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1938 - Dr. N.C. Beese studying an experimental Tellurium vapor discharge lamp

EXPERIMENTAL DAYLIGHT

CD 1966023 E&MP27.109

Electric Lighting

March 1938

Dr. N.C. Beese studying an experimental Tellurium vapor discharge lamp through a glass filter in the Research Laboratory of the Westinghouse Lamp Division, Westinghouse Electric & Manufacturing Co., Bloomfield, N.J.

additional caption...

Experimental Daylight--
Because it has a continuous spectrum like the sun and unlike other materials used in vapor lamps, tellurium vapor is the object of this inquisitive scientist's study.

He is Dr. N.C. Beese of the Westinghouse Lamp Division at Bloomfield, N.J. The tellurium vapor lamp is one of many new sources of lighting being studied by scientists the world over. Tellurium is a semi-metallic element.  


Original Caption by Science Service
Westinghouse

additional information 2.14.2008

Atomic Number: 52
Atomic Radius: 143.2 pm
Atomic Symbol: Te
Melting Point: 449.5 deg C
Atomic Weight: 127.60
Boiling Point: 988 deg C
Electron Configuration: [Kr]5s24d105p4
Oxidation State: 6, 4, -2

History
(L. tellus: earth) Discovered by Muller von Reichenstein in 1782; named by Klaproth, who isolated it in 1798.

Sources
Tellurium is occasionally found native, but is more often found as the telluride of gold (calaverite), and combined with other metals. It is recovered commercially from anode muds produced during the electrolytic refining of blister copper. The U.S., Canada, Peru, and Japan are the largest Free World producers of the element.

Properties
Crystalline tellurium has a silvery-white appearance, and when pure it exhibits a metallic luster. It is brittle and easily pulverized. Amorphous tellurium is found by precipitating tellurium from a solution of telluric or tellurous acid. Whether this form is truly amorphous, or made of minute crystals, is open to question. Tellurium is a p-type semiconductor, and shows greater conductivity in certain directions, depending on alignment of the atoms.

Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements. In air, tellurium burns with a greenish-blue flames, forming the dioxide. Molten tellurium corrodes iron, copper, and stainless steel.

Handling
Tellurium and its compounds are probably toxic and should be handled with care. Workmen exposed to as little as 0.01 mg/m3 of air, or less, develop "tellurium breath," which has a garlic-like odor.

Isotopes
Thirty isotopes of tellurium are known, with atomic masses ranging from 108 to 137. Natural tellurium consists of eight isotopes.

Uses
Tellurium improves the machinability of copper and stainless steel, and its addition to lead decreases the corrosive action of sulfuric acid on lead and improves its strength and hardness. Tellurium is used as a basic ingredient in blasting caps, and is added to cast iron for chill control. Tellurium is used in ceramics. Bismuth telluride has been used in thermoelectric devices.

courtesy Los Alamos National Laboratory - periodic tables

 



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