X-Ray Induced Insulator-Metal Transitions in CMR Manganites

1997 ◽  
Vol 494 ◽  
Author(s):  
V. Kiryukhin ◽  
D. Casa ◽  
B. Keimer ◽  
J. P. Hill ◽  
A. Vigliante ◽  
...  
Keyword(s):  
Lattice Structure ◽  
Charge Ordering ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Practical Applications ◽  
Transitional State ◽  
Current Voltage ◽  
Highly Nonlinear ◽  
Type Of Transition

ABSTRACTIn this work we report a study of the photoinduced insulator-to-metal transition in manganese oxide perovskites of the formula Pr1-xCaxMnO3. The transition is closely related to the magnetic field induced insulator-to-metal transition (CMR effect) observed in these materials. It is accompanied by a dramatic change in the magnetic properties and lattice structure: the material changes from an insulating charge-ordered canted antiferromagnet to a ferromagnetic metal. We present an investigation of the transport and structural properties of these materials over the course of the transition (which usually takes about an hour to complete). The current-voltage characteristics exhibited by the material during the transition are highly nonlinear, indicating a large inhomogeneity of the transitional state. Possible practical applications of this novel type of transition are briefly discussed. We also report a high-resolution x-ray diffraction study of the charge-ordering in these materials. The temperature dependent charge ordering structure observed in these compounds is more complex than previously reported.

Rectifying characteristics and tunable magnetoresistance in heterojunctions of La0.9Hf0.1MnO3/0.05 wt.% Nb-doped SrTiO3

2017 ◽  
Vol 31 (25) ◽  
pp. 1745022 ◽  
Author(s):  
Yaping Qi ◽  
Xiangbo Liu ◽  
Hao Ni ◽  
Ming Zheng ◽  
Liping Chen ◽  
...  
Keyword(s):  
Band Structure ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Ferromagnetic Transition ◽  
Grown Film ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Current Voltage ◽  
Current Voltage Characteristics

La[Formula: see text]Hf[Formula: see text]MnO3 films were grown on 0.05 wt.% Nb-doped SrTiO3 substrates by pulsed laser deposition. X-ray diffraction measurements demonstrated that our samples were of good epitaxy and single-crystal. The temperature-dependent resistance has been investigated. It was observed that the as-grown film of La[Formula: see text]Hf[Formula: see text]MnO3 exhibited a typical paramagnetic-ferromagnetic transition. Heterojunctions of La[Formula: see text]Hf[Formula: see text]MnO3/0.05 wt.% Nb-doped SrTiO3 exhibited-asymmetric current–voltage characteristics and a remarkable temperature-dependent rectifying behavior in a wide temperature range (from 40 K to 300 K). And the most remarkable observation of this work is the existence of a crossover from positive to negative magnetoresistance in the La[Formula: see text]Hf[Formula: see text]MnO3/0.05 wt.% Nb-doped SrTiO3 heterojunction as the temperature decreases. A temperature-dependent magnetoresistance was studied as well. The rectifying characteristics and tunable magnetoresistance of these heterojunctions may be attributed to band structure of La[Formula: see text]Hf[Formula: see text]MnO3/0.05 wt.% Nb-doped SrTiO3 heterojunction.

Temperature-Dependent Structure of a High-k (Ba,La)(Ti,Ce)O3 Ceramic

2014 ◽  
Vol 602-603 ◽  
pp. 705-709 ◽  
Author(s):  
Da Yong Lu ◽  
Qiao Li Liu ◽  
Yao Long Dong ◽  
Wei Cheng
Keyword(s):  
Lattice Structure ◽  
Raman Band ◽  
Peak Position ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Dielectric Peak ◽  
High K ◽  
Coefficient Of Linear Expansion ◽  
Increasing Temperature

The lattice structure of a high-k BL3TC5 [(Ba1-xLax)(Ti1-x/4-yCey)O3 (x = 0.03, y = 0.05)] ceramic with cubic structure at room temperature was investigated using temperature-dependent X-ray diffraction (XRD) and Raman spectroscopy. The XRD results indicated that with increasing temperature, the cubic lattice of BL3TC5 showed a lower coefficient of linear expansion (α = 7.7 × 10-6/°C) relative to the cubic BaTiO3 (9.3 × 10-6/°C), but no abnormal change in cell volume occurred around the dielectric peak temperature Tm (= 38 °C). The peak position of the ~835 cm-1 Raman band induced by the substitution of La3+ ions for Ba sites in BL3TC5 was nearly independent of temperature on each side of Tm, whereas a slight fall (3 cm-1) in the peak position around Tm was detectable. The link between the dielectric peak with DPT and the lattice change was discussed.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

2013 ◽  
Vol 68 (9) ◽  
pp. 971-978 ◽  
Author(s):  
Inga Schellenberg ◽  
Ute Ch. Rodewald ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Magnetic Moment ◽  
Induction Furnace ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Arc Melting ◽  
Intermediate Valent

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion

SYNTHESIS OF NEW 1223-TYPE LAYERED CUPRATE (Tl, V) (Sr, Ba)2Ca2Cu3O9 WITH TC(ρ=0) ABOVE 110 K

1993 ◽  
Vol 07 (11) ◽  
pp. 761-769 ◽  
Author(s):  
Z.Y. CHEN ◽  
Z.Z. SHENG ◽  
Y.F. LI ◽  
D.O. PEDERSON
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Practical Applications ◽  
Layered Cuprates

A new series of 1223-type (Tl, V)-based layered cuprates (Tl, V)(Sr,Ba) 2 Ca 2 Cu 3 O 9 has been successfully synthesized and identified by powder X-ray diffraction. Partial substitutions of V for Tl and Ba for Sr promote the formation of (Tl, V)-based 1223-type compounds. Nominal samples ( Tl 1−x V x) ( Sr 2−y Ba y) Ca 2 Cu 3 O z with x=0.25–0.50 and y=0.25–1.50 are pure or nearly-pure 1223 phase and exhibit TC(ρ=0) in the range of 100–110 K. This new (Tl, V)-based high TC material may be of importance in practical applications.

Non-uniform distribution of dopant iron ions in TiO2 nanocrystals probed by X-ray diffraction, Raman scattering, photoluminescence and photocatalysis

2015 ◽  
Vol 3 (8) ◽  
pp. 1846-1853 ◽  
Author(s):  
S. Manu ◽  
M. Abdul Khadar
Keyword(s):  
Raman Scattering ◽  
Uniform Distribution ◽  
Semiconductor Nanocrystals ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
Tio2 Nanocrystals ◽  
X Ray ◽  
Practical Applications ◽  
Mechanism Operative

The phenomenon of ‘self-purification’ is a real mechanism operative in nanocrystals and this should be taken into account while doping semiconductor nanocrystals with external impurities for practical applications.

Synthesis, Structural, Morphological and I-V Characteristics of Polyaniline-MgCl Composite

2022 ◽  
Vol 1048 ◽  
pp. 141-146
Author(s):  
Madihally Nagaraja ◽  
Geetha Thippeswamy ◽  
Sushma Prashanth ◽  
Jayadev Pattar ◽  
Mahesh Hampapatna Mahesh
Keyword(s):  
Structural Analysis ◽  
Oxidative Polymerization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sem Micrographs ◽  
Morphological Studies ◽  
Current Voltage ◽  
Amorphous Nature ◽  
Diffraction Patterns ◽  
Polymerization Method

Composite of polyaniline-MgCl has been synthesized using oxidative polymerization method. Synthesized samples were characterized for structural analysis using FTIR and XRD. Morphological studies were carried by SEM micrographs. Current-Voltage (I-V) properties are obtained through Kiethly source meter. FTIR spectrum of polyaniline-MgCl composite indicates all the characteristic peaks of polyaniline. X-ray diffraction patterns represented the amorphous nature of polyaniline-MgCl composite. SEM micrographs confirmed the presence of MgCl particles in polyaniline matrix. I-V characteristics have shown the ohmic type behavior of polyaniline and polyaniline-MgCl composite.

Temperature-dependent surface X-ray diffraction on

1997 ◽  
Vol 370 (2-3) ◽  
pp. 268-276 ◽  
Author(s):  
H.L. Meyerheim ◽  
I.K. Robinson ◽  
R. Schuster
Keyword(s):  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray
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