Binary Single Crystals Research Articles

Tuning heterogeneous ion-radiation damage by composition in NixFe1-x binary single crystals.

Radiation-induced heterogeneous damage is the single largest source of failures seen in structural components in nuclear power reactors. Single crystal materials without grain boundaries, show considerable promise for overcoming this problem. In this work, such heterogeneous damage was further overcome in NixFe1-x single crystal alloys via a simple strategy of fine-tuning the composition. [001] NixFe1-x (x = 0, 0.38 and 0.62 at%) single crystals prepared using the Bridgman method were irradiated over a wide fluence range (4 × 1013 to 4 × 1015 ions per cm2). The irradiation-induced defect evolution was studied using Rutherford backscattering/channeling spectrometry, Monte Carlo simulations, transmission electron microscopy and nanoindentation. The results indicate an increased radiation tolerance of Ni0.38Fe0.62 compared to pure Ni and Ni0.62Fe0.38. The structural analysis performed by transmission electron microscopy revealed that defects tend to agglomerate at one place in Ni and Ni0.62Fe0.38, while in Ni0.38Fe0.62 no defect accumulation zone (characteristic damage peak) has been captured either at low or high fluence. Moreover, we found that the hardness change with the increase of Fe content is due to different arrangements of Fe atoms in the crystal structure, which influences the obtained mechanical properties of NixFe1-x in the pristine state and after ion implantation.

Orientation Effects during Scattering of Ar+ Ions from the InP(001) Surface under Grazing-Angle Ion Bombardment

In the approximation of binary collisions, computer simulation of the trajectories of Ar+ ions scattered from the InP(001)〈110〉 and 〈$$\bar {1}$$10〉 surfaces have been carried out. It is shown that the trajectories of the ions scattered from the surface of a binary single crystal are mainly determined by crystallographic directions that have a significant effect on the processes of scattering and neutralization of ions. The energy and angular distributions of small-angle scattering of Ar+ ions with Е0 = 3 keV from the surface of an InP(001) single crystal are calculated. It is established that the contribution of the near-surface region to ion scattering, which gives rise to the appearance of several discrete peaks in the low-energy part of the spectrum, can be clearly distinguished in the energy distribution.

Compression-Induced Polycrystal-Glass Transition in Binary Crystals

A polycrystal will transform into a glass when its grain size is sufficiently reduced. However, it is not clear how the polycrystal-glass boundary can be identified, whether the boundary is a sharp point or a crossover regime, and what features exist at this boundary. These questions have rarely been explored, partly because ultrafine-grained polycrystals are unstable. Here we compress binary single crystals composed of hard and soft disks into polycrystals and further into glasses by simulation. Through this approach, we can continuously increase the fraction of mismatched particles and produce tiny grains not accessible before. Such full spectrum of grain size enables us to study the polycrystal-glass transition. We observe rich structural, mechanical, dynamical, and thermodynamic features at the sharp polycrystal-glass boundary. These features could serve as criteria for the polycrystal-glass transition. Our analyses reveal the Hall-Petch and inverse Hall-Petch behaviors in two-dimensional polycrystals and identify three glass regimes. We find that compressing binary crystals can produce stable ultrafine grains only when compressible parts abound and appropriate two length scales exist in the soft-particle interactions. Our approach can guide the fabrication and stabilization of ultrafine-grained polycrystals. The observations cast light on the crossover regime of polycrystals and glasses.7 MoreReceived 10 January 2018Revised 2 September 2018DOI:https://doi.org/10.1103/PhysRevX.8.041023Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasGlass transitionNanocrystalsPolycrystalsPhysical SystemsColloidal glassGlassesMetallic glassesCondensed Matter, Materials & Applied PhysicsPolymers & Soft Matter

Enhanced pyroelectric properties and thermal stability of Mn-doped 0.29Pb(In1/2Nb1/2)O3-0.29Pb(Mg1/3Nb2/3)O3–0.42PbTiO3 single crystals

The pyroelectric properties and thermal stability of a [001]-oriented tetragonal 1 mol. % Mn-doped 0.29Pb(In1/2Nb1/2)O3-0.29Pb(Mg1/3Nb2/3)O3-0.42PbTiO3 [Mn-PIN-PMN-PT(29/29/42)] ternary single crystal were investigated. The single crystal exhibited a high pyroelectric coefficient of p = 6.0 × 10−4 C m−2 K−1 and figures of merit (FOMs) at 1 kHz for a current responsivity of Fi = 2.4 × 10−10 mV−1, a voltage responsivity of Fv = 0.08 m2 C−1, and a detectivity of Fd = 19.8 × 10−5 Pa−1/2 which were weakly dependent on frequency. These all increased linearly upon increasing temperature to 120 °C. Furthermore, the values of p for the ternary single crystal were weakly dependent on thermal annealing temperatures (Ta), maintaining over 75% of the original value at Ta < 160 °C, which was 70 °C higher than that of the [111]-oriented rhombohedral 1 mol. % Mn-doped 0.73Pb(Mg1/3Nb2/3)O3–0.27PbTiO3 [Mn-PMN-PT(73/27)] binary single crystal. These excellent pyroelectric properties, together with good thermal stability and wide operational temperature, make the [001]-oriented tetragonal Mn-PIN-PMN-PT(29/29/42) single crystal a promising candidate for pyroelectric detection and thermal imaging applications.

Magneto-mechanical and Pseudoelastic Damping of Fe–Al Based Single Crystals

Damping behavior of Fe–16.0~28.0at%Al and Fe–23.0at%Al–2.0at%M (M=Cr, Mn, Co, Ni) in the wide strain amplitude range was examined and the damping mechanism was discussed. In Fe–Al binary single crystals, magneto-mechanical damping caused by irreversible motion of magnetic domain walls took place at low strain amplitudes. On the other hand, pseudoelasticity based on reversible motion of 1/4 ‹111› superpartial dislocations appeared in Fe–23.0at%Al single crystals which also contributed to the high damping capacity at high strain amplitudes. The effect of Cr, Mn, Co and Ni on the vibration attenuation of Fe–23.0at%Al crystals was also examined. As a result, Ni doping was found to be effective in the increase in both internal friction and yield strength of Fe–Al alloys.

Piezoelectric ceramics and single crystals for ultrasonic medical transducers

Complex system ceramics Pb(Sc 1/2 Nb 1/2 )O 3 -Pb (Mg 1/3 Nb 2/3 )O 3 -Pb(Ni 1/2 Nb 1/2 )O 3 -(Pb 0.965 ,Sr 0.035 )(Zr,Ti) O 3 (PSN-PMN-PNN-PSZT abbreviated to PSMNZT) with extremely high dielectric constants, e T 33 /e 0 and e S 33 /e 0 , have been synthesized by the conventional technique and the dielectric and piezoelectric properties of the ceramics have been investigated for ultrasonic medical transducers. On the other hand, relaxor-PbTiO 3 single crystals (SCs) of xPb(In1/2Nbi/2)03-yPb(Mgi/3Nb2/3)03-zPbTi03 (PIN-PMN-PT abbreviated to PIMNT 100x/100y/100z) with high phase transition temperature between rhombohedral and tetragonal phase, T rt , and high Curie temperature, Tc, have been investigated for medical array transducers in order to overcome the shortcomings of the binary SCs such as 0.91Pb(Zn 1/3 Nb 2/3 )O 3 -0.09PbTi03 (PZNT91/9) and 0.68Pb(Mg 1/3 Nb 2 /3)03-0.32PbTiO 3 (PMNT68/32). Moreover, the pulse echo characteristics of the ultrasonic probes using the piezoelectric ceramic and piezoelectric SC are discussed on the basis of simulation employing Mason's model in this paper.

Durable, Ultraluminous Structure for Incandescent, High‐Power White‐LED

A new particle‐ and resin‐free system composed of transparent, binary single crystals entangled with each other continuously has been successfully developed for a light source for illumination. These single crystals exist in a semi‐coherent state like a block copolymer; one of these single crystals exhibits effective photoluminescence and the other plays an important role as a light guide of excitation and emitting lights. This material can have low backscattering and high quantum efficiency, resulting in twice the emission light of conventional particle‐dispersed systems. Furthermore, this system shows outstanding durability, because of its thermostructural properties. This concept will be expanded into wide combinations to create incandescent systems in the future.

Crystal growth and electrical properties of lead indium niobate–lead titanate binary single crystal

The largest Pb(In 1/2Nb 1/2)O 3–PbTiO 3(PIN-PT) binary system single crystal (about 20 mmx10 mm×5 mm, 4.5 g) near the morphotropic phase boundary composition with well-developed (1 0 0) planes was grown by the flux method using PbO–PbF 2–B 2O 3 flux. The PIN-PT(72/28) single crystal was found by simultaneous microdifferential thermal analysis and thermogravimetric analysis to show a peritectic melting at 1283°C with a partial decomposition of the perovskite crystal into a pyrochlore phase, followed by a liquidus point at 1294°C. The electromechanical coupling coefficient in rectangular bar mode, k 33′=78%, for phased array ultrasonic transducers was obtained by using the rhombohedral PIN-PT(72/28) single crystal oriented along the [0 0 1] axis. k 33′=78% is the highest value reported so far among all the piezoelectric materials with a T c>250°C and is almost independent of temperature, and even at 200°C decreased only by about 5%. The piezoelectric constant d 33=700pC/N was obtained. The relative permittivity Đ r decreases after poling. For instance, the Đ r value of 2650 before poling, decreases to 1500 after poling.

Effect of the addition of Ag on the strengthening of Al 3Li phase in Al–Li single crystals

The variation of the critical resolved shear stress as a function of aging condition has been measured in ternary Al–∼(1.9–2.0) wt% Li–∼0.4 wt% Ag single crystals and has been analyzed using the same version of order-hardening theory as in our previous work in binary single crystals. The result showed that the antiphase boundary energy of the Al 3Li lattice on {111} definitively increases from about 0.118 J/m 2 in binary crystals to 0.128±0.012 J/m 2 in ternary crystals, in good agreement with the analysis of the transition behavior from shearing to looping and of the dislocation pair spacings. A strong segregation tendency of Ag into the Al 3Li lattice is believed to be responsible for this increment. Our previous result of γ apb (0.118±0.006 J/m 2) in binary crystals is, although unlikely from the recent suggestion of Nembach, the best value one can obtain from the recent knowledge of order-hardening theory. This is slightly larger than that (about 0.100 J/m 2) obtained from the analysis of the transition from shearing to looping and somewhat larger than the result (about 0.085 J/m 2) of the first-principles calculation. Three factors are discussed as principal causes of a possibility of an overestimation of γ apb on applying order-hardening theory.

Transition behaviour of deformation mode from shearing to looping in an Al-Li-Ag ternary single crystal

The transition behaviour of the deformation mode from shearing to Orowan looping has been investigated in ternary Al- 2.0 wt% Li-0.4 wt% Ag single crystals using transmission electron microscopy. The critical loop size corresponding to the critical planar particle size for the transition and the dislocation pair spacing are distinctively small compared with those in an Al-Li binary single crystal. The antiphase-boundary energy of the delta phase is thus estimated to be distinctively large (about 0.123 J m ) compared with the binary crystal (about 0.100 J m ). The significant enhancement of the antiphaseboundary energy of the delta phase in an Ag-containing crystal is believed to be due to a strong enrichment of the delta phase with Ag.

Microstructure and Mechanical Properties of a Single Crystal NiAl Alloy with Zr or HF Rich G-Phase Precipitates.

ABSTRACTThe possibility of producing NiAl reinforced with the G-phase (Ni16X6Si7), where X is Zr or Hf, has been investigated. The microstructures of these NiAl alloys have been characterized in the as-cast and annealed conditions. The G-phases are present as fine cuboidal precipitates (10 to 40 nm) and have lattice parameters almost four times that of NiAl. They are coherent with the matrix and fairly resistant to coarsening during annealing heat treatments. Segregation and non-uniform precipitate distribution observed in as-cast materials were eliminated by homogenization at temperatures near 1600 K. Slow cooling from these temperatures resulted in large plate shaped precipitates, denuded zones, and a loss of coherency in some of the large particles. Faster cooling produced a homogeneous fine distribution of cuboidal G-phase particles (≤10 nm) in the matrix. Preliminary mechanical properties for the Zr-doped alloy are presented and compared to binary single crystal NiAl. The presence of these precipitates appears to have an important strengthening effect at temperatures≥1000 K compared to binary NiAl single crystals.

Oxidation and reduction in irradiated binary crystals of resorcinol and progesterone

The binary single crystals of resorcinol and progesterone were x-irradiated at 4.2 K. The semiquinone of resorcinol was generated by radiation induced oxidation. The oxidation and reduction products were identified from ESR and ENDOR measurements. (AIP)

Phase Diagram and Growth of Single Crystals in the Anthracene-Acridine Binary System

Abstract The revision of the phase diagram of the anthracene-acridine system by thermal analysis revealed the compositions of terminal solid solutions amounting to 2 and 88 mole % of anthracene respectively, and a eutectic at 8% of anthracene and 384.4[ddot]K. Relatively stable binary single crystals of composition ranging from 0 to 45 mole % of acridine in anthracene and from 2 to 10 mole % of anthracene in acridine have been obtained by the vapour growth technique. The lattice constants of the mixed crystals have been determined.