Mineralogical characterization of manganese oxide minerals of the Devonian Xialei manganese deposit

The Guangxi Zhuang Autonomous Region is an important manganese ore district in Southwest China, with manganese ore resource reserves accounting for 23% of the total manganese ore resource reserves in China. The Xialei manganese deposit (Daxin County, Guangxi) is the first super-large manganese deposit discovered in China. The Mn oxide in the supergene oxidation zone of the Xialei deposit was characterized using scanning electron microscopy (SEM), energy spectrometer (EDS), transmission electron microscopy (TEM, HRTEM), and X-ray diffraction analysis (XRD). The Mn oxides have a gray-black/steel-gray color, a semi-metallic-earthy luster, and appear as oolitic, pisolitic, banded, massive, and cellular textures. Scanning electron microscopy images show that the manganese oxide minerals are present as fine-spherical particles with an earthy surface. TEM and HRTEM indicate the presence of oriented bundled and staggered nanorods, and nanopores between the crystals. The Mn oxide ore can be classified into two textural types: (1) oolitic and pisolitic (often with annuli) Mn oxide, and (2) massive Mn oxide. Pyrolusite, cryptomelane, and hollandite are the main Mn oxide minerals. The potassium contents of cryptomelane and pyrolusite are discussed. The unit cell parameters of pyrolusite are refined

A Vertically-Aligned Lcos With Submillisecond Response Time

We demonstrated a TFT-grade fluorinated, UV-stable, high birefringence and low viscosity negative Δε LC mixture and characterized its physical properties. With this mixture in a thin-cell-gap LCOS, we can achieve submillisecond response time at an elevated temperature, which enables color sequential projection displays without noticeable color breakup. © 2013 Society for Information Display

A Vertically-Aligned LCOS with Submillisecond Response Time

Abstract We demonstrated a TFT-grade fluorinated，UV-stable, high birefringence and low viscosity negative Δε LC mixture and characterized its physical properties. With this mixture in a thincell-gap LCOS, we can achieve submillisecond response time at an elevated temperature, which enables color sequential projection displays without noticeable color breakup

Submillisecond-Response Polymer Network Liquid Crystal Phase Modulators

A submillisecond-response and light scattering-free polymer-network liquid crystal (PNLC) for infrared spatial light modulators is demonstrated. Our new liquid crystal host exhibits a higher birefringence, comparable dielectric anisotropy, and slightly lower visco-elastic constant than a commonly employed commercial material, HTG-135200. Moreover, the electro-optical performance of our PNLCs with different monomer concentrations, cell gaps, and liquid crystal (LC) hosts is compared and discussed from four aspects: operating voltage, hysteresis, relaxation time, and light scattering loss. The temperature effect on hysteresis is also analyzed. Potential applications of PNLCs for laser beam steering and spatial light modulators especially in the infrared region are foreseeable

The Application of EPMA in the Textural Characterization of Cryptomelane in the Xialei Manganese Deposit, Southwest Guangxi

BACKGROUND: OMS-2 has shown great significance in ion exchange, catalyst, energy and environment, but the research of natural OMS-2 mineral material cryptomelane is still lacking in the detailed characterization of the composition, structure and genetic research. Annulus and core-rim structures are representative in the structure of manganese oxide minerals. It is of great significance to clarify the mineral species and explore its composition characteristics, its origin and develop the application of manganese oxides. The Mn ore resource of Guangxi account for 23% of the manganese ore resource reserves in China. The Xialei Mn deposit located in Southwest Guangxi is the earliest super-large Mn deposit discovered in China, with an average grade of about 30% for the manganese oxide ore. OBJECTIVES: To explore the annulus and core-rim texture and its composition of cryptomelane in the Xialei Mn deposit.METHODS: Quantitative analysis and element mapping of EPMA and microscopy were carried out.RESULTS: The element intensity of the cryptomelane with annulus texture was Mn, K, Mg, Al, Zn, Ba, P, Fe in order of average from strong to weak. The average element intensity of the cryptomelane with core-rim texture was Mn, K, Ca, Mg, Zn, Ba, P, Fe from strong to weak. The K content gradually increased (2.31%-4.17%, 0.38-0.62 atoms per formula unit) from the middle to the rim of the cryptomelane, indicating K enrichment during oxidization and the stable status of Mn oxides.CONCLUSIONS: The change in the trend of K and Mn ions is the direct cause of the formation of the annulus and core-rim texture, reflecting the changes of oxidation environment. Potassium content gradually increases from the inner to outer zone, which may indicate the enrichment of potassium during the oxidation process, and also reflects manganese oxide gradually tending to the most stable state

Manganese Oxide Minerals from the Xiangtan Manganese Deposit in South China and Their Application in Formaldehyde Removal

Because of the nano-scale tunnel constructed by the active Mn-O octahedron in cryptomelane, cryptomelane-type manganese oxides have high activity in the oxidation of several volatile organic compounds (VOCs). Natural cryptomelane, in the form of supergene oxide manganese ore, carpets much of South China. In the lower part of the Datangpo Formation of Nanhua System on the southeastern Yangtze Platform, cryptomelane is one of the major manganese oxides in black shale of the Xiangtan manganese deposit in this deposit. Formaldehyde is a dominant indoor pollutant among volatile organic compounds (VOCs), and applications of synthetic cryptomelane have been reported to eliminate it. To study the removal capacity of naturally outcropping cryptomelane, representative samples of manganese oxide (the primary mineral component of cryptomelane) from the Xiangtan Mn deposit were analyzed in this study. The chemical composition, crystal structure and micromorphology of the manganese oxide minerals were explored using ICP-AES, XRD, EPMA, SEM and HR-TEM techniques. Fine-grained and poorly crystalline, these minerals consist primarily of cryptomelane, along with minor amounts of pyrolusite, hollandite, lithiophorite, limonite and quartz. Natural cryptomelane is a monoclinic crystal, and its cell parameters are refined. The results of catalytic tests revealed that natural cryptomelane has obvious catalytic activity in the oxidation of formaldehyde in a static environment under room temperature. This study may provide a natural mineral material as an inexpensive and efficient catalyst for the purification of formaldehyde in industrial or indoor air treatment