Thin Film X-ray Diffraction Research Articles

Large-Scale Molecular Packing and Morphology-Dependent High Performance Organic Field-Effect Transistor by Symmetrical Naphthalene Diimide Appended with Methyl Cyclohexane

The influence of structural ordering of methyl cyclohexane appended naphthalene diimide (NMeCy2) thin films and their correlation with enhanced device performances are presented here. The vacuum-deposited thin-film microstructure and morphology of NMeCy2 have been investigated using thin-film X-ray diffraction (XRD), atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM) and were comparable with the bulk-phase crystalline structure and packing of NMeCy2. The organic field-effect transistor (OFET) fabricated on a glass substrate consists of a bilayer polymer dielectric poly(methyl methacrylate) (PMMA) over poly(vinyl alcohol) (PVA) and an inorganic high-k dielectric Al2O3 as the third layer. NMeCy2 thermally deposited at an optimized substrate temperature (Tsub) of 60 °C displayed excellent molecular packing over a large area that resulted in the improved field-effect performance with electron mobility (μe) value of 0.6 cm2 V–1 s–1 and current on/off ratio (Ion/off) of 106 via modifications in dielectric configuration. Furthermore, the device afforded an unprecedented threshold voltage (VTh) of 5.23 V with this material. We have been successful in developing a facile, reliable, and cheap method to tune the dielectric features which can culminate in improved field-effect transport properties.

Generation of Agsi Film By Magnetron Sputtering for Use As Anodes in Lithium Ion Batteries

In the present work we deposit Si film with 20%at. Ag, to improve the capacity retention and the cycleability of Si anode. The physical properties of the as-synthesized sample is investigated by thin film X-ray diffraction (XRD) and scanning electron microscopy (SEM). The as-prepared sample is used as negative electrode materials for lithium ion battery, whose charge-discharge properties, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and cycle performance are examined in detail. The galvanostatic test result shows that the electrode delivers 1800 mAh/g initially with 99% Coulombic efficiency and retains 85% of its initial discharge capacity after 50 cycle. This outstanding property of the electrode can be related to the presence of Ag, which decreases the polarization of the anode. Keywords: Ag based anodes, lithium ion batteries, magnetron sputtering.

Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species.

Effect of alkyl substituents: 5,15-bis(trimethylsilylethynyl)- vs. 5,15-bis(triisopropylsilylethynyl)-tetrabenzoporphyrins and their metal complexes

The copper(II), nickel(II), etc. complexes of 5,15-bis(trimethylsilylethynyl)tetrabenzoporphyrin ( TMS - H 2 BP ) and 5,15-bis(triisopropylsilylethynyl)tetrabenzoporphyrin ( TIPS - H 2 BP ) have been prepared from the corresponding bicycle[2.2.2]octadiene(BCOD)-fused precursors by the retro-Diels–Alder reaction. X-ray diffraction (XRD) analyses show that TMS - H 2 BP and its metal complexes of zinc(II) ( TMS - ZnBP ) and copper(II) ( TMS - CuBP ) adopt flat molecular conformations and form herringbone-type packing structures in the single crystalline state. TIPS - H 2 BP and the zinc(II) and copper(II) complexes ( TIPS - ZnBP and TIPS - CuBP ) are similar to the TMS derivatives in molecular conformation, but these TIPS derivatives form one-dimensional slipped-stack structures. The nickel complexes TMS - NiBP and TIPS - NiBP have U-shaped structures because of the small size of nickel(II) ion. Solution processed organic thin-film transistors of the benzoporphyrins were fabricated and TMS - H 2 BP showed the highest hole mobility of 0.11 cm2.V-1.s-1. Bulk heterojunction organic solar cells based on TMS- or TIPS - H 2 BP and their metal complexes as p-type and PC 71 BM as n-type materials were fabricated by solution process. Atomic force microscopy and thin-film XRD measurements indicated that the film crystallinities were increased by raising the annealing temperature over 180°C or by changing the substituents from triisopropylsilyl to trimethylsilyl. The best power-conversion efficiency (PCE) of 1.49% was achieved with TMS - ZnBP by annealing at 180°C with a moderate crystallinity and smooth surface.

Controlled electrochemical synthesis of yttrium (III) hexacyanoferrate micro flowers and their composite with multiwalled carbon nanotubes, and its application for sensing catechin in tea samples

We report the hierarchical growth of yttrium (III) hexacyanoferrate (YHCF), having a shape that resembles that of rose flower petals on a glassy carbon electrode (GCE) modified with functionalized multiwalled carbon nanotubes. The modified GCE displays excellent electrocatalytic activity toward catechin (CA) oxidation. The morphology and impedimetric response of YHCF were optimized by controlling the number of depositing cycles. As-synthesized YHCF micro flower was characterized by thin film X-ray diffraction (XRD) and infrared (IR) spectroscopic methods, respectively. By taking the advantage of a template-free, surfactant-less, and simple procedure, YHCF micro flowers have been prepared. The sensitivity and low detection limit of functionalized multiwalled carbon nanotube (fMWCNT)/YHCF/GCE toward CA are 1.311 μA μM−1 cm−2 and 0.28 μM, respectively. Moreover, the fabricated GCE exhibits sufficient recovery for CA determination in green tea and oolong tea samples.

Improving electrochemical performance of tin-based anodes formed via oblique angle deposition method

An oblique angle electron beam co-deposition technique was used to fabricate nanostructured Sn-based thin films: Sn, Cu–Sn and Cu–Sn–C. The morphological and structural properties of the films were observed via scanning electron microscopy (SEM) and thin film X-ray diffraction (XRD) methods. The electrochemical (CV and EIS) and the galvanostatic test results demonstrated that the addition of Cu with or without C affected the electrochemical performance of the thin film positively since Cu and C improved both the mechanical and the electrical properties of the nanostructured Sn thin film electrode. The high cycleability and capacity retention were achieved when the nanostructured Cu–Sn–C thin film was used as an anode material since C increased the mechanical tolerance of the thin film to the volume expansion due to its grain refiner effect. Cu not only improved the electrical conductivity and the adhesion of the film to substrate but also the mechanical tolerance of the film with its ductile property.

Microstructure and magnetic properties of patterned nano crystalline zinc ferrite thin film fabricated by pulse laser deposition

Patterned nano crystalline ZnFe2O4 thin film was fabricated on quartz substrate by pulse laser deposition. XRD and Raman spectroscopic techniques were employed for structural characterization of the film. Silencing of a small number of prominent ferrite XRD peaks in thin film signify mild textured film growth. The observed XRD peak position swing with respect to the target material in thin film indicates formation of lateral strain in opposite directions during film growth. The thin film XRD peak position shift with target material data as reference is explained by suggesting an appropriate film growth model. Designated ferrite Raman emission peaks originated from film surface authenticates the stoichiometric and structural stability of ferrite material. AFM images indicate specific pattern formation with nanogranular morphology. Magnetic property measurements of the thin film revealed enhanced properties which are explained on the basis of texture, lattice strain, and surface features that are originated from patterned thin film growth.

Solution-Processable Organic Photovoltaic Cell Based on the Oligothiophene with Solubilizing β-alkyl Groups

We synthesized a linear π-conjugated small molecule (β-DH5T) based on thiophene, using the palladium-catalyzed Suzuki coupling. The oligothiophene was designed to contain β-substituted solubilizing alkyl groups to facilitate solution processing. The organic photovoltaic cell based on β-DH5T:PC71BM gave a power conversion efficiency of 0.46% with a short-circuit current of 4.69 mA/cm2, an open-circuit voltage of 0.60 V, and a fill factor of 0.35, giving under AM 1.5G illumination (100 mW/cm2). The optical and electrochemical properties and molecular alignment of oligothiophene were investigated using UV-visible absorption spectroscopy, cyclic voltammetry, and thin-film X-ray diffraction studies.

Structured SiCu thin films in LiB as anodes

Both helical and inclined columnar Si–10at.% Cu structured thin films were deposited on Cu substrates using glancing angle deposition (GLAD) technique. In order to deposit Cu and Si two evaporation sources were used. Ion assistance was utilized in the first 5min of the GLAD to enhance the adhesion and the density of the films. These films were characterized by thin film XRD, GDOES, SEM, and EDS. Electrochemical characterizations were made by testing the thin films as anodes in half-cells for 100cycles. The results showed that the columnar SiCu thin film delivered 2200mAhg−1, where the helical one exhibited 2600mAhg−1, and, their initial coulombic efficiencies were found to be 38%–50% respectively. For the columnar and the helical thin film anodes, sustainable 520 and 800mAhg−1 with 90% and 99% coulombic efficiencies were achieved for 100cycles. These sustainable capacities showed the importance of the thin film structure having nano-sized crystals and amorphous particles. The higher surface area of the helices increases the capacity of the electrode because the contact area of the thin film anode with Li ions is increased, and the polarization which otherwise forms on the anode surface due to SEI formation is decreased. In addition, because of larger interspaces between the helices the ability of the anode to accommodate the volumetric changes is improved, which results in a higher coulombic efficiency and capacity retention during cycling test.

An investigation of ruthenium coating from LiCl–KCl eutectic melt

In this study, electrodeposition of ruthenium (Ru) from LiCl–KCl eutectic melt was investigated in a systematic manner and the effects of process parameters namely current density, time and agitation of electrolyte on the thickness and morphology of Ru layer were explored. The presence of Ru on graphite substrates was confirmed by thin film X-ray diffraction method. The Ru coatings formed at all electrodeposition conditions appeared as a white/gray deposit. The typical “faceted structure” was observed on the surface of Ru deposited at 3 and 7mA/cm2. Fracture cross-section examinations revealed the columnar morphology of Ru which was twinned with boundaries. The smooth appearance of Ru coating became uneven and rough with coarse nodules at 12mA/cm2. The thickness of Ru increased with increasing both current density and time at stationary electrodeposition conditions. A dense and 7.5μm thick Ru coating was possible to grow on graphite without any agitation at 3mA/cm2 for 2h. The highest cathodic current efficiency (η), 99.68%, was achieved at 3mA/cm2 after 2h of electrodeposition time with the rotating cathode speed of 50rpm. The cross sectional micro-indentation studies indicated that the Ru layer has hardness as high as 450±10HV.

In vitro bioactivity and corrosion resistance of Zr incorporated TiO2 nanotube arrays for orthopaedic applications

The present investigation deals with the incorporation of zirconium (Zr) ions onto TiO2 nanotube arrays (TNT) by simple dip coating method for biomedical implants. The electrochemical behaviour of the specimens were studied with potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy (EIS), while surface analysis involved field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, thin film x-ray diffraction (TF-XRD) and contact angle measurements. The FE-SEM morphology revealed that self-organised TNT was tightly arrayed with an average diameter of 110±4nm. The wall thickness and length of 15±2nm and 2.1±0.3μm respectively were developed by electrochemical anodization of titanium sheet in a mixture of ethylene glycol and NH4F electrolyte. The EDS, ATR-FTIR and TF-XRD studies were revealed the incorporation of Zr onto TNT specimens. Hydroxyapatite (HAp) was grown over Zr ions incorporated TNT (Zr-TNT) via in vitro immersion method. The HAp grown Zr-TNT exhibited higher bioactivity as well as enhanced corrosion resistance when compared to other specimen. Hence, Zr-TNT could be a viable material for the use as orthopaedic implant with good bioactivity and corrosion resistance.

An Investigation into the Oxygen Evolution Reaction at Manganese/ Manganese Ruthenium and Ruthenium Oxide Films in Base

Alkaline water electrolysis has been proposed as an environmentally inoffensive route to the production of the large volumes of hydrogen gas required by a possible hydrogen economy [1-5]. In practice, the efficiency of water electrolysis is limited by the large anodic over-potential of the oxygen evolution reaction (OER) [5]. Over the past thirty years, considerable research effort has been devoted to the design, synthesis and characterization of OER anode materials, with the aim of achieving useful rates of active oxygen evolution at the lowest possible over-potential, in order to optimize the overall electrolysis process. Currently, the optimal OER anode materials are Ruthenium and Iridium oxides, since these oxides exhibit the lowest overpotentials for the OER at practical current densities [6]. However, the high cost of these materials compared to other metals and their poor long term stability in alkaline solution renders their widespread commercial utilisation uneconomical [7]. For these reasons, the oxides of the first row transition metals (e.g. manganese, iron, cobalt and nickel) offer a compromise solution. Even though they are not as electrocatalytically active, their relatively low cost and long term corrosion resistance in alkaline solution makes them attractive OER anode materials [7-11].In the present work, we focus on the redox properties and electrocatalytic behaviour with respect to anodic oxygen evolution of manganese and ruthenium oxide electrodes prepared at different molar ratios in aqueous alkaline solution. These films can be prepared simply via thermal decomposition of a metal salt [12]. The structure and morphology of the thermally decomposed oxide materials are examined using thin film XRD, high resolution SEM and FTIR. The redox behavior of the resulting oxide films is investigated as a function of molar ratio and annealing temperature using cyclic voltammetry. The kinetics of the OER at these films has been studied using a range of electrochemical techniques including steady-state polarization and open circuit potential decay curves. In particular, Tafel slopes and reaction orders with respect to hydroxide ion activity are determined. Interestingly, the electrochemical performance for the films is strongly dependent on the molar ratio used, as evident from figure attached. Based on the available kinetic data, a reaction mechanism utilizing the active surfaquo group concept, is proposed. Turnover Frequency numbers are also obtained. Acknowledgements This publication has emanated in part from research conducted with the financial support of Science Foundation Ireland (SFI) under Grant Number SFI/10/IN.1/I2969.

Dissolution behavior of bioactive glass ceramics with different CaO/MgO ratios in SBF-K9 and r-SBF

In the present work, we studied dissolution behavior of three glass ceramics samples each having 34SiO2–14.5P2O5–1CaF2–0.5MgF2 (%wt) and ratio of CaO/MgO varying from 11.5:1 to 1:11.5 in conventional SBF (SBF-K9) and revised SBF (r-SBF) that has ionic concentration exactly equal to that of human blood plasma. For that purpose, samples were immersed in fluids for different time periods upto 25 days. Thin film XRD analysis revealed the diffusive nature of the phases on the surfaces of samples after soaking for different time periods in r-SBF. It showed the poor precipitation and small thickness of the HCAp layer on the samples as compared to that in SBF-K9, thus indicating the fitness and sensitivity of r-SBF for in-vitro characterization of samples. AAS, FTIR and EDS revealed slow bonding rate on the surfaces of the samples in r-SBF than that in SBF-K9 that showed the dependence of bond formation on the composition of the materials as well as on the physiological fluid used for in-vitro characterization. The rate of HCAp formation was slower in r-SBF due to more competitive adsorption of CO3− ions to Ca and Mg ions owing to greater amount of CO3− in r-SBF than that in SBF-K9. It shows the importance of CO3− content in the physiological fluids for the in-vitro assessment of samples. So, r-SBF is recommended to be used for assessment of samples to clearly understand their behavior in-vivo.

Biomimetic Synthesis, Characterization, and Adhesion Properties of Bone-Like Apatite on Heat and Alkaline-Treated Titanium Alloy

The effects of alkaline treatment solution and concentration on the formation and adhesive strength of biomimetic synthesized bone-like apatite on Ti6Al4V surface were examined. Specimens were soaked in 5, 10 M solutions of NaOH or in 0.01, 0.03 M solutions of Ca(OH)2 at 80°C for 24 and 72 h. Subsequently, the substrates were heat-treated at 600°C for 1 h for consolidation of sodium or calcium titanate hydrogel layers. Finally, they were soaked in simulated body fluid (SBF) for one, three, and 14 days at 36.5°C. The surface of the specimens was characterized using scanning electron microscopy and thin film X-ray diffraction. It was found that the optimum condition for desirable apatite formation is 72 h soaking in 5 M NaOH at 80°C and three days’ immersion in SBF. The best adhesive strength result was for 24 h soaking in 0.03 M Ca(OH)2 at 80°C and 14 days’ immersion in SBF.

A Nanoarchitectured Porous Electrode Assembly of NiSi Thin Film for Lithium Ion Batteries

This study proposes to produce well-aligned nanorod arrays containing NiSi thin film to improve the electrochemical performance of Si based anodes. In this respect, NiSi thin films made of nanorods are produced via glancing angle electron beam deposition (GLAD) technique. The structural and morphological properties are investigated using thin film X-ray diffraction (XRD) and scanning electron microscopy (SEM). The well aligned nanorod arrays containing NiSi thin film anode exhibits a long cycle life with a moderate capacity retention (around 1100mAhg-1 for 100 cycles). This remarkable electrochemical performance can be explained by the electrode composition, structure and morphology: During Li+ insertion into the alloyed thin film electrodes, Si acts as active center, which reacts with Li+ to form amorphous LixSi alloys, while the nanosized Ni particles are believed to provide electrical conduction network inside the active material and buffer volume expansions with the help of the homogenously distributed nanosized interspaces (porosities among the nanorods) present in the thin film.

Improving the Electrochemical Performance of the Tin Based Anodes formed via Oblique Angle Deposition Method

An oblique angle electron beam co-deposition technique was used to fabricate nanostructured Sn based thin films: Sn, Cu-Sn and Cu-Sn-C. The morphological and structural properties of the films were observed via scanning electron microscopy (SEM) and thin film X-ray diffraction methods (XRD). The cyclic voltammetry (CV) and the galvanostatic test results demonstrated that the addition of Cu with or without C affected the electrochemical performance of the thin film positively since Cu and C improved both the mechanical and the electrical properties of the nanostructured Sn thin film electrode. The high cycleability and the capacity retention were achieved when the nanostructured Cu-Sn-C thin film was used as an anode material since C increased the mechanical tolerance of the thin film to the volume expansion due to its grain refiner effect, and Cu not only improved the electrical conductivity and the adhesion of the film to substrate but also the mechanical tolerance of the film with its ductile property.

Nanocolumnar Structured Porous Cu-Sn Thin Film as Anode Material for Lithium-Ion Batteries

Two nanocolumnar structured porous Cu-Sn films were produced by tuning the duration of the process using an oblique angle deposition (OAD) technique of electron beam coevaporation method. The structural and morphological properties of these porous Cu-Sn films are characterized using thin film X-ray diffraction, scanning electron microcopy (SEM) and atomic force microscopy (AFM). Galvanostatic half-cell electrochemical measurements were conducted in between 5 mV to 2.5 V using a Li counter electrode, demonstrating that the Cu rich Cu6Sn5 thin film having homogenously distributed nanocolumns achieved a good cycleability up to 100 cycles with a high capacity retention, whereas the Cu6Sn5 nanostructured porous thick film with inhomogeneous morphology showed only a very short cycle life (<25 cycles).The difference in the electrochemical performances of the thin and thick nanocolumnar structured porous Cu-Sn films resulting from different evaporation duration was evaluated on the basis of X-ray photoelectron spectroscopy (XPS) analysis on the cycled samples.

Benzothienobenzothiophene-Based Conjugated Oligomers as Semiconductors for Stable Organic Thin-Film Transistors

Two benzothienobenzothiophene (BTBT)-based conjugated oligomers, i.e., 2,2'-bi[1]benzothieno[3,2-b][1]benzothiophene (1) and 5,5'-bis([1]benzothieno[3,2-b][1]benzothiophen-2-yl)-2,2'-bithiophene (2), were prepared and characterized. Both oligomers exhibit excellent thermal stability, with 5% weight-loss temperatures (T(L)) above 370 °C; no phase transition was observed before decomposition. The highest occupied molecular orbital (HOMO) levels of 1 and 2 are -5.3 and -4.9 eV, respectively, as measured by ultraviolet photoelectron spectroscopy. Thin-film X-ray diffraction and atomic force microscopy characterizations indicate that both oligomers form highly crystalline films with large domain sizes on octadecyltrimethoxysilane-modified substrates. Organic thin-film transistors with top-contact and bottom-gate geometry based on 1 and 2 exhibited mobilities up to 2.12 cm(2)/V·s for 1 and 1.39 cm(2)/V·s for 2 in an ambient atmosphere. 1-based devices exhibited great air and thermal stabilities, as evidenced by the slight performance degradation after 2 months of storage under ambient conditions and after thermal annealing at temperatures below 250 °C.

Fluoride Conversion Coating on Biodegradable AZ31B Magnesium Alloy

A fluoride conversion coating was successfully prepared on AZ31B magnesium alloy by chemical reaction in hydrofluoric acid. Morphologies, composition, bonding strength, corrosion properties, in vitro cytotoxicity and antibacterial properties of the coating were investigated, respectively. The scanning electron microscopy observations revealed a dense coating with some irregular pores. The thin-film X-ray diffraction analysis indicated that the coating was mainly composed of MgO and MgF2. The electrochemical impedance spectroscopy results showed that the fluoride conversion coating significantly improved the corrosion resistance of AZ31B. The hydroxyapatite formed on the surface of the fluoride coated AZ31B after being immersed in the simulated blood plasma indicated the good bioactivity of the material. The in vitro cytotoxicity test showed that the fluoride coated AZ31B alloy was not toxic to BMMSCs (human bone marrow-derived mesenchymal stem cells). It was also found that the fluoride coated AZ31B alloy had antibacterial capability.

Fabrication and characterization of TiO2-ZrO2-ZrTiO4 nanotubes on TiZr alloy manufactured via anodization.

Titanium and its alloys are able to grow a stable oxide layer on their surfaces and have been used frequently as substrates for anodization in an electrochemical surface treatment. A nanotubular oxide layer is formed in the presence of fluorine anion (F-) via anodization due to the competition between oxide formation and solvatization. In this study, a highly ordered titania-zirconia-zirconium titanate (TiO2-ZrO2-ZrTiO4) nanotubular layer was formed on the surface of Ti50Zr alloy via anodic oxidation in an F- containing electrolyte. The sizes of the nanotubes (i.e., the inner and outer diameters, and wall thicknesses), morphology, crystal structure, hydrophilic properties and components of the TiO2-ZrO2-ZrTiO4 nanotubular layer before and after annealing were examined by scanning electron microscopy (SEM), thin film X-ray diffraction, X-ray photoelectron spectroscopy (XPS) analysis and water contact angle measurements. The results indicated that the inner diameter, outer diameter and wall thickness of the as-formed TiO2-ZrO2-ZrTiO4 nanotubes were distributed in the ranges of 3-120 nm, 12-165 nm and 3-32 nm, respectively, and depended on the F- concentration of the electrolyte and the applied potential during anodization. The number of smaller nanotubes increased with increasing F- concentration and the mean nanotube inner and outer diameters increased with increasing applied potential. The as-formed TiO2 and ZrTiO4 nanotubes exhibited an amorphous structure and the as-formed ZrO2 nanotubes displayed an orthorhombic structure. These phases transformed into anatase TiO2 and orthorhombic ZrO2 and ZrTiO4 after annealing. The hydrophilic properties of the TiO2-ZrO2-ZrTiO4 nanotubular layer were affected by the size distribution of the nanotubes. The surface roughnesses and the nanotubular character transformed the nanotubes to exhibit superhydrophilic properties after annealing. The TiO2-ZrO2-ZrTiO4 nanotubular surface on Ti50Zr alloy exhibited higher surface energy than that of the TiO2 nanotubular surface on commercially pure (CP) titanium.