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1.
Oğuz Çelikel 《Optical and Quantum Electronics》2007,39(2):147-156
Gyroscopes, which sense changes on absolute angular rate and are classified into Interferometric Fiber Optic Gyroscopes (IFOG),
Ring Laser Gyroscopes (RLG) and Micro- Electro-Mechanical Systems (MEMS) Gyroscopes, are critical components of the navigation
systems together with accelerometers. Being dominant over other types of gyroscopes in terms of performance and cost, IFOGs
have widely been used in metrology and in particular defense/aerospace industry. This paper covers the design details of both
optical and electronic components of IFOG prototype, the sensing mechanism of which is based on Sagnac Phase Shift, constructed
in Optics Laboratory of National Metrology Institute of TURKEY as absolute angular rate sensor. In the prototype IFOG, open-loop
configuration was applied, a single mode telecommunication optical fiber and an EDFA pumped by DFB laser emitting at 1549.0 nm
were used as sensing coil and broadband source, respectively. The voltage data carrying Sagnac Phase Shift was extracted by
a phase tracking circuit consisting of an active RC band pass filter, an amplifier with adjustable gain and an AD630 balanced
modulator chip which was operated as lock-in. For the prototype IFOG, peak to peak noise of 8 (°/h) and bias stability of
1.57 (°/h) were attained respectively. Moreover the scale factor of 13.83 (°/h)/mV was derived with deviation of 0.73%. 相似文献
2.
W. Deng T. Ohgi H. Nejo D. Fujita 《Applied Physics A: Materials Science & Processing》2001,72(5):595-601
Highly conductive and transparent indium tin oxide (ITO) thin films, each with a thickness of 100 nm, were deposited on glass
and Si(100) by direct current (DC) magnetron sputtering under an argon (Ar) atmosphere using an ITO target composed of 95%
indium oxide and 5% tin oxide for photon-STM use. X-ray diffraction, STM observations, resistivity and transmission measurements
were carried out to study the formation of the films at substrate temperatures between 40 and 400 °C and the effects of thermal
annealing in air between 200 and 400 °C for between1 and 5 h. The film properties were highly dependent on deposition conditions
and on post-deposition film treatment. The films deposited under an Ar atmosphere pressure of ∼1.7×10-3 Torr by DC power sputtering (100 W) at substrate temperatures between 40 and 400 °C exhibited resistivities in the range
3.0–5.7×10-5 Ω m and transmissions in the range 71–79%. After deposition and annealing in air at 300 °C for 1 h, the films showed resistivities
in the range 2.9–4.0×10-5 Ω m and transmissions in the range 78–81%. Resistivity and transmission measurements showed that in order to improve conductive
and transparent properties, 2 h annealing in air at 300 °C was necessary. X-ray diffraction data supported the experimental
measurements of resistivity and transmission on the studies of annealing time. The surface roughness and film uniformity improve
with increasing substrate temperature. STM observations found the ITO films deposited at a substrate temperature of 325 °C,
and up to 400 °C, had domains with crystalline structures. After deposition and annealing in air at 300 °C for 1 h the films
still exhibited similar domains. However, after deposition at substrate temperatures from 40 °C to 300 °C, and annealing in
air at 300 °C for 1 h, the films were shown to be amorphous. More importantly, the STM studies found that the ITO film surfaces
were most likely to break after deposition at a substrate temperature of 325 °C and annealing in air at 300 °C for 2 or 3 h.
Such findings give some inspiration to us in interpreting the effects of annealing on the improvement of conductive and transparent
properties and on the transition of phases. In addition, correlations between the conductive/transparent properties and the
phase transition, the annealing time and the phase transition, and the conductive/transparent properties and the annealing
time have been investigated.
Received: 10 July 2000 / Accepted: 27 October 2000 / Published online: 9 February 2001 相似文献
3.
The non-stoichiometry and chemical diffusion coefficient of SrFe1−xCoxO3-δ have been measured by steady state and transient thermogravimetry in the temperature range 750–1200 °C at different oxygen
partial pressures. At high oxygen partial pressures, the chemical diffusion coefficient was in the range 1·10−4 – 7·10−4 cm2/s. This, combined with high concentration of disordered vacancies make these materials perhaps the fastest solid oxygen ion
diffusers known at high temperatures and high oxygen partial pressures. However, due to the high concentration of defects
in SrFe1−xCoxO3-δ the compound transforms from a cubic (disordered) perovskite to a brownmillerite type of structure under reduced oxygen partial
pressures below approx. 900 °C. Due to this phase transition, the mobility of oxygen vacancies in SrFe1−xCoxO3-δ decreases up to about an order of magnitude at 850 °C. We also observe an ordering effect at 1000 °C, although smaller in
size, and this is suggested to be due to short range ordering of four-coordinated polyhedra of Fe. For possible use as oxygen
separation membranes, phase stability against sulphur and carbon containing atmospheres is also discussed with respect to
the formation of carbonates and sulphates.
Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999. 相似文献
4.
The distinctive features of the low-frequency internal friction Q
−1(T) of (Cu-Sn)-Nb composites at high temperatures (up to 400°C) are investigated for strains in the range 10−5–10−4. Considerable hysteresis of Q
−1(T) in the heating-cooling cycle is recorded, including the presence of a minimum at ∼175°C when the sample is heated to 400°C
and two peaks P
2 (at 280°C) and P
1 (at ∼100°C) when the sample is cooled from 400°C. The activation energy of the anomalous internal friction background (up
to 175°C), the oxygen diffusion parameters, and the oxygen concentration in the niobium fibers (all of which govern the peak
P
2) are calculated, and the value and temperature dependence of the yield point of the bronze matrix (which govern the peak
P
1) are estimated.
Zh. Tekh. Fiz. 68, 114–117 (November 1998) 相似文献
5.
Doped bismuth ruthenates and bismuth ruthenate-stabilized bismuth oxide composites were studied as prospective cathode material
for solid oxide fuel cells. Symmetric cells were fabricated on gadolinium-doped ceria electrolytes and studied by electrochemical
impedance spectroscopy. Ca- and Ag-doped bismuth ruthenate electrodes (5–10 mol%) showed the same characteristic frequency
as undoped bismuth ruthenate but with higher activation energy and slightly better performance above ∼550 °C. At 700 °C, area-specific
resistance (ASR) of undoped, 5 mol% Ca and 5 mol% Sr-doped bismuth ruthenate electrode was 1.45, 1.24, and 1.41 Ωcm2, respectively. The change in ASR as a function of oxygen partial pressure and current bias suggests that the rate-limiting
steps for oxygen reduction in bismuth ruthenate systems are charge transfer and surface diffusion of dissociatively adsorbed
oxygen to triple phase boundaries. Introduction of the erbia-stabilized bismuth oxide (ESB) phase reduced both the rate-limiting
steps resulting in much improved electrode performance. At 700 °C, composite electrodes containing 31.25–43.75 wt% ESB exhibited
an ASR of 0.08–0.11 Ωcm2. 相似文献
6.
The precipitation of the fcc γ-phase of iron has been studied by a systematic series of isothermal and isochronal (0–48 h)
heat treatments (300–800°C) on a supersaturated solution ofCuFe containing 3 at% Fe. The optimal conditions (450–600°C) for precipitation of the maximum fraction (90%) of iron attainable
within 48 h in the form of γ-Fe have been delineated from analysis of the room temperature spectra. The time dependence for
formation of γ-Fe precipitates is well described by the equation for long term annealing. An activation energyE
a
≈0.6 eV for the formation of γ-Fe in Cu is obtained. It indicates short range rather than long range diffusion in theCuFe sample studied. 相似文献
7.
In the temperature range 15–770°C, a correlation between the dielectric and structural specific features of lead cadmium tungstate
is established. When studying the structure of Pb2CdWO6 in the temperature range 15 ≤ T ≤ 770°C, the unit-cell parameters and atomic parameters of the orthorhombic phase with space group Pmc21 (15 ≤ T ≤ 380°C) and cubic phase with space group Fm3m (380 ≤ T ≤ 770°C) are determined. It is revealed that the antiferroelectric state observed in of Pb2CdWO6 in the orthorhombic phase is associated with antiparallel displacements of Pb atoms. In the cubic phase, the Cd atoms are
found to have disordered static displacements along [100]-type directions. 相似文献
8.
M. Miettinen M. Johansson S. Suvanto J. Riikonen U. Tapper T. T. Pakkanen V.-P. Lehto J. Jokiniemi A. Lähde 《Journal of nanoparticle research》2011,13(10):4631-4645
Silicon–carbon nanoceramics have been synthesised from hexamethyldisilane (HMDS) by the atmospheric pressure chemical vapour
synthesis (APCVS). Direct aerosol phase synthesis enables continuous production of high purity materials in one-stage process.
The particle formation is based on the decomposition of the precursor in a high temperature reactor. Reaction of the gas phase
species leads to homogeneous nucleation and formation of the nanoparticles with a narrow size distribution (geometric mean
diameter range of particle number size distribution 160–200 nm with 1.5–1.6 geometric standard deviation at reaction temperatures
800–1200 °C). A systematic investigation of the influence of the process temperature on the powder characteristics, including
the particle size, crystallinity, chemical structure, surface and bulk composition and surface morphology, was carried out.
At the reactor temperature of 800 °C, the synthesised nanoparticles were amorphous preceramics containing mostly SiC4, Si–CH2–Si and Si–H units. The composition of the powder turned towards nanocrystalline 3C–SiC (crystal size under 2 nm) when the
reaction temperature was increased to 1200 °C. The reaction temperature appeared to be a key parameter controlling the structure
and properties of the synthesised powders. 相似文献
9.
We study the thermal stability, local structure, and electrical properties of the α-MnO2 phase doped with Sn and Co. It is found that doping prevents the transformation from α-MnO2 to α-Mn2O3 that occurred in the temperature range of 500–600 °C. Samples have been synthesized in an acidic medium using the reduction
of potassium permanganate by fumaric acid. X-ray diffraction patterns (XRD) of pure and doped α-MnO2 prepared at 450 °C do not show new peaks related to dopant species. Thermogravimetric analysis (TGA) of the Sn and Co doped
MnO2 reveals that transformation from MnO2 to α-Mn2O3 starts above 700 °C. The increase in the thermal stability is attributed to the presence of Sn or Co ions incorporated inside
the large 2 × 2 tunnels as revealed by Fourier transform infrared (FTIR) spectra measurements. An increase in the electrical
conductivity with the presence of Sn or Co ions is observed. Electrochemical features of the doped MnO2 samples in alkaline cells are reported and compared with that of the pristine α-MnO2 phase. 相似文献
10.
This paper reports on the electrochemical properties and chemical stability of a recently developed Ca2+ and Sm3+-doped oxide ion conducting electrolyte, Ce0.85Ca0.05Sm0.1O1.9 (CCS), employed in an intermediate temperature solid oxide fuel cell (IT-SOFC) using conventional Sm0.5Sr0.5CoO3 (SSC) and La0.8Sr0.2MnO3 (LSM) cathodes in air at elevated temperatures. The materials were prepared by conventional solid-state reactions using their
corresponding metal oxides and salts in the temperature range of 1,200–1,450 °C in air. Powder X-ray diffraction (PXRD) and
impedance spectroscopy were employed for phase formation, chemical compatibility, and electrochemical characterization. PXRD
studies on 1:1 weight ratio of heat-treated (1,000 °C for 3 days) mixtures of SSC or LSM and CCS revealed the presence of
fluorite-type and perovskite-like phases. The area-specific resistance (ASR) value in air was lower for SSC cathodes (4.3–0.15 Ω
cm2) compared to those of LSM (407–11 Ω cm2) over the investigated temperature range of 600–800 °C. As expected, a significant increase in ASR was observed in Ar as
compared to air. 相似文献
11.
A study of the changes in the structure of melt-quenched Fe90Zr10 amorphous alloys by x-ray diffraction, Auger spectroscopy, and transmission electron microscopy is reported. The samples
were subjected to isochronous (for 1 h) and isothermal anneals at 100–650 °C. It is shown that an amorphous alloy annealed
for one hour at 300–500 °C crystallizes with formation of a supersaturated solid solution of Zr in α Fe and the intermetallic compound Fe3Zr. Isothermal anneal at 100 °C for up to 7000 h produces nanocrystallites 110–30 nm in size, with fuzzy interfaces between
the grains. An alloy subjected to such an anneal contains two solid solutions of Zr in Fe, having a cubic and a weakly tetragonal
lattice. Crystallization taking place during low-temperature anneals is preceded by phase segregation of the alloy within
the amorphous state. The lattice periods of the solid solutions have been determined. The possibility of the alloy crystallizing
by spinodal decomposition during prolonged annealing is discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 1769–1772 (October 1998) 相似文献
12.
Samson T. H. Silalahi Q. V. Vu H. Y. Yang K. Pita Yu Mingbin 《Applied Physics A: Materials Science & Processing》2010,98(4):867-871
Controllable size of silicon (Si) nanocrystals can be achieved by a two-step rapid thermal annealing technique consisting
of rapid annealing at 1000°C in nitrogen ambient and rapid oxidation at 600–800°C of a radio frequency magnetron co-sputtered
Si-rich oxide/SiO2 superlattice structure. The photoluminescence (PL) spectra related to Si nanocrystals were observed in the visible range
(600–900 nm). After rapid oxidation, the size of the nanocrystals was reduced and the quality of the Si nanocrystal/SiO2 interface was improved, resulting in a blue shift and an increase of the PL peak intensity. Finally, annealing in air increases
the PL intensity further. 相似文献
13.
The Ba(Ce0.8Zr0.2)0.95Yb0.05O2.975 ceramics electrolyte was prepared via a Pechini method using metal nitrate salts as starting materials. An optimum annealing
temperature of 1,400 °C was needed to obtain a pure perovskite-like phase with orthorhombic structure. Particle size distribution
showed a bimodal distribution that corresponds to the loose powders and agglomerates size. Scanning electron micrograph revealed
that the loose powders were in the nanosize range (70–200 nm). These ultrafine loose powders enhanced the densification of
a pellet with relative density ∼95% obtained at 1,400 °C. The sample formed clear and compact grains with submicron sizes.
Impedance results showed that the impedance semicircle of the grain was observed only at T ≤ 250 °C. The introduction of 20 mol% Zr improved the chemical stability of BaCe0.95Yb0.05O2.975 sample in atmosphere containing carbon dioxide at 600 °C. The sample also exhibited high proton conductivity in wet hydrogen. 相似文献
14.
The electrophysical properties and structure of the nonstoichiometric high-temperature superconductor YBa2Cu3O
y
restored at T = 930–950°C after low-temperature decomposition (T = 200°C) into phases different in the oxygen content have been studied. It has been shown that, unlike heat treatments at
T ≤ 900°C, the superconducting properties are almost completely restored for 3–5 h during grain recrystallization, which is
impossible at lower temperatures. After short-term annealing at T = 930–950°C (for 1–2 h), the ceramic material still contains a significant number of structural defects, most likely, in
cation sublattices. These defects can contribute to the pinning of magnetic vortices, which substantially increases the critical
current density in magnetic fields up to 2 T as compared to ceramic materials produced by the conventional technology. 相似文献
15.
Inorganic–organic hybrid membranes were prepared by sol–gel process with tetramethoxysilane/methyltrimethoxysilane/diisopropyl
phosphite and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid as precursors. The Fourier transform infrared spectroscopy (FT-IR) and 31P, 29Si, 1H, 13C, and 19F nuclear magnetic resonance measurements have shown good chemical stability and complexation of (POH[(CH3)2CHO]2) with [BMIMBF4] ionic liquid in the fabricated hybrid membranes. The influence of the textural properties of all the prepared composite
membranes could be interpreted from nitrogen adsorption–desorption measurements. The average pore size was increased proportionally
with the ionic liquid weight percent ratio in the host phosphosilicate matrix from 2.59 to 11.71 nm, respectively. Thermogravimetric
analysis and differential thermal analysis measurements confirmed that the hybrid membranes were thermally stable up to 260 °C.
Thermal stability of the hybrid membranes was significantly enhanced by the presence of inorganic SiO2 framework and high stability of [BF4] anion. For all the composite membranes, the conductivities were measured within the temperature range (−30 °C) to 150 °C,
and a maximum conductivity of 7 × 10−3 S/cm at 150 °C was achieved for 40 wt.% ionic liquid-based composite membrane under nonhumidified conditions. 相似文献
16.
A. V. Semirov D. A. Bukreev A. A. Moiseev V. A. Lukshina E. G. Volkova S. O. Volchkov G. V. Kurlyandskaya 《Technical Physics》2011,56(3):395-399
The temperature dependences of the magnetic properties and the magnetoimpedance effect of soft magnetic nanocrystalline Fe73.5Si16.5B6Nb3Cu1 alloy ribbons are studied in the temperature range 24–160°C. A high temperature sensitivity of the impedance and the magnetoimpedance
effect of the ribbons are detected in the ac frequency range 0.1–50 MHz. At an ac frequency of 50 MHz, the change in the impedance
reaches 0.2 Ω/°C (0.5%/°C) in the temperature range 85–160°C. When the temperature increases, a monotonically decreasing character
of the dependence of the magnetoimpedance effect on the applied magnetic field changes into a dependence having an increasing
initial segment. The effect of temperature on the magnetoimpedance properties of the soft magnetic nanocrystalline ribbons
is shown to result from temperature-induced changes in their electrical conductivity, magnetization, and effective magnetic
anisotropy. 相似文献
17.
Ning Han Haidi Liu Xiaofeng Wu Dongyan Li Linyu Chai Yunfa Chen 《Applied Physics A: Materials Science & Processing》2011,104(2):627-633
ZnO and Sn-, Ga- and Mn-doped ZnO nanoparticles were prepared by a coprecipitation method, and characterized by scanning electron
microscopy (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD) and Raman spectra. The gas sensing properties were
studied using formaldehyde, relative humidity, NH3, toluene and CO as the probes. The results show that all particles have wurtzite ZnO phase, though Sn–ZnO has a relatively
smaller particle (and crystallite) size than the other three samples. Gas sensing property tests reveal that the temperature
where the gas sensing maximum is gained (T
M) is changed by different dopants: Sn–ZnO and Mn–ZnO have relatively lower T
M (∼100°C lower) compared with that of pure ZnO, while Ga–ZnO has the same T
M as pure ZnO except in CO sensing. Thermoluminescence (TL) spectra were used to investigate the mechanism of T
M change. The peak positions of Ga–ZnO and ZnO are the same at 300–350°C, while that of Sn–ZnO shifts to 250–300°C, which might
contribute to the same T
M of Ga–ZnO and pure ZnO and relatively lower T
M of Sn–ZnO. In the case of Mn–ZnO, the luminescence emission is evidently limited by its black color. 相似文献
18.
L. Pintilie I. Pintilie D. Petre T. Botila M. Alexe 《Applied Physics A: Materials Science & Processing》1999,69(1):105-109
Thermally stimulated current (TSC) measurements performed in the 100 K–400 K temperature range on Bi4Ti3O12 (BiT) thin films annealed at 550 °C and 700 °C had revealed two trapping levels having activation energies of 0.55 eV and
0.6 eV. The total trap concentration was estimated at 1015 cm−3 for the samples annealed at 550 °C and 3×1015 cm−3 for a 700 °C annealing and the trap capture cross-section was estimated about 10−18 cm2. From the temperature dependence of the dark current in the temperature range 20 °C–120 °C the conduction mechanism activation
energy was found to be about 0.956–0.978 eV. The electrical conductivity depends not only on the sample annealing temperature
but also whether the measurement is performed in vacuum or air. The results on the dark conductivity are discussed considering
the influence of oxygen atoms and oxygen vacancies.
Received: 28 January 1998 / Accepted: 8 January 1999 / Published online: 5 May 1999 相似文献
19.
Jairo A. Cardona-Bedoya Alfredo Cruz-Orea Orlando Zelaya-Angel Julio G. Mendoza-Alvarez 《Journal of nanoparticle research》2008,10(3):519-523
GaNAs thin films were deposited on Corning glass substrates by radio frequency (r.f.) sputtering in molecular nitrogen ambient.
The stoichiometry in the GaNAs alloy was controlled by changing the nitrogen incorporation in the film during the growth process,
through the variation of the r.f. power in the range 30–80 watts which produced films with N concentrations in the range:
x = 0.85–0.90. The structural and optical properties of the GaNAs thin films were studied by X-ray diffraction (XRD), photoacoustic
(PA) and photoluminescence (PL) spectroscopies. XRD measurements show a broad diffraction band with a peak close to the (002)
diffraction line of the GaN hexagonal phase, and a slight shoulder at the position corresponding to the (111) GaAs cubic phase.
The PA absorption spectra showed a remarkable shift to higher energies of the absorption edge as the r.f. power decreases
corresponding to the films with higher N concentrations. Thermal annealing of the GaNAs films at temperatures of 450 °C produced
a GaAs nanocrystalline phase with grain sizes in the range 10–13 nm, as confirmed by the XRD measurements that showed a well-defined
peak in the (111) GaAs direction, and also by the PA spectra which showed an absorption band at energies around 1.45 eV due
to the quantum confinement effects. PL spectra of thermal-annealed GaNAs films showed a very intense emission at 1.5 eV which
we have associated to transitions between the first electron excited level and acceptor states in the GaAs nanocrystallites. 相似文献
20.
Sven C. Vogel Frank Stein Martin Palm 《Applied Physics A: Materials Science & Processing》2010,99(3):607-611
In the central part of the Fe–Al system between about 58 and 65 at.% Al, a high-temperature phase denoted as ε occurs with a hitherto unknown crystallographic structure. The phase is stable between 1231°C and 1095°C. In order to study the crystallographic structure of the ε phase, in situ high-temperature neutron time-of-flight diffraction experiments have been performed at the HIPPO instrument at the Los Alamos Neutron Science Center (LANSCE). The ε phase was found to have the formula Fe5Al8 with a body-centred cubic structure of the Hume–Rothery Cu5Zn8 type (I $\bar{4}3In the central part of the Fe–Al system between about 58 and 65 at.% Al, a high-temperature phase denoted as ε occurs with a hitherto unknown crystallographic structure. The phase is stable between 1231°C and 1095°C. In order to study
the crystallographic structure of the ε phase, in situ high-temperature neutron time-of-flight diffraction experiments have been performed at the HIPPO instrument
at the Los Alamos Neutron Science Center (LANSCE). The ε phase was found to have the formula Fe5Al8 with a body-centred cubic structure of the Hume–Rothery Cu5Zn8 type (I[`4]3\bar{4}3m (No. 217), Z=4, cI52) and 52 atoms in the unit cell. Its lattice parameter is a=8.9756(2) ? at 1120°C, which is 3.02 times that of cubic FeAl (B2) at the same temperature. We report here the evolution
of the crystallographic parameters over the temperature range between 1080°C and 1120°C. 相似文献