Defects in hydrothermal grown ZnO single crystals are studied as a function of annealing temperature using positron annihilation, x-ray diffraction, Rutherford backscattering, Hall, and cathodoluminescence measurements. Positron lifetime measurements reveal the existence Zn vacancy related defects as-grown state. The decreases upon above 600 °C, which implies disappearance defects, then remains constant up to 900 °C. backscattering rocking curve show improvement crystal quality due Although...

The structure of silicene fabricated on a Ag(111) surface was determined using reflection high-energy positron diffraction with linac-based brightness-enhanced intense beam. From the rocking curve analysis, verified to have buckled spacing $0.83\phantom{\rule{0.28em}{0ex}}\AA{}$ between top and bottom Si layers. distance layer in first Ag be $2.14\phantom{\rule{0.28em}{0ex}}\AA{}$. These results agree theoretically predicted values from previous study [Phys. Rev. Lett. 108, 155501 (2012)]...

Icosaniobate [Nb20O54]8- was synthesized by reacting [H4Nb6O19]4- with NO in tetrahydrofuran or MeNO2. A single-crystal X-ray diffraction study of its n-tetrabutylammonium salt [a = 17.7284(18) A, b 33.542(3) c 34.316(2) Z 4, and space group P22(1)2(1)] revealed a dimeric structure where two decaniobate ions are condensed sharing terminal O atoms. Unlike that [(NbW5O18)2O]4-, the Nb-O-Nb bridges icosaniobate bent. The nonlinear bridging reduces maximum possible symmetry anion to mm2, which...

Undoped ZnO single crystals were implanted with aluminum ions up to a dose of ${10}^{15}{\mathrm{Al}}^{+}/{\mathrm{cm}}^{2}.$ Vacancy defects in the layers detected using positron lifetime and Doppler broadening measurements slow beams. It shows that vacancy clusters, which are close size ${\mathrm{V}}_{8},$ generated by implantation. Postimplantation annealing S parameter increases temperature range from $200\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$...

Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for first time in samples with no magnetic layer. A spin-polarized positron beam used to probe spin polarization of outermost surface electrons Bi/Ag/Al2O3 and Ag/Bi/Al2O3 when charge currents were only associated Ag layers. An opposite found between application a current same direction. The polarizations both systems decreased exponentially layer thickness, suggesting occurrence diffusion from Bi/Ag...

Abstract Current-induced spin polarization (CISP) on the outermost surfaces of Au, Cu, Pt, Pd, Ta and W nanoscaled films were studied using a spin-polarized positron beam. The Au Cu showed no significant CISP. In contrast, exhibited large CISP (3~15% per input charge current 10 5 A/cm 2 ) opposite to those Pt Pd. sign obeys same rule in Hall effect suggesting that spin-orbit coupling is mainly responsible for magnitude explained by Rashba-Edelstein mechanism rather than diffusive effect....

ZnO single crystals implanted with O+ and B+ ions were studied by positron annihilation Raman scattering measurements. Positron results show that vacancy clusters are generated implantation. For the B+-implanted sample, have a sufficient increase in size evolve into microvoids after annealing up to 500°C. These need high temperature of 900–1000°C be annealed out. However, for O+-implanted shows only slight during process, they removed at much lower 700–800°C. The different process is...

Vacancy-type defects in as-grown ZnO single crystals have been identified using positron annihilation spectroscopy. The grown-in are supposed to be zinc vacancy $({V}_{\mathrm{Zn}})$-related defects, and can easily removed by annealing above $600\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$. ${V}_{\mathrm{Zn}}$-related also introduced when subjected $3\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ electron irradiation with a dose of...

Detailed structure of the rutile-TiO₂(110)-(1 × 2) has been determined using newly developed technique total-reflection high-energy positron diffraction (TRHEPD).

The Doppler broadening of annihilation radiation (DBAR) spectra Fe, Co, Ni, and Gd polycrystals measured using spin-polarized positrons from a $^{68}\mathrm{Ge}$-$^{68}\mathrm{Ga}$ source in magnetic fields exhibited clear asymmetry upon field reversal. differential DBAR between field-up field-down conditions were qualitatively reproduced calculations considering polarization electrons. magnitudes the field-reversal for Ni samples was approximately proportional to effective magnetization....

It is shown that the reflection high-energy positron diffraction (RHEPD) pattern from a Si(111)-(7 × 7) reconstructed surface for total condition, is, (TRHEPD) pattern, does not contain contributions atoms in bulk. Now, method of observing formed only by on topmost straightforward measurement bulk sample available.

We investigated the ferromagnetism of ZnO induced by oxygen implantation using spin-polarized positron annihilation spectroscopy together with magnetization measurements. The measurements showed appearance after and its disappearance during post-implantation annealing at temperatures above 573 K. Doppler broadening radiation (DBAR) spectrum asymmetry upon field reversal implantation. obtained differential DBAR between positive negative magnetic fields was well-explained a theoretical...

ZnO crystals were implanted with N+, O+, and Al+, co-implanted O+∕N+ Al+∕N+ ions. Positron annihilation measurements indicate introduction of vacancy clusters upon implantation. In the N+-implanted samples, these are only partially annealed at 800°C, as compared their entire recovery in O+- Al+-implanted samples 800–900°C, suggesting a strong interaction between nitrogen clusters. However, sample, most disappear 800°C. Probably oxygen scavenges to enhance annealing Upon further 1000–1100°C,...

We measured the Doppler broadening of annihilation radiation (DBAR) spectra $3d$ (Fe, Co, and Ni) $4f$ (Gd, Tb, Dy) ferromagnets under a magnetic field by using spin-polarized positrons from ${}^{68}$Ge-${}^{68}$Ga source. The results showed that DBAR these metals have notably different magnetic-field dependences. differences among Fe, Ni reflect upper minority spin bands Fe Co are nearly empty while those still mostly occupied. For rare-earth instead inner electrons, $5d$ electrons mediate...

A 10 keV positron beam has been developed using coaxially symmetric electromagnetic lenses for reflection high-energy diffraction (RHEPD) experiments. The brightness is ∼107 e+/s/cm2/rad2/V which comparable to that obtained enhancement technique. parallel and normal coherence lengths are over 100 40 Å, respectively, long enough observe patterns associated with large surface super-structures. RHEPD from a Si(111)-(7×7) reconstructed have successfully observed much better quality than...

Undoped ZnO single crystals were implanted with multiple-energy N+ ions ranging from 50 to 380 keV doses 1012 1014 cm−2. Positron annihilation measurements show that vacancy defects are introduced in the layers. The concentration of increases increasing ion dose. annealing behaviour can be divided into four stages, which correspond formation and recovery large clusters disappearance vacancy–impurity complexes, respectively. All implantation-induced removed by at 1200 °C. Cathodoluminescence...

We report the observation of reflection high-energy positron diffraction from a $7\ifmmode\times\else\texttimes\fi{}7$ reconstructed Si(111) surface with well-collimated 20-kV beam. The pattern clearly exhibited (1/7)--(3/7) order Laue zones in addition to zeroth and first zones. From dynamical calculation rocking curve total region, vertical position adatom layer was determined be 1.52 \AA{} relative stacking fault layer. This value is greater than that predicted first-principles study...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIonic surfactants soluble in hard water and hydrocarbons: behavior of organized surfactant solutions as a function the hydrophilic-lipophilic balanceKozo Shinoda, Masaki Maekawa, Yutaka ShibataCite this: J. Phys. Chem. 1986, 90, 7, 1228–1230Publication Date (Print):March 1, 1986Publication History Published online1 May 2002Published inissue 1 March...