We report the synthesis, crystal structures, and spectral, thermal, and magnetic properties of a family of metal-organic perovskite ABX(3), [C(NH(2))(3)][M(II)(HCOO)(3)], in which A = C(NH(2))(3) is guanidinium, B = M is a divalent metal ion (Mn, Fe, Co, Ni, Cu, or Zn), and X is the formate HCOO(-). The compounds could be synthesized by either diffusion or hydrothermal methods from water or water-rich solutions depending on the metal. The five members (Mn, Fe, Co, Ni, and Zn) are isostructural and crystallize in the orthorhombic space group Pnna, while the Cu member in Pna2(1). In the perovskite structures, the octahedrally coordinated metal ions are connected by the anti-anti formate bridges, thus forming the anionic NaCl-type [M(HCOO)(3)](-) frameworks, with the guanidinium in the nearly cubic cavities of the frameworks. The Jahn-Teller effect of Cu(2+) results in a distorted anionic Cu-formate framework that can be regarded as Cu-formate chains through short basal Cu-O bonds linked by the long axial Cu-O bonds. These materials show higher thermal stability than other metal-organic perovskite series of [AmineH][M(HCOO)(3)] templated by the organic monoammonium cations (AmineH(+)) as a result of the stronger hydrogen bonding between guanidinium and the formate of the framework. A magnetic study revealed that the five magnetic members (except Zn) display spin-canted antiferromagnetism, with a Néel temperature of 8.8 (Mn), 10.0 (Fe), 14.2 (Co), 34.2 (Ni), and 4.6 K (Cu). In addition to the general spin-canted antiferromagnetism, the Fe compound shows two isothermal transformations (a spin-flop and a spin-flip to the paramagnetic phase) within 50 kOe. The Co member possesses quite a large canting angle. The Cu member is a magnetic system with low dimensional character and shows slow magnetic relaxation that probably results from the domain dynamics.
We report here a new class of ammonium metal-formate frameworks of [NH 2 NH 3 ][M(HCOO) 3 ] (M = Mn 2+ , Zn 2+ , Co 2+ and Mg 2+ ) incorporating hydrazinium as the cationic template and component.The perovskite Mn and Zn members possess anionic 4 12•6 3 metal-formate frameworks with cubic cavities occupied by the NH 2 NH 3 + cations, while the Co and Mg members have chiral 4 9 •6 6 metal-formate frameworks, with chiral hexagonal channels accommodating NH 2 NH 3 + cations. On heating, the Mn and Zn members undergo phase transitions around 350 K. The structures change from low temperature (LT) polar phases in Pna2 1 to high temperature (HT) non-polar phases in Pnma, due to the thermally activated librational movement of the NH 2 end of the NH 2 NH 3 + in the cavity and significant framework regulation.The Co and Mg members in LT belong to non-polar P2 1 2 1 2 1 , are probably antiferroelectric, and they show phase transitions at 380 K (Co) and 348 K (Mg), and the structures change to polar HT phases in P6 3 , triggered by the order-disorder transition of the cation from one unique orientation in LT to three of trigonally-disorder state in HT. Accompanying the phase transitions, which are ferro-to para-electric for Mn and Zn members while antiferro-to ferro-electric for Co and Mg, prominent anisotropic thermal expansions including negative ones, and dielectric anomalies, are observed. The spontaneous polarization values are estimated at 3.58 (Mn, 110 K), 3.48 (Zn, 110 K), 2.61 (Co, 405 K) and 3.44 (Mg, 400 K) μC cm −2 , respectively, based on the positive and negative charge separations in the polar structures. The structureproperty relevance is established based on the order-disorder transitions of NH 2 NH 3 + and the conformity and adaptability of the metal-formate frameworks to match such order-disorder alternations. The Mn and Co members show spin-canted antiferromagnetic long-range-ordering, with Néel temperatures of 7.9 K and 13.9 K, respectively. Therefore, the two members show coexistence of electric and magnetic orderings in the low temperature region, and they are possible molecule-based multiferroics.
A systematic study has been carried out on the 3d divalent metal formate 3D magnetic frameworks templated by protonated amines, and the achievements have revealed that metal formate frameworks are very malleable, and their structures depend on the size, shape, charge, and hydrogen bonding geometries of the templating cations. Six kinds of metal formate frameworks have been created. They are chiral frameworks with a (4(9) . 6(6)) topology, perovskite ones with a (4(12) . 6(3)) topology, bi-nodal frameworks of (4(12) . 6(3))(4(9) . 6(6))(n) (n = 1, 2, 3) topologies, and porous diamond frameworks with 6(6) topology. These materials display promising and abundant magnetic, dielectric, porous, and optical properties and the possible combination of them. Therefore, they are of great interest for the study of molecule-based materials. It has been demonstrated that formate, being the smallest and simplest carboxylate, cheap and with low toxicity, thus more biocompatible and environmentally friendly, and having been more or less ignored, will find an important role in the construction of molecule-based materials and provide new materials with interesting properties.
We report the synthesis, crystal structures, IR, and thermal, dielectric, and magnetic properties of a new series of ammonium metal formate frameworks of [HONH(3)][M(II)(HCOO)(3)] for M = Mn, Co, Ni, Zn, and Mg. They are isostructural and crystallize in the nonpolar chiral orthorhombic space group P2(1)2(1)2(1), a = 7.8121(2)-7.6225(2) Å, b = 7.9612(3)-7.7385(2) Å, c = 13.1728(7)-12.7280(4) Å, and V = 819.27(6)-754.95(4) Å(3). The structures possess anionic metal formate frameworks of 4(9)·6(6) topology, in which the octahedral metal centers are connected by the anti-anti formate ligands and the hydroxylammonium is located orderly in the channels, forming strong O/N-H···O(formate) hydrogen bonds with the framework. HONH(3)(+) with only two non-H atoms favors the formation of the dense chiral 4(9)·6(6) frameworks, instead of the less dense 4(12)·6(3) perovskite frameworks for other monoammoniums of two to four non-H atoms because of its small size and its ability to form strong hydrogen bonding. However, the larger size of HONH(3)(+) compared to NH(4)(+) resulted in simple dielectric properties and no phase transitions. The three magnetic members (Mn, Co, and Ni) display antiferromagnetic long-range ordering of spin canting, at Néel temperatures of 8.8 K (Mn), 10.9 K (Co), and 30.5 K (Ni), respectively, and small spontaneous magnetizations for the Mn and Ni members but large magnetization for the Co member. Thermal and IR spectroscopic properties are also reported.
A niccolite series of [bnH2 2+][M(HCOO)3]2 (bnH2 2+=1,4‐butyldiammonium) shows four kinds of metal‐dependent phase transitions, from high temperature para‐electric phases to low‐temperature ferro‐, antiferro‐, glass‐like, and para‐electric phases. The conformational flexibility of bnH2 2+ and the different size, mass, and bonding character of the metal ion lead to various disorder‐order transitions of bnH2 2+ in the lattice and relevant framework modulations, thus different phase transitions and dielectric responses. The magnetic members display a coexistence or combination of electric and magnetic orderings in the low‐temperature region.
Although appearance based trackers have been greatly improved in the last decade, they are still struggling with some challenges like occlusion, blur, fast motion, deformation, etc. As known, occlusion is still one of the soundness challenges for visual tracking. Other challenges are also not fully resolved for the existed trackers. In this work, we focus on tackling the latter problem in both color and depth domains. Neutrosophic set (NS) is as a new branch of philosophy for dealing with incomplete, indeterminate and inconsistent information. In this paper, we utilize the single valued neutrosophic set (SVNS), which is a subclass of NS, to build a robust tracker. First, the color and depth histogram are employed as the appearance features, and both features are represented in the SVNS domain via three membership functions T , I, and F. Second, the single valued neutrosophic cross-entropy measure is utilized for fusing the color and depth information. Finally, a novel SVNS based MeanShift tracker is proposed. Applied to the video sequences without serious occlusion in the Princeton RGBD Tracking dataset, the performance of our method was compared with those by the state-of-the-art trackers. The results revealed that our method outperforms these trackers when dealing with challenging factors like blur, fast motion, deformation, illumination variation, and camera jitter.
The employment of linear di-, tri-, and tetra-ammoniums has generated a hierarchy in the binodal (412⋅63)(49⋅66)n topologies with n = 1, 2, and 3, respectively, for the cobalt formate frameworks with increasing length of the cavities to match the ammoniums. This indicates the length-directing effect of the polyammoniums. The dynamic movements of polyammoniums between favored sites or orientations within the cavities lead to slow dielectric relaxations. All materials are spin-canted antiferromagnets in low temperatures and show reduced spontaneous magnetizations from di- and tri-, to tetra-ammoniums, because of the increased number of unique Co ions or the antiferromagnetically coupled sublattices.
Linguistic neutrosophic numbers (LNN) is presented by Fang and Ye in 2017, which can describe the truth, falsity, and indeterminacy linguistic information independently. In this paper, the LNN and the Bonferroni mean operator are merged together to propose a LNN normalized weighted Bonferroni mean (LNNNWBM) operator and a LNN normalized weighted geometric Bonferroni mean (LNNNWGBM) operator and the properties of these two operators are proved. Further, multi-attribute group decision methods are introduced based on the proposed LNNNWBM and LNNNWGBM operators, and then an example is provided to demonstrate the application and validity of the proposed methods. In addition, in order to consider the effect of the parameters p and q on the decision results, different pairs of parameter values are employed to verify the decision results.
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