William E. Estes

Bio: William E. Estes is an academic researcher from University of North Carolina at Chapel Hill. The author has contributed to research in topics: Copper & Magnetic susceptibility. The author has an hindex of 12, co-authored 25 publications receiving 721 citations.

Magnetic and structural characterization of dibromo- and dichlorobis(thiazole)copper(II)

Abstract: : The temperature dependence of the magnetic susceptibility and the electron paramagnetic resonance spectra of the thiazole complexes dichloro- and dibromobis(thiazole)copper(II) are reported, along with a complete three-dimensional X-ray structure analysis of the dichloro complex based on counter data. The dichloro complex, Cu(C3H3NS)2C12, crystallizes in space group of the monoclinic system with two independent formula units in a cell of dimensions a = 7.332(6), b = 3.853(4), c = 17.493(17) angstrom, and Beta = 93.70(1). The structure has been refined by full-matrix least-squares methods using 1172 independent data to a final value of the conventional R-factor (on F) of 0.028. The structure, which consists of infinite chains of doubly chloride bridged copper(II) ions, is reminiscent of those of the pyridine analogs, with a Cu-Cu separation of 3.853(4) angstrom and bridging angle of 91.89(2). The magnetic data and interchain exchange interactions are discussed in the light of the structural properties of the systems.

The magnetic properties of several quasi two-dimensional Heisenberg layer compounds: A new class of ferromagnetic insulators involving halocuprates

Abstract: Magnetic susceptibility measurements on powdered samples of bis(benzylammonium) tetrachlorocuprate (II), bis(phenethylammonium) tetrachlorocuprate(II), bis(3‐phenyl‐1‐propylammonium) tetrachlorocuprate(II), and bis(benzylammonium) tetrabromocuprate(II) have shown that these four substances order ferromagnetically with Curie temperatures of 8.0±0.5, 9.0±0.2, 7.0±0.5, and 12.3±1.0 K, respectively. Fits of a series expansion for a two‐dimensional lattice to the magnetic susceptibility data obtained from powdered samples in the paramagnetic region yielded exchange constants J for the chloride compounds in the range 16.7–18.8 K, and a value of 25.3 K for the bromide compound. For these fits the

Magnetic properties and superexchange in single chloride-bridged copper(II) chain compounds

Abstract: Magnetic susceptibility data have been measured in the temperature range 1.75 to 60 K for the following structurally characterized, single chloride-bridged copper(II) chain compounds: dichlorobis(dimethyl sulphoxide)copper(II), dichlorobis(imidazole)copper(II), aquo(caffeine)dichlorocopper(II), and dichloro[2-(2′-methylaminoethyl)pyridine]copper(II). The first two compounds exhibit antiferromagnetic intrachain interactions with exchange coupling constants of –6.1 and –2.1 cm–1, respectively, while the second two compounds exhibit ferromagnetic interactions with J values of 0.48 and 1.58 cm–1 respectively. Except for dichlorobis(imidazole)copper(II), which undergoes long-range magnetic ordering below 7.7 K, the exchange coupling constants become more negative as the angle at the chloride bridge increases from 113.6° in dichloro[2-(2′-methylaminoethyl)pyridine]copper(II) to 144.6° in dichlorobis(dimethyl sulphoxide)copper(II).

Layered organic-inorganic hybrid perovskites: structure, optical properties, film preparation, patterning and templating engineering

Abstract: Organic–inorganic perovskites are a class of interesting compound in the perovskite family due to their unique structures of alternately stacking sheets of organic and inorganic components on the molecular scale. In this highlight, the basic knowledge and recent advances in organic–inorganic perovskites are reviewed with particular emphasis on the feature work including: the novel - and -oriented perovskite structures, synthesis, film preparation, patterning methods and optoelectronic properties of hybrid perovskites. Moreover, the small functional organic molecules can be templated into a regular arrangement by the inorganic perovskite framework. This unique material with nature-formed lamellar structure has the potential to be used as a template to create novel derivatives and bring about unique physical properties. Some interesting examples, such as intercalated polymer and silica network by topochemical polymerisation, fabrication of disk-like semiconductor nanocrystals and metal nanoparticles by hybrid perovskite templates are described.

Room-Temperature Magnetic Bistability in Organic Radical Crystals

Abstract: A large first-order magnetic phase transition in an organic radical, 1,3,5-trithia-2,4,6-triazapentalenyl, is described. The transition occurs with a wide thermal hysteresis loop over the temperature range 230 to 305 kelvin. The high-temperature phase is paramagnetic, and its structure consists of a uniform one-dimensional stacking of the radical. The low-temperature phase is diamagnetic because of strong dimerization along the stacking direction. The results may have applications in thermal sensors, switching units, and information storage media based on organic radical crystals.