A Microscopy and FTIR and PL Spectra Study of Polycrystalline Diamonds from Mengyin Kimberlite Pipes

The results of a microscopy and FTIR and PL spectra study of the natural polycrystalline diamonds from the Mengyin kimberlite pipes show that they can be classified as the euhedral faceted polycrystalline diamonds (EFPCDs) and anhedral rounded polycrystalline diamonds (ARPCDs). Different diamond grains or their points were formed in different conditions or processes. They were not formed in diamond nucleation stage, but in the diamond growth period. They probably originated from the relatively deeper mantle and were formed in the environment like the peridotitic (P) type diamond single crystals. The EFPCDs did not undergo a remarkable dissolution process during their formation and were possibly fast formed shortly before the kimberlite eruption. The ARPCDs not only were formed at a higher temperature than the EFPCDs but also underwent a notable dissolution process and had been stored relatively longer in the mantle. Fluids or melts probably participated in the formation of the ARPCDs or modified them during the period of their storage in the mantle.

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Diamond growth in mantle fluids

Lithos ◽

10.1016/j.lithos.2016.10.004 ◽

2016 ◽

Vol 265 ◽

pp. 4-15 ◽

Cited By ~ 9

Author(s):

Hélène Bureau ◽

Daniel J. Frost ◽

Nathalie Bolfan-Casanova ◽

Clémence Leroy ◽

Imène Esteve ◽

...

Keyword(s):

Diamond Growth ◽

Mantle Fluids

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Diamond Nucleation Studies on Refractory Metals and Nickel

MRS Proceedings ◽

10.1557/proc-339-291 ◽

1994 ◽

Vol 339 ◽

Author(s):

S. D. Wolter ◽

B. R. Stoner ◽

P. C. Yang ◽

W. Lui ◽

J. T. Glass

Keyword(s):

High Temperature ◽

Initial Data ◽

Refractory Metal ◽

Hydrogen Absorption ◽

Substrate Material ◽

Diamond Growth ◽

Relative Importance ◽

Lattice Match ◽

Diamond Nucleation ◽

Temperature Pretreatment

ABSTRACTDiamond nucleation has been investigated on a variety of potential heteroepitaxial substrate materials. Previous work in this laboratory has demonstrated heteroepitaxial nucleation on both Si and SiC substrates via bias-enhanced nucleation (BEN). In this study the effects of BEN of diamond on refractory metal substrates is investigated in detail. Initial data suggest a strong correlation between the carbide forming nature of the substrate material and the rate of nucleation during biasing. Our second avenue of research involves low pressure diamond growth on nickel. This material is a promising material due to its close lattice match and recent evidence of epitaxy reported by other researchers. To form heteroepitaxial diamond on nickel a high temperature pretreatment routine has been established and is the basis for this area of research. The relative importance of hydrogen absorption during this routine is explored and correlated to the formation and degree of diamond epitaxy.

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P-type CuInSe2 thin films prepared by selenization of one-step electrodeposited precursors

Journal of Materials Research ◽

10.1557/jmr.2009.0261 ◽

2009 ◽

Vol 24 (7) ◽

pp. 2293-2300 ◽

Cited By ~ 5

Author(s):

Lei Wan ◽

Yongsheng Cao ◽

Deliang Wang

Keyword(s):

Film Surface ◽

Atomic Ratio ◽

Flux Agent ◽

Solar Cell Application ◽

Element Transport ◽

Good Crystalline Quality ◽

One Step ◽

Higher Temperature ◽

P Type ◽

Selenization Temperature

In this study, p-type CuInSe2 (CIS) films were prepared by selenization of one-step electrodeposited Cu-In-2Se (atomic ratio) precursors. To obtain high-quality, dense, and homogeneous CIS films for solar cell application, the effects of substrate temperatures during selenization and precursor compositions on the final microstructures were systematically investigated. The precursor layers evolved in very different ways under different selenization conditions. The final microstructures and phases of the films depended critically on the precursor compositions, selenization temperature, and the selenization thermal process history. Low melting temperature CuxSe phase, which tended to segregate at the film surface, can efficiently assist the CIS grain growth. Large hexagonal CuSe platelets were formed at a temperature as low as 170 °C in Cu-rich precursor, which acted as an element-transport flux agent at higher temperature under high Se vapor and reacted with In-Se selenide to form CIS at temperatures above 500 °C. Good crystalline quality chalcopyrite CIS film was obtained at a selenization temperature of 550 °C.

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Variation in Morphological and Quality Parameters in Garlic (Allium sativum L.) Bulb Influenced by Different Photoperiod, Temperature, Sowing and Harvesting Time

Plants ◽

10.3390/plants9020155 ◽

2020 ◽

Vol 9 (2) ◽

pp. 155 ◽

Cited By ~ 4

Author(s):

Muhammad Jawaad Atif ◽

Bakht Amin ◽

Muhammad Imran Ghani ◽

Muhammad Ali ◽

Zhihui Cheng

Keyword(s):

Abiotic Factors ◽

Soluble Sugar ◽

Growth Period ◽

Sowing Date ◽

Quality Parameters ◽

Plant Age ◽

Bulb Formation ◽

Garlic Bulb ◽

Soluble Solid ◽

Higher Temperature

Photoperiod (light) and temperature as abiotic factors having significant impact on the garlic bulb morphology and quality. In various bulb plants including garlic, bulbing is affected by photoperiod, temperature, sowing date and the plant age. In this backdrop experiments were performed to understand the effect of different photoperiods (10 h/14 h, 12 h/12 h and 14 h/10 h (light/dark)), temperatures (25 °C/18 °C and 30 °C/20 °C (light/dark)), sowing dates (D0801: 1st August, D0901: 1st September and D1001: 1st October) and plant ages (A80, A60 and A40: 80, 60 and 40 days after planting) on garlic cultivars viz; G103, G024 and G2011-5. Parameters including morphological (plant height, fresh weight and pseudostem diameter), bulb attributes (diameter, weight, height and bulbing index), growth period and bulb quality related traits (total soluble solid (TSS), contents of soluble protein, soluble sugar, total sugar, glucose, sucrose, fructose, starch, total phenol and total flavonoid) were assayed. Longer photoperiod (14 h), higher temperature (30 °C), early sowing (D0801) and maximum plant age (A80) had maximum morphological and bulb quality related traits for cv. G103. These results showed that early sowing, maximum plant age, longer photoperiod and higher temperature are important for garlic bulb formation and quality. Moreover, the regulation of garlic bulb morphology and quality is achievable over the switch of sowing date, plant age, light and growth temperature.

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The Origin of Mis-Oriented Diamond Grains Nucleated Directly on (001) Silicon Surface

MRS Proceedings ◽

10.1557/proc-529-139 ◽

1998 ◽

Vol 529 ◽

Cited By ~ 1

Author(s):

R.Q. Zhang ◽

W.J. Zhang ◽

C. Sun ◽

X. Jiang ◽

S.-T. Lee

Keyword(s):

Grain Orientation ◽

Silicon Surface ◽

Diamond Films ◽

Orientation Distribution ◽

Interface Structure ◽

Silicon Surfaces ◽

Diamond Growth ◽

Diamond Nucleation ◽

Interfacial Structures ◽

Zero Degree

AbstractThe origin of mis-oriented diamond grains frequently observed in heteroepitaxial diamond films on (001) silicon surfaces was studied. By statistically analyzing the in-plane rotation angles of diamond grains in scanning electron microscopy observations, it was found that the distribution of the grain orientation is not random and two satellite distribution peaks at about 20° and 30° accompany the main distribution peak at zero degree referenced to the <110> direction of substrate. The interface structure corresponding to the main distribution peak at zero degree of oriented diamond growth has been proposed in our previous studies. In this study, our molecular orbital PM3 simulation of a step-by-step diamond nucleation further reveals two other metastable diamond/silicon interfacial structures. The orientations of the corresponding diamond grains are parallel to the (001) silicon surface but with in-plane rotations of 20° and 30° respectively with respect to the <110> direction. We relate these two mis-oriented growths to the two satellite peaks of grain orientation distribution. Based on this study, the possibility in experiment to reduce the formation of mis-oriented configurations and to obtain a perfectly oriented diamond growth is discussed.

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Diamond-coated carbon fiber

Journal of Materials Research ◽

10.1557/jmr.1994.0636 ◽

1994 ◽

Vol 9 (3) ◽

pp. 636-642 ◽

Cited By ~ 26

Author(s):

J. Ting ◽

M.L. Lake

Keyword(s):

Carbon Fiber ◽

Microwave Plasma ◽

Diamond Growth ◽

Gas Mixture ◽

Diamond Formation ◽

Diamond Deposition ◽

Diamond Nucleation ◽

Pan Fiber ◽

Coated Carbon ◽

Pan Fibers

Diamond deposition was attempted on polyacrylonitrile (PAN) fiber and vapor grown carbon fiber (VGCF). PAN fibers were severely etched in a microwave plasma, whereas diamond was successfully deposited on VGCF. A diamond growth rate of 0.1 μm/h on VGCF was determined at a gas mixture of 99.9 sccm H2/0.1 sccm CH4 and a pressure of 30 Torr. It is proposed that diamond formation on VGCF occurs on not only the prism planes, but also the basal planes owing to the unique structure of VGCF. An explanation is proposed to explain diamond nucleation on the basal planes.

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Thermoelectric Properties of Co1-xNbxSb3 Prepared by Induction Melting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.486-487.602 ◽

2005 ◽

Vol 486-487 ◽

pp. 602-605 ◽

Cited By ~ 1

Author(s):

J.B. Park ◽

S.-W. You ◽

K.W. Cho ◽

J.I. Lee ◽

Soon Chul Ur ◽

...

Keyword(s):

Electrical Conductivity ◽

Thermoelectric Properties ◽

Induction Melting ◽

Thermoelectric Power Factor ◽

Seebeck Coefficients ◽

Maximum Value ◽

High Temperature Maximum ◽

Higher Temperature ◽

Nb Doping ◽

P Type

Induction melting was attempted to prepare the undoped and Nb-doped CoSb3 compounds, and their thermoelectric properties were investigated. Single phase d-CoSb3 was successfully obtained by induction melting and subsequent annealing at 400°C for 2 hours in vacuum. The positive signs of Seebeck coefficients for all the specimens revealed that Nb atoms acted as p-type dopants by substituting Co atoms. Electrical conductivity decreased and then increased withincreasing temperature, indicating mixed behaviors of metallic and semiconducting conductions. Electrical conductivity increased by Nb doping, and it was saturated at high temperature. Maximum value of the thermoelectric power factor was shifted to higher temperature with the increasing amount of Nb doping, mainly originated from the Seebeck coefficient variation.

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Synthesis of diamond films on Hastelloy

Journal of Materials Research ◽

10.1557/jmr.1992.2785 ◽

1992 ◽

Vol 7 (10) ◽

pp. 2785-2790 ◽

Cited By ~ 16

Author(s):

V.P. Godbole ◽

J. Narayan

Keyword(s):

Diamond Film ◽

Composite Layer ◽

Chemical Vapor ◽

Polycrystalline Diamond ◽

Diamond Growth ◽

Chemical Vapor Deposition Method ◽

Nucleation Sites ◽

Higher Temperature ◽

Lower Temperature ◽

Hot Filament

We have developed a two-step hot filament chemical vapor deposition method to form polycrystalline films of diamond on Hastelloy substrates. The first step at a lower temperature results in the deposition of a composite layer of carbon, diamond-like carbon, and diamond, which provide nucleation sites for diamond growth in the second step at a higher temperature. To obtain a cleaner amorphous carbon-free diamond film, we introduced an intermediate hydrogen etching step. Using this procedure, we have obtained high quality polycrystalline diamond film on Hastelloy substrates, as characterized by scanning electron microscopy and Raman measurements.

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Diamond growth on carbide surfaces using a selective etching technique

Journal of Materials Research ◽

10.1557/jmr.1994.2154 ◽

1994 ◽

Vol 9 (8) ◽

pp. 2154-2163 ◽

Cited By ~ 22

Author(s):

K.J. Grannen ◽

R.P.H. Chang

Keyword(s):

Vapor Deposition ◽

Microwave Plasma ◽

Diamond Films ◽

Chemical Vapor ◽

Diamond Powder ◽

Nucleation And Growth ◽

Diamond Growth ◽

Etching Technique ◽

Diamond Nucleation ◽

Nucleation And Growth Mechanism

Microwave plasma-enhanced chemical vapor deposition of diamond films on silicon carbide and tungsten carbide (with 6% cobalt) surfaces using fluorocarbon gases has been demonstrated. No diamond powder pretreatment is necessary to grow these films with a (100) faceted surface morphology. The diamond films are characterized by scanning electron microscopy and Raman spectroscopy. The proposed nucleation and growth mechanism involves etching of the noncarbon component of the carbide by atomic fluorine to expose surface carbon atoms and diamond nucleation and growth on these exposed carbon atoms. Hydrogen is necessary in the growth process to limit the rapid etching of the carbide substrates by corrosive fluorine atoms.

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H-Terminated Diamond Surface Band Bending Characterization by Angle-Resolved XPS

Surfaces ◽

10.3390/surfaces3010007 ◽

2020 ◽

Vol 3 (1) ◽

pp. 61-71 ◽

Cited By ~ 1

Author(s):

Gonzalo Alba ◽

David Eon ◽

M. Pilar Villar ◽

Rodrigo Alcántara ◽

Gauthier Chicot ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Chemical Vapour ◽

Diamond Surface ◽

Diamond Growth ◽

Surface Band ◽

Band Bending ◽

New Approach ◽

Shallow Acceptors ◽

New Interpretation ◽

P Type

Concerning diamond-based electronic devices, the H-terminated diamond surface is one of the most used terminations as it can be obtained directly by using H2 plasma, which also is a key step for diamond growth by chemical vapour deposition (CVD). The resultant surfaces present a p-type surface conductive layer with interest in power electronic applications. However, the mechanism for this behavior is still under discussion. Upward band bending due to surface transfer doping is the most accepted model, but has not been experimentally probed as of yet. Recently, a downward band bending very near the surface due to shallow acceptors has been proposed to coexist with surface transfer doping, explaining most of the observed phenomena. In this work, a new approach to the measurement of band bending by angle-resolved X-ray photoelectron spectroscopy (ARXPS) is proposed. Based on this new interpretation, a downward band bending of 0.67 eV extended over 0.5 nm was evidenced on a (100) H-terminated diamond surface.

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