2 edition of growth of single crystal lanthanum tetraboride found in the catalog.
growth of single crystal lanthanum tetraboride
J A. Deacon
by Brighton College of Technology, Department of Applied Physics in Brighton
Written in English
|Contributions||Brighton College of Technology. Department of Applied Physics.|
A technique has been developed for the growth of single crystals of lanthanum tetraboride LaB4, from solution in La. Under optimum conditions, crystal size is . Single crystal growth of transition metal oxides from polytungstate fluxes. Journal of Physics and Chemistry of Solids , 26 (2), DOI: /(65)
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Yttrium boride refers to a crystalline material composed of different proportions of yttrium and boron, such as YB 2, YB 4, YB 6, YB 12, YB 25, YB 50 and YB They are all gray-colored, hard solids having high melting temperatures. The most common form is the yttrium hexaboride YB exhibits superconductivity at relatively high temperature of K and, similar to LaB 6, is an . Single crystals of holmium oxalate heptahydrate are grown by gel diffusion method using organic agar gel as a medium of growth. The crystals grow in the agar gel with hexagonal morphology having well defined habit faces Powder X-ray diffraction results show that the crystals belong to monoclinic system bearing the space group P21/c with cell parameters; a = ?, b = .
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A technique has been developed for the growth of single crystals of lanthanum tetraboride LaB4, from solution in La. Under optimum conditions, crystal size is limited by the size of the crucible.
Lattice parameters, thermal expansion coefficient, and microhardness are reported and the growth facets have been identified.
An initial check on the electron emitting Cited by: It is shown that the main sourse of dislocations arising during growth of single crystals is generation by fiat segregation which according to diffraction investigations has a different structure from both lanthanum hexaboride and tetraboride.
Keywords: Lanthanum hexaboride; Single crystal real structure by: ournal of Crystal Growth () — ‘~orth-Holland Growth of single crystals of lanthanum aluminate O.W.
Berkstresser, A.J. Valentino and C.D. Brandle ~ T&T Bell Laboratories, Murray Hill, New JerseyUSA Single crystals of lanthanum aluminate have application as a substrate for deposition of thin films of the high temperature Cited by: METHODS USED TO GROW LCB SINGLE CRYSTALS Lanthanum Calcium Borate single crystals can be grown using melt growth method by employing both by Top-Seeded Solution Growth (TSSG) technique and by crystal pulling method using Czochralski technique.
The detailed phase diagram of La2O3-CaO-B2O3 is not available for the LCB compound. The X-ray diffraction profile of the powder from a single crystal of La 2 Zr 2 O 7, shown in Fig.
2, reveals the presence of some low-angle weak superlattice reflections (with (h k l)=(1 1 1), (3 3 1), and (5 1 1)), which are a distinct feature of the pyrochlore-type the peaks observed could be indexed in the cubic Fd 3 ¯ m space group (see Table 2 for the Cited by: The spherulitic, dendritic and single-crystal growth of hydrated lanthanum tartrate by controlled diffusion in silica gels is reported.
The influence of growth parameters, e.g. reactant concentrations, gel pH, gel ageing, on the size and nucleation density of crystals has been studied.
Operative mechanisms of crystallization, results of growth kinetics and morphology of. Single crystal specimens of GdB6 free from inclusions of the tetraboride phase were produced. This was achieved using a shielding medium with a relatively low excess pressure of argon ensuring at the same time the high homogeneity of the melt of the zone as a result of intensive stirring.
Because of the high work function of the electron of GdB6 and the instability of this. Crystal growth Table 1 gives a detailed summary of the experiments and results on morphology, nucleation density and size of lanthanum tartrate crystals grown in silica gel.
The results in table 1 shows that single crystals of lanthanum tartrate grows at a gel pH of 4, and for a gel pH>, the crystals attain spherulitic morphology.
Single crystals of La4Mo7O27 have been successfully grown by the flux growth method H3BO3 as the flux in a plantium crucible using the starting materials of La2O3, H3BO3 and MoO3 in a molar ratio ofin which H3BO3 acted as a flux.
Transparent colorless crystals were obtained with size of × × mm3 under the optimized crystal growth conditions: growth. The rare-earth tetraborides are exceptional in that the rare-earth ions are topologically equivalent to the frustrated Shastry-Sutherland lattice.
In this paper, we report the growth of large single crystals of RB 4 (where R = Nd, Gd → Tm, and Y) by the floating-zone method, using a high-power xenon arc-lamp furnace.
The crystal boules have been characterized and tested for. Single crystal LaB 6, EuB 6, CeB 6, BaB 6, (La, Eu)B 6, (La, Y)B 6, (La, Ba)B 6, (La, Cs)B 6, (Eu, Y)B 6 and (Eu, Ba)B 6, hexaborides have been grown from an aluminium flux using oxide ls of ~1 mm or more per side have been synthesized.
Longer, rod-like shapes were produced by exponential cooling. Deviations from Vegards law were observed for. the growth of NdLCB single crystals.
In the growth experiments the platinum wire has been used as the seed for the growth of NdLCB crystals. Figure shows the platinum wire used as seed and Figure (a) and (b) shows the as grown crystal from platinum wires.
Figure Thermal cycle for the growth of NdLCB single crystals. The flux growth technique is particularly preferable because it readily allows crystal growth at a temperature well below the melting point of the solute.
In addition, crystals grown from ux have an enhedral habit and afl reasonably lower degree of dislocation density. In this paper, the ux growth of Lafl.
single crystals by. Single crystal lanthanum hexaboride (LaB 6) has been grown in a tammann furnace. In the furnace and at K, lanthanum (La) and boron (B) are melted in proportion to the stoichiometry mass ratio in 30–45 kg/cm 2 argon atmosphere. When the diffusion time at K took less, the cubical crystal grew and when it took longer, the needlelike crystal grew.
The crystal. Muratov, “The specific heat of single-crystal lanthanum hexaboride over a wide temperature range,” in: Powder Materials for Use under Extreme Conditions [in Russian], Inst. Probl. Materialoved., AN Ukr. SSR, Kiev (), pp.
26– Google Scholar. Journal of Crystal Growth 70 () North-Holland, Amsterdam THE CRYSTAL GROWTH OF URANIUM TETRABORIDE UB4 FROM THE MELT A. MENOVSKY, J.J.M. FRANSE and J.C.P. KLAASSE Natuurkundig Laboratorium der Universiteit van Amsterdam, Valckenierstraat 65 XE Amsterdam, The Netherlands A bulk single crystal.
To better determine the optical properties of the rare‐earth oxysulfide phosphors and to lay the foundation for their application in single‐crystal form as scintillators and lasers we have grown, for the first time, single crystals of these materials.
A description of present growth techniques will be presented. Materials problems and our progress toward their solutions will. Single‐crystal lanthanum hexaboride (LaB 6) rods 1 mm in diameter by more than mm in length have been fabricated by the laser‐heated floating zone process.
The procedure is described and the effects of process parameters such as power input and pulling and feeding rates on the geometry of the molten zone and on the quality of the grown rods are discussed. Electron beam emission apparatus useful for example in scanning electron microscopes or electron beam lithography comprises a lanthanum hexaboride (LaB 6) single crystal cathode formed from a rod whose axis is parallel to a crystallographic axis.
The rod tip is formed with four flat surfaces oblique to the rod axis, each exposing a crystal plane, so that. Single crystals of pure and Lanthanum doped L-Alanine Tartrate were grown by slow evaporation method. The cell parameters were determined using single crystal X.
Abstract This manuscript is a review of single crystal growth of high temperature superconducting materials. The introductory sections cover fundamentals of crystal growth with emphasis on special considerations for superconducting compounds, and the growth techniques that have been applied to these materials.The high ionic conductivity in lithium lanthanum titanate perovskite ceramics, Li3xLa(2/3)-xTiO3 (LLTO), is well-known for the x ≈ lithium concentration.
The grain conductivity is approximately 10–3 Scm–1 at room temperature, which makes this compound one of the best candidates for the development of solid-state electrolytes. However, lower grain boundary .A new lanthanum calcium borate with the composition La2CaB10O19 has been synthesized.
Single crystals have been grown from a melt close to the stoichiometric composition. The compound crystallizes in the monoclinic system, space group C2, with a = (3) Å, b = (2) Å, c = (2) Å, α = γ = 90°, β = °, and two formula units per cell.
The crystal .