• Korean Journal of Materials Research
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• v.33 no.9
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• pp.367-371
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• 2023

In this study we examine variations in the structure of perovskite compounds of LaBa₂Cu₂O₉, LaBa2₂CaCu₃O₁₂ and LaBa₂Ca₂Cu₅O₁₅ synthesized using the solid state reaction method. The samples' compositions were assessed using X-ray fluorescence (XRF) analysis. The La: Ba: Ca: Cu ratios for samples LaBa₂Cu₂O₉, LaBa2₂CaCu₃O₁₂ and LaBa₂Ca₂Cu₅O₁₅ were found by XRF analysis to be around 1:2:0:2, 1:2:1:3, and 1:2:2:5, respectively. The samples' well-known structures were then analyzed using X-ray diffraction. The three samples largely consist of phases 1202, 1213, and 1225, with a trace quantity of an unknown secondary phase, based on the intensities and locations of the diffraction peaks. According to the measured parameters a, b, and c, every sample has a tetragonal symmetry structure. Each sample's mass density was observed to alter as the lead oxide content rose. Scanning electron microscope (SEM) images of the three phases revealed that different Ca-O and Cu-O layers can cause different grain sizes, characterized by elongated thin grains, without a preferred orientation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.5
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• pp.644-648
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• 1995

Transparent xBa(La$_{1}$2/Nb$_{1}$2/)O$_{3}$-(1-x)Pb(Zr, Ti)O$_{3}$ (x=8.5, 9.0[mol.%], Zr/Ti=70/30~40/60) ceramics were fabricated by the two-stage sintering method, the electrooptic properties were investigated with Ba(La$_{1}$2/Nb$_{1}$2/)O$_{3}$ content and Zr/Ti composition ratio. Decreasing the Zr/Ti ratio, the electrooptic property was changed from a quadratic electrooptic effect to a linear electrooptic effcet. In the BLN-PZT 9.0/50/50 specimen having the tetragonal structure, the linear electrooptic coefficient had the highest value of 6.01*10$^{-10}$ [m/V] and in the BLN-PZT 9.0/55/45 specimen which located near the MPB region, the quadratic electrooptic coefficient had the highest value of 10.53*10$^{-16}$ [m$^{2}$/V$^{2}$].

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.629-635
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• 1997

The effects of the annealing atmospheres(O2, N2) and sintering additives that Bi2O3 is a major composition on the microwave dielectric and sintering propertie of (1-x)CaTiO3-xLaAlO3 system were investigated. The annealing atmospheres and the increase of annealing time after sintering did not affect the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) of (1-x)CaTiO3-xLaAlO3 system. However, the Q.f0 values of (1-x)CaTiO3-xLaAlO3 were very sensitive to annealing atmospheres. As the annealing time increased under O2 atmosphere the Q.f0 values of (1-x)CaTiO3-xLaAlO3 enhanced untill 10 hrs in 0.3$\leq$x$\leq$0.6 region, but degraded over that time. The increasing rate of Q.f0 value increased wth increasing x. On the other hand, as the annealing time increased under N2 atmosphere the Q.f0 values were constant in x$\leq$0.6 region, increased gradually in x$\geq$0.7 region. When 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% as sintering additives were added to (Ca0.5La0.5) (Ti0.5Al0.5)O3 (x=0.5) the sintering temperature of 1$600^{\circ}C$ was lowered to 140$0^{\circ}C$, and the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) were not nearly changed. The addition of 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% to (Ca0.5La0.5)(Ti0.5Al0.5)O3 made the Q.f0 values to be lower about 15% and 34%, respectively.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.607-614
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• 1996

The structural changes and dielectric properties of Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 compounds substituted by 0∼50 mol.% of Na+/La3+ mixed ions were investigated by X-ray diffraction method, IR and Raman spectroscopy, and LCR meter. The amount of perovskite phase increased with the increases of Na+/La3+ substituents and sintering temperatures. Although the superlattice lines due to 1:1 ordering were not detected by X-ray diffraction method, it was found, from the Raman spectroscopy and the increase of diffuseness coefficient, that the ordering behavior was related to the decrease of A site ion size. Dielectric properties in Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 were affected by the amount of perovskite phase, grain size, and density. The phase transitions were broadened and phase transition temperatures were lowered by the increase of Na+/La3+ ions.

• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.283-288
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• 1988

The titled properties on reduction of the perovskite $LaBO_3$ (B = Fe, Co, Ni) have been investigated by means of temperature-programmed reduction, isothermal reduction and X-ray diffraction methods. Nominal composition of $LaFeO_{3.18},\;LaCoO_{3.00}\;and\;LaNiO_{2.92}$ are determined. Reduction reaction of these mixed oxides differed according to B-site transition metal and thermal stability on reduction decreased as following order: $LaFeO_{3.18}$ > $LaCoO_{3.00}$ > $LaNiO_{2.92}$. From the results of isothermal reaction, kinetics on reduction of the perovskite has been discussed in detail.

• Korean Journal of Optics and Photonics
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• v.7 no.2
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• pp.162-166
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• 1996

We report a fiber optic interferometric electric field sensor that utilizes electrostrictive ceramics-1%, 2%, 3%, La-doped 0.9MN/0.1PT, respectively-as the transducing elements. It is also experimentally observed that 3% La-doped PMN/PT among the three elements has the largest electrostrictive coefficient $M=3.87{\times}10^ {-16}(m/V)^2$ at 3.38 kHz and displays small hysteresis. The optical fiber sensor with the 3% La-doped PMN/PT exhibits minimum detectable field of 2.08(V/m)/ $\sqrt{Hz}$ and has a good linearity over the dynamic range 40 dB.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.233-239
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• 1995

$La_{1/3}NbO_3$ and $La_{1/3}TaO_3$ large single crystal was prepared by the infrared floating zone method and their crystal structure and dielectric properties were investigated from the viewpoint of A - site vacancy. In $La_{1/3}TaO_3$ crystal, the crystal symmetry and approximate lattice constants was tetragonal and a $\approx$ 0.397, b $\approx$ 0.397 and c $\approx$ 0.775 from the nonextinction and the reciprocal lattice point length seen on Weissenberg and Precession photographs. The jump of some $2/3La^{3+}$ ions leads to increase the moving paths due to the generation of new vacancies at middle empty sites and thus this result is confirmed to provoke the dielectric anomaly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.21-23
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• 1994

By adding La₂O₃ to optical multicomponent glass composition, after making mother glass and core fiber that enable to enlarge the infrared transmittance region, then surveyed the optical properties. Through thermal analysis of the glass abstained by melt-quenching after selecting stable basic composition on devitrification and replace SiO₂ by 4-12wt% La₂O₃. As La₂O₃ increases up to l2wt% transition temperature, refractive index, density, deformation temperature increased, whereas thermal expansion coefficient decreased. As a result of inspectig transmittance in UV/VIS/IR region, visable region indicated the decrease of transmittance by increasing the La₂O₃ and transmittance region was enlarged by increasing the La₂O₃ in IR region. Also, fabricate core fiber at 820℃ and severy the optical loss we could fact that La₂O₃ composition added 12wt% showed the minimum optical loss.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1019-1023
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• 1996

The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.6-9
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• 2012

Eu3+-doped RE2O3 (RE = Gd, Y and La) phosphors were prepared by solvothermal reaction method and their crystalline structure, phase transformation and surface morphologies were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). The obtained RE2O3:Eu3+ phosphors are nanocrystalline-sized. The luminescence properties of Eu3+ ions in different host materials, namely, Gd2O3, Y2O3 and La2O3 have been investigated. PACS number: 32.50.+d, 78.55.-m, 81.40.Tv.