[en] First principles calculations of HfO₂ and La-doped HfO₂ structures were carried out to investigate the effect of La doping on the relative permittivity of HfO₂ films. In this study 6.25% of La was incorporated into HfO₂. Upon examination, we found out that La addition increased the value of the relative permittivity from 19 to 26 and this was because the La-induced distortion increased the range of frequencies that contribute to the IR-active modes

[en] Present article is devoted to stationary potentials of Al + 6 % Li alloy with lanthanum. Corrosion-electrochemical properties of Al + 6 % Li alloy with lanthanum were studied. It was defined that lanthanum additives increase the anode stability of Al + 6 % Li alloy. The elaborated compositions could be used as an anode protector for corrosion protection of steel items and constructions.

[en] Particularities of rolling process for rods of tungsten doped alloys and the design of test-commercial rolling mill of the MK-210 type are considered. The new process using rolling mills with four-roll passes permits to manufacture products with the uniformly developed structure and high surface quality. The yield of suitable products using a wire with 1.5-2.0 mm diameter produced of rolled billets is 15% higher than that of the mill one

[en] The impact energy of 93W-4. 9Ni-2. 1Fe(wt %) alloy decreases sharply with the concentration of sulfur added up to 200 ppm even after heat-treatment at 1,150 deg C in N₂ atmosphere and waterquenching. The result shows definitively that the S present at the level of a few tens ppm causes an embrittlement of this alloy. The structure and the composition of the fracture surface are consistent with the previous suggestion that the embrittlement arises from S segregation at the grain-matrix interface. With the addition of Ca or La to the S doped alloy the impact energy increases to that of the alloy without S. The fracture structure and the S concentration measured at the interfaces also show that Ca or La addition suppresses effectively the S segregation at the grain-matrix interface by forming S containing Ca or La compounds. When Ca is added to the alloy to which no S was deliberately added (with about 19 ppm P and 1 ppm S), the impact energy does not vary with the cooling rate after the heat-treatment at 1,150 deg C, and is unaffected by additional heat-treatment at 600 deg C. It appears that P segregation and its embrittling effect are also reduced by forming P containing Ca compounds. The variation of the impact energy of this alloy with the amount of S or P in the raw material powder or with the heat-treatment condition can therefore be substantially reduced by adding Ca or La. (Author)

[en] Lanthanum-modified bismuth titanate, Bi_4-xLa_xTi₃O₁₂ (BLT), thin films with a La concentration of 0.25≤x≤1.00 were grown on Pt/Ti/SiO₂/Si substrates by using pulsed-laser deposition. The BLT films showed well-saturated polarization-electric field curves whose remnant polarizations were 16.1 μC/cm², 27.8 μC/cm², 19.6 μC/cm², and 2.7 μC/cm², respectively, for x=0.25, 0.05, 0.75, and 1.00. The fatigue characteristics became better with increasing x up to 0.75. The Au/BLT/Pt capacitor with a La concentration of 0.50 showed an interesting dependence of the remanent polarization on the number of repetitive read/write cycles. On the other hand, the capacitor with a La concentration of 0.75 showed fatigue-free characteristics

[en] Full text: In this work, ceramic samples of [(Bi_0.5Na_0.5)_0.94Ba_0.06]₍₁--_x-)La_xTiO₃ (abbreviation: BNT-6BT+xLa), with x=0; 0.001; 0.007; 0.014 and 0.02, were prepared via conventional mixed-oxide method. The powders were calcined in 900 deg C for 3h and conventionally sintered in 1150 deg C for 3h. Structural properties of BNT-6BT+xLa ceramics were investigated by powder method X-ray diffraction (XRD) (Shimazdu, XRD-6000 model). XRD patterns obtained for all sintered samples confirm the formation of complex perovskite structure and showed the absence of spurious phases. In the case of BNT-6BT+0La composition was confirmed, using Rietveld refinement method, that belong to the morphotropic phase boundary (MPB) of the BNT-BT system. On the other hand, for La-doped compositions, changes in the XRD data due increase of lanthanum (shown in diffraction peaks around 46 degrees) suggest the tendency of decrease of the Tetragonal phase, this could mean the Rhombohedral phase stabilization and the leaving of the MPB. In order to analyze the influence of La-doping in BNT-6BT over the anelastic response, elastic energy dissipation (internal friction) and complex elastic modulus, were carried out measurements of these properties as a function of temperature and frequency using a Dynamic Mechanical Analyzer (PerkinElmer, DMA8000 model), in temperature range between room temperature and 600 deg C, and frequencies in a Hz bandwidth. The evolution of the structural phase transition and mechanical relaxation processes exhibited by BNT-6BT+xLa samples were analyzed by mean of anelastic relaxation spectra. (author)

No abstract available

[en] Studies of commercial heats of AF1410 steel suggest that under appropriate conditions additions of rare-earth elements can significantly enhance fracture toughness. This improvement in toughness is not due to an extremely low inclusion volume fraction but is apparently due to the formation of larger and more widely spaced inclusions. The purpose of this work is to discuss our experience in using rare-earth additions to laboratory scale vacuum induction melted and subsequently vacuum arc remelted heats of ultra-high strength steels to achieve inclusion distributions similar to those observed in commercial heats modified with lanthanum additions. The results indicate that lanthanum additions of 0.015 wt.% to low sulfur steels which have been well deoxidized using carbon-vacuum deoxidation can result in lanthanum rich inclusions which are similar in size, volume fraction and spacing to those obtained in commercially produced heats of ultra-high strength steel to which lanthanum has been added. The heat of steel to which lanthanum additions of 0.015 wt.% were made had significantly higher toughness than did the heat of the same steel in which the sulfur had been gettered as small and closely spaced particles of MnS and which had an inclusion volume fraction similar to that of the heat modified by the addition of 0.015 wt.% lanthanum. This improvement in toughness was attributed to an increase in inclusion spacing. An addition of 0.06 wt.% lanthanum was excessive. Such an addition of lanthanum resulted in a huge volume fraction of large cuboidal inclusions which primarily contain lanthanum and oxygen and which are extremely detrimental to toughness

[en] On the base of microstructure analysis the optimum lanthanum amount (for good modification) for (AK7, AK9, AK11, AK52, AK104 alloys was determined. Influence of lanthanum amount (as the modifier) on the impact strength of alloys was established. (author)

[en] Using the X-ray and scanning electron microscopy as well as X-ray structural and micro X-ray spectral analyses studied are structure and phase composition of condensed layers of low-alloyed chromium, deposited in (1.3x10^-3 Pa) vacuum on fine-crystalline molybdenum sublayer by the method of electro-arc spraying of the Cr-0.3% La compact alloy. It is shown that alloying with lanthanum opens the way for improvement of the quality chromium condensates