Realizing nearly isotropic thermoelectric properties in 2D-layered SnS nanomaterials through highly symmetric metastable-phase powder precursors

Metastable materials offer a broad and novel platform for the development of next-generation science and technology.Phase engineering including synthesis of materials with unconventional phases and phase transition of metastable materials has been explored in layered materials but has not tackled their anisotropy issue yet.The high anisotropy in layered materials further adds the cost of orientation screening of materials.Herein,we report the effect of Ag doping on facilitating the formation of metastableπ-cubic phase SnS during the solvothermal synthesis process.On this basis,we construct cubic-to-orthorhombic(CTO)samples and elucidate the intrinsic mechanisms of its nearly isotropic thermoelectric properties by characterizing the texturing information and analyzing the valence charge density calculated by density functional theory(DFT).This work demonstrates a convenient approach to synthesize layered materials with isotropic electrical and thermal transport behaviors through a precursor of metastable phase.

Batch synthesis of rare-earth nickelates electronic phase transition perovskites via rare-earth processing intermediates

The rare-earth nickelates(RENiO_(3)) exhibit an exceptional complex electronic phase diagram and multiple electronic phase transitions that enrich promising applications in correlated electronic devices beyond conventional semiconductors.Nevertheless,the practical applications of RENiO_(3) are challenged by their intrinsic thermodynamic metastability in material synthesis and high material cost.Therefore,developing an economical strategy to achieve the batch synthesis of RENiO_(3) is of vital importance.In this work,we enlarged the synthesis amount of RENiO_(3) up to 20 g per batch using chloride(KCI) assisted molten salt reaction.By optimizing the reaction conditions,the powder of RENiO_(3) with the cubic shape and average size of ~2μm was effectively synthesized,while their phase purity exceeded 95%.In addition,the cost to synthesize RENiO_(3) was further reduced by using rare-earth extraction intermediate products as the raw materials,instead of using the pure rare-earth precursors.It also achieved wide adjustments in the metal-to-insulator-transition temperature from160 to 420 K without significantly reducing the transition sharpness.By enlarging the synthesis amount and the reducing the cost,it paves the way to the device application of RENiO_(3).