Structure and magnetism of copper-substituted cobalt ludwigite Co3O2BO3

Abstract

The single crystals Co 3 O 2 BO 3 with partial (4%) substitution of Co by Cu ions were synthesized by the flux technique. X-ray diffraction and magnetic properties investigations were carried out. The x-ray diffraction measurements have shown that Cu clearly prefers only one from four nonequivalent crystallographic positions with the smallest electric field gradient. The ferrimagnetic ordering near T N = 43 K and high magnetic hardness in this magnetic phase are similar to Co 3 O 2 BO 3 . The small reduction of the effective magnetic moment was revealed under copper substitution.

Ludwigites: From natural mineral to modern solid solutions

“…Currently several solid solutions based on Co 3 BO 5 were received and investigated. Substitution of Co was produced by magnetic ions of Mn, Cu and non‐magnetic ‐ Ga, Ti, Mg, Sn .…”

Mixed Valent, Distorted Cobalt Ludwigite (Co3BO5/Co3O2BO3) and Its Composite with Reduced Multiwalled Carbon Nanotubes (R‐MWCNT) in Enhancing the Domain Edge‐Sharing Oxygen as Superior Water Oxidation Electrocatalysts

“…Figure a shows a comparison of X‐ray diffraction pattern (XRD) of mixed valent Co 3 BO 5 , R‐MWCNTs, standard pattern of Co 3 BO 5 and Co 3 BO 5 ‐R‐MWCNTs hybrid. Detail crystal structure for this material could be found in earlier reports explaining the basic electronic, magnetic properties of the material ,,. The crystal structure of both the cobalt borate and ludwigite are orthorhombic.…”

“…Here the Co−B i is found to be more active than that of Co−P i . Despite the several researches on Co−B i (Co 3 B 2 O 6 , Orthorhombic crystal structure, space group: P nmn ), another analogue of Co−B i , called cobalt boron oxide/ cobalt oxyborate with the empirical formula Co 3 BO 5 (also known as Cobalt‐ludwigite, Orthorhombic crystal structure, space group: P bam ) has not been explored yet for OER till date although the magnetic propertiesand structural features have been studied well after incorporating iron in the lattice ,…”

“…Although Co 3 BO 5 beholds smaller interlayer spacing (comparatively larger c value for borate), but the overall size is bigger (both the a and b value in unit cell) in x and y direction indicating more space in the outer domain rather than interlayer spacing unlike the borate analogue. The mono‐μ‐oxo bridges with Co ion creates distorted structure which contributes towards increased volume and more edge domains ,. The edge domains having principal role towards catalytic activity rather than interlayer spacing as there is no experimental evidence for the electrolytes or bigger ions to be accommodated in the interlayer spacing of borates and the catalytic activity is dependent on the surface structures rather than bulk .…”

Low Lying Magnetic States of the Mixed Valence Cobalt Ludwigite

“…Since, as with the Fe mixed compound, no feature was found in specific heat measurements, the magnetic state below 19K was characterized as a spin glass freezing. In CoMgGaO 2 BO 3 [22], Co 2.4 Ga 0.6 O 2 BO 3 [23] and Co 2.88 Cu 0.12 O 2 BO 3 [24], whose magnetic temperatures were found to be 25K, 37K [26]. So far, it is the only hetero-metallic ludwigite to show a sharp peak in the specific heat versus temperature curve, thus indicating long range magnetic ordering.…”