Effect of CuO2 planes on the structural and superconducting transport properties of [CuTl − 12(n − 1)n;n = 2,3,4] superconductor family

2016 ◽  
Vol 30 (18) ◽  
pp. 1650112
Author(s):  
M. Usman Muzaffar ◽  
Nawazish A. Khan
Keyword(s):  
Transport Properties ◽  
Solid State Reaction Method ◽  
Fermi Velocity ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Axis Length ◽  
Superconducting Parameters ◽  
Absorption Measurements

[Formula: see text] [Formula: see text] superconducting bulk samples have been synthesized by using two-step solid state reaction method. We investigated the effects of [Formula: see text] planes on the structural and superconducting transport properties of [Formula: see text] superconducting family. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) absorption spectroscopy and DC-resistivity [Formula: see text] measurements. These samples are [Formula: see text]-axis length oriented and have shown orthorhombic crystal structure. All the samples have shown metallic variations of resistivity from room temperature down to onset of superconductivity. The zero resistivity critical temperature [Formula: see text] increases with the increase in superconducting planes and normal state resistivity systematically decreases, which show the density of inadvertent defects decreases in the final compound. The apical oxygen phonon modes are hardened as observed in the FTIR absorption measurements. The intrinsic microscopic superconducting parameters, such as the cross-over temperatures, coherence length along [Formula: see text]-axis [Formula: see text] at 0 K, inter-layer coupling [Formula: see text], inter-grain coupling [Formula: see text] and fermi velocity [Formula: see text], were extracted from the fluctuation-induced conductivity (FIC) analysis. FIC analysis also showed the improvement in superconductivity with the increase in [Formula: see text] planes.

Structural, Dielectric and Electrical Studies of Ba4CaRTi3Nb7O30 (R = Eu, Dy) Ferroelectric System

2013 ◽  
Vol 547 ◽  
pp. 41-48 ◽  
Author(s):  
Prasun Ganguly ◽  
A.M. Biradar ◽  
A.K. Jha
Keyword(s):  
Single Phase ◽  
Microstructural Analysis ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Paraelectric Phase Transition ◽  
Orthorhombic Crystal Structure

The polycrystalline samples of Ba4CaRTi3Nb7O30 (R = Eu, Dy), members of tungsten-bronze family, were prepared by high-temperature solid state reaction method and studied for their dielectric and electrical properties. X-ray diffraction (XRD) analysis reveals the formation of single-phase compounds having orthorhombic crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compounds have well defined grains, which are distributed uniformly throughout the sample. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor kind of ferroelectric-paraelectric phase transition of diffuse nature. Ferroelectric, piezoelectric and pyroelectric studies of the compounds have been discussed in this paper. The temperature dependence of dc conductivity of the compounds have been investigated. The conductivity study over a wide temperature range suggests that the compounds have negative temperature coefficient of resistance (NTCR) behaviour.

Thermal enhancement of 2H11/2→4I15/2 up-conversion luminescence of Er3+ doped K2Yb(PO4)(MoO4) phosphors

2021 ◽  
Author(s):  
Hongqiang Cui ◽  
Yongze Cao ◽  
Lei Zhang ◽  
Yuhang Zhang ◽  
Siying Ran ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Reaction Method ◽  
X Ray ◽  
Thermal Enhancement

Er3+ with different concentrations doped K2Yb(PO4)(MoO4) phosphors were prepared by a solid-state reaction method, and the layered orthorhombic crystal structure of the samples was confirmed by X-ray diffraction (XRD). Under...

Decoupling of the CuO2 plane and superconductivity in Cu0.5Tl0.5Ba2(Ca2−ySry)Cu3O10−δ(y = 0–0.4) samples

2016 ◽  
Vol 30 (17) ◽  
pp. 1650097
Author(s):  
Nawazish A. Khan ◽  
M. Usman Muzaffar
Keyword(s):  
Flux Pinning ◽  
High Temperature Superconductors ◽  
Normal Pressure ◽  
Cuo2 Plane ◽  
Fermi Velocity ◽  
Orthorhombic Crystal ◽  
Ginzburg Landau ◽  
Orthorhombic Crystal Structure ◽  
Axis Length

[Formula: see text]–[Formula: see text] samples have been synthesized at normal pressure at 860[Formula: see text]C. The main objectives of these experiments to study the role of inter-plane decoupling in suppressing the superconductivity of high temperature superconductors (HTSC). These samples have shown orthorhombic crystal structure and the [Formula: see text]-axis length increases with increased Sr-doping. All the samples have shown metallic variations of resistivity [Formula: see text] from room temperature down to the onset of superconductivity. The magnitude of the superconductivity is suppressed and the apical oxygen modes are hardened with Sr-doping. These studies have shown that Sr-doping promotes decoupling of conducting [Formula: see text] planes which suppress the superconducting properties of final compound. The excess conductivity analyses have shown increases in the width of two-dimensional (2D) Lawrence–Doniach (LD) regime with Sr-doping. The coherence length along the [Formula: see text]-axis [Formula: see text], the inter-layer coupling [Formula: see text], the phase relaxation time of the carriers [Formula: see text] and the Fermi velocity [Formula: see text] of superconductor carriers is suppressed. The underlying reason for the suppression of superconductor properties is the decrease in the density of carriers in the superconductor planes. However, the values of [Formula: see text], [Formula: see text] and [Formula: see text] have been found to increase with the increased Sr-doping, which is suggested to be originating from the enhancement in the flux pinning character which is induced by Sr-doping. The values of magnetic field penetration depth [Formula: see text] and the Ginzburg–Landau (GL) parameter [Formula: see text] decrease with Sr-doping and it is also suggested to be originating from the increase of flux pinning character of the samples with Sr-doping.

IMPEDANCE SPECTROSCOPY AND MAGNETIC PROPERTIES OF AURIVILLIUS STRUCTURES

2012 ◽  
Vol 02 (03) ◽  
pp. 1250015
Author(s):  
S. K. PATRI ◽  
R. N. P. CHOUDHARY ◽  
C. RINALDI
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Complex Impedance ◽  
Hysteresis Loops ◽  
Solid State Reaction Method ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Layered Perovskite Structure

Bi 9-x Fe 5+x Ti 3 O 27 (x = 0-3) compounds of bismuth layered perovskite structure have been successfully prepared by solid-state reaction method. X-ray diffraction (XRD) studies revealed the orthorhombic crystal structure of all the compounds. Impedance spectroscopy has been studied to characterize the electrical properties of polycrystalline Bi 9-x Fe 5+x Ti 3 O 27 (x = 0-3) compounds. The shape of complex impedance curves inferred the contribution of bulk and grain boundary effects on the electrical properties of the compounds. Temperature dependent magnetization measurements were made from 2 K to 300 K. Narrow hysteresis loops observed at room temperature indicate antiferromagnetic behavior of the compounds.

Flame Retardant Polyamide 6 Composites Using NMH or NMH/MCA/APP

2011 ◽  
Vol 189-193 ◽  
pp. 1208-1211 ◽  
Author(s):  
Yan Shen ◽  
Shao Guo Wen ◽  
Ji Hu Wang ◽  
Hong Bo Liu ◽  
Hai Liang Qi ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Magnesium Hydroxide ◽  
Flame Retardants ◽  
Polyamide 6 ◽  
X Ray Diffraction ◽  
Upward Trend ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Orthogonal Experiments ◽  
Nitrogen Phosphorus

In this paper, flame retardant Polyamide 6 (PA6) composites were prepared by nano-magnesium hydroxide (NMH) or its composites with melamine cyanurate(MCA) and ammonium polyphosphate(APP). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the structure of nano-magnesium hydroxide. The properties including tensile properties, molten index (MFI), rockwell hardness and density of flame retardant PA6 were analyzed. Orthogonal experiments were used to study flame retardancy of PA6 with NMH, MCA and APP. The results showed NMH had hexagonal orthorhombic crystal structure with size of 300×200×100nm. Density of polyamide 6 showed an upward trend when the content of NMH was increasing, the mechanical properties and hardness changed little while processing performance serious declined. The flame retardance of nitrogen-phosphorus -inorganic flame retardants was not desirable.

Effect of Sintering on Structural and Transport Properties on Nanosized Pr0.85Na0.15MnO3

2015 ◽  
Vol 1107 ◽  
pp. 272-277 ◽  
Author(s):  
Siau Wei Ng ◽  
Kean Pah Lim ◽  
S.A. Halim ◽  
Hassan Jumiah ◽  
Albert H.M. Gan ◽  
...  
Keyword(s):  
Grain Size ◽  
Transport Properties ◽  
Electrical Transport ◽  
Boundary Effect ◽  
Sol Gel ◽  
Magnetic Layer ◽  
Electrical Transport Properties ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Semiconductor Behavior

We have investigated the structural, microstructure and electrical transport properties of nanosized Pr0.85Na0.15MnO3 (PNMO) synthesized by sol-gel technique and sinter from 600°C to 1000°C. The grain size increases from 67 nm (S600) up to 284 nm (S1000) due to the grain growth during heat treatment. XRD showed that single phase orthorhombic crystal structure of PNMO is fully forms started at 600°C. The resistivity decreased with the increased of grain size and crystallite size due to the reduction of grain boundary effect (dead magnetic layer) which improved their grain conductivity.All samples showed semiconductor behavior where their metal insulator transition temperatures (TMIT) were estimated to be lower than 80K.

scholarly journals Structure and Magnetism of Co2Ge Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1371 ◽  
Author(s):  
Onur Tosun ◽  
Frank M. Abel ◽  
Balamurugan Balasubramanian ◽  
Ralph Skomski ◽  
David J. Sellmyer ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Orthorhombic Phase ◽  
Blocking Temperature ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Average Size ◽  
Cluster Beam Deposition ◽  
Curie Temperature Tc ◽  
Beam Deposition

The structural and magnetic properties of Co2Ge nanoparticles (NPs) prepared by the cluster-beam deposition (CBD) technique have been investigated. As-made particles with an average size of 5.5 nm exhibit a mixture of hexagonal and orthorhombic crystal structures. Thermomagnetic measurements showed that the as-made particles are superparamagnetic at room temperature with a blocking temperature (TB) of 20 K. When the particles are annealed at 823 K for 12 h, their size is increased to 13 nm and they develop a new orthorhombic crystal structure, with a Curie temperature (TC) of 815 K. This is drastically different from bulk, which are ferromagnetic at cryogenic temperatures only. X-ray diffraction (XRD) measurements suggest the formation of a new Co-rich orthorhombic phase (OP) with slightly increased c/a ratio in the annealed particles and this is believed to be the reason for the drastic change in their magnetic properties.

Rietveld Refinement and DC Conductivity of Na0.5K0.5NbO3 Ceramics

2012 ◽  
Vol 585 ◽  
pp. 210-213 ◽  
Author(s):  
Monica Sindhu ◽  
N. Ahlawat ◽  
Sujata Sanghi ◽  
Ashish Agarwal ◽  
A. Ashima ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Base Material ◽  
Polycrystalline Sample ◽  
Solid State Reaction Method ◽  
Dc Conductivity ◽  
Potassium Sodium Niobate ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Refinement Method

Potassium Sodium Niobate, Na0.5K0.5NbO3 is a promising base material for lead free piezoceramics. The polycrystalline sample Na0.5K0.5NbO3 was synthesized using solid state reaction method. The crystal structure and phase purity was studied by XRD and analysed using Rietveld refinement method. Good agreement was observed between the observed and calculated patterns in Rietveld refinement. The refinement inferred orthorhombic crystal structure with Amm2 space group. The impedance spectroscopy of the sample was performed in frequency range 10 Hz to 7 MHz in temperature range 573K to 703K. The activation energy was obtained to be 0.67eV from the reciprocal temperature variation of dc conductivity which follows the Arrhenius law.

scholarly journals Ferroelectric Properties ofNa2Pb2R2W2Ti4V4O30(R = Dy, Pr) Ceramics

2007 ◽  
Vol 2007 ◽  
pp. 1-5 ◽  
Author(s):  
Piyush R. Das ◽  
Banarji Behera ◽  
R. N. P. Choudhary ◽  
B. K. Samantray
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
Orthorhombic Crystal Structure ◽  
Preparation Conditions ◽  
Polarization Study ◽  
Ferroelectric Phase Transitions

The polycrystalline samples ofNa2Pb2R2W2Ti4V4O30(R = Dy, Pr) were prepared by low-temperature, (i.e., at650∘C) solid-state reaction technique. The preparation conditions have been optimized using thermogravimetry analysis (TGA) technique. X-ray diffraction (XRD) studies of the compounds showed the formation of a single-phase orthorhombic crystal structure at room temperature. Studies of dielectric properties (ɛrand tanδ) of the compounds at frequencies 10, 100, and 1000 kHz in a wide temperature range (room temperature–500∘C) exhibit ferroelectric phase transitions at132∘Cfor NPDWTV and at122∘Cfor NPPWTV of diffuse type. Ferroelectric properties of the materials are confirmed by polarization study.

STUDY ON THE SUPERCONDUCTIVITY OF Ba2(Y1−xLax)Cu3O7−y

1988 ◽  
Vol 02 (03n04) ◽  
pp. 621-628
Author(s):  
C. DONG ◽  
J.K. LIANG ◽  
C.G. CUI ◽  
S.L. LI ◽  
Y.M. NI ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Continuous Solid Solution ◽  
Mixed Valence ◽  
Tetragonal Structure ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Semiconductor Behavior ◽  
Low Dimensional

A series of samples with the nominal composition Ba 2( Ba 1−x La x) Cu 3 O 7−y, (0≤x≤1), was synthesized by solid state reaction. An X-ray diffraction study showed that a continuous solid solution exists between Ba 2 YCu 3 O 7−y and Ba 2 LaCu 3 O 7−y and there is a composition induced order-disorder transition from an orthorhombic to a tetragonal structure when x value is near 0.9. All the samples with orthorhombic crystal structure are superconductors with Tc onset above 90K. The transition midpoint temperature decreases smoothly when La content increases. The samples with x≥0.9 have a tetragonal structure and show semiconductor behavior with an exception of the x=1.0 sample which is a superconductor. Based on our previous and present studies, we concluded that the low dimensional character of the crystal structure and the mixed-valence state of copper or oxygen are necessary conditions for high-Tc superconductivity in copper-containing oxides.

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