Large single crystals of LnBaCo2O5.5: Initial nucleation, growth and study

New Member of the “112” Family, LaBaCo2O5.5: Synthesis, Structure, and Magnetism

“…[19][20][21][22][23] Several neutron diffraction studies have been conducted to establish the spin state of cobalt and the magnetic structure in LnBaCo 2 O 5.5 compounds with Ln ) Pr, Nd, Tb, Ho, and Y. 6,18,[24][25][26][27][28][29][30] The models proposed for the magnetic structure of these compounds are all different, and there is controversy even between two different studies on the same compound. 6,18 There are at least three possible reasons for these discrepancies: (i) small deviations from the ideal "O5.5" stoichiometry, (ii) variation of the degree of ordering in oxygen vacancies due to the different method of synthesis, and (iii) influence of the size of the Ln 3+ cation.…”

Comparison of the electronic structure of LnBaCo2O5+δ (Ln=Gd, Dy; Ln-112) and LnBaCo4O7 (Ln=Yb; Ln-114) single-crystal surfaces using resonant photoemission

“…where the MI transitions of most of the later series Ln-112 oxides are expected[2,6,7]. A typical example is shown in Fig.4(a), for a crystal of Dy-112 which has been oxygen annealed after synthesis to achieve an oxygen content close to ı = 0.5; here we expect the MI transition at around 326 K[25].…”

“…and LnBaCo 4 O 7+ı (Ln = Yb; Ln-114, ı ≈ 0.2) of typical dimension 2 mm × 3 mm × 2 mm were grown from an overstoichiometric melt [7,18,19]. Oxygen content was controlled by post-growth annealing in O 2 or N 2 and measured in typical cases using iodometric titration.…”

“…The samples were characterised by X-ray and neutron diffraction, and magnetisation measurements [7,19,20].…”

“…show giant magnetoresistive behaviour in narrow composition ranges around ı = 0.5 corresponding to Co 3+ ), a range of poorlyunderstood spin state transitions, and a temperature-dependent metal-insulator (MI) transition [1][2][3][4][5][6][7]. Co 3+ is present in two environments, octahedral and pyramidal (with CoO 5 coordination)…”