A series of monoclinic distorted double perovskites of the general formula Ln 2MIrO6 (Ln = La, Pr, Nd, Sm–Gd; M = Mg, Ni) were grown as highly faceted single crystals from a potassium hydroxide flux. The structural distortions and the magnetic interactions in A2BB′O6 double perovskites can be “designed” via a judicious choice of A, B, and B′ cation sizes and by selecting magnetic or nonmagnetic ions to occupy the A, B, and/or B′ sites. A study of the relationship between the number of magnetic ions, the degree of monoclinic distortion, and the resulting magnetic interactions was conducted. Magnetic susceptibility and field dependent magnetization measurements were performed for all synthesized compounds. It was determined that smaller A-site lanthanide cations cause more pronounced monoclinic distortions, resulting in smaller M–O–Ir (M = Mg, Ni) bond angles that correlate with higher magnetic ordering temperatures. The magnetic susceptibility and field dependent magnetization data were both consistent with canted antiferromagnetism for most titled compositions, indicating a possible trend of increased spin canting, and thus increased ferromagnetic-like interactions, as a function of smaller lanthanide A site cation size.

Crystallographic structure information, magnetic agreement indices, neutron diffraction patterns and magnetic data plots, ICSD and CCDC numbers (PDF) Data for BaFe 4 O 7 (CIF) Data for Ba 0.89 K 0.22 Fe 4 O 7 (CIF)

The triangular lattice compound TlYbS2 was prepared as large single crystals via a molten flux growth technique using sodium chloride. Anisotropic magnetic susceptibility measurements down to 0.4 K indicate a complete absence of long-range magnetic order. Despite this lack of long-range order, short-range antiferromagnetic interactions are evidenced through broad transitions, suggesting frustrated behavior. Variable magnetic field measurements reveal metamagnetic behavior at temperatures ≤ 2 K. Complex low temperature field-tunable magnetic behavior, in addition to no observable long-range order down to 0.4 K, suggest that TlYbS2 is a frustrated magnet and a possible quantum spin liquid candidate. [25][26][27][28][29][30][31][32][33] Recently, Yb(III) containing compounds such as NaYbO2, 1, 2 NaYbS2, 9 and YbMgGaO4 4,10,11,13,34 have been presented as QSL candidates, all crystallizing in a layered triangular lattice of trigonal space group R-3m. Due to the odd number of 4f electrons and strong SOC, these materials behave as effective spin Jeff = ½. A similar family of 4f-containing delafossites, of the general formula A(I)Ln(III)Ch(II) [A = Na, Rb, K; Ch = O, S, Se, Te], 31 has also been proposed as a

The crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, BaNiIrO and BaNiO, are reported. The 12R perovskite, BaNiIrO, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains IrNiO mixed-metal-cation units in which direct metal-metal bonding between nickel(IV) and iridium(V) is inferred. X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).

Millimeter sized crystals of six oxides of approximate composition Ba 4 M z Pt 3-z O 9 (M = Co, Ni, Cu, Zn, Mg, Pt) were grown from molten K 2 CO 3 fluxes and found to crystallize in a 2H hexagonal perovskite-related structure type. The compositions of these incommensurate structures, which belong to the A 3n+3m A' n B 3m+n O 9m+6n family of 2H hexagonal perovskite related oxides, were characterized by X-ray diffraction, energy dispersive spectroscopy, and magnetic susceptibility measurements. The specific synthetic considerations, crystal growth conditions, and magnetic susceptibility measurements are discussed.

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The crystal chemistry and magnetic properties for two triple perovskites, BaFeIrO and BaNiIrO, grown as large, highly faceted single crystals from a molten strontium carbonate flux, are reported. Unlike the idealized AMM'O hexagonal symmetry characteristic of most triple perovskites, including BaNiIrO BaFeIrO possesses significant site-disorder, resulting in a noncentrosymmetric polar structure with trigonal symmetry. The valence of iron and iridium in the heavily distorted Fe/Ir sites was determined to be Fe(III) and Ir(V) by X-ray absorption near edge spectroscopy (XANES). Density functional theory calculations were conducted to understand the effect of the trigonal distortion on the local Fe(III)O electronic structure, and the spin state of iron was determined to be S = 5/2 by Mössbauer spectroscopy. Conductivity measurements indicate thermally activated semiconducting behavior in the trigonal perovskite. Magnetic properties were measured and near room temperature magnetic ordering (T = 270 K) was observed for BaFeIrO.

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