Gainza, JavierSerrano Sáánchez, FedericoRodrigues, Joao Elias F. S.Nemes, Norbert MarcelMartínez, José LuisAlonso, José Antonio2023-06-172023-06-172021-041996-194410.3390/ma14081946https://hdl.handle.net/20.500.14352/7390© 2021 by the authors. Licensee MDPI This research was funded by the Spanish Ministry of Science, Innovation, and Universities for funding the project number: MAT2017-84496-R.In this review, we describe different families of metastable materials, some of them with relevant technological applications, which can be stabilized at moderate pressures 2-3.5 GPa in a piston-cylinder press. The synthesis of some of these systems had been previously reported under higher hydrostatic pressures (6-10 GPa), but can be accessed under milder conditions in combination with reactive precursors prepared by soft-chemistry techniques. These systems include perovskites with transition metals in unusual oxidation states (e.g., RNiO_(3) with Ni^(3+), R = rare earths); double perovskites such as RCu_(3)Mn_(4)O_(12) with Jahn-Teller Cu^(2+) ions at A sites, pyrochlores derived from Tl_(2)Mn_(2)O_(7) with colossal magnetoresistance, pnictide skutterudites M_(x)Co_(4)Sb_(12) (M = La, Yb, Ce, Sr, K) with thermoelectric properties, or metal hydrides Mg_(2)MH_(x) (M = Fe, Co, Ni) and AM_(g)H_(3) (A: alkali metals) with applications in hydrogen storage. The availability of substantial amounts of sample (0.5-1.5 g) allows a complete characterization of the properties of interest, including magnetic, transport, thermoelectric properties and so on, and the structural characterization by neutron or synchrotron X-ray diffraction techniques.engAtribución 3.0 Españajournal articlehttp://dx.doi.org/10.3390/ma14081946https://www.mdpi.com/open access538.9Cluster-glass behaviorCharge disproportionationmagnetic-structureNeutron-diffractionPerovskitesEvolutionCrystalHoMagnetoresistanceHigh-pressure synthesisRNiO_(3) perovskitesMetal-insulator transitionsCaCu_(3)Mn_(4)O_(12)Colossal magnetoresistanceSeNiO_(3)SeCoO_(3)NaMgH_(3)Tl_(2)Mn_(2)O_(7)CoSb_(3)Física de materialesFísica del estado sólido2211 Física del Estado Sólido