Recent Developments in High-Temperature Shape Memory Thin Films

Motemani, Yahya; Buenconsejo, Pio John S.; Ludwig, Alfred

doi:10.1007/s40830-015-0041-0

Cited by 13 publications

(8 citation statements)

References 55 publications

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“…Micro or nano sized thin film shape memory alloys (SMAs) have been already used in many different micro and nano electromechanical systems (M/NEMS) such as microactuators, microvalves, micropumps and mass, temperature or force sensors [1,6,7,10,11,[20][21][22][23][24][25][26][27][28][29][30]. SMA thin films can be patterned with standard lithography techniques thus they can be integrated into MEMS devices [30].…”

Section: Introductionmentioning

confidence: 99%

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Karaduman¹,

Canbay

2022

Turkish Journal of Science and Technology

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Micro/nano scale thin-film shape memory alloys (SMAs) have been used in many different miniaturized systems. Using them as thin-film metal components in fabrication of Schottky photodiodes has started a few years ago. In this work, a new SMA-photodiode device with CuAlNi/n-Si/Al structure was produced by coating nano-thick CuAlNi SMA film on n-Si wafer by thermal evaporation. The photoelectrical I-V, I-t and C-V photodiode characterization tests were carried out at room temperature under dark and different artifical light power intensities. It was observed that the new device exhibited photoconductive, photovoltaic and capacitive behaviors. By using the obtained data, the ideality factor (n) and barrier height (ϕb) were determined by conventional I-V method. The photodiode performance parameters of responsivity (Rph), photosensivity (%PS) and spesific detectivity (D*) were determined as good figure of merits. The current conduction mechanism analysis revealed that the space charge limited conduction (SCLC) mechanism is the dominant current conduction mechanism. By the drawn reverse squared C-2-V plots, the values of donor concentration (ND), diffusion potential (Vd), Fermi level (EF) and also barrier height (ϕb) were determined for the SMA-photodiode. The results indicated that the new SMA-photodiode device can be useful in optoelectronic communication systems and photosensing applications.

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Section: Introductionmentioning

confidence: 99%

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Karaduman¹,

Canbay

2022

Turkish Journal of Science and Technology

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“…% . Transformation temperatures higher than 100 °C were also shown for thin films. ,, Therefore, Ti–Ta SMA can be utilized to develop high-temperature actuators, where the excellent cold workability of Ti–Ta is a benefit. , So far, most of the interest in Ti–Ta alloys was based on bulk materials beside a few reports about the thin film form. ,,,− Motemani et al. , have fabricated Ti 100– x Ta x ( x = 30 and 33) actuator thin films by magnetron sputtering at room temperature. These films showed an actuation response at temperatures above 100 °C, which is promising for development of high-temperature microactuators for applications in microsystem technologies.…”

Section: Introductionmentioning

confidence: 99%

Crystallographic Structure Analysis of a Ti–Ta Thin Film Materials Library Fabricated by Combinatorial Magnetron Sputtering

Kadletz¹,

Motemani

Iannotta³

et al. 2018

ACS Comb. Sci.

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Ti-Ta thin films exhibit properties that are of interest for applications as microactuators and as biomedical implants. A Ti-Ta thin film materials library was deposited at T = 25 °C by magnetron sputtering employing the combinatorial approach, which led to a compositional range of TiTa to TiTa. Subsequent high-throughput characterization methods permitted a quick and comprehensive study of the crystallographic, microstructural, and morphological properties, which strongly depend on the chemical composition. SEM investigation revealed a columnar morphology having pyramidal, sharp tips with coarser columns in the Ti-rich and finer columns in the Ta-rich region. By grazing incidence X-ray diffraction four phases were identified, from Ta-lean to Ta-rich: ω phase, α″ martensite, β phase, and a tetragonal Ta-rich phase (Ta). The crystal structure and microstructure were analyzed by Rietveld refinement and clear trends could be determined as a function of Ta-content. The lattice correspondences between β as the parent phase and α″ and ω as derivative phases were expressed in matrix form. The β ⇌ α″ phase transition shows a discontinuity at the composition where the martensitic transformation temperatures fall below room temperature (between 34 and 38 at. % Ta) rendering it first order and confirming its martensitic nature. A short study of the α″ martensite employing the Landau theory is included for a mathematical quantification of the spontaneous lattice strain at room temperature (ϵ̂ = 22.4(6) % for pure Ti). Martensitic properties of Ti-Ta are beneficial for the development of high-temperature actuators with actuation response at transformation temperatures higher than 100 °C.

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“…In the last two decades traditional and new processing techniques were analyzed from a fundamental and technological point of view [6][7][8][9][10]. Moreover, new alloy systems received considerable attention, including Ni-free shape memory alloys [11], highentropy SMAs [12][13][14][15] and high-temperature SMAs (HTSMAs) [16][17][18][19]. Ma et al [18] have pointed out that SMAs with high transformation temperatures can enable simplifications and improvements in operating efficiency of many functional components designed to operate at temperatures above 100°C in the automotive, aerospace, manufacturing and energy exploration industries.…”

Section: Introductionmentioning

confidence: 99%

Laboratory-Scale Processing and Performance Assessment of Ti–Ta High-Temperature Shape Memory Spring Actuators

Paulsen

Dumlu

Piorunek

et al. 2021

Shap. Mem. Superelasticity

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Ti75Ta25 high-temperature shape memory alloys exhibit a number of features which make it difficult to use them as spring actuators. These include the high melting point of Ta (close to 3000 °C), the affinity of Ti to oxygen which leads to the formation of brittle α-case layers and the tendency to precipitate the ω-phase, which suppresses the martensitic transformation. The present work represents a case study which shows how one can overcome these issues and manufacture high quality Ti75Ta25 tensile spring actuators. The work focusses on processing (arc melting, arc welding, wire drawing, surface treatments and actuator spring geometry setting) and on cyclic actuator testing. It is shown how one can minimize the detrimental effect of ω-phase formation and ensure stable high-temperature actuation by fast heating and cooling and by intermediate rejuvenation anneals. The results are discussed on the basis of fundamental Ti–Ta metallurgy and in the light of Ni–Ti spring actuator performance.

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Recent Developments in High-Temperature Shape Memory Thin Films

Cited by 13 publications

References 55 publications

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Crystallographic Structure Analysis of a Ti–Ta Thin Film Materials Library Fabricated by Combinatorial Magnetron Sputtering

Laboratory-Scale Processing and Performance Assessment of Ti–Ta High-Temperature Shape Memory Spring Actuators

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