Production of crystalline refractory metal oxides containing colloidal metal precipitates and useful as solar-effective absorbers
- Knoxville, TN
- Oak Ridge, TN
This invention is a new process for producing refractory crystalline oxides having improved or unusual properties. The process comprises the steps of forming a doped-metal crystal of the oxide; exposing the doped crystal in a bomb to a reducing atmosphere at superatmospheric pressure and a temperature effecting precipitation of the dopant metal in the crystal lattice of the oxide but insufficient to effect net diffusion of the metal out of the lattice; and then cooling the crystal. Preferably, the cooling step is effected by quenching. The process forms colloidal precipitates of the metal in the oxide lattice. The process may be used, for example, to produce thermally stable black MgO crystalline bodies containing magnetic colloidal precipitates consisting of about 99% Ni. The Ni-containing bodies are solar-selective absorbers, having a room-temperature absorptivity of about 0.96 over virtually all of the solar-energy spectrum and exhibiting an absorption edge in the region of 2 .mu.m. The process parameters can be varied to control the average size of the precipitates. The process can produce a black MgO crystalline body containing colloidal Ni precipitates, some of which have the face-centered-cubic structure and others of which have the body-centered cubic structure. The products of the process are metal-precipitate-containing refractory crystalline oxides which have improved or unique optical, mechanical, magnetic, and/or electronic properties.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 4376755
- OSTI ID:
- 864515
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
crystalline
refractory
metal
oxides
containing
colloidal
precipitates
useful
solar-effective
absorbers
process
producing
improved
unusual
properties
comprises
steps
forming
doped-metal
crystal
oxide
exposing
doped
bomb
reducing
atmosphere
superatmospheric
pressure
temperature
effecting
precipitation
dopant
lattice
insufficient
effect
net
diffusion
cooling
preferably
step
effected
quenching
forms
example
produce
thermally
stable
black
mgo
bodies
magnetic
consisting
99
ni-containing
solar-selective
room-temperature
absorptivity
96
virtually
solar-energy
spectrum
exhibiting
absorption
edge
region
parameters
varied
control
average
size
face-centered-cubic
structure
body-centered
cubic
products
metal-precipitate-containing
unique
optical
mechanical
electronic
process parameters
crystalline oxide
colloidal metal
energy spectrum
reducing atmosphere
refractory metal
metal oxide
process comprises
atmospheric pressure
metal oxides
thermally stable
superatmospheric pressure
process parameter
electronic properties
crystal lattice
average size
absorption edge
oxides containing
centered cubic
temperature effecting
crystalline bodies
cubic structure
body-centered cubic
containing magnetic
producing refractory
cooling step
/423/126/252/501/