scholarly journals Nonvolatile modulation of electronic structure and correlative magnetism of L10-FePt films using significant strain induced by shape memory substrates

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Chun Feng ◽  
Jiancheng Zhao ◽  
Feng Yang ◽  
Kui Gong ◽  
Shijie Hao ◽  
...  
Keyword(s):  
Shape Memory ◽  
Elastic Strain ◽  
Lattice Strain ◽  
Physical Nature ◽  
Strain Engineering ◽  
Strain Effect ◽  
Pure Strain ◽  
Electronic Density ◽  
Fept Film ◽  
Novel Approach

Abstract Tuning the lattice strain (εL) is a novel approach to manipulate the magnetic, electronic and transport properties of spintronic materials. Achievable εL in thin film samples induced by traditional ferroelectric or flexible substrates is usually volatile and well below 1%. Such limits in the tuning capability cannot meet the requirements for nonvolatile applications of spintronic materials. This study answers to the challenge of introducing significant amount of elastic strain in deposited thin films so that noticeable tuning of the spintronic characteristics can be realized. Based on subtle elastic strain engineering of depositing L10-FePt films on pre-stretched NiTi(Nb) shape memory alloy substrates, steerable and nonvolatile lattice strain up to 2.18% has been achieved in the L10-FePt films by thermally controlling the shape memory effect of the substrates. Introduced strains at this level significantly modify the electronic density of state, orbital overlap and spin-orbit coupling (SOC) strength in the FePt film, leading to nonvolatile modulation of magnetic anisotropy and magnetization reversal characteristics. This finding not only opens an efficient avenue for the nonvolatile tuning of SOC based magnetism and spintronic effects, but also helps to clarify the physical nature of pure strain effect.

Annealing effects on phase transformation and powder microstructure of nanocrystalline zirconia polymorphs

1999 ◽  
Vol 14 (1) ◽  
pp. 90-96 ◽  
Author(s):  
R. Ramamoorthy ◽  
S. Ramasamy ◽  
D. Sundararaman
Keyword(s):  
Monoclinic Phase ◽  
Lattice Strain ◽  
Dopant Concentration ◽  
Precipitation Method ◽  
Strain Effect ◽  
Volume Percentage ◽  
Annealing Temperatures ◽  
Annealing Effects ◽  
Nanocrystalline Zirconia ◽  
Average Size

Nanocrystalline zirconia powders in pure form and doped with yttria and calcia were prepared by the precipitation method. In the as-prepared condition, all the doped samples show only monoclinic phase, independent of the dopants and dopant concentration. On annealing the powders at 400 °C and above, in the case of 3 and 6 mol% Y2O3 stabilized ZrO2 (3YSZ and 6YSZ), the monoclinic phase transforms to tetragonal and cubic phases, respectively, whereas in 3 and 6 mol% CaO stabilized ZrO2 (3CSZ and 6CSZ), the volume percentage of the monoclinic phase gradually decreases up to the annealing temperature of about 1000 °C and then increases for higher annealing temperatures. The presence of monoclinic phase in the as-prepared samples of doped zirconia has been attributed to the lattice strain effect which results in the less symmetric lattice. For the annealing temperatures below 1000 °C, the phenomenon of partial stabilization of the tetragonal phase in 3CSZ and 6CSZ can be explained in terms of the grain size effect. High resolution transmission electron microscopy (HRTEM) observations reveal the lattice strain structure in the as-prepared materials. The particles are found to be a tightly bound aggregate of small crystallites with average size of 10 nm. The morphology of the particles is observed to be dependent on the dopants and dopant concentration.

scholarly journals In Situ Generation of Green Hybrid Nanofibrillar Polymer-Polymer Composites—A Novel Approach to the Triple Shape Memory Polymer Formation

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1900
Author(s):  
Ramin Hosseinnezhad ◽  
Iurii Vozniak ◽  
Fahmi Zaïri
Keyword(s):  
Polymer Blends ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Cellulose Nanofibers ◽  
Polymeric Materials ◽  
Novel Approach ◽  
Phase Transition Temperatures ◽  
Triple Shape Memory

The paper discusses the possibility of using in situ generated hybrid polymer-polymer nanocomposites as polymeric materials with triple shape memory, which, unlike conventional polymer blends with triple shape memory, are characterized by fully separated phase transition temperatures and strongest bonding between the polymer blends phase interfaces which are critical to the shape fixing and recovery. This was demonstrated using the three-component system polylactide/polybutylene adipateterephthalate/cellulose nanofibers (PLA/PBAT/CNFs). The role of in situ generated PBAT nanofibers and CNFs in the formation of efficient physical crosslinks at PLA-PBAT, PLA-CNF and PBAT-CNF interfaces and the effect of CNFs on the PBAT fibrillation and crystallization processes were elucidated. The in situ generated composites showed drastically higher values of strain recovery ratios, strain fixity ratios, faster recovery rate and better mechanical properties compared to the blend.

Weakened Lattice-Strain Effect in MoOx@NPC-Supported Ruthenium Dots toward High-Efficiency Hydrogen Generation

2021 ◽  
Author(s):  
Min Song ◽  
Haeseong Jang ◽  
Chuang Li ◽  
Min Gyu Kim ◽  
Xuqiang Ji ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Lattice Strain ◽  
High Efficiency ◽  
Hydrogen Generation ◽  
Crystalline Substance ◽  
Strain Effect

Designing conductive amorphous buffer layer between crystals (or lowering the crystallinity of one component) to minimize lattice-strain influence between highly crystalline substance and nearby constitute, alleviating the lattice strain thus...

Modeling Smart Materials Using Hysteretic Recurrent Neural Networks

2009 ◽  
Author(s):  
Arun Veeramani ◽  
John Crews ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Real Time Control ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
Time Control ◽  
Novel Approach ◽  
Three Phase ◽  
Ferromagnetic Shape Memory

This paper describes a novel approach to modeling hysteresis using a Hysteretic Recurrent Neural Network (HRNN). The HRNN utilizes weighted recurrent neurons, each composed of conjoined sigmoid activation functions to capture the directional dependencies typical of hysteretic smart materials (piezoelectrics, ferromagnetic, shape memory alloys, etc.) Network weights are included on the output layer to facilitate training and provide statistical model information such as phase fraction probabilities. This paper demonstrates HRNN-based modeling of two- and three-phase transformations in hysteretic materials (shape memory alloys) with experimental validation. A two-phase network is constructed to model the displacement characteristics of a shape memory alloy (SMA) wire under constant stress. To capture the more general thermo-mechanical behavior of SMAs, a three-phase HRNN model (which accounts for detwinned Martensite, twinned Martensite, and Austensite phases) is developed and experimentally validated. The HRNN modeling approach described in this paper readily lends itself to other hysteretic materials and may be used for developing real-time control algorithms.

A new approach to characterization of the transition temperatures of thin film NiTi shape memory alloys

2004 ◽  
Vol 19 (6) ◽  
pp. 1762-1767
Author(s):  
Nicholas W. Botterill ◽  
David M. Grant ◽  
Jianxin Zhang ◽  
Clive J. Roberts
Keyword(s):  
Thin Film ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transition Temperatures ◽  
New Approach ◽  
Novel Approach ◽  
Potential Applications ◽  
Niti Shape Memory Alloys

A novel approach in determining the transition temperatures of NiTi shape memory alloys was investigated and compared with conventional techniques. The technique is based on microthemal analysis using a scanning thermal microscope (SThM). In particular, this method has the potential to allow the transformation temperatures of thin films to be investigated in situ. Thin film shape memory alloys have potential applications, such as microactuators, where conventional analysis techniques are either not directly applicable to such samples or are difficult to perform.

scholarly journals Elastic strain engineering for unprecedented materials properties

MRS Bulletin ◽  
2014 ◽  
Vol 39 (2) ◽  
pp. 108-114 ◽  
Author(s):  
Ju Li ◽  
Zhiwei Shan ◽  
Evan Ma
Keyword(s):  
Elastic Strain ◽  
Strain Engineering ◽  
Materials Properties ◽  
Image Position

Abstract

scholarly journals Lattice Strain Analysis of a Mn-Doped CdSe QD System Using Crystallography Techniques

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 639 ◽  
Author(s):  
Hamizi ◽  
Johan ◽  
Ghazali ◽  
Wahab ◽  
Chowdhury ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Reaction Times ◽  
Strain Analysis ◽  
Xrd Analysis ◽  
Lattice Parameter ◽  
Strain Effect ◽  
Similar Reaction ◽  
Cdse Qds ◽  
Particle Size Reduction ◽  
Mn Doped

In this work, we report on the different sizes of manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) synthesized for 0 to 90 min using a reverse micelle organic solvent method and surfactant having a zinc blende structure, with physical size varying from 3 to 14 nm and crystallite size from 2.46 to 5.46 nm and with a narrow size distribution. At similar reaction times, Mn-doped CdSe QDs displayed the growth of larger QDs compared with the pure CdSe QDs. Due to the implementation of lattice strain owing to the inclusion of Mn atoms in the CdSe QD lattice, the lattice parameter was compressed as the QD size increased. Strain was induced by the particle size reduction, as observed from X-ray diffractometer (XRD) analysis. The analyses of the strain effect on the QD reduction are discussed relative to each of the XRD characteristics.

Sign in / Sign up

Export Citation Format

Share Document