Itinerant Vibrons and High-Temperature Superconductivity*

2000 ◽  
Vol 658 ◽  
Author(s):  
John B. Goodenough
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Temperature Superconductivity ◽  
Phase Segregation ◽  
Optical Mode ◽  
Temperature Changes ◽  
Critical Composition ◽  
Underdoped Region ◽  
Small Polarons ◽  
Electronic Behavior

ABSTRACTThe La2−xSrxCuO4 phase diagram is interpreted within the framework of a transition from localized to itinerant electronic behavior. In the underdoped region 0 < x < 0.1, holes in the x2 – y2 band are not small polarons; each occupies a mobile correlation bag of 5 to 6 copper centers at temperatures T > TF, a spinodal phase segregation into the parent antiferromagnetic phase and a polaron liquid is accomplished below TF by cooperative oxygen displacements. In the overdoped compositions > x > 0.25, holes are excluded from strong-correlation fluctuations within a Fermi liquid. In the intermediate range 0.1 < x < 0.25, the polaron liquid formed below room temperature changes character with increasing x and decreasing T. In the polaron liquid, mobile two-hole bags of four copper centers order with decreasing temperature into alternate CuO-Cu rows of a superconductive CuO2 sheet at a critical composition xc ≍ 1/6. It is argued that hybridization of itinerant electrons with optical-mode phonons propagating along the Cu-O-Cu rows produces heavy electrons responsible for high-temperature superconductivity.

scholarly journals Room-temperature oxygen vacancy migration induced reversible phase transformation during the anelastic deformation in CuO

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lei Li ◽  
Guoxujia Chen ◽  
He Zheng ◽  
Weiwei Meng ◽  
Shuangfeng Jia ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxygen Vacancy ◽  
Room Temperature ◽  
High Temperature Superconductivity ◽  
Experimental Investigations ◽  
Solid State Chemistry ◽  
Vacancy Migration ◽  
Scientific Disciplines ◽  
Anelastic Deformation ◽  
Reversible Phase

AbstractFrom the mechanical perspectives, the influence of point defects is generally considered at high temperature, especially when the creep deformation dominates. Here, we show the stress-induced reversible oxygen vacancy migration in CuO nanowires at room temperature, causing the unanticipated anelastic deformation. The anelastic strain is associated with the nucleation of oxygen-deficient CuOx phase, which gradually transforms back to CuO after stress releasing, leading to the gradual recovery of the nanowire shape. Detailed analysis reveals an oxygen deficient metastable CuOx phase that has been overlooked in the literatures. Both theoretical and experimental investigations faithfully predict the oxygen vacancy diffusion pathways in CuO. Our finding facilitates a better understanding of the complicated mechanical behaviors in materials, which could also be relevant across multiple scientific disciplines, such as high-temperature superconductivity and solid-state chemistry in Cu-O compounds, etc.

Fracture Mechanics of Y2O3 Ceramics at High Temperatures

2014 ◽  
Vol 89 ◽  
pp. 88-93
Author(s):  
Marek Boniecki ◽  
Zdzislaw Librant ◽  
Władysław Wesołowski ◽  
Magdalena Gizowska ◽  
Marcin Osuchowski ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
High Temperature ◽  
Fracture Mechanics ◽  
High Purity ◽  
Room Temperature ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Temperature Changes ◽  
Four Point Bending

Fracture toughness KIc and four-point bending strength σc at high temperature (up to 1500 °C) of Y2O3 ceramics of various grain size were measured. The ceramics were prepared by pressureless air sintering and next hot isostatic pressing of high purity (99.99%) Y2O3 powder. Relative density of about 99 % was achieved. Photos of microstructures revealed small pores distributed mainly inside grains. For smallest grain size (2 - 9 μm) ceramics KIc and σc are almost constant from 20 ° to 1200 °C and next they decrease. For biggest grain size (about 44 μm) they increase up to 800 °C and next they keep constant up to 1200 °C. The micrographs analyses of fracture surfaces indicated that transgranular mode of fracture at room temperature changes to almost intergranular at higher temperatures.

scholarly journals ELECTRON–PHONON INTERACTIONS CAUSE HTSC

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3153-3155 ◽  
Author(s):  
J. C. PHILLIPS
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Temperature Superconductivity ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Light Pulses ◽  
Pressure Changes

What is the microscopic interaction responsible for high temperature superconductivity (HTSC)? Here data on temporal relaxation of T c and the room temperature conductivity in YBa2Cu3O 6+x after abrupt alteration by light pulses or pressure changes are analyzed. The analysis proves, independently of microscopic details, that only electron–phonon interactions can cause HTSC in the cuprates; all other dynamical interactions are excluded by experiment.

Induction of high-temperature superconductivity in pulsed laser ablated La2CuO4thin films by room temperature chemical oxidation

1997 ◽  
Vol 9 (10) ◽  
pp. 823-826 ◽  
Author(s):  
Simon T. Lees ◽  
Peter P. Edwards ◽  
Ian Gameson ◽  
Martin O. Jones ◽  
Marcin Slaski ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Temperature Superconductivity ◽  
Pulsed Laser ◽  
Chemical Oxidation

scholarly journals Fluctuations and the Higgs Mechanism in Underdoped Cuprates

2020 ◽  
Vol 11 (1) ◽  
pp. 301-323 ◽  
Author(s):  
C. Pépin ◽  
D. Chakraborty ◽  
M. Grandadam ◽  
S. Sarkar
Keyword(s):  
High Temperature ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Higgs Mechanism ◽  
Pseudogap Phase ◽  
Theoretical Approaches ◽  
Underdoped Region ◽  
Underdoped Cuprates ◽  
The Rich ◽  
Ubiquitous Presence

The physics of the pseudogap phase of high-temperature cuprate superconductors has been an enduring mystery over the past 30 years. The ubiquitous presence of the pseudogap phase in underdoped cuprates suggests that understanding it is key to unraveling the origin of high-temperature superconductivity. We review various theoretical approaches to this problem, emphasizing the concept of emergent symmetries in the underdoped region of those compounds. We differentiate these theories by considering a few fundamental questions related to the rich phenomenology of these materials. Lastly, we discuss a recent idea regarding two kinds of entangled preformed pairs that open a gap at the pseudogap onset temperature, T*, through a specific Higgs mechanism. We review the experimental consequences of this line of thought.

scholarly journals PENGARUH PANJANG STACK SELUBUNG KABEL TERHADAP PERUBAHAN SUHU PADA SISTEM PENDINGIN TERMOAKUSTIK

2017 ◽  
Vol 2 (2) ◽  
pp. 119
Author(s):  
Indah Kharismawati ◽  
Hanif Rafika Putri
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Room Temperature ◽  
Initial Temperature ◽  
Temperature Drop ◽  
Maximum Temperature ◽  
Thermoelectric Cooler ◽  
Thermoelectric Coolers ◽  
Temperature Changes ◽  
Sheath Material

Research on environmentally friendly thermo-acoustic coolants uses a heat exchanger from the cable sheath material. The resonator tube used in the thermoelectric cooler is a 5.25 cm diameter PVC (polyvinyl chloride) tube with a length of 87 cm. Variations in stack lengths of 4cm, 5cm, 6cm, 7cm, and 8cm were performed to obtain results on thermoelectric coolers. Results are available on the use of stack length 4 cm high temperature 21.6 oC from the initial temperature), the stack length 5 cm high temperature 21.1 oC from the initial temperature (room temperature), the stack length of 6 cm resulted in a maximum temperature drop of 22.6 oC from the initial temperature (room temperature), the stack length of 7 cm resulted in a maximum temperature drop of 22.0 oC from the initial temperature (room temperature), while the stack length of 8 cm resulted in a decrease in temperature maximum of 23.3 oC from the initial temperature (room temperature). Keywords: Thermoacoustic, stack, temperature changes.

scholarly journals The Needle in the Haystack for Theory of High Temperature Superconductivity: Negative Nuclear Magnetic Moments

2018 ◽  
Author(s):  
Reginald Little
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Cooper Pair ◽  
High Temperature Superconductivity ◽  
Magnetic Moments ◽  
High Energy ◽  
Cooper Pairs ◽  
Nuclear Magnetic Moments ◽  
Relativistic Scattering ◽  
Nuclear Magnetic

This work outlines a theory for explaining high temperature superconductivity on the basis of relativistic scattering of Cooper pairs via beyond room temperature conditions causing high energy relativistic scattering of Cooper pairs with nuclei having positive and negative nuclear magnetic moments for fractionally reversibly fissing and fusing the nuclei for manifesting in the electronic lattice for altered quantum fields for more tightly binding the Cooper pair beyond the conventional critical temperature 40K limit for superconductivity beyond room temperature.

scholarly journals The Needle in the Haystack for Theory of High Temperature Superconductivity: Negative Nuclear Magnetic Moments

2018 ◽  
Author(s):  
Reginald Little
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Cooper Pair ◽  
High Temperature Superconductivity ◽  
Magnetic Moments ◽  
High Energy ◽  
Cooper Pairs ◽  
Nuclear Magnetic Moments ◽  
Relativistic Scattering ◽  
Nuclear Magnetic

This work outlines a theory for explaining high temperature superconductivity on the basis of relativistic scattering of Cooper pairs via beyond room temperature conditions causing high energy relativistic scattering of Cooper pairs with nuclei having positive and negative nuclear magnetic moments for fractionally reversibly fissing and fusing the nuclei for manifesting in the electronic lattice for altered quantum fields for more tightly binding the Cooper pair beyond the conventional critical temperature 40K limit for superconductivity beyond room temperature.

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