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Ordered double perovskite La2FeCrO6 nanoparticles (NPs) were synthesized via the citrate auto-combustion technique. The prepared sample was characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), and Raman spectroscopy, which confirmed the double perovskite structure of the studied sample. XRD illustrated that the investigated sample has an orthorhombic structure with an average crystallite size of 25.3 nm. La2FeCrO6 NPs exhibit a porous structure and spongy morphology, as determined through analyses using Brunauer–Emmett–Teller (BET) specific surface area and field emission scanning electron microscopy (FESEM). The studied sample exhibits anti-ferromagnetic (AFM) behavior with weak ferromagnetic (FM) components, as an example of d5(Fe3+)–d3(Cr3+) systems. The AFM behavior is caused by the super-exchange interaction between [Fe3+(d5)–O–Cr3+(d3)], according to the Kanamori–Goodenough (KG) rule. This behavior is induced by the pdπ hybridization between the eg orbital of the transition metal and the pσ orbital of the oxygen, while the one induced by the pdσ hybridization is FM. The number of excited-state configurations mediated by the pdπ hybridization in the Fe–Cr pair is greater than that mediated by pdσ hybridization. Pb(II) heavy metal ions are used in adsorption studies. The electrostatic nature of the bonding between Pb(II) and the La2FeCrO6 nano ferrite sample is thought to be the main cause of the observed high sorption of La2FeCrO6 to a Pb(II) ion. La2FeCrO6 has a favorable morphology, which bodes well for its prospective applications in Li-ion batteries, water purification, and gas sensors.

T HE NEW ORGANIC-inorganic hybrid 1,7-heptanediammonium-calcium tetrachloride, with molecular formula [(CH 2) 7 (NH 3) 2 ] CaCl 4 , crystallized in a monoclinic Pm space group, a= 4.625 Å , b = 11.205 Å , c = 12.391 Å , α = 90 0 β = 86.82 0 , γ = 90 0 , V = 641.2 Å 3 , density= 1.63 mgm-3 and Z= 2. Differential thermal scanning of the new organic-inorganic hybrid showed five phase changes; chain melting transitions at T 1 = 329.2 K and T 2 = 326.49 K and three transitions at T 3 = 283.6 K, T 4 = 278.8 K and T 5 = 260.8 K associated with solidsolid phase changes. Permittivity and ac conductivity as a function of temperature (170 K-425 K) and frequency (0.06 kHz