The recent report of near-ambient superconductivity in the nitrogen-doped lutetium hydride has attracted considerable attention.Subsequent follow-up studies confirmed the pressure-induced color changes in both N-free ...The recent report of near-ambient superconductivity in the nitrogen-doped lutetium hydride has attracted considerable attention.Subsequent follow-up studies confirmed the pressure-induced color changes in both N-free and N-doped LuH_(2) but failed to reproduce superconductivity. It remains a puzzle why the samples in the original report exhibited pronounced resistance anomaly reminiscent of the superconducting transition. Here, we show that percolation of metallic grains with high conductivity through the insulating surfaces in cold-pressed LuH_(2) samples can occasionally produce sharp resistance drops, which even display magnetic field and/or current dependences but stay far from zero resistance. The insulating surface of LuH2grain should be attributed to the modification of hydrogen stoichiometry or the contamination by oxygen/nitrogen, resulting in an increase of resistance by over six orders of magnitude. Such an effect is more significant than that discovered recently in LaH_(3±x), which may indicate that LuH_(2) can be a potential superionic conductor. Our results call for caution in asserting the resistivity drops as superconductivity and invalidate the background subtraction in analyzing the corresponding resistance data.展开更多
Pyroelectrics are a class of polar compounds that output electrical signals upon changes in temperature.With the rapid development of flexible electronics,organic pyroelectrics are highly desired.However,most organics...Pyroelectrics are a class of polar compounds that output electrical signals upon changes in temperature.With the rapid development of flexible electronics,organic pyroelectrics are highly desired.However,most organics suffer from low pyroelectric coefficients or low working temperatures.To date,the realization of superior pyroelectric performance in all-organics has remained a challenge.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 12025408, 11921004, 11834016, and 11888101)the Beijing Natural Science Foundation (Grant No. Z190008)+1 种基金the National Key R&D Program of China (Grant Nos. 2021YFA1400200, and 2021YFA1400300)the Strategic Priority Research Program of CAS (Grant No. XDB33000000)。
文摘The recent report of near-ambient superconductivity in the nitrogen-doped lutetium hydride has attracted considerable attention.Subsequent follow-up studies confirmed the pressure-induced color changes in both N-free and N-doped LuH_(2) but failed to reproduce superconductivity. It remains a puzzle why the samples in the original report exhibited pronounced resistance anomaly reminiscent of the superconducting transition. Here, we show that percolation of metallic grains with high conductivity through the insulating surfaces in cold-pressed LuH_(2) samples can occasionally produce sharp resistance drops, which even display magnetic field and/or current dependences but stay far from zero resistance. The insulating surface of LuH2grain should be attributed to the modification of hydrogen stoichiometry or the contamination by oxygen/nitrogen, resulting in an increase of resistance by over six orders of magnitude. Such an effect is more significant than that discovered recently in LaH_(3±x), which may indicate that LuH_(2) can be a potential superionic conductor. Our results call for caution in asserting the resistivity drops as superconductivity and invalidate the background subtraction in analyzing the corresponding resistance data.
基金This work is financially supported by the National Key Research and Development Program of China(2018YFE0202600,2016YFA0300301),the National Natural Science Foundation of China under granting numbers:No.51532010,91422303,51772323and the Key Research Program of Frontier Sciences,CAS,Grant No.QYZDJ-SSW-SLH013.
文摘Pyroelectrics are a class of polar compounds that output electrical signals upon changes in temperature.With the rapid development of flexible electronics,organic pyroelectrics are highly desired.However,most organics suffer from low pyroelectric coefficients or low working temperatures.To date,the realization of superior pyroelectric performance in all-organics has remained a challenge.