Electrical- Magnetic Transport and Magnetoresistance in La 0.7 Ca 0.3 MnO3/BN Composites

2011 ◽  
Vol 228-229 ◽  
pp. 379-384
Author(s):  
Yong Dan Zhu ◽  
Hong Hua Liao ◽  
Jian Jun Tan ◽  
An You Zuo ◽  
Jin Qiao Yi ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Solid State Reaction Method ◽  
Boundary Region ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Field ◽  
Maximum Value ◽  
Spin Polarized ◽  
Magnetic Transport ◽  
Lower Temperature

The electrical–magnetic transport properties of (La0.7Ca0.3MnO3)(1-x)/(BN)x composites has been investigated systemically by conventional solid-state reaction method. The results of X-ray diffraction (XRD) and scanning electronic microscopy (SEM) show that BN and LCMO coexist in the composites and BN mainly goes into the grain boundary region without any chemical reaction with La0.7Ca0.3MnO3, which are in accordance with the results of the magnetic measurements. It is very interesting that with increasing of BN content level (x < 0.25), the metal–insulator transition temperature (TP) remains constant (nearly at 275K), and the resistivity increases very slowly. But when x > 0.25, TP shifts to lower temperature and the resistivity increases dramatically. The resistivity threshold of the composites occurred at x = 0.25, and specially the magnetoresistance (MR) reaches a maximum value (about 26.32 %) at 100K in an applied magnetic field of 3kOe. The results also indicate that the doped BN has an important effect on the low field MR (LFMR), which results from spin-polarized tunneling.

ELECTRICAL TRANSPORT PROPERTIES AND MAGNETORESISTANCE OF (La0.7Ca0.3MnO3)1-x/(CuFe2O4)x COMPOSITES

2010 ◽  
Vol 17 (01) ◽  
pp. 33-38 ◽  
Author(s):  
YOUNG JOO KIM ◽  
SHALENDRA KUMAR ◽  
YONG JUN SEO ◽  
JIHO CHANG ◽  
CHAN GYU LEE ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Conventional Solid State Reaction ◽  
Low Field ◽  
Spin Polarized ◽  
Spin Dependent Scattering ◽  
Mr Effect ◽  
New Phase

The ( La 0.7 Ca 0.3 MnO 3)1-x/( CuFe 2O4)x (x = 0–0.15) composites were prepared by conventional solid state reaction method. We have investigated the structural, magnetic and electrical properties of ( La 0.7 Ca 0.3 MnO 3)1-x/( CuFe 2 O 4)x composites using X-ray diffraction (XRD), scanning electron microscopy, field cooled DC magnetization and magnetoresistance (MR) measurements. The resistance measured as a function of temperature demonstrates that pure LCMO samples display metal to semiconductor transition. On the other hand, all the LCMO/CFO composites samples clearly present the electrical behavior of insulator/semiconductor. It indicates that resistivity of the samples increase systemically with the increase of CFO content. The MR was measured in the presence of 0.5 T field. At low temperatures, it is clearly observed that the MR effect is enhanced with x = 0.03 of CFO composition. In summary, the spin-polarized tunneling and the spin-dependent scattering may be helpful to the improved low-field magnetoresistance (LFMR) effect. These phenomena can be explained by the segregation of a new phase related to CFO at the grain boundaries or surfaces of the LCMO grains.

Studies of Microstructure and Electro-Magnetic Transport Property of La0.67Ca0.33MnO3 Ceramic

2017 ◽  
Vol 373 ◽  
pp. 205-208
Author(s):  
Shou Lei Xu ◽  
Er Juan Xie ◽  
Xiu Qing Cao ◽  
Yu Yang Huang ◽  
Ding Kang Xiong ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Positron Lifetime ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
X Ray ◽  
Maximum Value ◽  
The Mean ◽  
Magnetic Transport ◽  
Electro Magnetic

The positron annihilation techniques and X-ray diffraction have been used to study the microstructure of the La0.67Ca0.33MnO3 ceramics prepared by the solid-state reaction method at different sintered temperatures (T=1573K, 1623K, 1673K, 1723K, 1773K, 1823K). And the electro-magnetic transport behavior of the samples was measured by VSM and Resistivity modular on PPMS. According to these results, all samples show a perovskite structure, the ferromagnetic-paramagnetic and metal-insulator transitions occur at the transition temperature Tc and TMI, respectively, which is almost the same. For La0.67Ca0.33MnO3 sintered at 1673K, the mean positron lifetime is the largest, the maximum value of the magnetization is achieved on the magnetization-temperature curve at H=0.2mT, while the transition temperature occurs at about 244K.

Study on Dielectric and Ferroelectric Properties of Gd-Doped Sr2Bi4Ti5O18 Ceramics

2011 ◽  
Vol 328-330 ◽  
pp. 1131-1134
Author(s):  
Qian Chen ◽  
Zhi Jun Xu ◽  
Rui Qing Chu ◽  
Yong Liu ◽  
Ming Li Chen ◽  
...  
Keyword(s):  
Piezoelectric Properties ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Structural Ceramics ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Maximum Value ◽  
Pure Bismuth ◽  
Ferroelectric And Piezoelectric Properties

Lead-free piezoelectric ceramics Sr2Bi4-xGdxTi5O18 were prepared by conventional solid-state reaction method. Pure bismuth layered structural ceramics with uniform gain size were obtained in all samples. The effect of Gd-doping on the dielectric, ferroelectric and piezoelectric properties of Sr2Bi4Ti5O18 ceramics were also investigated. It was found that that Gd3+ dopant gradually decreased the Curie temperature (Tc) with the lower dielectric loss (tand) of SBTi ceramics. In addition, Gd-doping with appropriate content improved the ferroelectric and piezoelectric properties of the SBTi ceramics. The piezoelectric constant (d33) of the Sr2Bi3.9Gd0.1Ti5O18 ceramic reached the maximum value, which is 22 pC/N. The results showed that the Sr2Bi4-xGdxTi5O18 ceramic was a promising lead-free piezoelectric material.

Structure and Electrical Characteristics of BaTiO3 and Ba0.99Er0.01TiO3 Ceramics

2018 ◽  
Vol 280 ◽  
pp. 127-133 ◽  
Author(s):  
F. A. Ismail ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
N.A.M. Ahmad Hambali
Keyword(s):  
Perovskite Phase ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Grain Sizes ◽  
Capacitance Voltage ◽  
Ion Incorporation ◽  
Voltage Breakdown

Conventional solid state reaction method was used to prepare BaTiO3 and Ba0.99Er0.01TiO3 ceramics. Influence of Er3+ ion incorporation on their structural, microstructural and electrical properties was studied. The phase pure samples were obtained when heated at 1400 °C for overnight. The tetragonal perovskite phase of BaTiO3 and Ba0.99Er0.01TiO3 was confirmed by using X-ray Diffraction (XRD) analysis which is in agreement with results obtained from Rietveld refinement analysis. The lattice parameters and unit cell volume of BaTiO3 increased when doped with Erbium. Microstructural analysis of BaTiO3 and Ba0.99Er0.01TiO3 ceramics showed that the grain sizes of BaTiO3 and Ba0.99Er0.01TiO3 significantly decreased. The dielectric properties of BaTiO3 and Ba0.99Er0.01TiO3 were investigated as a function of temperature and frequency. It revealed that the Curie temperature (TC) increased by doping Er content from 110 °C to 120 °C. Ba0.99Er0.01TiO3 exhibited the high value of dielectric constant (ε=5929) at TC of 120 °C. The capacitance-voltage characteristic revealed that the voltage breakdown for both BaTiO3 and Ba0.99Er0.01TiO3 exceeded 30 V.

La and Co doping effects on magnetoresistance of double perovskite Sr2FeMoO6

2015 ◽  
Vol 29 (20) ◽  
pp. 1550140 ◽  
Author(s):  
SongChol Ri ◽  
GwangSu Kim
Keyword(s):  
Magnetic Field ◽  
Doping Concentration ◽  
Magnetic Measurements ◽  
Double Perovskite ◽  
High Energy ◽  
X Ray Diffraction ◽  
Co Doping ◽  
Maximum Value ◽  
Doping Effects ◽  
Low Magnetic Field

Double perovskite Sr 2 FeMoO 6 (SFMO) with composition of Sr 2-x La x Fe 1-y Co y MoO 6(x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 at.%; y = 0, 0.05, 0.1, 0.2, 0.3, 0.5, 0.9 at.%) was synthesized by high energy ball milling and sintering. The sintered samples were investigated by means of X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and magnetic measurements. XRD results show that all the samples have single phase double perovskite structure. EDS spectrum confirmed that the actual composition of prepared samples is in agreement with nominal ones. With the increase of doping concentration of La, the magnetization decreases, whereas Curie temperature increases in SFMO. And with doping concentration of La, the magnetoresistance (MR) ratio with a low magnetic field of 480 kA/m increases, has its maximum value as 5% for x = 0.3 at 293 K. The degree of antisite disorder decreases with Co 2+ doping, and therefore results in increase of MR ratio. At room temperature, the MR ratio with a considerable low magnetic field for x = 0.3, y = 0.1 has maximum value as 6.5%.

Effects of La Doping on the Structural and Dielectric Properties of Barium Titanate Ceramics

2014 ◽  
Vol 975 ◽  
pp. 36-41
Author(s):  
Marcelo S. Silva ◽  
Nilson S. Ferreira
Keyword(s):  
Grain Boundary ◽  
Solid State Reaction Method ◽  
Boundary Region ◽  
Homogeneous Distribution ◽  
Sem Images ◽  
Tetragonal Crystal ◽  
Brick Layer Model ◽  
Lower Temperature ◽  
Clear Shift ◽  
Titanate Ceramics

Polycrystalline samples of Ba1-xLaxTiO3 (x = 0.0, 0.002, 0.004) were prepared by a standard high-temperature solid-state reaction method. XRD studies confirmed the formation of a polycrystalline compound with a tetragonal crystal structure. SEM images suggested the presence of a polycrystalline microstructure with certain degree of porosity, and the grains appeared to be distributed inhomogeneously throughout the pallet samples. Dielectric studies indicated a ferroelectric–paraelectric phase transition with a clear shift in the Curie temperature (Tc) of BaTiO3 towards a lower temperature upon doping. The brick-layer model was used to study the potential barrier and the structure of the grain-boundary region of the Ba9.998La0.002TiO3 and Ba9.996La0.004TiO3 ceramics. These ceramics exhibited good density and a homogeneous distribution of the grains. The thickness of the grain-boundary region was calculated to be approximately 200 nm.

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

MULTIFERROIC MATERIALS Bi1-xSmxFeO3: A STUDY OF RAMAN AND ABSORPTION SPECTROSCOPIES

2010 ◽  
Vol 19 (02) ◽  
pp. 247-254 ◽  
Author(s):  
NGUYEN VAN MINH ◽  
DAO VIET THANG
Keyword(s):  
Lattice Dynamics ◽  
Optical Band Gap ◽  
Solid State Reaction Method ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Lattice Constants ◽  
Raman Measurement

Multiferroic Bi 1-x Sm x FeO 3(x = 0.00, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. X-ray diffraction measurement was carried out to characterize the crystal structure and to detect the impurities existing in these ceramics. The substitution of rare earth Sm for Bi was found to decrease the impurity phase in BiFeO 3 ceramics. There is strong evidence that both lattice constants a and c of the unit cell become smaller as the Sm 3+ content is increased. The effect of introducing Sm 3+ is shown to decrease the optical band gap for doped sample Bi 1-x Sm x FeO 3. Additionally, the temperature-dependent Raman measurement performed for the lattice dynamics study of Bi 1-x Sm x FeO 3 samples reveals a strong band centered at around 1000–1300 cm-1 which is associated with the resonant enhancement of two-phonon Raman scattering in the multiferroic Bi 1-x Sm x FeO 3 samples. This two-phonon signal is shown to broaden with increasing x. The Raman spectra at low wavenumbers are suggested to be related with magnon in this system.

The Microstructure and Thermochromic Properties of La1-XSrXMnO3 Smart Materials

2013 ◽  
Vol 690-693 ◽  
pp. 648-653 ◽  
Author(s):  
Min Xu ◽  
Zhao Hui Fu ◽  
Lin Li ◽  
Jie Bing Wang ◽  
Chun Hua Wu ◽  
...  
Keyword(s):  
Smart Materials ◽  
Thermal Control ◽  
Solid State Reaction Method ◽  
Thermal Design ◽  
Radiative Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Thermal Radiative Properties ◽  
Potential Applications ◽  
Thermochromic Properties

The La1-xSrxMnO3 materials have potential applications in thermal control systems of microsatellites. The microstructure of La1-xSrxMnO3 materials is very sensitive to the compound of Sr incorporated into it. In this paper, preparation process of La1-xSrxMnO3 compounds was explored. Ceramic sintering process combined with a conventional solid state reaction method was used to prepare various components of La1-xSrxMnO3。 Annealing temperature, time and doped ratio were controlled in the experiment. X-ray diffraction and Raman spectroscopy were used to analyze phase structure and crystalline. Thermal radiative properties were measured on a Calorimetric Emissometer at 175K～375K. These investigations reveal that microstructure of La1-xSrxMnO3 compounds are affected by Sr2+doping level(x).Thermal emissivity of La0.825Sr0.175MnO3 materials vary widely from 0.68 to 0.37, which can meet requirement of future space thermal design.

Photoluminescence properties of Na1.45La8.55(SiO4)6(F0.9O1.1):Eu for applications as a reddish orange phosphor

2014 ◽  
Vol 07 (05) ◽  
pp. 1450060 ◽  
Author(s):  
Qun Shi ◽  
Dhia A. Hassan ◽  
Renjie Zeng
Keyword(s):  
Spectral Analysis ◽  
Solid State Reaction Method ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
X Ray ◽  
Analysis System ◽  
Reddish Orange ◽  
The Eu

Europium-doped Na 1.45 La 8.55-8.55x( SiO 4)6( F 0.9 O 1.1)(0.000 ≤ x ≤ 0.045) phosphors were prepared by a conventional solid-state reaction method at 1200°C and their properties were studied by X-ray diffraction (XRD), and a spectral analysis system. No impurities were observed. The phosphor could be excited at 254 nm, 395 nm and 465 nm to yield a reddish orange emission which was attributed to the 5 D 0 → 7 F j (j = 0–2) transitions of the Eu ion.

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