The effect of partial substitution of Ni by Mg on the structural, magnetic and spectroscopic properties of the double perovskite Sr₂NiTeO₆

Abstract

In this report, the structural, magnetic and spectroscopic properties of the freeze-drying synthesized Sr2Ni1-xMgxTeO6 (x = 0.0, 0.1, 0.2, 0.3 and 0.5) oxides are analyzed by means of X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD), electron paramagnetic resonance, diffuse reflectance and magnetic susceptibility. The XRPD and NPD data analysis using the mode-crystallography approach have revealed that at room temperature (RT), all the compositions are monoclinically distorted with the space group I2/m. The high and low temperature analyses have shown that these materials suffer a series of three structural phase transitions. The EPR results have shown that the spectra of all the compositions are centred at g≈ 2.28, indicating a slightly distorted octahedral environment of Ni(2+), which is in agreement with the crystal structure analysis. The increase of the Mg(2+) content in Sr2Ni1-xMgxTeO6, provokes a decrease of the dipolar interaction effects and thus, the resonance becomes narrower. This resonance does not completely disappear which leads to the idea that the long-range magnetic order is not completely established when x≥ 0.3. The substitution of the Ni(2+) (S = 1) ions by Mg(2+) (S = 0) ions, also induces a weakening of the antiferromagnetic interactions, which is reflected in the diminishing of the absolute value of θ and the Néel temperature TN. The magnetic structure determination revealed the existence of an antiferromagnetic coupling for x- and z-spin components of the nickel atoms.

Site-Selective d10/d0 Substitution in an S = 1/2 Spin Ladder Ba2CuTe1–xWxO6 (0 ≤ x ≤ 0.3)

“…10 This limits Te 6+ participation in J2 exchange, where a d-orbital contribution from the B'' cation is required. We also highlighted that the d 10 /d 0 effect extends beyond simple cubic structures to a large range of 3d transition metal B' = Co 11,12 , Ni [13][14][15] and Cu [16][17][18][19] double perovskites, all of which follow the same principle based on the nonmagnetic B''-site: d 0strong J2 (type II) or d 10 -strong J1 (type I/Néel order).…”

Nickel Iron Diselenide for Highly Efficient and Selective Electrocatalytic Conversion of Methanol to Formate

“…Typically, Fe 3+ , Ni 2+ , and Ni 0 have associated EPR signals, while Fe 2+ , Fe 0 , and Ni 3+ do not. [ 39–41 ] As displayed in Figure 2e, no obvious resonance signal was detected from NiSe 2 (black line). On the other hand, broad EPR signals were obtained for all the samples containing Fe, with the highest signal intensity being observed for the sample containing the lowest amount of Fe, Ni 0.75 Fe 0.25 Se 2 .…”

Structural, optical and dielectric properties of tellurium-based double perovskite Sr2Ni1−xZnxTeO6

“…The Rietveld renement revealed that all the compounds are in monoclinic unit cell in the I2/m space group, as reported by previous study. 16,17 The rened lattice angles for all compounds are a ¼ g ¼ 90 , whereas ß for x ¼ 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 are 90.018, 90.063, 90.046, 90.111, 90.141 and 90.063 , respectively; the rened unit cell volumes (V) of each samples are 247.580, 248.241, 248.692, 250.580, 251.199 and 252.042Å 3 , respectively. These results show that the unit cell volume of the crystal structure increases as the doping increases from x ¼ 0.0 to x ¼ 1.0.…”