scholarly journals The mineralogy and structure of use-wear polish on chert

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Patrick Schmidt ◽  
Alice Rodriguez ◽  
Kaushik Yanamandra ◽  
Rakesh K. Behera ◽  
Radu Iovita
Keyword(s):  
Infrared Spectroscopy ◽  
Amorphous Film ◽  
Amorphous Layer ◽  
Stone Tools ◽  
Surface Structures ◽  
Physical Processes ◽  
Amorphous Films ◽  
Use Wear ◽  
Competing Hypotheses ◽  
Amorphous Surface

AbstractPolished edges of archaeological stone tools are commonly investigated to obtain information on the tools’ uses in prehistory. Yet to this day, it remains unclear what exactly such polishes are and how they form. Answering these questions should allow the elaboration of new interpretative methods based on objective measurements. Two major competing hypotheses of polish formation have been proposed: abrasion and the formation of a thin amorphous film on the chert or flint surface. We employ reflectance infrared spectroscopy, a technique particularly sensitive to thin amorphous films, to investigate these two hypotheses. We found no added amorphous layer that would have formed upon friction against bone, antler, ivory or wood. Our observations suggest polish formation by abrasion, notwithstanding previous claims of added amorphous surface structures. This has implications for our understanding of the physical processes taking place during friction of chert and flint against different materials. Our results also open the possibility to propose new pathways for identifying different use-wear processes, based on the degree of abrasion.

Interface motion during recrystallization of amorphous NiSi2

1990 ◽  
Vol 48 (4) ◽  
pp. 524-525
Author(s):  
J. L. Batstone ◽  
D.A. Smith
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Amorphous Film ◽  
Nucleation And Growth ◽  
Recrystallization Process ◽  
Amorphous Films ◽  
Interface Motion ◽  
Si Substrates ◽  
Spherical Caps ◽  
Crystal Interfaces

Recrystallization of amorphous NiSi2 involves nucleation and growth processes which can be studied dynamically in the electron microscope. Previous studies have shown thatCoSi2 recrystallises by nucleating spherical caps which then grow with a constant radial velocity. Coalescence results in the formation of hyperbolic grain boundaries. Nucleation of the isostructural NiSi2 results in small, approximately round grains with very rough amorphous/crystal interfaces. In this paper we show that the morphology of the rccrystallizcd film is dramatically affected by variations in the stoichiometry of the amorphous film.Thin films of NiSi2 were prepared by c-bcam deposition of Ni and Si onto Si3N4, windows supported by Si substrates at room temperature. The base pressure prior to deposition was 6 × 107 torr. In order to investigate the effect of stoichiomctry on the recrystallization process, the Ni/Si ratio was varied in the range NiSi1.8-2.4. The composition of the amorphous films was determined by Rutherford Backscattering.

scholarly journals Dual Electrochemical Treatments to Improve Properties of Ti6Al4V Alloy

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2479
Author(s):  
Stefano Rossi ◽  
Luciana Volgare ◽  
Carine Perrin-Pellegrino ◽  
Carine Chassigneux ◽  
Erick Dousset ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Combined Treatment ◽  
Amorphous Film ◽  
Amorphous Layer ◽  
Good Alternative ◽  
Surface Treatments ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Fluid Environment

Surface treatments are considered as a good alternative to increase biocompatibility and the lifetime of Ti-based alloys used for implants in the human body. The present research reports the comparison of bare and modified Ti6Al4V substrates on hydrophilicity and corrosion resistance properties in body fluid environment at 37 °C. Several surface treatments were conducted separately to obtain either a porous oxide layer using nanostructuration (N) in ethylene glycol containing fluoride solution, or bulk oxide thin films through heat treatment at 450 °C for 3 h (HT), or electrochemical oxidation at 1 V for 3 h (EO), as well as combined treatments (N-HT and N-EO). In-situ X-ray diffraction and ex-situ transmission electron microscopy have shown that heat treatment gave first rise to the formation of a 30 nm thick amorphous layer which crystallized in rutile around 620 °C. Electrochemical oxidations gave rise to a 10 nm thick amorphous film on the top of the surface (EO) or below the amorphous nanotube layer (N-EO). Dual treated samples presented similar results with a more stable behavior for N-EO. Finally, for both corrosion and hydrophilicity points of view, the new combined treatment to get a total amorphous N-EO sample seems to be the best and even better than the partially crystallized N-HT sample.

scholarly journals Large Negative Photoresistivity in Amorphous NdNiO3 Film

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1411
Author(s):  
Alexandr Stupakov ◽  
Tomas Kocourek ◽  
Natalia Nepomniashchaia ◽  
Marina Tyunina ◽  
Alexandr Dejneka
Keyword(s):  
Energy Density ◽  
Optical Absorption ◽  
Power Density ◽  
Room Temperature ◽  
Amorphous Film ◽  
Amorphous Films ◽  
Metal Insulator ◽  
Wide Range ◽  
Potential Applications

A significant decrease in resistivity by 55% under blue lighting with ~0.4 J·mm−2 energy density is demonstrated in amorphous film of metal-insulator NdNiO3 at room temperature. This large negative photoresistivity contrasts with a small positive photoresistivity of 8% in epitaxial NdNiO3 film under the same illumination conditions. The magnitude of the photoresistivity rises with the increasing power density or decreasing wavelength of light. By combining the analysis of the observed photoresistive effect with optical absorption and the resistivity of the films as a function of temperature, it is shown that photo-stimulated heating determines the photoresistivity in both types of films. Because amorphous films can be easily grown on a wide range of substrates, the demonstrated large photo(thermo)resistivity in such films is attractive for potential applications, e.g., thermal photodetectors and thermistors.

Percussive-Abrasive Stone Tools from Chagyrskaya Cave: Results of Functional Analysis

2021 ◽  
Vol 49 (2) ◽  
pp. 23-31
Author(s):  
M. V. Seletsky ◽  
A. Y. Fedorchenko ◽  
P. V. Chistyakov ◽  
S. V. Markin ◽  
K. A. Kolobova
Keyword(s):  
Raw Materials ◽  
Stone Tools ◽  
Lithic Assemblage ◽  
Wear Analysis ◽  
Use Wear ◽  
Experimental Use ◽  
Abrasive Stone ◽  
Source Of Information ◽  
Reference Samples ◽  
Comprehensive Study

This article presents a comprehensive study of percussive-abrasive active stone tools from Chagyrskaya Cave, using experimental use-wear and statistical methods, supplemented by 3D-modeling. Experiments combined with use- wear analysis allowed us to determine the functions of these tools by comparing the working surfaces and use-wear traces in the Chagyrskaya samples with those in the reference samples. As a result, we identified 19 retouchers, four hammerstones for processing mineral raw materials, and one hammer for splitting bone, which indicates the dominance of secondary processing over primary knapping in the Chagyrskaya lithic assemblage. Using statistical analysis, we traced the differences in the dimensions of the manuports and lithics under study. These artifacts are a promising and underestimated source of information for identifying working operations associated with stone- and bone-processing; moreover, they can provide new data on the functional attribution of sites and the mobility of early hominins.

POINT COUNTER POINT: INTERPRETING CHIPPED CHERT BIFACES IN TERMINAL CLASSIC “PROBLEMATIC” ON-FLOOR DEPOSITS FROM STRUCTURES A2 AND A3 AT CAHAL PECH, BELIZE

2020 ◽  
Vol 31 (1) ◽  
pp. 161-174 ◽  
Author(s):  
W. James Stemp ◽  
Jaime J. Awe
Keyword(s):  
Stone Tools ◽  
Skeletal Remains ◽  
Classic Period ◽  
Direct Result ◽  
Terminal Phase ◽  
Ancient Maya ◽  
Terminal Classic ◽  
Use Wear ◽  
Different Types ◽  
Symbolic Meanings

AbstractProblematic deposits, containing different types of artifacts and skeletal remains, are typically recovered on or near the surfaces of the terminal phase of elite civic-ceremonial architecture at ancient Maya sites. These contexts often date to the Terminal Classic period (~a.d. 750–900). They have been variously interpreted as evidence for site abandonment, squatting, warfare, or dedication or termination rituals. Sixteen chert bifaces were recovered from problematic deposits at the bases of Structures A2 and A3 in the elite Plaza A at Cahal Pech, Belize. Stone tools from problematic deposits are rarely examined in significant detail. Based on stylistic, metric, and use-wear analyses, the bifaces were likely produced locally, used during important hunting or warfare activities, and then ritually deposited in the Terminal Classic. These bifaces were likely hafted to spearthrower darts and represented “success” at hunting or fighting. The recovery of weaponry in problematic deposits that is not the direct result of warfare is an important observation because Mayanists have generally interpreted their presence in these contexts as evidence of warfare. The fact that the points were recovered in groups of seven and nine may indicate that they had important symbolic meanings that connected them to supernatural or mythological places or entities.

Butchering or wood? A LSCM analysis to distinguish use-wear on stone tools

2020 ◽  
Vol 31 ◽  
pp. 102377
Author(s):  
Ana Álvarez-Fernández ◽  
Rebeca García-González ◽  
Belén Márquez ◽  
José Miguel Carretero ◽  
Juan Luis Arsuaga
Keyword(s):  
Stone Tools ◽  
Use Wear

Reaction of Amorphous Minb Films with Crystalline Metal Overlayers

1984 ◽  
Vol 37 ◽  
Author(s):  
E. A. Dobisz ◽  
B. L. Doyle ◽  
J. H. Perepezko ◽  
J. D. Wiley ◽  
P. S. Peercy
Keyword(s):  
Metal Film ◽  
Rutherford Backscattering Spectrometry ◽  
Amorphous Film ◽  
Depth Resolution ◽  
Rutherford Backscattering ◽  
Amorphous Films ◽  
The Stability ◽  
Metal Overlayers ◽  
Crystalline Metal ◽  
High Depth

AbstractIn many cases the stability of amorphous films is influenced by interaction with metallic crystalline overlayers. Such interactions between Au, Ni, Nb and Ta overlayers and a-(Ni-Nb) films are reported. During interdiffusion Au overlayers reacted with a-(Ni-Nb) to form two different adjacent crystalline layers. In order to study the influence of relaxation of the amorphous film on overlayer reaction several a-(Ni-Nb) samples were pre-annealed prior to Au deposition. High depth resolution Rutherford Backscattering Spectrometry (RBS) demonstrates that preannealing lowers the diffusion poefficient of Au in a-(Ni-Nb) at 4500C from 7.5×10−22 m2/s to 8.7×10−23 m22/s. During interdiffusion Ta was discovered to be substantially more inert than Au. For example, negligible interdiffusion between Ta and a-(Ni-Nb) at 505°C after 25 hours implies a diffusivity of less than 5×10−24 m2/s. These observations allow assessment of some of the requirements for increasing the stability of crystalline-amorphous metal film layered structures.

Dehydrogenation and Polymerization of TiOxHy Films in Obtaining Anatase Coating at Low Temperature

2002 ◽  
Vol 749 ◽  
Author(s):  
Kouichi Takayama ◽  
Shigeo Ohshio ◽  
Hidetoshi Saitoh
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Crystal Size ◽  
Chemical Vapor ◽  
Amorphous Films ◽  
X Ray ◽  
Titanium Tetra Isopropoxide

ABSTRACTChemical-vapor-deposition of titanium tetra-isopropoxide (TTIP) under the atmosphere at low temperature has been conducted. The structure of the obtained films was assessed using Fourier transform infrared spectroscopy, X-ray diffractometry and Raman spectroscopy. These analyses indicated that amorphous TiOxHy films were obtained at gas temperatures in the range of 150–300 °C, and crystalline anatase-TiO2 film was formed at 350 °C. This distinction is accounted for by plausible chemical reactions as follows; the hydroxyl reaction of TTIP below 350 °C promotes the formation of the amorphous TiOxHy. As the temperature goes up to 350 °C, dehydrogenation of the TiOxHy films promotes to form crystalline TiO2. Also the obtained amorphous films were annealed for 10 min under the atmosphere in assessing the transformation proceeding in the solid state. The structural change is shown at 350 °C, indicating that the crystalline phase would be formed via dehydrogenation and polymerization on the surface of the amorphous phase under the atmosphere. The crystal size of the annealed films was evaluated in assessment for the transformation.

The Effect of Polysilicon Deposition and Doping Processes on Double-Poly Capacitors - Electrical and AFM Evaluation

1993 ◽  
Vol 324 ◽  
Author(s):  
W. M. Paulson ◽  
L. H. Breaux ◽  
R. I. Hegde ◽  
P. J. Tobin
Keyword(s):  
Gas Phase ◽  
Diagnostic Technique ◽  
Surface Structures ◽  
Semiconductor Processing ◽  
Amorphous Films ◽  
Leakage Currents ◽  
Low Leakage ◽  
Oxide Removal ◽  
Non Destructive

AbstractWe have characterized the surface topography of silicon films from different deposition and doping process sequences using AFM and optical reflectivity. The resulting surface structures after deposition, doping, oxide growth, and oxide removal correlate with the electrical leakage currents and breakdown voltages of double polysilicon capacitors. As-deposited amorphous films had smoother surfaces than those deposited in the crystalline state. Gas-phase diffusion doping increases the surface roughness. Only the amorphous in situ doped films retained a smooth surface following oxidation, yielding low leakage capacitors with breakdown fields above 8 MV/cm. Surprisingly, implanted amorphous films exhibited the roughest interfaces, resulting in lower breakdown fields. This study has shown that AFM provides an effective, quick, non-destructive diagnostic technique for semiconductor processing.

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