Multiple electrical phase transitions in nanocrystalline aluminium-substituted cobalt ferrite

2018 ◽  
Vol 32 (32) ◽  
pp. 1850358 ◽  
Author(s):  
Sweety Supriya ◽  
Sunil Kumar ◽  
Lagen Kumar Pradhan ◽  
Rabichandra Pandey ◽  
Manoranjan Kar
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Electrical Properties ◽  
Cobalt Ferrite ◽  
Ferroelectric Material ◽  
Relaxation Transition ◽  
Ferroelectric Materials ◽  
Transition Temperatures ◽  
Electrical Parameters

Electrical properties of a series of nanocrystalline aluminium-substituted cobalt ferrite CoAl[Formula: see text]Fe[Formula: see text]O4 (CAFO) with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 have been explored. The electrical parameters have been measured by employing impedance and techniques. The impedance has measured as a function of frequency and temperature for all the samples. The impedance increases with the increase in Al concentration in CAFO. Cobalt ferrite is yet to be verified as a ferroelectric material. However, the electrical properties reported here are similar to conventional ferroelectric materials. Multiple (two) electrical phase transitions have been observed, the two transition temperatures are identified as T[Formula: see text] and T[Formula: see text] i.e., one is dipole relaxation transition (T[Formula: see text]) and other one is electrical phase transition temperature. Both AC and DC measurements indicate the transition temperatures.

Change of Phase Transition Temperature in Band Engineered Ferroelectric Lanthanum-Modified Bismuth Titanates

2020 ◽  
Vol 20 (11) ◽  
pp. 7135-7139
Author(s):  
Rui Tang ◽  
Sangmo Kim ◽  
Chung Wung Bark
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ferroelectric Properties ◽  
Solar Spectrum ◽  
Ferroelectric Material ◽  
Transition Temperatures ◽  
Phase Transition Temperatures ◽  
Increasing Temperature

The ferroelectric material chosen for a solar cell has to absorb as much of the solar spectrum as possible, therefore a low band gap is desirable, but it is rarely known for phase transition temperature on the bandgap engineered ferroelectric materials. The phase transition temperature of a ferroelectric material can be determined by monitoring its dielectric constant with increasing temperature, as the dielectric constant changes abruptly at the phase transition temperature. Here, we inform the measurement of the phase transition temperature of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 as well as cobalt and iron doped Bi3.25La0.75Ti3O12 bulk ceramics for photovoltaic cells based on dielectric monitoring with changing temperature. We synthesized lanthanum-modified bismuth-titanate-based ceramics with various doping concentrations transition metal to Ti. X-ray diffraction analysis revealed that all the compounds crystallized in an orthorhombic structure. Their morphologies and size distributions were observed using scanning electron microscopy. From the ultraviolet-visible spectroscopy absorption spectra of the synthesized powder, bandgaps were checked. An inductance-capacitance-resistance meter was used to obtain the relationship between dielectric responses and the temperature of the targets in a tube furnace. We observed that the dielectric constant increases gradually with increasing temperature, until the transition temperature and subsequently decreases, and we were able to determine the phase transition temperatures of the tested materials. Furthermore, the results revealed that all the doped bismuth titanates keep their phase transition temperatures, which were sufficiently high, to maintain their ferroelectric properties above room temperature.

scholarly journals Thermal, ferroelastic, and structural properties near phase transitions of organic–inorganic perovskite type [NH3(CH2)3NH3]CdBr4 crystals

RSC Advances ◽  
2021 ◽  
Vol 11 (29) ◽  
pp. 17622-17629
Author(s):  
Ae Ran Lim
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Thermal Behavior ◽  
Structural Properties ◽  
Structural Dynamics ◽  
Transition Temperatures ◽  
Inorganic Perovskite ◽  
Phase Transition Temperatures ◽  
Perovskite Type

We studied the thermal behavior and structural dynamics of [NH3(CH2)3NH3]CdBr4 near phase transition temperatures.

Various types of holographic metal/superconductor phase transitions with dark matter sector

2016 ◽  
Vol 26 (06) ◽  
pp. 1750046
Author(s):  
Yan Peng ◽  
Tao Chen ◽  
Guohua Liu ◽  
Pengwei Ma
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Dark Matter ◽  
Phase Transitions ◽  
Transition Temperature ◽  
De Sitter ◽  
Holographic Superconductor ◽  
Black Hole Background ◽  
Critical Phase ◽  
Matter Sector

We generalize the holographic superconductor model with dark matter sector by including the Stückelberg mechanism in the four-dimensional anti-de Sitter (AdS) black hole background away from the probe limit. We study effects of the dark matter sector on the [Formula: see text]-wave scalar condensation and find that the dark matter sector affects the critical phase transition temperature and also the order of phase transitions. At last, we conclude that the dark matter sector brings richer physics in this general metal/superconductor system.

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

Liquid Crystalline Norcholesterylesters: Influence of the Axial Methylgroups on the Phase Transitions and the Cholesteric Helix

1989 ◽  
Vol 44 (11) ◽  
pp. 1127-1130 ◽  
Author(s):  
H. Stegemeyer ◽  
K. Siemensmeyer ◽  
W. Sucrow ◽  
L. Appel
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Liquid Crystalline ◽  
Helical Structure ◽  
Transition Temperatures ◽  
Phase Transition Temperatures

Liquid crystalline norcholesteryl anisic esters were prepared in which the methylgroups 19, 21, 27, and 18 are removed successively from the cholestene skeleton. The influence of the axial methylgroups on the phase transition temperatures and the choleric helical structure has been investigated. On heating the 18.19.21.27-tetranorcholesteryl ester, at 155 °C an inversion of the helical screw sense from left to right was observed

scholarly journals Transient Phases and their Transition Temperatures of A-Si in Non-Isothermal Processes

1993 ◽  
Vol 321 ◽  
Author(s):  
Masakuni Suzuki ◽  
Akio Kitagaffa
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Glass Transition ◽  
Transition Temperature ◽  
Heating Rate ◽  
Random Networks ◽  
Transition Temperatures ◽  
Isothermal Processes ◽  
Transient Phases ◽  
New Phase

ABSTRACTThe heating rate dependence of the phase transition temperature was formulated based on the temperature dependence of nucleation of a new phase. The glass transition temperature of a-Si was explained in terms of van der Waals fluid of a-Si pseudo-Molecules which are produced by the fragmentation of continuous random networks of Si atoms. Transient phases and their transition temperatures as a function of the heating rate are summarized in the phase diagram.

Deuterium substitution effects on the structural and magnetic phase transitions of a hydrogen-bonded coordination polymer, bis(glycolato)copper(ii)

2016 ◽  
Vol 45 (42) ◽  
pp. 16774-16778 ◽  
Author(s):  
Shota Yoneyama ◽  
Takeshi Kodama ◽  
Koichi Kikuchi ◽  
Takumi Fujisawa ◽  
Akira Yamaguchi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Magnetic Phase ◽  
Structural Phase ◽  
Magnetic Phase Transitions ◽  
Substitution Effects ◽  
Hydroxyl Groups ◽  
Large Shift ◽  
Deuterium Substitution

Bis(glycolato)copper(ii) [Cu(HOCH2CO2)2] shows a large shift of the structural phase transition temperature by deuterium substitution of the hydroxyl groups in it.

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