China
Africa
Explore chapters and articles related to this topic
Industrial minerals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Petalite LiAlSi4O10, castorite, is a lithium aluminium phyllosilicate mineral which has been found to crystallise in the monoclinic system. It belongs to the feldspathoid group and is found in the lithium-bearing pegmatites co-located with spodumene, lepidolite, tourmaline and as an important ore of lithium. If heated to about 500° C it under 3 Kbar of pressure in the presence of a dense hydrous alkali borosilicate fluid with a minor carbonate component [887] petalite converts to spodumene and quartz. Abuyelite Li2CO3 is another petalite in spodumene-hosted fluid inclusions.
Systems Based on InN
Published in Tomashyk Vasyl, Ternary Alloys Based on III-V Semiconductors, 2017
The second modification crystallizes in the monoclinic structure with the lattice parameters a = 680 ± 5, b = 1190 ± 5, and c = 697 ± 5 pm and β = 116.8 ± 0.2° (Goggin et al. 1966). In moist air, this modification is extremely deliquescent and hydrolyzed. It could be prepared by the following four methods:
BaTiO3 induced modification on the dielectric, ferroelectric and electrical conductivity properties of Pb(Fe0.5Nb0.5)O3-BaTiO3 solid solution
Published in Phase Transitions, 2022
Geetanjali Biswal, Krishnamayee Bhoi, Dillip K. Pradhan, Banarji Behera, Piyush R. Das
Single phase (1-x)PFN-xBT solid solutions were synthesized successfully using the method of solid-state reaction. The refined Rietveld XRD patterns revealed the monoclinic crystal structure with Cm space group for all samples. FESEM study confirmed the uniform distribution and well grain growth with an average grain size of ∼0.89–1.6 μm. The average grain size decreases with an increase in BT concentration. Dielectric measurements were performed with varying frequency and temperature. The temperature-dependent showed a broad diffuse phase transition and decreases as BT concentration increased. The frequency-dependent follows universal Johnscher’s power law. The Ea were estimated from the Arrhenius plots of temperature-dependent AC conductivity (). Existence of ferroelectric property was confirmed by P–E loops and it is observed that the polarization decreases with a rise in BT concentration. The future work is to study the magnetic and magneto-electric properties of (1−x)PFN-xBT solid solutions. Based upon this, we may propose the suitability of these materials for device applications such as magnetic field sensors and other multi-functional devices.
Dispersion and absorption study of SH waves in sinusoidally corrugated heterogeneous viscoelastic layer sandwiched between heterogeneous isotropic half-space and magnetoelastic monoclinic half-space
Published in Waves in Random and Complex Media, 2021
During an earthquake, the seismic waves generated propagate through the different structures of the Earth. These structures which are composed of different materials has a substantial amount of influence on the wave propagation. Monoclinic materials have been known to be found in good quantities below the Earth and have a sizeable amount of influence on wave propagation. Therefore, it becomes obligatory to study such materials which possess some remarkable characteristics and has a substantial amount of contribution to the wave propagation. Quartz, lithium tantalate and lithium niobate are good examples of monoclinic materials. Monoclinic materials are especially found to exist in sedimentary rocks such as sandstone and shale, carbonate rocks, gneiss, quartzite, and other metamorphic rocks. Some distinguishable works by authors on the monoclinic medium are Kalyani et al. [19], Chattopadhyay and Choudhury [20], Singh and Khurana [21], and Singh et al. [22].
Reflection and transmission of thermoelastic waves at the corrugated interface of crystalline structure
Published in Journal of Thermal Stresses, 2020
Pooja Singh, Abhishek Kumar Singh, Amares Chattopadhyay
Mathematical treatments of wave reflection and transmission phenomena are widely applied in seismology, earthquake engineering, geophysics, seismic exploration, and nondestructive evaluation. The study of these occurrences is of great importance because this provides the essential information about the Earth’s interior with the help of seismic waves. The velocities of seismic waves are greater in crystalline rocks than that of sedimentary rocks. Monoclinic crystals possess three unequal crystallographic axes, where two axes intersect one another at an oblique angle, and the third axis is perpendicular to the plane of the other two. An example of seismological interest is a structure with multiple systems of vertical cracks because the shallow crust is pervasively cracked; this form of anisotropy is probably extremely common, especially in the vicinity of fault zones. Monoclinic materials are among those materials which have numerous remarkable characteristics and are also present in the Earth’s crust as crystals or other materials. The monoclinic system is the largest equilibrium system with almost all raw materials belonging to one of its three classes. This motivates us to study the reflection and transmission phenomena of plane waves in monoclinic materials. Many authors have performed some unique works on monoclinic material. Chattopadhyay and Saha [15] attempted a problem of reflection and refraction of P waves at the interface of two monoclinic media. Paswan et al. [16] analyzed the reflection and transmission of plane waves through a fluid layer of finite thickness sandwiched between two distinct monoclinic substrates.