Humans have long dreamed of turning one material into another easily.
The most popular stories were turning various objects into gold, sometimes via touch (Midas), other times via chemistry/magic (alchemy).
Fundamentally, the goal is to shift the chemical composition or structure of a material without requiring crazy conditions.
While it’s not gold, a team of international scientists has discovered just that in a strontium-iron-cobalt metal oxide (SFCO) that “breathes” oxygen.
Breath of life: The oxide can release oxygen when heated in a simple gas environment and take it back in…without losing structural integrity.
The study was led by Professor Hyoungjeen Jeen from the Department of Physics, Pusan National University, Korea, who said, “It is like giving the crystal lungs and it can inhale and exhale oxygen on command.”
Why it matters: Transition metal oxides (TMOs) have characteristics that make them attractive for energy storage, catalysis, superconductivity, and electronic devices, and the presence or absence of oxygen in the crystalline structure strongly influences those behaviors.
Previous shortfalls: Earlier work saw the crystalline structure break down or require conditions that would make commercial applications untenable.
What they did: The researchers were interested in the redox behavior of SFCO. They plopped it in reducing conditions using diluted hydrogen gas, heated the bonkers out of it, and held it at that high temperature for a while before cooling it again.
What they saw: As the crystalline structure adapted to conditions, there was “a cooperative but asymmetric redox response of Fe and Co in the SFCO system that stabilized an oxygen-deficient defective perovskite phase that cannot be accessed in single-cation systems.”
In other words, adding iron into the mix seemed to stabilize the structure and led researchers to think there’s a site and element-specific control on redox reactions in oxide systems with many cations.
Laying the groundwork: Importantly, the work opens the door to more research for programmable oxygen-deficient materials, where we can tweak the chemistry and/or structure of materials to make them behave the way we want under the conditions we want.
Why it matters: Controlling oxygen in materials is helpful in technologies like solid oxide fuel cells, thermal transistors, and smart windows that can adjust their heat flow based on various weather conditions.
The catch: The oxide requires cobalt, which is a mineral associated with unsafe mining practices and child labor in Democratic Republic of Congo, but maybe we geoscientists can play a role in finding other sources or similar materials.
Go deeper: For more information on the breakthrough, go here, or read the Nature paper here.