Synthesis, structural and magnetic properties NaZnFe$_2$(VO$_4$)$_3$

A new magnetic compound NaZnFe$_2$(VO$_4$)$_3$ obtained by solid-phase synthesis has been studied using X-ray diffraction, Mössbauer spectroscopy, electron paramagnetic resonance, measurement of the temperature dependence of the dielectric permeability, and magnetometry.
The crystalline structure of NaZnFe$_2$(VO$_4$)$_3$ is described by a triclinic spatial group of symmetry $P$1 with the parameters of an elementary crystalline chain: $a$ = 6.74318 (7) $\mathring{\mathrm{A}}$, $b$ = 8.1729 (1)$\mathring{\mathrm{A}}$, $c$ = 9.8421 (1) $\mathring{\mathrm{A}}$, $\alpha$ = 106.2611 (9)$^\circ$, $\beta$ = 104.55 (1)$^\circ$, $\gamma$ = 102.337 (1)$^\circ$, $V$ = 479.88 (1) $\mathring{\mathrm{A}}^3$, $Z$ = 2. Magnetic Fe$^{3+}$ cations in the cell occupy six positions populated together with diamagnetic Zn$^{2+}$ cations, which leads to states of magnetic inhomogeneity and local violation of charge neutrality.
Data from resonance and magnetic studies of NaZnFe$_2$(VO$_4$)$_3$ confirm the main role of high-spin Fe$^{3+}$ iron cations in the formation of magnetism with competing exchange magnetic interactions and a high value of the frustration index. It is shown that the magnetic subsystem of a sample with a negative asymptotic Neel temperature undergoes a magnetic transition from the paramagnetic state to the magnetic state of the spin glass when the temperature decreases.