There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

비만아 부모의 돌봄 경험: q 방법론

Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

Nanomaterials (NMs) are gaining significance in technological applications due to their tunable chemical, physical, and mechanical properties and enhanced performance when compared with their bulkier counterparts. This review presents a summary of the general types of NMs and provides an overview of the various synthesis methods of nanoparticles (NPs) and their functionalization via covalent or noncovalent interactions using different methods. It highlights the techniques used for the characterization of NPs and discusses their physical and chemical properties. Due to their unique properties, NMs have several applications and have become part of our daily lives. As a result, nanotoxicity research is gaining attention since some NPs are not easily degraded by the environment. Thus, this review also highlights research efforts into the fate, behavior, and toxicity of different classes of NMs in the environment.

Nanomaterials: Classification, properties, and environmental toxicities

Matrix–nano composites are a new generation of materials that have the potential for satisfying the recent demands of advanced applications and technologies. Pure ZnO was used in its micron–sized form in which 50% of weight of TiO2 nanoparticles was added to form ZnO:TiO2 composite. TiO2 nanoparticles were prepared using a low–cost sol–gel method. Both the samples, pure micron–sized ZnO matrix and TiO2:ZnO composite, were characterized by X–Ray Diffraction (XRD) measurement at room temperature using Cu Kα X–ray radiation source. XRD results reveal the single phasic nature of ZnO as well as dual phases of composite which consists of TiO2 phase as well as ZnO matrix phase. Dielectric constant is found to decrease with increase in frequency studied up to 2 MHz. Dielectric of composite is found to be larger than pure ZnO matrix. Relaxation formula and universal dielectric response (UDR) model were employed to understand the dielectric behaviors of the samples. Conductivity, which is larger for pure ZnO, has been understood in terms of Jonscher's power law mechanism for both the samples. Impedance measurements show an enhancement in its values for composite sample as compared to pure ZnO matrix sample throughout the frequency range studied.

Investigations on the structural and electrical properties of oxide nano-micro particles-matrix composite

In the present communication, nanostructured Bi0.9Nd0.1FeO3 (BNFO) multiferroics have been successfully synthesized by sol–gel method and finally sintered at different temperatures. In order to investigate the structural properties, X-ray diffraction (XRD) measurement was carried out at room temperature that reveals the single phase of BNFO samples. For microstructural behaviors and granular morphology of nanostructures, scanning electron microscopy (SEM) was performed. It is observed that grain morphology gets improved with increase in sintering temperature. For elemental analysis, energy dispersive X-ray analysis (EDAX) was carried out for all BNFO samples, which reveal appropriate doping of Nd at Bi site in BNFO samples. Frequency dependent dielectric measurements show that the dielectric constant increases with increase in sintering temperature, which has been understood on the basis granular morphology of the samples. Frequency dependent dielectric behavior follows the universal dielectric response (UDR) model for all BNFO samples. Magnetodielectric (MD) effect has been investigated in the frequency range of 20 Hz–2 MHz, which shows a strong dependence of sintering temperature and granular morphology of the samples. AC conductivity was found to obey the Jonscher’s universal power law, which suggests the correlated barrier hopping (CBH) process as a responsible mechanism for charge conduction across the BNFO lattices.

Sintering temperature dependent electrical properties of sol–gel grown nanostructured Bi 0.95 Nd 0.05 FeO 3 multiferroics

The results of the studies on structural disorder-induced modifications in the transport behaviour of La0.5Pr0.2Ca0.3−x
 Ba
 x
 MnO3 (LPCBMO) (0.05 ≤ x ≤ 0.30) manganites were reported. Structural studies using X-ray diffraction (XRD) measurements confirmed the single phasic nature of all the samples without any detectable impurities. The A-site size disorder (
 ${ {\sigma }}_{\mathrm{A}}^{\mathrm{2}}$
 ) increased from 3.81 × 10
 −5
 (x = 0.05) to 14.9 × 10−5 (x = 0.30). With the increase in structural disorder in LPCBMO system, the transport improved for the range: 0.15 ≤ x ≤ 0.30, which can be ascribed to the enhancement in one electron bandwidth which dominates over the structural disorder effect, while for lower values of x, strong competition existed between size disorder and one electron bandwidth. Below 50 K, all ρ–T plots showed resistivity minimum behaviour, which modified with disorder. This behaviour was discussed in detail on the basis of electron–electron interaction having the form: $ {\rho } {=} {[}\mathrm{1} {/} {(} {\sigma }_{\mathrm{0}} {+} {BT}^{\mathrm{1 {/}2}} {)} {]} {+} {\rho }_{ {n}} {T}^{ {n}}$
 . Variation in temperature sensitivity with disorder was also discussed in context of granular morphology and phase segregation scenario.

/pdf/investigations-on-structural-disorder-induced-modifications-57awh06yre.pdf

Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

Studies on electrical properties of Fe doped ZnO nanostructured oxides synthesized by sol-gel method

A nonsuperconducting La2Ba2Cu4O9+δ system has been made superconducting by the addition of CaCuO2, along with rare earth doping at the La site, with the stoichiometric composition La2−xRxCayBa2Cu4+yO10+δ (R=Nd, Gd, and y=2x) All the samples with 00<x<05; y=2x were characterized by x-ray diffraction and neutron diffraction measurements for structural properties and by ac susceptibility, dc resistivity, and iodometric analysis for superconducting properties The x=00 sample displays semiconducting behavior Increasing x increases Tc from less than 15 K for Nd/Gd samples with x=01 to ∼78 K for x=05 samples It is interesting to note that the hole concentration and Tc exhibit a strong correlation with increasing dopant concentration Neutron diffraction studies confirm the occupancy of Ca and Nd ions at the La site with a concomitant displacement of La on to the Ba site

Nikesh A. Shah

Papers

Investigations on the structural and electrical properties of oxide nano-micro particles-matrix composite

Sintering temperature dependent electrical properties of sol–gel grown nanostructured Bi 0.95 Nd 0.05 FeO 3 multiferroics

Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

Studies on electrical properties of Fe doped ZnO nanostructured oxides synthesized by sol-gel method

Structural and superconducting properties of La2−xRxBa2CayCu4+yO10+δ (R=Nd, Gd; y=2x) system