Ultrasonic Spectroscopy of Silicon Single Crystal

Sedlák, Petr; Tofel, Pavel; Sedláková, Vlasta; Majzner, Jiří; Šikula, Josef; Hasse, L.

doi:10.2478/v10178-011-0059-3

Cited by 3 publications

(4 citation statements)

References 4 publications

(5 reference statements)

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“…These methods are performed at Gdansk University of Technology [1][2][3][4][5]. The electro-ultrasonic spectroscopy (EUS) is also the method of NDT type [6][7][8][9][10]. The influence of the electro-ultrasonic signal with low frequency range of ultrasonic signal on specimen is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

Tofel

Škarvada

Šikula

et al. 2013

KEM

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Each material contains defects and in-homogeneities in a structure volume. It has influence on the properties of material (conductivity, mass density, mechanical properties). Interaction of the ultrasonic waves with defects or in-homogeneities in the solid state is not clear. Electro-ultrasonic spectroscopy can help to clarify this phenomenon. The electro-ultrasonic spectroscopy describes defects and un-homogeneities inside the sample structure. This method is quite different from electro-acoustic effect. Ultrasonic signal is in range from 20 kHz to 150 kHz. Ultrasonic signal changes geometry of the sample in elastic range only. The sizes of cracks are changing also in the sample volume. Conductivity near the area of cracks is strongly changing due to ultrasonic vibrations. It has influence on resistance of the sample which is changing along with a frequency of ultrasonic vibrations. The amplitude of the resistance change depends on the material, number of cracks, size of cracks and Eigen frequencies of the sample excited by ultrasonic wave. We applied the electro-ultrasonic spectroscopy on two types of varistors. It can be useful for understanding the relation between microstructure and mechanical properties of these types of varistors.

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Section: Introductionmentioning

confidence: 99%

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

Tofel

Škarvada

Šikula

et al. 2013

KEM

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“…: bismuth, cobalt, manganese) -in the ZnO mixed powder [1][2][3][4]. The composed material is usually cylindrically shaped in a press and fired later at high temperature (Fig.…”

Section: Varistor Structuresmentioning

confidence: 99%

“…Some of the methods are used in different production stages [1][2][3], other during exploitation [4,5] or in a laboratory only [6] but still there are no universal methods which could be applied for cheap and widespread varistor quality monitoring in their work. The pros and cons of these methods as well as their further development will be described.…”

Section: Introductionmentioning

confidence: 99%

Problems of Varistor Quality Assessment During Exploitation

Smulko¹,

Olesz²,

Hasse³

et al. 2012

Metrology and Measurement Systems

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Varistors are commonly used elements which protect power supply networks against high-voltage surges or lightning. Therefore, quality and endurance of these elements is important to avoid losses when an expensive laboratory equipment would not be protected from random overvoltages. Additionally, excessive leakage currents generate serious costs due to high energy consumption. The paper presents shortly properties of varistors that comprized different ZnO grain types and can have various quality which changes continuously during exploitation (due to exposition to overheating and overvoltage pulses). Therefore, it is important to monitor varistors during their ageing (causing changes within their microstructures). A few methods of varistor property diagnosis were considered and compared with the methods currently applied in laboratory or industry applications. A new measurement (diagnostic) system that can monitor varistors during ageing and can be widely applied in power networks is presented. The proposed system fulfills requirements of the industrial customers which demand various methods for power line protection. The proposed system can be simply developed into a more advanced wireless diagnostic system of long power supply lines.

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“…Analyses of electron transport parameters are the most promising methods which provide non-destructive evaluation. Experiments are based on the measurements of device I-V characteristics [7], I-V characteristic nonlinearity using the non-linearity index (NLI) [8,9], electronic noise spectroscopy [10 -12], and electro-ultrasonic spectroscopy [13].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Noise and Non-Linearity of I-V Characteristics of Positive Temperature Coefficient Chip Thermistors

Sita¹,

Sedláková²,

Majzner³

et al. 2013

Metrology and Measurement Systems

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Noise spectroscopy and I-V characteristic non-linearity measurement were applied as diagnostic tools in order to characterize the volume and contact quality of positive temperature coefficient (PTC) chip sensors and to predict possible contact failure. Correctly made and stable contacts are crucial for proper sensing. I-V characteristics and time dependences of resistance were measured for studied sensors and, besides the samples with stable resistance value, spike type resistance fluctuation was observed for some samples. These spikes often disappear after about 24 hours of voltage application. Linear I-V characteristics were measured for the samples with stable resistance. The resistance fluctuation of burst noise type was observed for some samples showing the I-V characteristic dependent on the electric field orientation. We have found that the thermistors with high quality contacts had a linear I-V characteristic, the noise spectral density is of 1/f type and the third harmonic index is lower than 60 dB. The samples with poor quality contacts show non-linear I-V characteristics and excess noise is given by superposition of g-r and 1/f n type noises, and the third harmonic index is higher than 60 dB.

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Ultrasonic Spectroscopy of Silicon Single Crystal

Cited by 3 publications

References 4 publications

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

Problems of Varistor Quality Assessment During Exploitation

Analysis of Noise and Non-Linearity of I-V Characteristics of Positive Temperature Coefficient Chip Thermistors

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