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A simple and convenient one step route is described for preparing a series of chalcospinels [Fe.sub.1-x][Cu.sub.x][Cr.sub.2][S.sub.4] by using high frequency sound waves. The results have provided an effective method for synthesizing doped ternary chalcospinels displaying magnetoresistive properties.

The enhancement in magnetoresistance ratio in the equiatomic B site composition is due to the onset of double exchange mediated ferromagnetic interaction. Double-exchange interactions induced in SrRuO(sub 3) perovskite by doping Mn ion is the observation made.

The influence of barrier effect of RuO2 and TiO2 on the magnetoresistance in CrO2 powder compacts is examined. The interparticle resistance and the magnetoresistance are enhanced by TiO2 due to the insulating conduction channel between the two CrO2 grains.

The structural, transport and magnetotransport properties of pulsed electron deposited [La.sub.0.6][Pb.sub.0.4]Mn[O.sub.3] and [La.sub.1-x][Pb.sub.x][Mn.sub.0.8][Ru.sub.0.2][O.sub.3] (0.2

The temperature dependence powder neutron diffraction studies on SrRu[O.sub.3] (SRO) and Sr[Ru.sub.0.5][Mn.sub.0.5][O.sub.3] (SRMO) are used for exploring the interplay between the structure and magnetic order in the presence of Ru-Mn interaction. The presence of [Mn.sup.3] ions have played a vital role in stabilizing the charge exchange (CE)-type antiferromagnetic ordering.

The Ru substitutional effects in [La.sub.1.2][Sr.sub.1.8][Mn.sub.2-x][Ru.sub.x][O.sub.7] (0

An electron-transport material, 2,5-dibenzthiazolyl thiophene (TBZT) characterized using the photogenerated time-of-flight technique, which shows a weak electric-field-dependent electron mobility is reported. The suitability of TBZT as an electron-transport material in the device structure employing bis [(2-(2'-hydroxyl phenyl) benzthiazolate] zinc (II) complex as an active layer is performed.

Clear evidence of a sustained double exchange effect in La0.6Pb0.4MnO3 doped with Ru up to 50% in the Mn-O-Mn sublattice is presented. It is observed that Ru makes a magnetic pair with Mn by the presence of Ru (V), which is similar in ionic size to the Mn (IV) ion, thereby, favoring the double exchange mediated transport phenomenon.

We present a simple and convenient one step route to prepare a series of chalcospinels Fe1-xCuxCr2S4 employing high frequency sound waves. The magnetic and electronic transport properties of the as-prepared spinels were studied, and this simple, easy, and efficient synthetic route may further encourage wider application of Cu-doped Fe chalcogenides in solid state magnetoelectronic devices. Furthermore, the adopted synthetic route highlights a one-pot synthesis employing organometallic precursors such as metal carbonyls, ethylenedimine, and elemental sulfur. The ease of synthesizing such complex spinel structures of Fe1-xCuxCr2S4 chalcogenides with x=0.3, 0.4, and 0.6 has been highlighted in this work. The rapid cavitational collapse results in sulfur deficiency in the system, which drastically alters the conduction behavior. All the compositions studied show a negative magnetoresistance response except for x=0.3 which exhibit an unusual positive magnetoresistance effect. Such an effect has been attributed to the sulfur deficiency occurring during the rapid cavitational collapse. Our experimental results provide one effective method for synthesis of doped ternary chalcospinels exhibiting magnetoresistive properties. [ABSTRACT FROM AUTHOR]

Sr4Ru2O9 has a P62C space group and differs from the Ruddelsden-Popper series of the strontium ruthenate family where Ru is distinctly present in Ru+5 state with no Jahn-Teller activity. A significant increase in magnetic moment and coercivity is observed along with lowering of resistivity, especially around a critical concentration of x=0.2 in Sr4-xLaxRu2-xMnxO9. Such an unusual effect is correlated to the mixed magnetic pair effect arising out from the variable oxidation states of Ru as suggested by x-ray photoelectron spectroscopic studies. Our results substantiate the long-range ferromagnetism observed for Ruthenium-substituted three-dimensional manganites. [ABSTRACT FROM AUTHOR]

We report an electron-transport material; 2,5-dibenzthiazolyl thiophene (TBZT) characterized using the photogenerated time-of-flight technique, which shows a weak electric-field-dependent electron mobility, typically of the order of 1.21×10-4 cm2/V s at 2.5×105 V/cm, two orders of magnitude higher than the Alq3 complex. This enhanced carrier mobility is facilitated by the excited-state configuration of the molecule as verified by the AM1–CI semiempirical calculations in the anionic form. We show the effect of high mobility electron transport on a bilayer electroluminescent device, ITO/TPD/ZBZT/TBZT (10 nm)/Al, using bis [(2-(2′-hydroxyl phenyl) benzthiazolate] zinc (II) complex as the emissive layer which resulted in a 25-nm significant shift in the recombination zone and an improved current–voltage characteristics by a factor of two. [ABSTRACT FROM AUTHOR]

Double exchange mediated magnetism and transport properties are exemplified in two-dimensional layered manganites, La[sub 1.2]Ca[sub 1.8]Mn[sub 2]O[sub 7]. We demonstrate here the role of ruthenium in showing increased metal-insulator transition temperature, T[sub P] and Curie temperature T[sub c], by about 15 K when Ru is substituted up to 10% (x = 0.2) at the Mn site. We discuss these unique features based on the existence of a redox ionic pair involving Mn[sup 3+]/Mn[sup 4+] ↔ Ru[sup 4+]/Ru[sup 5+] up to x∼0.2. Beyond the critical level (x∼0.2), Ru exists mostly in Ru[sup 4+] oxidation state leading to a weak double exchange interaction. We document here, an enhanced T[sub c] and T[sup P] in the layered manganites despite the disorder induced at the B site. [ABSTRACT FROM AUTHOR]

We report an enhanced negative magnetoresistance ratio of about 16% at 4.2 K at 1 T for CrO[sub 2]/TiO[sub 2] composites, compared to CrO[sub 2] powder compacts and CrO[sub 2]/RuO[sub 2] composite. The magnetoresistance ratio of 60% at 4.2 K is noted when TiO2 acts as tunneling barrier. The absence of substantial barrier heights with RuO[sub 2] grains does not alter the magnetoresistance compared to the CrO[sub 2] powder compacts. The insulating TiO[sub 2] grains increases the grain boundary barrier for the spin polarized tunneling, thereby enhancing the low field magnetoresistance. [ABSTRACT FROM AUTHOR]

Reports on the synthesis of bulk and thin films of La0.7Sr0.3Mn1-xRuxO3. Preparation of these films using pulsed laser deposition; Examination of the magnetization measurements of the bulk films; Comparison of the magnetoresistive behavior of Ru substituted films with the parent La0.7Sr0.3MnO3 films; Experimental procedures used in synthesis process; Summarization of the study.

Reports on the artificial fabrication of stacked monolayers of Fe/Cu on Cu(100) by pulsed laser deposition at 300 K employing reflection high energy electron diffraction. Use of pulsed laser deposition technique; Magneto-optical Kerr effect measurements.

Studies enhanced magnetoresistance in as-deposited oxygen-deficient thin films. Method of the study; Results and discussion; Conclusion.

Reports that highly-textured, as-deposited La[sub0.6]Pb[sub0.4]MnO thin films were grown in LaAlO[sub3] by pulsed laser deposition. Instrument used to obtain magnetic measurements.

Zirconium oxide (zirconia) exists in three crystalline forms of monoclinic, tetragonal and cubic structures at atmospheric pressures. The cubic form of zirconia is well known for its mechanical, electrochemical and optical applications. Fe-doped cubic zirconia (high temperature phase) compositions are synthesized by microwave combustion method. Here, we present a Mössbauer investigation of Zr1 − x Fe x O2 composition within a range of Fe (0.03 < x < 0.09). 57Fe Mössbauer spectra were recorded at room temperature and at low temperature (77 K) for all samples. 3% Fe-doped ZrO2 shows doublet and the corresponding 6% and 9% Fe-doped ZrO2 samples show superimposed sextet and doublets. The isomer shift and quadrupole moment indicate, Iron to be in III oxidation state and to occupy different octahedral sites, associated with some amount of disorder. X-ray powder diffraction pattern of Fe-doped ZrO2 samples appear as very well crystalline. The Miller indices refer to the cubic fluorite-type ZrO2 structure. The magnetic behavior shows increase in moment and decrease in coercivity, with increase in Fe concentration. The M vs. H plots of the as-prepared Zr1- x Fe x O2 essentially show typical hysteresis loops, indicating room temperature ferromagnetism. Thus, the introduced microwave combustion route is an effective process to achieve multifunctional Fe-doped Zirconia with coexistent magnetic properties. [ABSTRACT FROM AUTHOR]

Interconversion of intermolecular H-bonded di(benzimidazol-2-yl)-benzene to an intramolecular H-bonded isomer shows a strong blue to green shifted fluorescence. [ABSTRACT FROM AUTHOR]

Nanofilms of poly(tetrafluoroethylene) (PTFE; commercially coded as Teflon) shows advantage over inorganic spacer materials like Al2O3 and MgO in fabricating tunneling magneto resistive devices due to its relative dielectric constant and chemical inertness to provide a homogenous metal–organic interface. Pulsed electron deposition proves useful in fabricating such thin PTFE films (3–6 nm) for trilayer device such as Fe (100 nm)/PTFE (3–6 nm)/Fe (100 nm) on Si(100). Characteristic magnetic hysteresis loops demonstrating the magnetic tunnel junctions were realized for a PTFE organic layer thickness is less than 3 nm. The tunneling magnetoresistance measurement at room temperature shows a typical magnetoresistive feature, increasing with increasing PTFE thickness. [ABSTRACT FROM AUTHOR]

A stable nano body-centered cubic (bcc) CoFe2 alloy was isolated by employing a combination of N2H4.H2O reduction and sonochemical route under basic conditions. This alloy has proved to be a potential precursor for CoFe2O4 production. X-ray diffraction and transmission electron microscopy confirms the formation of a bcc phase CoFe2 alloy with particle size <10 nm and spherical morphology. Thermogravimetric analysis confirmed the oxidation of the alloy composition showing a weight gain between 200 and 500 °C, which corresponds to fully oxidized CoFe2O4. A significant increase in the saturation magnetization (Ms = 230 emu/g) for the nano CoFe2 alloy was observed in comparison with that of the theoretical bulk value (200 emu/g) at 300 K. [ABSTRACT FROM AUTHOR]

A detailed study of Ru substitution at the Mn site in La[sub 0.7]A[sub 0.3]Mn[sub 0.9]Ru[sub 0.1]O[sub 3] (A=Ca, Sr, Pb, Ba) polycrystalline samples shows an unusual magnetic pair between Ru[sup +4]/Ru[sup +5] and Mn[sup +4]/Mn[sup +3] redox couple. As a result, in the entire 10 at. % Ru-substituted compositions, the T[sub C] varies only by 10-30 K. The similarity of Mn[sup 4+]/Ru[sup 4+]:e[sub g] parentage facilitates a redox interaction between Mn and Ru ions, Ru[sup +4/+5]/Mn[sup +3/+4]. Ruthenium (IV) low spin state has a magnetic moment of 2.7-2.9μ[sub B], and with an extended 4d orbital, it enhances exchange coupling between Mn and Ru sites. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have isolated a stable nano bcc-CoFe2 alloy using a combi-sonoreduction process under basic conditions, serving as a potential precursor for CoFe2O4 production. X-ray and transmission electron microscopy (TEM) confirms the formation of a bcc phase CoFe2 alloy with particle size <10 nm, having spherical morphology. The thermo gravimetric analysis (TGA) confirms the alloy composition, showing a weight gain between 200 and 500°C, leading to a fully oxidized CoFe2O4. A significant increase in the saturation magnetization (Ms = 230 emu/g) for the nano CoFe2 alloy is observed compared to the theoretical bulk value (200 emu/g) at 300 K. [ABSTRACT FROM AUTHOR]

The substitutional effect of Ru on the magnetic and transport properties of double exchange ferromagnets, La0.7Sr0.3MnO3 and La0.5Sr0.5CoO3 has been investigated. It is found that substitution of 10% Ru at the Mn site of La0.7Sr0.3MnO3 decreases the Curie temperature by 20 K than that of the parent compound. However, a large decrease in the Curie temperature, ΔTc∼80 K and the system undergoes a transition from metallic state to insulating state is observed when 10% Ru is doped in La0.5Sr0.5CoO3. The marginal effect of Ru in the Mn–O–Mn sublattice in comparison to the Co–O–Co sublattice could be due to the magnetic exchange interaction between Mn and Ru by virtue of the fact that Ru exhibits variable valence states, Ru+4/Ru+5. The eg and t2g parentage of Ru+5 is similar to Mn+4 and therefore, Ru+5 ion appears to participate in the double exchange mediated ferromagnetic (FM) interaction. On the other hand, Ruthenium (IV) ion disrupts an intermediate spin state of cobalt (Co+3: t2g5eg1), forcing a double exchange FM state to anti-FM state. [Copyright &y& Elsevier]

Abstract: Wide band gap InGaZn6O9 films of thickness ~350 nm were deposited on sapphire (0001) at room temperature by using the pulsed laser deposition technique. The transparent films showed the optical transmission of >80% with the room temperature Hall mobility of ~10 cm2/V s and conductivity of 4×102 S/cm at a carrier density >1020 cm−3. The electrical properties as a function of deposition temperatures revealed that the conductivity and mobility almost retained up to the deposition temperature of 200 °C. The films annealed in different atmospheres suggested oxygen vacancy plays an important role in determining the electrical conductivity of the compound. Room temperature grown heterostructure of n-InGaZn6O9/p-SiC showed a good rectifying behavior with a leakage current density of less than 10− 9 A/cm2, current rectifying ratio of 105 with a forward turn on voltage ~3 V, and a breakdown voltage greater than 32 V. [Copyright &y& Elsevier]

The "green emission defect" (GED) produced by fluorenones has significantly retarded the commercial scope of fluorene-based B-OLEDs. In this paper, for the first time, it is demonstrated that the "green light" emitting fluorenones 7 can be converted to "blue light" emitting fluorenones 10 by appropriate positioning of donor-acceptor and chromophoric groups onto the fluorene/fluorenone backbone. Additionally, we report an elegant highly rapid synthetic route for donor-acceptor fluorenes and fluorenones at room temperature with excellent yields.

Amorphous nanoalloys of Co(100-x)Pt(x) (0 < or = x < or = 50) prepared sonochemically exhibit a negative magnetotransport effect, showing a maximum for platinum volume fraction of 10%. The oscillatory peak maxima observed in x = 30 composition for residual resistivity, rho0 and Tmin corresponds to the peak minima for the negative MR% in the range of compositions studied. We observe that in weakly exchange coupled amorphous alloys, the local magnetic order at Tmin and the disorder effects observed from rho0 become crucial.