(II) oxide]] in the production of certain kinds of glass such as optical [[crown glass (optics)|crown glass]]. While lead oxide raised the [[refractive index]], it also raised the [[optical dispersion|dispersive]] power, which barium oxide does not alter.<ref>{{cite encyclopedia  | title = Barium Oxide (chemical compound)  | encyclopedia = Encyclopædia Britannica  | year = 2007  | url = http://www.britannica.com/eb/topic-53368/barium-oxide  | access-date = 2007-02-19 }}</ref> Barium oxide also has use as an [[ethoxylation]] [[catalyst]] in the reaction of [[ethylene oxide]] and [[Alcohol (chemistry)|alcohol]]s, which takes place between 150 and 200&nbsp;°C.<ref>{{Cite web  | last1 = Nield  | first1 = Gerald  | last2 = Washecheck  | first2 = Paul  | last3 = Yang  | first3 = Kang  | title = United States Patent 4210764  | date = 1980-07-01  | url = http://www.freepatentsonline.com/4210764.html  | access-date = 2007-02-20 }}</ref>

It is most known for its use in the [[Brin process]], named after its inventors, a reaction that was used as a large scale method to produce oxygen before [[air separation]] became the dominant method in the beginning of the 20th century, as BaO can be a source of pure oxygen through heat fluctuation.

BaO(s) + ½O<sub>2</sub>(g) ⇌ BaO<sub>2</sub>(s)

It oxidises to BaO<sub>2</sub> by formation of a [[peroxide]] [[ion]] ({{Chem2|[O\sO](2–)}}, or {{chem2|O2(2–)}}) — with the same charge of {{Chem2|O(2–)}}, and therefore keeping the electrochemical balance with the most stable {{Chem2|Ba(2+)}}. Using the [[Kröger–Vink notation|Kröger-Vink notation]], 

½{{Chem2|O2}}(g) + O{{Su|b=O|p=2–}} ⇌ [O{{Su|b=2|p=}}]{{Su|b=O|p=2–}}

where J{{Su|b=O}} is the species J in the oxygen position within the rock-salt lattice. The complete peroxidation of BaO to BaO<sub>2</sub> occurs at moderate temperatures by oxygen uptake within the BaO rock-salt lattice:
[[File:Oxygen incorporation into BaO.png|border|left|thumb|246x246px|Barium oxide peroxidation from oxygen uptake, adapted from Middleburgh et al, 2012.<ref name=":0">{{Cite journal |last=Middleburgh |first=Simon C. |last2=Lagerlof |first2=Karl Peter D. |last3=Grimes |first3=Robin W. |date=2013 |title=Accommodation of Excess Oxygen in Group II Monoxides |url=https://ceramics.onlinelibrary.wiley.com/doi/abs/10.1111/j.1551-2916.2012.05452.x |journal=Journal of the American Ceramic Society |language=en |volume=96 |issue=1 |pages=308–311 |doi=10.1111/j.1551-2916.2012.05452.x |issn=1551-2916|url-access=subscription }}</ref>]]

Calculations using [[Density functional theory|Density Functional Theory (DFT)]] suggest that the oxygen incorporation reaction is exothermic, and that the most energetically favoured occupation site is indeed the peroxide ion at the oxide lattice — other than interstitial positions, for instance. However, the increased entropy of the system is what leads BaO<sub>2</sub> to decompose to BaO and release O<sub>2</sub> between 800 and 1100 K (520 and 820 °C).<ref name=":0" /> The reaction was used as a large scale method to produce oxygen before [[air separation]] became the dominant method in the beginning of the 20th century. The method was named the [[Brin process]], after its inventors.<ref>{{cite journal|author1-link=William B. Jensen | last1 = Jensen | first1 = William B. | title = The Origin of the Brin Process for the Manufacture of Oxygen | journal = Journal of Chemical Education | volume = 86 | pages = 1266 | year = 2009 | doi = 10.1021/ed086p1266 | issue = 11 |bibcode = 2009JChEd..86.1266J }}</ref>