Light element analysis in oxycarbonate superconductors using EELS

Abstract

Elemental analysis in an oxycarbonate superconductor ((Cu,N,C)Sr2CaCu2Oy) is conducted using transmission electron microscope-electron energy-loss spectroscopy with detector-gain correction. The gain correction enables highly sensitive elemental analysis and precise measurement of energy-loss near edge structures (ELNESs). It is found that carbon is included as a CO3 group, because the carbon K-edge in the oxycarbonate shows the same ELNES observed from CaCO3. Nitrogen ELNES is similar to that of Sr(NO3)2, so nitrogen is contained as a NO3 group. Although both CO3(2-) and NO3- have similar planar atomic arrangements, the nitrogen ELNES observed is different from that of carbon. EEL spectrum simulation based on DV-Xalpha method is used to interpret the difference.

Synthesis of CxSr2Ca2Cu3Oz Superconductor from Sr2Ca2Cu3Oy Precursor

“…2(b) were assigned as à and à , respectively. 26) The carbon edge energy-loss near-edge structure (ELNES) of a collodion film on a microgrid was different from those of the other samples with respect to the energy difference between à and à and the shape of the ELNES; therefore, the C-K edge in Fig. 4(a) is not due to contamination by an amorphous carbon.…”

“…Carbon was detected by electron energy loss spectroscopy (EELS; Gatan GIF Tridiem), because TEM-EELS is preferable to X-ray absorption near-edge structure (XANES) for the analysis of light elements in a very small area. [24][25][26] The thin edge of a particle was selected for chemical analysis. DC magnetic susceptibility was monitored utilizing a superconducting quantum interference device (SQUID) magnetometer (Quantum Design MPMS-XL) in the field cooling (FC) mode with an external magnetic field of 10 Oe at 5-120 K.…”

Layered Cuprates Containing Flat Fragments: High-Pressure Synthesis, Crystal Structures and Superconducting Properties

“…Incorporation of nitrate to the crystal structures of (Cu,N,C)Sr 2 Ca n−1 Cu n O y was confirmed by EELS [ 104 ]. It is very interesting that the two different superstructures were observed simultaneously in the case of n = 3, 2a × b × 2c and 4 a × b × 2c.…”

Visualizing the Atomic Configuration of Carbonate Groups in a (Cu,C)Ba2Ca3Cu4O11+δ Superconductor

“…Compared with the standard spectra of CaCO 3 , it is concluded that the carbon atoms are probably existing in the form of CO 3 2− groups, consistent with the previous predictions and the results of infrared transmission spectra. [7,19,25,26] Besides, the K edge of amorphous carbon is acquired as a reference and the sharp difference firmly excludes the possibility of carbon contamination during the TEM sample preparation.…”