The effect of particle size on the heat capacity of titanium dioxide

1954 ◽  
Vol 224 (1157) ◽  
pp. 228-235 ◽  
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Heat Capacity ◽  
Titanium Dioxide ◽  
Theoretical Calculations ◽  
Particle Size Effect ◽  
The Other ◽  
Optical Modes ◽  
Modes Of Vibration ◽  
Effect Of Particle Size

The heat capacities of four samples of titanium dioxide, differing in particle size, have been measured in the temperature range 12 to 270° K in order to determine the effect of particle size on the specific heat. Contrary to the prediction of existing theories, no effect attributable to a change in particle size has been found in the low-temperature region. On the other hand, above 50° K a pronounced particle-size effect is evident which may be accounted for qualitatively as an effect on the optical modes of vibration of the solid. The complexity of the titanium dioxide crystal structure precludes any quantitative theoretical calculations.

FREQUENCY SPECTRA OF FREE LATTICES AND PARTICLE SIZE EFFECTS ON THE HEAT CAPACITY OF SOLIDS

1955 ◽  
Vol 33 (6) ◽  
pp. 1079-1087 ◽  
Author(s):  
D. Patterson
Keyword(s):  
Particle Size ◽  
Heat Capacity ◽  
Low Temperature ◽  
Temperature Effect ◽  
Size Effects ◽  
Continuum Model ◽  
Free Boundaries ◽  
Frequency Spectra ◽  
Optical Modes ◽  
Effect Of Particle Size

The effect of particle size on the heat capacity of solids has been investigated using lattices with free boundaries as models. A monatomic lattice shows a low temperature effect associated with the acoustic modes. This can be compared with results obtained from a continuum model. With a diatomic lattice, however, an effect is also associated with the optical modes and is apparent at higher temperatures. The possibility that this latter effect can explain some recent experimental results is examined.

A LOW TEMPERATURE PARTICLE SIZE EFFECT ON THE HEAT CAPACITY OF SODIUM CHLORIDE

1955 ◽  
Vol 33 (2) ◽  
pp. 240-244 ◽  
Author(s):  
D. Patterson ◽  
J. A. Morrison ◽  
F. W. Thompson
Keyword(s):  
Particle Size ◽  
Heat Capacity ◽  
Sodium Chloride ◽  
Low Temperature ◽  
Size Effect ◽  
Specific Heat ◽  
Significant Contribution ◽  
Particle Size Effect ◽  
Extensive Property ◽  
Effect Of Particle Size

An effect of particle size upon the heat capacity of sodium chloride has been found in the temperature range 9° to 21°K. The experiments were done with three NaCl samples of specific surfaces between 38 and 59 sq. meters per gm. The observed effect has the temperature dependence predicted by theory but its magnitude is three to four times larger than expected. It is unlikely that adsorbed gases have made any significant contribution in the experiments. The accuracy with which the specific heat and surface area differences have been determined is not high enough to show definitely whether or not the surface specific heat is an extensive property of the surface.

Quantitative Determimatioh of Sulfur, Chlorine, Potassium, Calcium, Scandium and Titanium in Aqueous Solutions by Radioisotopic Excited Fluorescent Spectrometer and by Conventional X-Ray Spectrometer

1970 ◽  
Vol 14 ◽  
pp. 102-126 ◽  
Author(s):  
Frank L. Chan ◽  
W. Barclay Jones
Keyword(s):  
Particle Size ◽  
Aqueous Solutions ◽  
Experimental Results ◽  
The Other ◽  
X Rays ◽  
Helium Atmosphere ◽  
X Ray ◽  
Effect Of Particle Size ◽  
The One

AbstractAn x-ray spectrometer with experimental results is herewith described using a radiosotope source Fe55 having a halflife of 2.6 years. As a result of the disintegration, the managanese x-rays are capable of exciting fluorescent x-rays of such elements as sulfur, chlorine, potassium, calcium, scandium and titanium in aqueous solutions. These elements with the Ka wavelengths ranging from 5.3729 Å to 2.7496 Å may be designated as between the very soft x-rays on the one hand and the hard x-rays on the other. The x-ray spectrometer presently described has achieved a resolution of 136 ev, FWHM.Simultaneously, these elements have also been quantitatively determined by conventional x-ray fluorescent spectrometers. Since one of the spectrometers is designed to operate in vacuum as well as in helium or air, determination of sulfur, potassium and calcium were carried out in vacuum. Determination of chlorine was carried out in a helium atmosphere, Calcium, scandium and titanium were determined in air with an air-path spectrometer.In the present study aqueous solutions containing these elements were used. The use of aqueous solutions has the inherent advantages of being homogeneous and free from effect of particle size.

Thermodynamic investigations of zeolites NaX and NaY

2006 ◽  
Vol 84 (2) ◽  
pp. 134-139 ◽  
Author(s):  
Liyan Qiu ◽  
Patricia A Laws ◽  
Bi-Zeng Zhan ◽  
Mary Anne White
Keyword(s):  
Particle Size ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Size Effect ◽  
Thermodynamic Stability ◽  
Aluminum Content ◽  
Particle Size Effect ◽  
Al Content ◽  
Heat Capacity Measurements ◽  
Zeolitic Materials

Understanding of the thermodynamic stability of zeolites is important in the prediction of thermodynamic equilibrium. Therefore, we have undertaken an investigation of the thermodynamic stability of the zeolites NaX and NaY through heat capacity measurements from ca. 30 to 300 K. No phase transitions were observed, and zeolite NaX does not show a significant particle size effect when the particle size is reduced to ca. 30 nm. The results show that the specific heat capacity increases with the Al content in the zeolite. Both NaX and NaY are found to be thermodynamically stable with respect to their elements because of enthalpic stabilization and with slight entropic destabilization. These data are used along with literature data for many other zeolitic materials to show that the thermodynamic stability of zeolites is enhanced with increasing aluminum content. Key words: zeolite, heat capacity, thermodynamic stability, nano effects.

Effect of particle size on the flocculation of sub-micron titanium dioxide by polyacrylic acid

2020 ◽  
Vol 149 ◽  
pp. 106253 ◽  
Author(s):  
Xianfeng Sun ◽  
Liqiang Ma ◽  
Xiaoli Tan ◽  
Kaipeng Wang ◽  
Qi Liu
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Polyacrylic Acid ◽  
Effect Of Particle Size

SURFACE ENERGIES OF THE ALKALI HALIDES

1955 ◽  
Vol 33 (2) ◽  
pp. 232-239 ◽  
Author(s):  
G. C. Benson ◽  
G. W. Benson
Keyword(s):  
Particle Size ◽  
Sodium Chloride ◽  
Theoretical Calculations ◽  
Alkali Halides ◽  
Experimental Measurements ◽  
Calorimetric Study ◽  
Heat Of Solution ◽  
Surface Energies ◽  
Effect Of Particle Size ◽  
Surface Enthalpy

Previous theoretical calculations and experimental measurements of the surface energies or enthalpies of the alkali halides are reviewed briefly. A new attempt to determine the surface enthalpy associated with the {100} face of sodium chloride from a calorimetric study of the effect of particle size on the heat of solution is described. The result (305 ergs/cm.2 at 25 °C.) appears to be larger than might be predicted on the basis of the classical Born-Mayer theory.

Particle Size Effect on FeS Spontaneous Combustion Characters in Petroleum

2014 ◽  
Vol 608-609 ◽  
pp. 971-975
Author(s):  
Man Yang ◽  
Xian Feng Chen ◽  
Yu Jiao Shang ◽  
Ren Dong Bao
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Reaction Mechanisms ◽  
Spontaneous Combustion ◽  
Oxidation Kinetic ◽  
Mesh Size ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Heating Rates ◽  
Effect Of Particle Size

In order to evaluate the effect of particle size on FeS Spontaneous Combustion Characters, four different grain diameters of FeS particles (100, 170, 220, 320-mesh) were detected in the experiment. The reaction process at heating rates of 5°C /min in air flow from 30°C to 900°C were studied by TG-DSC and oxidation kinetic analysis. The activation energies of samples were calculated by the Coats-Redfern method. It is found that four reaction mechanisms are involved in FeS spontaneous combustion for different particle sizes; the activation energy values change from 307.4 to 398.05 kJ/mol; larger size particles have higher activation energy values; so grain diameters larger than 100-mesh size samples are less inclined to be oxidized and self-ignited.

Sign in / Sign up

Export Citation Format

Share Document