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Semi-precious stones
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Tourmaline is a crystalline boron silicate mineral that incorporates elements such as aluminium, iron, lithium, magnesium, potassium or sodium. It is a semi-precious stone which exhibits a wide variety of colours including dichroism, in that they change colour when viewed from different directions. Some tourmaline gems are altered by heat treatment or irradiation to improve their colour. Additionally, some heavily included tourmalines, such as rubellite, are sometimes clarity-enhanced [1007].
Measurement of underwater shockwave pressure characteristics by explosive energy and electric pulse power energy
Published in Kennis Chan, Testing and Measurement: Techniques and Applications, 2015
H. Sakamoto, Y. Watabe, S. Honda, Y. Ohbuchi
the same as propagation observation's one. A pressure sensor and an explosive are set in the support frame. The support frame is stored in the pressure container. In order to measure underwater shock wave pressure, one tourmaline sensor was used. When the tourmaline receives pressure, the voltage is generated by the piezoelectric effect. By measuring this voltage
Analogue systems and concepts
Published in Geoff Lewis, Communications Technology Handbook, 2013
When certain crystalline substances such as quartz, Rochelle salts or tourmaline are mechanically stressed, they produce electrical charges. Conversely, the application of an electric field produces mechanical strain. If this field is an alternating one, then the molecular structure will vibrate. If the frequency is adjusted it will be found that at some particular value, the vibration will reach a maximum amplitude. This phenomenon is known as the piezo (or pressure) electric effect which gives rise to a resonant characteristic. Frequency controlling elements are cut in slab form to accurate dimensions from the parent crystal and then highly polished.
Photocatalytic mechanism of tourmaline/BiVO4 composites with different ratios
Published in Inorganic and Nano-Metal Chemistry, 2020
Shuyan Qi, Yadong Zhao, Ninglong Ma, Huanyan Xu
Tourmaline is a kind of natural nonmetallic ore with electrode property.[16] Specially, the tourmaline can release negative ions,[17] which has the advantages of piezoelectricity, infrared radiation and so on. At present, brightly colored tourmaline is used as a gemstone mineral, and the component of some technological equiptments. However, many tourmalines are not very ornamental, which are regarded as mine waste and have not been properly developed and utilized.[18] The spontaneous polarization characteristic of tourmaline is the most widely application. The film of tourmaline and TiO2 can effectively reduce the forbidden band width of TiO2. Moreover, the spontaneous polarization characteristics of tourmaline can effectively separate the TiO2 electron-hole pairs, reducing the recombination ratio, and finally improving the photocatalytic effect of TiO2[19] in this work, in order to solve the high ratio recombination of electrons and holes tourmaline/BiVO4 with different ratios were prepared by sol-gel method, and the effect of different tourmaline incorporation on the photocatalytic mechanism of BiVO4 was observed.