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1.
Kai Jiang Jinzhong Zhang Wenlei Yu Zhigao Hu Junhao Chu 《Applied Physics A: Materials Science & Processing》2012,106(4):877-884
The Ba0.4Sr0.6−x
Mn
x
TiO3 (BSMT) ceramics with different Mn composition (from 1% to 10%) have been prepared via the conventional solid-state reaction
sintering. The X-ray diffraction analysis shows that the ceramics are polycrystalline with the single perovskite phase. The
lattice vibrations and optical properties have been investigated using Raman scattering, spectroscopic ellipsometry (SE),
and infrared reflectance spectra. It was found that the optical bandgap for the BSMT ceramics is varied between 3.40 and 3.65
eV. The three first-order Raman-active phonon modes can be observed, and the frequency of the A
1(LO3)/E(LO) mode shows a blue shift of 8 cm−1 with the Mn composition, which can be attributed to the distortion of the TiO6 octahedron. With increasing Mn composition, the frequency of the infrared-active TO4 mode decreases from 532 to 520 cm−1, owing to the local variation of the lattice constant induced by the Mn incorporation. Moreover, the optical functions of
the ceramics from the far-infrared to ultraviolet region are obtained based on the SE and reflectance spectra, which is useful
for the potential applications in ferroelectric-based optoelectronic devices. 相似文献
2.
We analyze the possibility of obtaining M-type hexagonal ferrites of barium, strontium, and lead with multiferroid properties with the help of ceramic technology. Using the modified ceramic technology (especially pure initial raw materials, admixture of B2O3, and sintering in the oxygen atmosphere), we obtained for the first time the BaFe12O19 and SrFe12O19 samples with intense multiferroid properties at room temperature. At the same time, the employed technology does not make it possible to obtain PbFe12O19 samples exhibiting ferroelectricity. The multiferroid characteristics of experimental samples are compared with the characteristics of classical high-temperature multiferroic BiFeO3 and with the characteristics of BaFe12O19, SrFe12O19, and PbFe12O19 ferrite ceramics obtained in accordance with polymer precursor technology. We propose a mechanism explaining multiferroid properties of the hexagonal ferrite ceramic samples and note the importance of our results for applications. 相似文献
3.
K. G. Abdulvakhidov M. A. Vitchenko I. V. Mardasova É. N. Oshaeva B. K. Abdulvakhidov 《Technical Physics》2007,52(11):1458-1461
PbIn0.5Nb0.5O3 (PIN) ferroelectric relaxer ceramics obtained by the solid-phase method is studied. Prior to sintering, the synthesized charge is subjected to mechanical action in Bridgman anvils at room temperature. The electrophysical properties of the reference sample and test samples are compared. It is concluded that mechanical treatment of the material at the stage of preparation allows one to control the physical properties of ferroelectric ceramics. Starting from a certain amount of the action, the electrophysical properties of PIN ceramics vary nonmonotonically. 相似文献
4.
M. M. Chugunova I. A. Kamenskikh V. V. Mikhailin S. A. Usenko 《Optics and Spectroscopy》2010,109(6):887-892
We present the results of studying the luminescence properties of transparent ceramics Y3Al5O12:Yb obtained by the vacuum sintering and nanocrystalline technology. In the course of research, we measured the luminescence
and luminescence excitation spectra, as well as the temperature and kinetic behavior of luminescence. Our results are analyzed
in comparison with the characteristics of corresponding single crystals. We revealed that processes of generation and relaxation
of electronic excitations that occur in ceramics, in particular, in the charge transfer state, are similar to processes occurring
in crystals. The behavior of two charge-transfer luminescence bands at 340 and 490 nm is studied. In the range 300–600 nm,
we revealed a broad emission band of radiation of other type, which is also observed in spectra of undoped ceramics. This
broad band is attributed to F+ centers. Emission and excitation spectra of charge transfer luminescence at a maximum of the temperature dependence of 100
K are measured for the first time. We found that, upon excitation in the charge transfer band, luminescence in ceramics is
more intense than in single crystals with similar concentrations of Yb and has a higher quenching temperature. 相似文献
5.
Hua Gong Jian Zhang Ding-Yuan Tang Guo-Qiang Xie Hui Huang Jan Ma 《Journal of nanoparticle research》2011,13(9):3853-3860
Well-dispersed Nd:Y2O3 powders with uniform particle size of about 60 nm were synthesized from freeze-dried precursors. Highly transparent 2 at.%
Nd:YAG ceramics were fabricated from the as-synthesized Nd:Y2O3 powders and commercial Al2O3 powders by vacuum sintering at 1,750 °C for 5 h. Phase evolution, microstructures, and spectroscopic properties of the Nd:YAG
transparent ceramics were investigated. Freeze-drying played an important role in the synthesis of high-quality Nd:Y2O3 nanosized powders, which were essential for the fabrication of highly transparent Nd:YAG ceramics. Optical transmittance
of a 3-mm thick sample reached 82% in the wavelength range of 200–900 nm. 5.23 W output power was obtained with 14.3 W diode
laser pumping, giving a slope efficiency of 36.5%. 相似文献
6.
K. G. Abdulvakhidov M. A. Vitchenko I. V. Mardasova E. N. Oshaeva 《Technical Physics》2008,53(5):661-663
The relaxor ceramics PbSc0.5Ta0.5O3 produced from an ultradispersed powder is studied by X-ray diffraction and dielectric measurements. Before sintering, the
powder was subjected to treatment in Bridgman anvils in combination with shear deformation. This method is shown to affect
the order parameter and dielectric properties of the ceramics without using long-term high-temperature annealing. 相似文献
7.
D. Bochenek 《The European physical journal. Special topics》2008,154(1):15-18
The work shows basic features of ferromagnetic ceramics
Pb(Fe1 - xNbx)O3 with various contents of Fe/Nb (x=1/3, 1/2,
2/3). The synthesis were carried out by powders sintering and calcination whereas densification by hot uniaxial pressing and
conventional sintering methods. Optimum conditions of PFN obtention with various contents were
based on X-ray, microstructural, dielectrical and conductivity tests together with increase of iron contents in Pb(Fe1 - xNbx)O3 usage parameters of those ceramics worsen. Optimum parameters are shown by
the ceramics with contents Pb(Fe1 / 2Nb1 / 2)O3 synthetized using calcination method and densified by hot uniaxial pressing method. 相似文献
8.
Dunmin Lin K.W. Kwok H.L.W. Chan 《Applied Physics A: Materials Science & Processing》2008,91(1):167-171
(K0.5Na0.5)(Nb1-xTax)O3 lead-free piezoelectric ceramics have been prepared by an ordinary sintering technique. The results of X-ray diffraction
reveal that Ta5+ diffuses into the K0.5Na0.5NbO3 lattices to form a solid solution with an orthorhombic perovskite structure. Because of the high melting temperature of KTaO3, the (K0.5Na0.5)(Nb1-xTax)O3 ceramics can be sintered at higher temperatures. The partial substitution of Ta5+ for the B-site ion Nb5+ decreases both paraelectric/cubic–ferroelectric/tetragonal and ferroelectric/tetragonal–ferroelectric/orthorhombic phase
transition temperatures, TC and TO-T. It also induces a relaxor phase transition and weakens the ferroelectricity of the ceramics. The ceramics become ‘softened’,
leading to improvements in d33, kp, kt and εr and a decease in Ec, Qm and Np. The ceramics with x=0.075–0.15 become optimum, having d33=127–151 pC/N, kp=0.43–0.44, kt=0.43–0.44, εr=541–712, tanδ=1.75–2.48% and TC=378–329 °C.
PACS 77.65.-j; 77.84.Dy; 77.84.-s 相似文献
9.
S. Wongsaenmai W. Qu S. Ananta R. Yimnirun X. Tan 《Applied Physics A: Materials Science & Processing》2007,88(4):757-761
Ferroelectric ceramics with formula Pb0.8Ba0.2[(In1/2Nb1/2)1-xTix]O3 (PBINT) (x=0.0,0.1,0.2,0.3,0.4 and 0.5) were prepared via a two-step solid state reaction method. It was found that ceramics
with compositions in the range of x=0.0∼0.3 showed a pseudo-cubic structure, whereas the ceramic with x=0.5 displayed a tetragonal
structure. All compositions showed significant frequency dispersion in their dielectric properties. The remanent polarization
Pr as well as the coercive field Ec, measured at room temperature, increases with the Ti content. The experimental results obtained in this system are summarized
into a phase diagram, with the morphotropic phase boundary (MPB) located at x=0.4. Compared with the Pb[(In1/2Nb1/2)1-xTix]O3 solid solution system, incorporating Ba in the A-site leads to a significant decrease in the dielectric maximum temperature
Tmax, a suppression of the dielectric relaxation parameter γ, and a shift of the MPB composition to a higher Ti content.
PACS 77.84.Dy; 77.80.Bh; 77.22.Ch 相似文献
10.
Using an ordinary ceramic fabrication technique, we fabricated lead-free (1-x)(K0.5Na0.5)NbO3-xBa(Ti0.95Zr0.05)O3 ceramics with CuO sintering aid . Ba(Ti0.95Zr0.05)O3 diffuses into (K0.5Na0.5)NbO3 to form a new solid solution. The ceramics with perovskite structure possess orthorhombic phase at x≤0.04 and become tetragonal
phase at x≥0.06. Both the paraelectric cubic–ferroelectric tetragonal and the ferroelectric tetragonal–ferroelectric orthorhombic
phase transition temperatures decrease with increasing the concentration of Ba(Ti0.95Zr0.05)O3. The doping of CuO effectively promotes the densification of the ceramics. The coexistence of the orthorhombic and tetragonal
phases at 0.04<x<0.06 and the improvement in sintering performances of the ceramics significantly enhance the piezoelectric
and dielectric properties at room temperature. The ceramics with x=0.04–0.06 and y=0.75–1.50 possess excellent properties:
d33=119–185 pC/N, kP=37–44%, kt=35–49%, ε=341–1129, cosδ=0.7–4.4% and Tc=312–346 °C.
PACS 77.65.-j; 77.84.Dy; 77.84.-s 相似文献
11.
The maximum dielectric permittivity of Ti-doped Ta2O5 ceramics may reach 450 by a laser-sintering technique. The aim of this study is to investigate the mechanisms of the dielectric
enhancement based on the unique structural and morphological properties of the laser-sintered ceramics. The reason for the
dielectric enhancement is due to the crystal structure distortion in the high-temperature phase, the oriented grain growth
taking place in a direction deviating from [001] in the laser-sintered ceramics. The concurrent nature of quenching effects,
a sharp temperature gradient and mass transfer in liquid phase originated from laser high energy irradiation with strict directivity
leads to the structural and morphological properties.
PACS 81.40.Tv; 61.80.Ba; 77.22.-d; 77.22.Ch 相似文献
12.
Sh. M. Khaliullin V. D. Zhuravlev V. G. Bamburov L. V. Ermakova 《Physics of Atomic Nuclei》2015,78(12):1382-1388
Submicron CaZrO3 powder is obtained in combustion reactions (solution combustion synthesis—SCS) with glycine. It is found that SCS reduces the sintering temperature of CaZrO3 powders. The dielectric properties of calcium zirconate ceramics are studied by the electrochemical impedance method. It is shown that a ceramics of powders obtained by the SCS method has high dielectric characteristics. 相似文献
13.
Photopyroelectric spectroscopy of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> - ZnO ceramics
A. Zakaria Z. Rizwan M. Hashim A. Halim Shaari W. Mohmood Mat Yunus 《The European physical journal. Special topics》2008,153(1):33-35
Photopyroelectric spectroscopy is used to study the
band-gap energy of the ceramic (ZnO + xSb2O3), x = 0.1 - 1.5 mol%
and the ceramic (ZnO + 0.4 mol% Bi2O3 + xSb2O3), x = 0 - 1.5 mol% sintered at isothermal temperature, 1280 °C, for 1 and 2 hours. The wavelength of incident light, modulated
at 9 Hz, is kept in the visible range and the photopyroelectric spectrum with
reference to doping level is discussed. The band-gap energy is reduced from
3.2 eV, for pure ZnO, to 2.86, 2.83 eV for the samples without
Bi2O3at 0.1 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. It is reduced to 2.83, 2.80 eV for the samples
with Bi2O3 at 0 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. The steepness factor σA which
characterizes the slop of exponential optical absorption is discussed with
reference to the doping level. The phase constitution is determined by XRD
analysis; microstructure and compositional analysis of the selected areas
are analyzed using SEM and EDX. 相似文献
14.
J.-H. Park J.-S. Bae B.-E. Jun B.-C. Choi J.-H. Jeong 《Applied Physics A: Materials Science & Processing》2007,86(1):63-65
Bi3.25La0.75Ti3-yNbyO12 (y=0.0, 0.03, 0.09, 0.15, 0.21) were synthesized using the solid-state reaction method. The effects of Nb doping on ferroelectric properties were studied through dielectric and P-E measurements. The value of Pr increases with increasing Nb content. Bi3.25La0.75Ti3-yNbyO12 ceramics exhibit a maximum remanent polarization of Pr=27 μC/cm2 at an Nb content of y=0.09. These results indicate that Nb doping can improve the ferroelectric properties of BLT ceramics. The Curie temperature, Tc, decreased with increasing Nb-content, and the ferroelectric phase transition of BLTNy is a second-order transition without thermal hysteresis. PACS 77.55.+f; 77.80.-e; 77.22.Jp 相似文献
15.
Yuan Li Tiantian Yang Weiwei Wu Zhenzhu Cao Weiyan He Yanfang Gao Jinrong Liu Guorong Li 《Ionics》2018,24(11):3305-3315
Al-Mo codoped Li7La3Zr2O12 ceramics with fine grain were prepared by sol-gel method. The influences of Al-Mo codoping on the structure, microstructure, and conductivity of Li7La3Zr2O12 were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy. The cubic phase Li7La3Zr2O12 has been stabilized by partial substitution of Al for Li and Mo for Zr. Li6.6-3yAlyLa3Zr1.8Mo0.2O12 (0?≤?y?≤?0.1) has been sintered at 1040–1060 °C for 3 h. The liquid sintering facilitated its densification. The relative density of the composition with x?=?0.075 was approximately 96.4%. Results indicated that the Al-Mo codoped LLZO synthesized by sol-gel method effectively lowered its sintering temperature, accelerated densification, and improved the ionic conductivity. 相似文献
16.
The dielectric, optical, and electro-optical properties of transparent ferroelectric ceramics 75PbMg1/3Nb2/3O3-25PbTiO3 (75PMN-25PT) with different La concentrations (2, 3, and 4 at %) have been studied. It has been shown that all the samples
under study undergo a diffuse phase transition, and the degree of diffuseness increases with an increase in the La concentration.
The temperature dependences of the optical transmission in different regimes of applying an electric field and the quadratic
electro-optical effect have been investigated. It has been found that, at room temperature, the maximum electro-optical effect
is observed in the ceramics with a La concentration of 3 at %. This is explained by the fact that the measurement temperature
is close to the Vogel-Fulcher temperature at which the minimum electric field is required to induce ferroelectric states from
the relaxor phase. 相似文献
17.
Structure of ceramics obtained by the plasma spray deposition of spherical TiO2 powders has been investigated. An electron microscopy study of the surfaces and cross sections of particles in the initial powder and of the deposited ceramic coatings was performed. X-ray diffraction and Raman scattering data proved that the coatings were mainly structured as rutile. In addition, Raman and X-ray diffraction data have revealed an amorphous phase, an anatase phase, and non-stoichiometric phases Ti8O15, Ti10O19, Ti7O13, etc. being present in the coatings. The observed suppression of (011) and (111) XRD peaks and an increased intensity of (110) peak are indicative of a predominant orientation of grains in the synthesized ceramics. Mechanisms of formation of the complex coating structure are discussed. 相似文献
18.
Tingyin Ning Cong Chen Yueliang Zhou Heng Lu Dongxiang Zhang Hai Ming Guozhen Yang 《Applied Physics A: Materials Science & Processing》2009,94(3):567-570
CaCu3Ti4O12 (CCTO) thin films were successfully prepared on LaAlO3 substrates by pulsed laser deposition technique. We measured the nonlinear optical susceptibility of the thin films using
Z-scan method at a wavelength of 532 nm with pulse durations of 25 ps and 7 ns. The large values of the third-order nonlinear
optical susceptibility, χ
(3), of the CCTO film were obtained to be 2.79×10−8 esu and 3.30×10−6 esu in picosecond and nanosecond time regimes, respectively, which are among the best results of some representative nonlinear
optical materials. The origin of optical nonlinearity of CCTO films was discussed. The results indicate that the CCTO films
on LaAlO3 substrates are promising candidate materials for applications in nonlinear optical devices. 相似文献
19.
A. V. Pavlenko A. V. Turik L. A. Shilkina S. P. Kubrin Yu. V. Rusalev L. A. Reznichenko I. N. Andryushina 《Physics of the Solid State》2018,60(3):515-519
Polycrystalline samples of SrFe2/3W1/3O3 (SFWO) ceramic were obtained by solid-phase reactions with subsequent sintering using conventional ceramic technology. X-ray diffraction analysis showed that at room temperature, the SFWO ceramic is single-phase and has a perovskite-type structure with tetragonal symmetry and parameters a = 3.941(9) Å, c = 3.955(6) Å, and c/a = 1.0035. In studying the magnetic properties and the Mössbauer effect in SFWO ceramics, it is found that the material is a ferrimagnet, and the iron ions are only in the valence state of Fe3+. It is suggested that in the temperature range of T = 150–210°C, a smeared phase transition from a cubic (paraelectric) phase to a tetragonal (ferroelectric) phase takes place in SFWO with decreasing temperature. 相似文献
20.
S. A. Sadykov D. K. Palchaev Zh. Kh. Murlieva N. M.-R. Alikhanov M. Kh. Rabadanov S. Kh. Gadzhimagomedov S. N. Kallaev 《Physics of the Solid State》2017,59(9):1771-1777
The structure and electrical properties of BiFeO3 ceramics obtained by spark plasma sintering of a nanopowder are investigated. The nanopowder was synthesized by burning of an organic nitrate precursor. The ac conductivity was measured in a frequency range of 1 kHz–10 MHz in a temperature interval of 25–500°C. It is established that the temperature conductivity coefficients above and below ~350°C significantly differ with both alternating and direct currents. The frequency dependence of the conductivity obeys the Jonscher power law σ ~ ω s , where s < 1. The interpretation of this behavior is given in the framework of the model of correlated hops of charge carriers over potential barriers. It is assumed that the hopping mechanism is realized between Fe2+ and Fe3+ ions in ceramic grains. The role of oxygen vacancies in the conduction is also discussed. 相似文献