Ferroelectric Tunability Studies in Doped BaTiO3 and Ba1−xSrxTiO3

2000 ◽  
Vol 658 ◽  
Author(s):  
Dong Li ◽  
M. A. Subramanian
Keyword(s):  
Curie Temperature ◽  
Phase Change ◽  
Tetragonal Phase ◽  
Cryogenic Temperature ◽  
Room Temperature ◽  
Co Doping ◽  
Structure Changes

ABSTRACTAcceptor and Donor codoped BaTiO3 and Ba1−xSrxTiO3 are prepared. For Ba1−xLaxTi1−xFexO3,BaTiO3 remains as tetragonal phase up to about 5mol% LaFeO3. For x ≥0.06, the structure changes to cubic at room temperature. The phase change shifts the Curie temperature to lower value and increases the tunability at room temperature. Doping of other acceptor (Al, Cr) and donor (Sm, Gd, Dy) ions has the same effect although with varying levels of tuning. BaTiO3: 4%LaFeO3 has the highest tunability among the studied systems, which is even higher than Ba0.6Sr0.4TiO3. Co-doping of (La, Fe) and (La, Al) in Ba1−xSrxTiO3 also lowers the Curie temperature and increases the tunability of high Ba content samples at cryogenic temperature.

Solvothermal Preparation and Thermal Phase Change Behaviors of Nanosized Tetragonal-Phase Silver Selenide (Ag2Se)

2013 ◽  
Vol 850-851 ◽  
pp. 128-131 ◽  
Author(s):  
Jun Li Wang ◽  
Hui Feng ◽  
Wei Ling Fan
Keyword(s):  
Transition Temperature ◽  
Phase Change ◽  
Photoelectron Spectroscopy ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Variable Temperature ◽  
Cubic Phase ◽  
Silver Selenide ◽  
X Ray ◽  
Change Behaviors

Nanocrystalline silver selenide (Ag2Se) with an average diameter of 100 nm were prepared by a facile solvothermal method. X-ray energy dispersive (EDS) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies confirmed that the products were pure Ag2Se. Room-temperature powder X-ray diffraction (XRD) measurements indicated that the as-prepared Ag2Se nanocrystals exhibit a metastable tetragonal polymorphic phase, rather than the common orthorhombic phase at room temperature. The variable-temperature XRD and differential scanning calorimetry (DSC) thermal analysis techniques were used to investigate the phase change behaviors of the tetragonal Ag2Se nanocrystals, and the results showed that the low-temperature tetragonal phase transforms to the high-temperature cubic phase at about 106 °C. This transition temperature is lower by ~30 °C than the orthorhombic-cubic transition temperature (133140 °C) previously reported for Ag2Se. Meanwhile, two exothermic peaks, loaded at 61 and 89 °C, respectively, were detected in the cooling DSC scan for the cubic to tetragonal phase transition, and the reason was discussed.

scholarly journals EPR Spectra of Sintered Cd1−xCrxTe Powdered Crystals with Various Cr Content

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Integral Intensity ◽  
Resonance Field ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Simple Method ◽  
Paramagnetic Curie Temperature ◽  
Cr Content ◽  
Electron Paramagnetic

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.

scholarly journals The Al Doping Effect on Epitaxial (In,Mn)As Dilute Magnetic Semiconductors Prepared by Ion Implantation and Pulsed Laser Melting

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4138
Author(s):  
Ye Yuan ◽  
Yufang Xie ◽  
Ning Yuan ◽  
Mao Wang ◽  
René Heller ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Ion Implantation ◽  
Diluted Magnetic Semiconductors ◽  
Laser Annealing ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Pulsed Laser ◽  
Laser Melting ◽  
Co Doping ◽  
Diluted Magnetic

One of the most attractive characteristics of diluted ferromagnetic semiconductors is the possibility to modulate their electronic and ferromagnetic properties, coupled by itinerant holes through various means. A prominent example is the modification of Curie temperature and magnetic anisotropy by ion implantation and pulsed laser melting in III–V diluted magnetic semiconductors. In this study, to the best of our knowledge, we performed, for the first time, the co-doping of (In,Mn)As diluted magnetic semiconductors by Al by co-implantation subsequently combined with a pulsed laser annealing technique. Additionally, the structural and magnetic properties were systematically investigated by gradually raising the Al implantation fluence. Unexpectedly, under a well-preserved epitaxial structure, all samples presented weaken Curie temperature, magnetization, as well as uniaxial magnetic anisotropies when more aluminum was involved. Such a phenomenon is probably due to enhanced carrier localization introduced by Al or the suppression of substitutional Mn atoms.

Exploiting novel optical thermometry near room temperature with a combination of phase-change host and luminescent Pr3+ ion

2021 ◽  
Vol 414 ◽  
pp. 128884
Author(s):  
Shuxian Wang ◽  
Jinpu Zhang ◽  
Zhengmao Ye ◽  
Haohai Yu ◽  
Huaijin Zhang
Keyword(s):  
Phase Change ◽  
Room Temperature ◽  
Optical Thermometry

Electronic structure engineering of tin telluride through co-doping of bismuth and indium for high performance thermoelectrics: a synergistic effect leading to a record high room temperature ZT in tin telluride

2019 ◽  
Vol 7 (16) ◽  
pp. 4817-4821 ◽  
Author(s):  
U. Sandhya Shenoy ◽  
D. Krishna Bhat
Keyword(s):  
Electronic Structure ◽  
Synergistic Effect ◽  
Band Gap ◽  
High Performance ◽  
Room Temperature ◽  
Band Offset ◽  
Valence Band Offset ◽  
Co Doping ◽  
Tin Telluride ◽  
Structure Engineering

Resonance states due to Bi and In co-doping, band gap enlargement, and a reduced valence-band offset in SnTe lead to a record high room-temperature ZT.

Room temperature rectification in tapered-channel thermal diodes through nanoscale confinement-induced liquid–solid phase change

2021 ◽  
Vol 129 (7) ◽  
pp. 075103
Author(s):  
Matt Jacobs ◽  
Xinran Zhou ◽  
Edgar Olivera ◽  
Ryan Sheil ◽  
Shu Huang ◽  
...  
Keyword(s):  
Phase Change ◽  
Room Temperature ◽  
Solid Phase ◽  
Tapered Channel

Screening and Design of Novel 2D Ferromagnetic Materials with High Curie Temperature above Room Temperature

2018 ◽  
Vol 10 (45) ◽  
pp. 39032-39039 ◽  
Author(s):  
Zhou Jiang ◽  
Peng Wang ◽  
Jianpei Xing ◽  
Xue Jiang ◽  
Jijun Zhao
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Ferromagnetic Materials ◽  
High Curie Temperature

Nanocell fabrication on GaSb at room temperature and cryogenic temperature

2012 ◽  
Author(s):  
Noriko Nitta ◽  
Kazuhiro Yokoyama ◽  
Masafumi Taniwaki
Keyword(s):  
Cryogenic Temperature ◽  
Room Temperature

Martensitic Transformation and Mechanical Properties of Fe-Doped Ni54Mn21Ga25 Alloys

2011 ◽  
Vol 687 ◽  
pp. 500-504
Author(s):  
S. X. Xue ◽  
S.S. Feng ◽  
P. Y. Cai ◽  
Q T Li ◽  
H. B. Wang
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Magnetic Properties ◽  
Martensitic Transformation ◽  
Curie Temperature ◽  
Directional Solidification ◽  
Transformation Temperature ◽  
Room Temperature ◽  
Martensitic Transformation Temperature ◽  
Polycrystalline Alloys

Ni54Mn21-xFexGa25（x=0,1,3,5,7,9）polycrystalline alloys were prepared by the technique of directional solidification and the effect of substituting Fe for Mn on the martensitic transformation and mechanical properties of the alloys was analyzed. It was found that the Curie temperature increased with increasing substitution while the martensitic transformation temperature decreased. The Fe-doped Ni54Mn21Ga25 alloys exhibit excellent magnetic properties at room temperature; the typical Ni54Mn20Fe1Ga25 alloy shows a large magnetic-induced-strain of -1040 ppm at a magnetic field of 4000 Oe.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

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