New Materials from High Pressure

Abstract: https://reurl.cc/bN9qO6

Biography: https://reurl.cc/bN9xml

High pressure methods are important for synthesising new materials, and exploring changes of structure and property in dense matter. New oxide and nitride materials recently synthesized by our group and of interest for electronic and energy applications will be reviewed here. Examples are perovskites with Mn²⁺ at A-sites, such as MnVO₃ [1], the double perovskite Mn₂FeReO₆ [2] and double double perovskites MnRMnSbO₆ and CaMnFeReO₆ with order of A and B site cations [3,4,5]. A remarkable variety of new iron oxides has recently been reported at high pressures, and we have explored the substitutional chemistry of Fe₄O₅. Notably, CaFe₃O₅ (prepared at ambient pressure) shows electronic phase separation driven by trimeron formation [6]. A high pressure method using sodium azide has recently been developed to synthesise nitrides in high oxidation states giving the iron(IV) nitride, Ca₄FeN₄ [7], an electron-localised Ni²⁺ nitride, Ca₂NiN₂ [8], and a rare example of a nitride perovskite, LaReN₃ [9]. The latter material can be decomposed to give novel reduction products LaReN_2.5 and layered LaReN₂ demonstrating topotactic reduction chemistry analogous to that of perovskite oxides like LaNiO₃ and SrFeO₃. The the first examples of Ruddlesden-Popper (layered perovskite) nitrides have recently been prepared; R₂ReN₄ (R = Pr, Nd) and Ce₂TaN₄ [10].