Permittivity and Microstructure of (Ba,Sr)TiO3 Films: Temperature and Electric Field Response

1999 ◽  
Vol 603 ◽  
Author(s):  
Yu.A. Boikov ◽  
T. Claeson ◽  
Z. Ivanov ◽  
E. Olsson
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Electric Field ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Transition Point ◽  
Phase Transition Point ◽  
Bulk Single Crystal ◽  
Temperature Range ◽  
Field Response

AbstractEpitaxial heterostructures (001)(Y,Nd)Ba2Cu3O7-δ∥(100)SrTiO3∥(001)(Nd,Y)Ba2Cu3O7-δ,(100)SrRuO3∥(100)Ba0.8Sr0.2TiO3∥(100)SrRuO3, (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 and (100)SrTiO3∥(001)YBa2Cu3O7-δ have been grown by laser ablation. There was only a small difference of the dielectric permittivity, in the temperature range 180-300K, between a bulk single crystal and an epitaxial (100)SrTiO3 layer inserted between either high-Tc superconducting or SrRuO3 electrodes. At T<1 50K, on the other hand, the response of the dielectric permittivity of the SrTiO3 layer on temperature or electric field depended to a large extent upon the materials used as bottom and top electrodes in the heterostructures. The temperature dependence of the dielectric permittivity for the SrTiO3 layer in (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 was well extrapolated by a Curie-Weiss relation in the range of T=80-300K, with about the same Curie constant (C0=7.5 × 104 K) and Curie temperature (TCurie=21K) as in a bulk single crystal. At temperatures higher the phase transition point (65 K), the electric field response of the permittivity of the SrTiO3 layer between high-TC superconducting or metallic oxide electrodes was well extrapolated by the same relation used for a bulk single crystal. The smallest loss factor, tanδ, was measured for the capacitance (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 (T ≈ 50-300K, f=100kHz). The measured conductance G for the SrTiO3 layer in the (001)(Y,Nd)Ba2Cu3O7-δ heterostructure fitted well the relation InG∼-(ED/kT), with ED=0.08-0.09 eV in a temperature range close to 300K. Pronounced hysteresis was observed in the temperature dependence of the dielectric permittivity for the (100)Ba0.8Sr0.2TiO3 layer at temperatures close to the phase transition point, like in the case of a bulk single crystal. The permittivity of the (100)Ba0.8Sr0.2TiO3 layer decreased more than 50% when an electric field of 2.5×106V/m (T ≈ 300K, f=100 kHz ) was applied.

scholarly journals Crystal Structure and Dielectric Property of Endohedral Lithium Fullerene

2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dielectric Property ◽  
Low Temperature ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Structure Analysis ◽  
X Ray ◽  
Dielectric Phase

Endohedral lithium fullerene Li+@C60 can have a dielectric polarization by the off-centered location of the Li+ cation inside the C60 cage. The x-ray structure analysis of the PF6– salt [Li@C60](PF6) revealed that the Li+ cation occupies two off-centered equivalent positions at 20 K and hence the crystal is non-polar [1]. The disordered structure at low temperature is explained by a static orientation disorder of polar Li+@C60 cations and/or a dynamic tunneling of the Li+ cation inside the C60 cage. The Li+ tunneling would be suppressed by an intermolecular interaction at lower temperature and a dielectric phase transition might be induced. We reveal the dielectric property and crystal structure of [Li@C60](PF6) below 20 K in this study. The temperature dependence of the dielectric permittivity was measured for the single crystal down to 9 K. The dielectric permittivity increases with decreasing temperature according to the Curie-Weiss law. Such a behavior was also observed in H2O@C60 crystal but not in empty C60 crystal [2]. No dielectric phase transition was observed in H2O@C60 down to 8 K. In contrast, a dielectric anomaly suggesting a phase transition was observed in [Li@C60](PF6) around 18 K. The single-crystal x-ray diffraction experiment below 20 K was also performed at SPring-8 BL02B1. The crystal has a cubic structure at 20 K [1]. The temperature dependence of the cubic lattice constant shows no anomaly around 18 K. However, diffraction peaks that are forbidden for the given structure appear below 18 K. Thus the crystal symmetry is lowered by the dielectric phase transition. We present the result of the crystal structure analysis of the newly discovered low-temperature phase.

Characterisation of Phase Transition in Strontium Barium Niobate by Bond Method

2010 ◽  
Vol 163 ◽  
pp. 264-267 ◽  
Author(s):  
Krystyna Wokulska ◽  
Paweł Pacek ◽  
Jan Dec ◽  
Tadeusz Łukasiewicz ◽  
M. Świrkowicz
Keyword(s):  
Phase Transition ◽  
Temperature Dependence ◽  
Transition Point ◽  
Structural Phase ◽  
Lattice Parameter ◽  
Phase Transition Point ◽  
Temperature Behaviour ◽  
X Ray ◽  
Distinct Temperature ◽  
Bond Method

The high quality Sr0.61Ba0.39Nb2O6 (SBN61) single crystals without any striations were obtained by Czochralski pulling method. The temperature dependence of the lattice parameters of the investigated crystals was studied using a precision X-ray Bond's method. The angular precision of the goniometer 1 arcsine and metric value of Cu K1 (λ = 1.54059292Å) allowed to obtain high precision and accuracy of lattice parameter measurements. The received results allowed to determine the Curie temperature and character of the phase transition in this material. The lattice parameter a monotonically increases and shows hardly visible inflection point at TC when increasing the temperature. The temperature dependence of the lattice parameter c displays quite distinct temperature behaviour. Contrastingly, it decreases with increasing the temperature experiencing an evident anomaly in the vicinity of the structural phase transition point. Obtained value of the ferroelectric phase transition point is TC = 346 ± 3K.

Mössbauer Spectroscopic Studies of (Me2NH2)2SnX6 (X = Cl or Br) and Their Related Complexes

2002 ◽  
Vol 57 (6-7) ◽  
pp. 607-612
Author(s):  
Motomi Katada ◽  
Dilara Afroj ◽  
Takashi Yamauchi ◽  
Satoshi Kawata
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Powder Diffraction ◽  
Transition Point ◽  
Molecular Motion ◽  
Spectroscopic Studies ◽  
Phase Transition Point ◽  
X Ray ◽  
Spectral Area

The temperature dependence in the 119Sn Mössbauer spectral area for {(CH3)2NH2}2SnCl6 was found to be almost linear, although a phase transition of the complex has been suggested by IR, 35Cl NQR and NMRstudies, while an anomaly in the temperature dependence for {(CH3)2NH2}2SnBr6 was found at 235 K, which is close to the phase transition temperature 253 K determined by 89Br NQR. These differences are attributable to molecular motion of the dimethylammonium ion in the complexes. The X-ray powder diffraction pattern of {(CH3)2NH2}2SnCl6 did not change near the phase transition point, but that of {(CH3)2NH2}2SnBr6 changed at 108 - 123 K and 233 - 253 K

Electric field-associated deformation of polyelectrolyte gel near a phase transition point

1992 ◽  
Vol 46 (4) ◽  
pp. 635-640 ◽  
Author(s):  
Tohru Shiga ◽  
Yoshiharu Hirose ◽  
Akane Okada ◽  
Toshio Kurauchi
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Transition Point ◽  
Phase Transition Point ◽  
Polyelectrolyte Gel
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