High pO2 Flux Growth and Characterization of NdNiO3 Crystals

Abstract

Single crystals of the perovskite nickelate NdNiO3 with dimensions of up to 50 μm on edge have been successfully grown using the flux method at a temperature of 400 °C and oxygen pressure of 200 bar. The crystals were investigated by a combination of techniques, including high-resolution synchrotron X-ray single-crystal and powder diffraction and physical property measurements such as magnetic susceptibility and resistivity. Resistivity measurements revealed a metal-insulator transition (MIT) at TMIT~180 K with apparent thermal hysteresis; however, no superlattice peaks or peak splitting below TMIT, which corresponds to a structural transition from Pbnm to P21/n, was observed. The successful growth of NdNiO3 crystals at relatively low temperatures and oxygen pressure provides an alternative approach for preparing single crystals of interesting perovskites such as RNiO3 (R = Sm-Lu) and parent phases of superconducting square planar nickelates.

Flux Growth of Trilayer La4Ni3O10 Single Crystals at Ambient Pressure

“…In contrast, single crystals of RNiO 3 with dimensions of about 100 μm on edge were grown using the flux method at a temperature of 900–1500 °C and under a pressure of 4–4.5 GPa. , Recently, Klein et al successfully grew crystals of RNiO 3 (R = Nd, Sm, Gd, Dy, Y, Ho, Er, Lu) with sizes up to 75 μm under pO 2 = 2000 bar and T = 850 °C using LiCl–KCl flux . More recently, our group successfully grew single crystals of NdNiO 3 with sizes up to 50 μm below 400 °C and oxygen pressure of 200 bar using NaOH/KOH as flux, substantially reducing the growth temperature and oxygen pressure …”

“…38 More recently, our group successfully grew single crystals of NdNiO 3 with sizes up to 50 μm below 400 °C and oxygen pressure of 200 bar using NaOH/KOH as flux, substantially reducing the growth temperature and oxygen pressure. 39 Whether single crystals of rare earth nickelates with nickel valence of >2 can be grown at ambient pressure remains an open question. Indeed, polycrystalline powders of La 4 Ni 3 O 10 were synthesized at ambient pressure using the solid-state and citrate routes, 40 and LaNiO 3 polycrystalline powders were synthesized using the flux method, 41 indicating that it may be possible to grow single crystals of La 4 Ni 3 O 10 and LaNiO 3 at ambient pressure.…”