Effect of Zn Substitution on the Structural and Physical Properties of Delafossite-Type Oxide CuCrO2

In this paper, we report the effect of non-magnetic Zn-doped CuCrO₂. The structure, Raman spectroscopy, magnetic properties, dielectric permittivity, and electric polarization have been investigated. The incorporation of Zn²⁺ generates very anisotropic microstrains in the structure. The temperature dependence of magnetic susceptibly for all samples exhibits a magnetic dilution and paramagnetic behavior at high temperature. It is argued that non-magnetic substitution destabilizes the antiferromagnetic order of Cr³⁺ ions and modulates the spin configuration. The coupling between the magnetic order, dielectric permittivity and polarization is also characterized.     

Preparation, structure and infrared spectrum of NaEuP2O7

Crystals of NaEuP₂O₇ have been grown by the flux technique and characterized by X-ray diffraction. Single crystal structure of NaEuP₂O₇ has been solved, for the first time; it crystallizes in the monoclinic P2₁/n space group with lattice parameters : a = 5.238(2), b = 8.443(4), c = 12.486(6) Å, β = 91.404°(2), V = 552.0(4) ų, Z = 4. The crystal structure has been refined yielding a final R(F²) =0.049 and R_w(F²) = 0.138 for 1313 independent reflections (F_o² ≥ 2σ(F_o²)). In this structure, the PO₄ tetrahedral are linked by bridging oxygen to give P₂O₇ groups, these groups are connected to the EuO₈ polyhedron by sharing two oxygen corners to form three-dimensional framework in which channels are noticed and where the sodium ions are located. The frequencies of the vibrational modes of the crystal were obtained from measurements of the infrared spectra.     

Metal transition doping effect on the structural and physical properties of delafossite-type oxide CuCrO2

In this paper we reported on the non magnetic substitution effects on the structural, spectroscopic, and magnetic properties of the CuCrO₂ delafossite. The incorporation of M³⁺ generates very anisotropic microstrains in the structure beside a magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. It is argued that non magnetic-substitution destabilizes the antiferromagnetic order of Cr³⁺ ions and modulates the spin configuration leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized.