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Systems Based on GaP
Published in Vasyl Tomashyk, Quaternary Alloys Based on III-V Semiconductors, 2018
GaPO4·2H2O exists in two polymorphic modifications. First modification crystallizes in the monoclinic structure with the lattice parameters a = 977 ± 1, b = 964 ± 1, c = 968 ± 1 pm, and β = 102.7 ± 0.2° and the calculated and experimental densities of 2.998 and 3.00 g·cm−3, respectively (Mooney-Slater 1966). The crystals of this modification were obtained by the very slow dilution or neutralization of an acid solution of the gallium phosphate held at moderately elevated temperatures.
Self-Limiting Two-Dimensional Surface Oxides of Liquid Metals
Published in Mohammad Karbalaei Akbari, Serge Zhuiykov, Ultrathin Two-Dimensional Semiconductors for Novel Electronic Applications, 2020
Mohammad Karbalaei Akbari, Serge Zhuiykov
Gallium phosphate is a semiconductor material with trigonal structure with the cell parameters of a = 4.87 Å, c = 11.05 Å, and γ = 120° (Figure 3.11 a, b) [51]. The high-temperature thermal stability of gallium phosphate (up to 930°C) placed this semiconductor material in an outstanding technical position compared with the similar materials like α-quartz. It was found that the GaPO4 has recognizable piezoelectric properties. The piezoelectricity facilitates the mutual conversion of electrical energy or pulses to mechanical forces or oscillations. The advent of 2D materials with piezoelectric characteristics is highly interesting since it opens up new opportunities for development of miniature power and electric instruments. In these devices the atomic scale mechanical displacement, vibration and bending can be turned into electrical pulses and then facilitate the harvesting of kinetic energies of oscillation of piezoelectric materials. The loss of centrosymmetry is the main structural specifications of 2D materials with piezoelectric properties [51]. The doped graphene, h-BN and many transition metal chalcogenides (TMDCs) with odd numbers of layers are capable of showing piezoelectric properties. These theoretical investigations also confirmed the piezoelectric characteristics of transition metal oxides, aluminum nitride, GeS, and SnSe2. Most of the piezoelectric functions of 2D materials are observed at the low temperatures [52–57]. The stable piezoelectric performance of 2D materials at the high temperatures now is highly required for technical applications, since the performance of 2D piezoelectric materials are failed due to the structural changes at the high working temperatures. Furthermore, the ultra-uniform deposition of homogenous 2D piezoelectric materials over the large-area substrates is highly challenging. Thus, this field requires a tremendous attention for further technological developments.
Optimisation of Rayleigh wave Laser-EMAT with the application of surface constraint mechanism
Published in Nondestructive Testing and Evaluation, 2023
Pan He, Wenze Shi, Chao Lu, Guo Chen, Yao Chen, Ying Zhu, Yuan Liu
High-temperature ultrasonic testing technologies include piezoelectric ultrasonic testing, air-coupled ultrasonic testing, electromagnetic ultrasonic testing, laser ultrasonic testing, etc. Even if the piezoelectric transducer uses a high-temperature resistant probe or a piezoelectric crystal made of high melting point materials such as bismuth titanate (Bi4Ti3O12), lithium niobate (LiNbO3) or gallium phosphate (GaPO4), it still cannot realise continuous on-line detection and monitoring under high-temperature environment above 500°C [5,6]. Piezoelectric ultrasonic probes require a coupling agent for acoustic impedance matching. However, finding a coupling agent that can sustain high-temperature resistance for long-term monitoring during high-temperature detection is difficult. Air-coupled ultrasound mainly operates in the through-transmission ultrasonic inspection, which is suitable for composite materials, wood, ceramics, and other loose and multi-vacancy materials and is difficult to be applied to metal materials with high acoustic impedance [7,8]. Compared with piezoelectric and air-coupled ultrasounds, non-contact detection techniques such as electromagnetic acoustic transducer (EMAT) and laser ultrasonic do not require coupling agents and have low requirements for surface roughness of the tested metal. Therefore, it is more suitable for non-destructive testing in harsh environments such as high-temperature, rapid and on-line detection [9,10].
Nanoparticle concentrations and composition in a dental office and dental laboratory: A pilot study on the influence of working procedures
Published in Journal of Occupational and Environmental Hygiene, 2018
Andreja Lang, Maja Ovsenik, Ivan Verdenik, Maja Remškar, Čedomir Oblak
The electron microscopic analysis of filters 1 and 3 with the particles collected in the clean part of the dental laboratory confirmed that it is the working procedures and the materials that caused high concentrations of nanoparticles in the working atmosphere. We performed an X-ray dispersive analysis of a selected area of the filters with several particles. We found silicon (SiO2 is a component of dental ceramics), phosphorus (gallium phosphate), aluminum (aluminum silicate is a component of dental ceramics and aluminum oxide is a material used in sandblasting), iron, and zinc (enter Stellite dental alloys).