Materials synthesized via solid state and solution metathesis reactions

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7275041

Jarvis, Jr, R F

Metathesis (or exchange) reactions are used as new synthetic routes for producing materials in both solid-state and solution reactions. Solid-state metathesis reactions produce transition metal phosphides. Solution exchange reactions synthesize nanocrystalline metal tellurides. Transition metal phosphides, normally produced in long, high-temperature reactions (days at >800[degrees]C), are formed in solid-state metathesis reactions in only seconds. Transition metal halides vigorously react with sodium phosphide to form metal phosphide, byproduct salt that is easily washed away with water, and elemental phosphorus which is boiled from the system by the reaction's great exothermicity. MoP and WP reactions spontaneously ignite upon mixing the precursors producing metal phosphides and Mo or W. Incomplete mixing of the precursors causes the formation of the metal. The ZrP and HfP reactions, however, do not spontaneously ignite because of the stability of ZrCl[sub 4] and HfCl[sub 4]. Group IV phosphide sealed-tube reactions form the low-temperature, hexagonal phases of ZrP and HfP. However, application of a hot wire to the precursors initiates a self-propagating reaction that produces the high-temperature, cubic phases of ZrP and HfP. The high-temperature phases are formed by the rapid cooling that occurs after the reaction, quenching the system and isolating the cubic phases. These are the first extensive studies of solid-state metathesis reactions forming metastable compounds. CdTe, HgTe, and Hg[sub 1-x]Cd[sub x]Te are difficult materials to produce stoichiometrically because of the high vapor pressures of Hg and Cd above 200[degrees]C. However, CdI[sub 2] was previously reacted with Na[sub 2]Te in solution to form CdTe and byproduct NaI. This solution exchange synthesis has now been extended to include reactions of Na[sub 2]Te with HgI[sub 2] or mixtures of HgI[sub 2] and CdI[sub 2] to form HgTe and Hg[sub 1-x]Cd[sub x]Te, respectively.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 7275041
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CADMIUM COMPOUNDS
CADMIUM TELLURIDES
CHALCOGENIDES
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
HAFNIUM COMPOUNDS
HAFNIUM PHOSPHIDES
MERCURY COMPOUNDS
MERCURY TELLURIDES
MOLYBDENUM COMPOUNDS
MOLYBDENUM PHOSPHIDES
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PNICTIDES
REFRACTORY METAL COMPOUNDS
SYNTHESIS
TELLURIDES
TELLURIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN PHOSPHIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM PHOSPHIDES